diff options
Diffstat (limited to 'pkg/sentry/fs/ext')
27 files changed, 2251 insertions, 0 deletions
diff --git a/pkg/sentry/fs/ext/BUILD b/pkg/sentry/fs/ext/BUILD new file mode 100644 index 000000000..3c2a02eac --- /dev/null +++ b/pkg/sentry/fs/ext/BUILD @@ -0,0 +1,11 @@ +package(licenses = ["notice"]) + +load("//tools/go_stateify:defs.bzl", "go_library") + +go_library( + name = "ext", + srcs = ["ext.go"], + importpath = "gvisor.dev/gvisor/pkg/sentry/fs/ext", + visibility = ["//pkg/sentry:internal"], + deps = ["//pkg/sentry/fs/ext/disklayout"], +) diff --git a/pkg/sentry/fs/ext/assets/README.md b/pkg/sentry/fs/ext/assets/README.md new file mode 100644 index 000000000..b6eac4f40 --- /dev/null +++ b/pkg/sentry/fs/ext/assets/README.md @@ -0,0 +1,28 @@ +### Tiny Ext4 Image + +The image is of size 64Kb which supports 64 1k blocks and 16 inodes. This is the +smallest size mkfs.ext4 works with. + +This image was generated using the following commands. + +```bash +fallocate -l 64K tiny.ext4 +mkfs.ext4 -j tiny.ext4 +``` + +You can mount it using: + +```bash +sudo mount -o loop tiny.ext4 $MOUNTPOINT +``` + +`file.txt`, `bigfile.txt` and `symlink.txt` were added to this image by just +mounting it and copying (while preserving links) those files to the mountpoint +directory using: + +```bash +sudo cp -P {file.txt,symlink.txt,bigfile.txt} $MOUNTPOINT/ +``` + +The files in this directory mirror the contents and organisation of the files +stored in the image. diff --git a/pkg/sentry/fs/ext/assets/bigfile.txt b/pkg/sentry/fs/ext/assets/bigfile.txt new file mode 100644 index 000000000..3857cf516 --- /dev/null +++ b/pkg/sentry/fs/ext/assets/bigfile.txt @@ -0,0 +1,41 @@ +Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus faucibus eleifend orci, ut ornare nibh faucibus eu. Cras at condimentum massa. Nullam luctus, elit non porttitor congue, sapien diam feugiat sapien, sed eleifend nulla mauris non arcu. Sed lacinia mauris magna, eu mollis libero varius sit amet. Donec mollis, quam convallis commodo posuere, dolor nisi placerat nisi, in faucibus augue mi eu lorem. In pharetra consectetur faucibus. Ut euismod ex efficitur egestas tincidunt. Maecenas condimentum ut ante in rutrum. Vivamus sed arcu tempor, faucibus turpis et, lacinia diam. + +Sed in lacus vel nisl interdum bibendum in sed justo. Nunc tellus risus, molestie vitae arcu sed, molestie tempus ligula. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nunc risus neque, volutpat et ante non, ullamcorper condimentum ante. Aliquam sed metus in urna condimentum convallis. Vivamus ut libero mauris. Proin mollis posuere consequat. Vestibulum placerat mollis est et pulvinar. + +Donec rutrum odio ac diam pharetra, id fermentum magna cursus. Pellentesque in dapibus elit, et condimentum orci. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Suspendisse euismod dapibus est, id vestibulum mauris. Nulla facilisi. Nulla cursus gravida nisi. Phasellus vestibulum rutrum lectus, a dignissim mauris hendrerit vitae. In at elementum mauris. Integer vel efficitur velit. Nullam fringilla sapien mi, quis luctus neque efficitur ac. Aenean nec quam dapibus nunc commodo pharetra. Proin sapien mi, fermentum aliquet vulputate non, aliquet porttitor diam. Quisque lacinia, urna et finibus fermentum, nunc lacus vehicula ex, sed congue metus lectus ac quam. Aliquam erat volutpat. Suspendisse sodales, dolor ut tincidunt finibus, augue erat varius tellus, a interdum erat sem at nunc. Vestibulum cursus iaculis sapien, vitae feugiat dui auctor quis. + +Pellentesque nec maximus nulla, eu blandit diam. Maecenas quis arcu ornare, congue ante at, vehicula ipsum. Praesent feugiat mauris rutrum sem fermentum, nec luctus ipsum placerat. Pellentesque placerat ipsum at dignissim fringilla. Vivamus et posuere sem, eget hendrerit felis. Aenean vulputate, augue vel mollis feugiat, justo ipsum mollis dolor, eu mollis elit neque ut ipsum. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Fusce bibendum sem quam, vulputate laoreet mi dapibus imperdiet. Sed a purus non nibh pretium aliquet. Integer eget luctus augue, vitae tincidunt magna. Ut eros enim, egestas eu nulla et, lobortis egestas arcu. Cras id ipsum ac justo lacinia rutrum. Vivamus lectus leo, ultricies sed justo at, pellentesque feugiat magna. Ut sollicitudin neque elit, vel ornare mauris commodo id. + +Duis dapibus orci et sapien finibus finibus. Mauris eleifend, lacus at vestibulum maximus, quam ligula pharetra erat, sit amet dapibus neque elit vitae neque. In bibendum sollicitudin erat, eget ultricies tortor malesuada at. Sed sit amet orci turpis. Donec feugiat ligula nibh, molestie tincidunt lectus elementum id. Donec volutpat maximus nibh, in vulputate felis posuere eu. Cras tincidunt ullamcorper lacus. Phasellus porta lorem auctor, congue magna a, commodo elit. + +Etiam auctor mi quis elit sodales, eu pulvinar arcu condimentum. Aenean imperdiet risus et dapibus tincidunt. Nullam tincidunt dictum dui, sed commodo urna rutrum id. Ut mollis libero vel elit laoreet bibendum. Quisque arcu arcu, tincidunt at ultricies id, vulputate nec metus. In tristique posuere quam sit amet volutpat. Vivamus scelerisque et nunc at dapibus. Fusce finibus libero ut ligula pretium rhoncus. Mauris non elit in arcu finibus imperdiet. Pellentesque nec massa odio. Proin rutrum mauris non sagittis efficitur. Aliquam auctor quam at dignissim faucibus. Ut eget ligula in magna posuere ultricies vitae sit amet turpis. Duis maximus odio nulla. Donec gravida sem tristique tempus scelerisque. + +Interdum et malesuada fames ac ante ipsum primis in faucibus. Fusce pharetra magna vulputate aliquet tempus. Duis id hendrerit arcu. Quisque ut ex elit. Integer velit orci, venenatis ut sapien ac, placerat porttitor dui. Interdum et malesuada fames ac ante ipsum primis in faucibus. Nunc hendrerit cursus diam, hendrerit finibus ipsum scelerisque ut. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. + +Nulla non euismod neque. Phasellus vel sapien eu metus pulvinar rhoncus. Suspendisse eu mollis tellus, quis vestibulum tortor. Maecenas interdum dolor sed nulla fermentum maximus. Donec imperdiet ullamcorper condimentum. Nam quis nibh ante. Praesent quis tellus ut tortor pulvinar blandit sit amet ut sapien. Vestibulum est orci, pellentesque vitae tristique sit amet, tristique non felis. + +Vivamus sodales pellentesque varius. Sed vel tempus ligula. Nulla tristique nisl vel dui facilisis, ac sodales augue hendrerit. Proin augue nisi, vestibulum quis augue nec, sagittis tincidunt velit. Vestibulum euismod, nulla nec sodales faucibus, urna sapien vulputate magna, id varius metus sapien ut neque. Duis in mollis urna, in scelerisque enim. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Nunc condimentum dictum turpis, et egestas neque dapibus eget. Quisque fringilla, dui eu venenatis eleifend, erat nibh lacinia urna, at lacinia lacus sapien eu dui. Duis eu erat ut mi lacinia convallis a sed ex. + +Fusce elit metus, tincidunt nec eleifend a, hendrerit nec ligula. Duis placerat finibus sollicitudin. In euismod porta tellus, in luctus justo bibendum bibendum. Maecenas at magna eleifend lectus tincidunt suscipit ut a ligula. Nulla tempor accumsan felis, fermentum dapibus est eleifend vitae. Mauris urna sem, fringilla at ultricies non, ultrices in arcu. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Nam vehicula nunc at laoreet imperdiet. Nunc tristique ut risus id aliquet. Integer eleifend massa orci. + +Vestibulum sed ante sollicitudin nisi fringilla bibendum nec vel quam. Sed pretium augue eu ligula congue pulvinar. Donec vitae magna tincidunt, pharetra lacus id, convallis nulla. Cras viverra nisl nisl, varius convallis leo vulputate nec. Morbi at consequat dui, sed aliquet metus. Sed suscipit fermentum mollis. Maecenas nec mi sodales, tincidunt purus in, tristique mauris. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec interdum mi in velit efficitur, quis ultrices ex imperdiet. Sed vestibulum, magna ut tristique pretium, mi ipsum placerat tellus, non tempor enim augue et ex. Pellentesque eget felis quis ante sodales viverra ac sed lacus. Donec suscipit tempus massa, eget laoreet massa molestie at. + +Aenean fringilla dui non aliquet consectetur. Fusce cursus quam nec orci hendrerit faucibus. Donec consequat suscipit enim, non volutpat lectus auctor interdum. Proin lorem purus, maximus vel orci vitae, suscipit egestas turpis. Donec risus urna, congue a sem eu, aliquet placerat odio. Morbi gravida tristique turpis, quis efficitur enim. Nunc interdum gravida ipsum vel facilisis. Nunc congue finibus sollicitudin. Quisque euismod aliquet lectus et tincidunt. Curabitur ultrices sem ut mi fringilla fermentum. Morbi pretium, nisi sit amet dapibus congue, dolor enim consectetur risus, a interdum ligula odio sed odio. Quisque facilisis, mi at suscipit gravida, nunc sapien cursus justo, ut luctus odio nulla quis leo. Integer condimentum lobortis mauris, non egestas tellus lobortis sit amet. + +In sollicitudin velit ac ante vehicula, vitae varius tortor mollis. In hac habitasse platea dictumst. Quisque et orci lorem. Integer malesuada fringilla luctus. Pellentesque malesuada, mi non lobortis porttitor, ante ligula vulputate ante, nec dictum risus eros sit amet sapien. Nulla aliquam lorem libero, ac varius nulla tristique eget. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Ut pellentesque mauris orci, vel consequat mi varius a. Ut sit amet elit vulputate, lacinia metus non, fermentum nisl. Pellentesque eu nisi sed quam egestas blandit. Duis sit amet lobortis dolor. Donec consectetur sem interdum, tristique elit sit amet, sodales lacus. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Fusce id aliquam augue. Sed pretium congue risus vitae lacinia. Vestibulum non vulputate risus, ut malesuada justo. + +Sed odio elit, consectetur ac mauris quis, consequat commodo libero. Fusce sodales velit vulputate pulvinar fermentum. Donec iaculis nec nisl eget faucibus. Mauris at dictum velit. Donec fermentum lectus eu viverra volutpat. Aliquam consequat facilisis lorem, cursus consequat dui bibendum ullamcorper. Pellentesque nulla magna, imperdiet at magna et, cursus egestas enim. Nullam semper molestie lectus sit amet semper. Duis eget tincidunt est. Integer id neque risus. Integer ultricies hendrerit vestibulum. Donec blandit blandit sagittis. Nunc consectetur vitae nisi consectetur volutpat. + +Nulla id lorem fermentum, efficitur magna a, hendrerit dui. Vivamus sagittis orci gravida, bibendum quam eget, molestie est. Phasellus nec enim tincidunt, volutpat sapien non, laoreet diam. Nulla posuere enim nec porttitor lobortis. Donec auctor odio ut orci eleifend, ut eleifend purus convallis. Interdum et malesuada fames ac ante ipsum primis in faucibus. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut hendrerit, purus eget viverra tincidunt, sem magna imperdiet libero, et aliquam turpis neque vitae elit. Maecenas semper varius iaculis. Cras non lorem quis quam bibendum eleifend in et libero. Curabitur at purus mauris. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus porta diam sed elit eleifend gravida. + +Nulla facilisi. Ut ultricies diam vel diam consectetur, vel porta augue molestie. Fusce interdum sapien et metus facilisis pellentesque. Nulla convallis sem at nunc vehicula facilisis. Nam ac rutrum purus. Nunc bibendum, dolor sit amet tempus ullamcorper, lorem leo tempor sem, id fringilla nunc augue scelerisque augue. Nullam sit amet rutrum nisl. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Donec sed mauris gravida eros vehicula sagittis at eget orci. Cras elementum, eros at accumsan bibendum, libero neque blandit purus, vitae vestibulum libero massa ac nibh. Integer at placerat nulla. Mauris eu eleifend orci. Aliquam consequat ligula vitae erat porta lobortis. Duis fermentum elit ac aliquet ornare. + +Mauris eget cursus tellus, eget sodales purus. Aliquam malesuada, augue id vulputate finibus, nisi ex bibendum nisl, sit amet laoreet quam urna a dolor. Nullam ultricies, sapien eu laoreet consequat, erat eros dignissim diam, ultrices sodales lectus mauris et leo. Morbi lacinia eu ante at tempus. Sed iaculis finibus magna malesuada efficitur. Donec faucibus erat sit amet elementum feugiat. Praesent a placerat nisi. Etiam lacinia gravida diam, et sollicitudin sapien tincidunt ut. + +Maecenas felis quam, tincidunt vitae venenatis scelerisque, viverra vitae odio. Phasellus enim neque, ultricies suscipit malesuada sit amet, vehicula sit amet purus. Nulla placerat sit amet dui vel tincidunt. Nam quis neque vel magna commodo egestas. Vestibulum sagittis rutrum lorem ut congue. Maecenas vel ultrices tellus. Donec efficitur, urna ac consequat iaculis, lorem felis pharetra eros, eget faucibus orci lectus sit amet arcu. + +Ut a tempus nisi. Nulla facilisi. Praesent vulputate maximus mi et dapibus. Sed sit amet libero ac augue hendrerit efficitur in a sapien. Mauris placerat velit sit amet tellus sollicitudin faucibus. Donec egestas a magna ac suscipit. Duis enim sapien, mollis sed egestas et, vestibulum vel leo. + +Proin quis dapibus dui. Donec eu tincidunt nunc. Vivamus eget purus consectetur, maximus ante vitae, tincidunt elit. Aenean mattis dolor a gravida aliquam. Praesent quis tellus id sem maximus vulputate nec sed nulla. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur metus nulla, volutpat volutpat est eu, hendrerit congue erat. Aliquam sollicitudin augue ante. Sed sollicitudin, magna eu consequat elementum, mi augue ullamcorper felis, molestie imperdiet erat metus iaculis est. Proin ac tortor nisi. Pellentesque quis nisi risus. Integer enim sapien, tincidunt quis tortor id, accumsan venenatis mi. Nulla facilisi. + +Cras pretium sit amet quam congue maximus. Morbi lacus libero, imperdiet commodo massa sed, scelerisque placerat libero. Cras nisl nisi, consectetur sed bibendum eu, venenatis at enim. Proin sodales justo at quam aliquam, a consectetur mi ornare. Donec porta ac est sit amet efficitur. Suspendisse vestibulum tortor id neque imperdiet, id lacinia risus vehicula. Phasellus ac eleifend purus. Mauris vel gravida ante. Aliquam vitae lobortis risus. Sed vehicula consectetur tincidunt. Nam et justo vitae purus molestie consequat. Pellentesque ipsum ex, convallis quis blandit non, gravida et urna. Donec diam ligula amet. diff --git a/pkg/sentry/fs/ext/assets/file.txt b/pkg/sentry/fs/ext/assets/file.txt new file mode 100644 index 000000000..980a0d5f1 --- /dev/null +++ b/pkg/sentry/fs/ext/assets/file.txt @@ -0,0 +1 @@ +Hello World! diff --git a/pkg/sentry/fs/ext/assets/symlink.txt b/pkg/sentry/fs/ext/assets/symlink.txt new file mode 120000 index 000000000..4c330738c --- /dev/null +++ b/pkg/sentry/fs/ext/assets/symlink.txt @@ -0,0 +1 @@ +file.txt
\ No newline at end of file diff --git a/pkg/sentry/fs/ext/assets/tiny.ext4 b/pkg/sentry/fs/ext/assets/tiny.ext4 Binary files differnew file mode 100644 index 000000000..a6859736d --- /dev/null +++ b/pkg/sentry/fs/ext/assets/tiny.ext4 diff --git a/pkg/sentry/fs/ext/disklayout/BUILD b/pkg/sentry/fs/ext/disklayout/BUILD new file mode 100644 index 000000000..e4cb26645 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/BUILD @@ -0,0 +1,46 @@ +package(licenses = ["notice"]) + +load("//tools/go_stateify:defs.bzl", "go_library", "go_test") + +go_library( + name = "disklayout", + srcs = [ + "block_group.go", + "block_group_32.go", + "block_group_64.go", + "dirent.go", + "dirent_new.go", + "dirent_old.go", + "disklayout.go", + "inode.go", + "inode_new.go", + "inode_old.go", + "superblock.go", + "superblock_32.go", + "superblock_64.go", + "superblock_old.go", + "test_utils.go", + ], + importpath = "gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout", + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/binary", + "//pkg/sentry/fs", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/kernel/time", + ], +) + +go_test( + name = "disklayout_test", + size = "small", + srcs = [ + "block_group_test.go", + "dirent_test.go", + "inode_test.go", + "superblock_test.go", + ], + embed = [":disklayout"], + deps = ["//pkg/sentry/kernel/time"], +) diff --git a/pkg/sentry/fs/ext/disklayout/block_group.go b/pkg/sentry/fs/ext/disklayout/block_group.go new file mode 100644 index 000000000..32ea3d97d --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/block_group.go @@ -0,0 +1,127 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// BlockGroup represents a Linux ext block group descriptor. An ext file system +// is split into a series of block groups. This provides an access layer to +// information needed to access and use a block group. +// +// See https://www.kernel.org/doc/html/latest/filesystems/ext4/globals.html#block-group-descriptors. +type BlockGroup interface { + // InodeTable returns the absolute block number of the block containing the + // inode table. This points to an array of Inode structs. Inode tables are + // statically allocated at mkfs time. The superblock records the number of + // inodes per group (length of this table) and the size of each inode struct. + InodeTable() uint64 + + // BlockBitmap returns the absolute block number of the block containing the + // block bitmap. This bitmap tracks the usage of data blocks within this block + // group and has its own checksum. + BlockBitmap() uint64 + + // InodeBitmap returns the absolute block number of the block containing the + // inode bitmap. This bitmap tracks the usage of this group's inode table + // entries and has its own checksum. + InodeBitmap() uint64 + + // ExclusionBitmap returns the absolute block number of the snapshot exclusion + // bitmap. + ExclusionBitmap() uint64 + + // FreeBlocksCount returns the number of free blocks in the group. + FreeBlocksCount() uint32 + + // FreeInodesCount returns the number of free inodes in the group. + FreeInodesCount() uint32 + + // DirectoryCount returns the number of inodes that represent directories + // under this block group. + DirectoryCount() uint32 + + // UnusedInodeCount returns the number of unused inodes beyond the last used + // inode in this group's inode table. As a result, we needn’t scan past the + // (InodesPerGroup - UnusedInodeCount())th entry in the inode table. + UnusedInodeCount() uint32 + + // BlockBitmapChecksum returns the block bitmap checksum. This is calculated + // using crc32c(FS UUID + group number + entire bitmap). + BlockBitmapChecksum() uint32 + + // InodeBitmapChecksum returns the inode bitmap checksum. This is calculated + // using crc32c(FS UUID + group number + entire bitmap). + InodeBitmapChecksum() uint32 + + // Checksum returns this block group's checksum. + // + // If SbMetadataCsum feature is set: + // - checksum is crc32c(FS UUID + group number + group descriptor + // structure) & 0xFFFF. + // + // If SbGdtCsum feature is set: + // - checksum is crc16(FS UUID + group number + group descriptor + // structure). + // + // SbMetadataCsum and SbGdtCsum should not be both set. + // If they are, Linux warns and asks to run fsck. + Checksum() uint16 + + // Flags returns BGFlags which represents the block group flags. + Flags() BGFlags +} + +// These are the different block group flags. +const ( + // BgInodeUninit indicates that inode table and bitmap are not initialized. + BgInodeUninit uint16 = 0x1 + + // BgBlockUninit indicates that block bitmap is not initialized. + BgBlockUninit uint16 = 0x2 + + // BgInodeZeroed indicates that inode table is zeroed. + BgInodeZeroed uint16 = 0x4 +) + +// BGFlags represents all the different combinations of block group flags. +type BGFlags struct { + InodeUninit bool + BlockUninit bool + InodeZeroed bool +} + +// ToInt converts a BGFlags struct back to its 16-bit representation. +func (f BGFlags) ToInt() uint16 { + var res uint16 + + if f.InodeUninit { + res |= BgInodeUninit + } + if f.BlockUninit { + res |= BgBlockUninit + } + if f.InodeZeroed { + res |= BgInodeZeroed + } + + return res +} + +// BGFlagsFromInt converts the 16-bit flag representation to a BGFlags struct. +func BGFlagsFromInt(flags uint16) BGFlags { + return BGFlags{ + InodeUninit: flags&BgInodeUninit > 0, + BlockUninit: flags&BgBlockUninit > 0, + InodeZeroed: flags&BgInodeZeroed > 0, + } +} diff --git a/pkg/sentry/fs/ext/disklayout/block_group_32.go b/pkg/sentry/fs/ext/disklayout/block_group_32.go new file mode 100644 index 000000000..3e16c76db --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/block_group_32.go @@ -0,0 +1,72 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// BlockGroup32Bit emulates the first half of struct ext4_group_desc in +// fs/ext4/ext4.h. It is the block group descriptor struct for ext2, ext3 and +// 32-bit ext4 filesystems. It implements BlockGroup interface. +type BlockGroup32Bit struct { + BlockBitmapLo uint32 + InodeBitmapLo uint32 + InodeTableLo uint32 + FreeBlocksCountLo uint16 + FreeInodesCountLo uint16 + UsedDirsCountLo uint16 + FlagsRaw uint16 + ExcludeBitmapLo uint32 + BlockBitmapChecksumLo uint16 + InodeBitmapChecksumLo uint16 + ItableUnusedLo uint16 + ChecksumRaw uint16 +} + +// Compiles only if BlockGroup32Bit implements BlockGroup. +var _ BlockGroup = (*BlockGroup32Bit)(nil) + +// InodeTable implements BlockGroup.InodeTable. +func (bg *BlockGroup32Bit) InodeTable() uint64 { return uint64(bg.InodeTableLo) } + +// BlockBitmap implements BlockGroup.BlockBitmap. +func (bg *BlockGroup32Bit) BlockBitmap() uint64 { return uint64(bg.BlockBitmapLo) } + +// InodeBitmap implements BlockGroup.InodeBitmap. +func (bg *BlockGroup32Bit) InodeBitmap() uint64 { return uint64(bg.InodeBitmapLo) } + +// ExclusionBitmap implements BlockGroup.ExclusionBitmap. +func (bg *BlockGroup32Bit) ExclusionBitmap() uint64 { return uint64(bg.ExcludeBitmapLo) } + +// FreeBlocksCount implements BlockGroup.FreeBlocksCount. +func (bg *BlockGroup32Bit) FreeBlocksCount() uint32 { return uint32(bg.FreeBlocksCountLo) } + +// FreeInodesCount implements BlockGroup.FreeInodesCount. +func (bg *BlockGroup32Bit) FreeInodesCount() uint32 { return uint32(bg.FreeInodesCountLo) } + +// DirectoryCount implements BlockGroup.DirectoryCount. +func (bg *BlockGroup32Bit) DirectoryCount() uint32 { return uint32(bg.UsedDirsCountLo) } + +// UnusedInodeCount implements BlockGroup.UnusedInodeCount. +func (bg *BlockGroup32Bit) UnusedInodeCount() uint32 { return uint32(bg.ItableUnusedLo) } + +// BlockBitmapChecksum implements BlockGroup.BlockBitmapChecksum. +func (bg *BlockGroup32Bit) BlockBitmapChecksum() uint32 { return uint32(bg.BlockBitmapChecksumLo) } + +// InodeBitmapChecksum implements BlockGroup.InodeBitmapChecksum. +func (bg *BlockGroup32Bit) InodeBitmapChecksum() uint32 { return uint32(bg.InodeBitmapChecksumLo) } + +// Checksum implements BlockGroup.Checksum. +func (bg *BlockGroup32Bit) Checksum() uint16 { return bg.ChecksumRaw } + +// Flags implements BlockGroup.Flags. +func (bg *BlockGroup32Bit) Flags() BGFlags { return BGFlagsFromInt(bg.FlagsRaw) } diff --git a/pkg/sentry/fs/ext/disklayout/block_group_64.go b/pkg/sentry/fs/ext/disklayout/block_group_64.go new file mode 100644 index 000000000..9a809197a --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/block_group_64.go @@ -0,0 +1,93 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// BlockGroup64Bit emulates struct ext4_group_desc in fs/ext4/ext4.h. +// It is the block group descriptor struct for 64-bit ext4 filesystems. +// It implements BlockGroup interface. It is an extension of the 32-bit +// version of BlockGroup. +type BlockGroup64Bit struct { + // We embed the 32-bit struct here because 64-bit version is just an extension + // of the 32-bit version. + BlockGroup32Bit + + // 64-bit specific fields. + BlockBitmapHi uint32 + InodeBitmapHi uint32 + InodeTableHi uint32 + FreeBlocksCountHi uint16 + FreeInodesCountHi uint16 + UsedDirsCountHi uint16 + ItableUnusedHi uint16 + ExcludeBitmapHi uint32 + BlockBitmapChecksumHi uint16 + InodeBitmapChecksumHi uint16 + _ uint32 // Padding to 64 bytes. +} + +// Compiles only if BlockGroup64Bit implements BlockGroup. +var _ BlockGroup = (*BlockGroup64Bit)(nil) + +// Methods to override. Checksum() and Flags() are not overridden. + +// InodeTable implements BlockGroup.InodeTable. +func (bg *BlockGroup64Bit) InodeTable() uint64 { + return (uint64(bg.InodeTableHi) << 32) | uint64(bg.InodeTableLo) +} + +// BlockBitmap implements BlockGroup.BlockBitmap. +func (bg *BlockGroup64Bit) BlockBitmap() uint64 { + return (uint64(bg.BlockBitmapHi) << 32) | uint64(bg.BlockBitmapLo) +} + +// InodeBitmap implements BlockGroup.InodeBitmap. +func (bg *BlockGroup64Bit) InodeBitmap() uint64 { + return (uint64(bg.InodeBitmapHi) << 32) | uint64(bg.InodeBitmapLo) +} + +// ExclusionBitmap implements BlockGroup.ExclusionBitmap. +func (bg *BlockGroup64Bit) ExclusionBitmap() uint64 { + return (uint64(bg.ExcludeBitmapHi) << 32) | uint64(bg.ExcludeBitmapLo) +} + +// FreeBlocksCount implements BlockGroup.FreeBlocksCount. +func (bg *BlockGroup64Bit) FreeBlocksCount() uint32 { + return (uint32(bg.FreeBlocksCountHi) << 16) | uint32(bg.FreeBlocksCountLo) +} + +// FreeInodesCount implements BlockGroup.FreeInodesCount. +func (bg *BlockGroup64Bit) FreeInodesCount() uint32 { + return (uint32(bg.FreeInodesCountHi) << 16) | uint32(bg.FreeInodesCountLo) +} + +// DirectoryCount implements BlockGroup.DirectoryCount. +func (bg *BlockGroup64Bit) DirectoryCount() uint32 { + return (uint32(bg.UsedDirsCountHi) << 16) | uint32(bg.UsedDirsCountLo) +} + +// UnusedInodeCount implements BlockGroup.UnusedInodeCount. +func (bg *BlockGroup64Bit) UnusedInodeCount() uint32 { + return (uint32(bg.ItableUnusedHi) << 16) | uint32(bg.ItableUnusedLo) +} + +// BlockBitmapChecksum implements BlockGroup.BlockBitmapChecksum. +func (bg *BlockGroup64Bit) BlockBitmapChecksum() uint32 { + return (uint32(bg.BlockBitmapChecksumHi) << 16) | uint32(bg.BlockBitmapChecksumLo) +} + +// InodeBitmapChecksum implements BlockGroup.InodeBitmapChecksum. +func (bg *BlockGroup64Bit) InodeBitmapChecksum() uint32 { + return (uint32(bg.InodeBitmapChecksumHi) << 16) | uint32(bg.InodeBitmapChecksumLo) +} diff --git a/pkg/sentry/fs/ext/disklayout/block_group_test.go b/pkg/sentry/fs/ext/disklayout/block_group_test.go new file mode 100644 index 000000000..0ef4294c0 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/block_group_test.go @@ -0,0 +1,26 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "testing" +) + +// TestBlockGroupSize tests that the block group descriptor structs are of the +// correct size. +func TestBlockGroupSize(t *testing.T) { + assertSize(t, BlockGroup32Bit{}, 32) + assertSize(t, BlockGroup64Bit{}, 64) +} diff --git a/pkg/sentry/fs/ext/disklayout/dirent.go b/pkg/sentry/fs/ext/disklayout/dirent.go new file mode 100644 index 000000000..685bf57b8 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/dirent.go @@ -0,0 +1,69 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "gvisor.dev/gvisor/pkg/sentry/fs" +) + +const ( + // MaxFileName is the maximum length of an ext fs file's name. + MaxFileName = 255 +) + +var ( + // inodeTypeByFileType maps ext4 file types to vfs inode types. + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#ftype. + inodeTypeByFileType = map[uint8]fs.InodeType{ + 0: fs.Anonymous, + 1: fs.RegularFile, + 2: fs.Directory, + 3: fs.CharacterDevice, + 4: fs.BlockDevice, + 5: fs.Pipe, + 6: fs.Socket, + 7: fs.Symlink, + } +) + +// The Dirent interface should be implemented by structs representing ext +// directory entries. These are for the linear classical directories which +// just store a list of dirent structs. A directory is a series of data blocks +// where is each data block contains a linear array of dirents. The last entry +// of the block has a record size that takes it to the end of the block. The +// end of the directory is when you read dirInode.Size() bytes from the blocks. +// +// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#linear-classic-directories. +type Dirent interface { + // Inode returns the absolute inode number of the underlying inode. + // Inode number 0 signifies an unused dirent. + Inode() uint32 + + // RecordSize returns the record length of this dirent on disk. The next + // dirent in the dirent list should be read after these many bytes from + // the current dirent. Must be a multiple of 4. + RecordSize() uint16 + + // FileName returns the name of the file. Can be at most 255 is length. + FileName() string + + // FileType returns the inode type of the underlying inode. This is a + // performance hack so that we do not have to read the underlying inode struct + // to know the type of inode. This will only work when the SbDirentFileType + // feature is set. If not, the second returned value will be false indicating + // that user code has to use the inode mode to extract the file type. + FileType() (fs.InodeType, bool) +} diff --git a/pkg/sentry/fs/ext/disklayout/dirent_new.go b/pkg/sentry/fs/ext/disklayout/dirent_new.go new file mode 100644 index 000000000..29ae4a5c2 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/dirent_new.go @@ -0,0 +1,61 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "fmt" + + "gvisor.dev/gvisor/pkg/sentry/fs" +) + +// DirentNew represents the ext4 directory entry struct. This emulates Linux's +// ext4_dir_entry_2 struct. The FileName can not be more than 255 bytes so we +// only need 8 bits to store the NameLength. As a result, NameLength has been +// shortened and the other 8 bits are used to encode the file type. Use the +// FileTypeRaw field only if the SbDirentFileType feature is set. +// +// Note: This struct can be of variable size on disk. The one described below +// is of maximum size and the FileName beyond NameLength bytes might contain +// garbage. +type DirentNew struct { + InodeNumber uint32 + RecordLength uint16 + NameLength uint8 + FileTypeRaw uint8 + FileNameRaw [MaxFileName]byte +} + +// Compiles only if DirentNew implements Dirent. +var _ Dirent = (*DirentNew)(nil) + +// Inode implements Dirent.Inode. +func (d *DirentNew) Inode() uint32 { return d.InodeNumber } + +// RecordSize implements Dirent.RecordSize. +func (d *DirentNew) RecordSize() uint16 { return d.RecordLength } + +// FileName implements Dirent.FileName. +func (d *DirentNew) FileName() string { + return string(d.FileNameRaw[:d.NameLength]) +} + +// FileType implements Dirent.FileType. +func (d *DirentNew) FileType() (fs.InodeType, bool) { + if inodeType, ok := inodeTypeByFileType[d.FileTypeRaw]; ok { + return inodeType, true + } + + panic(fmt.Sprintf("unknown file type %v", d.FileTypeRaw)) +} diff --git a/pkg/sentry/fs/ext/disklayout/dirent_old.go b/pkg/sentry/fs/ext/disklayout/dirent_old.go new file mode 100644 index 000000000..2e0f9c812 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/dirent_old.go @@ -0,0 +1,50 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import "gvisor.dev/gvisor/pkg/sentry/fs" + +// DirentOld represents the old directory entry struct which does not contain +// the file type. This emulates Linux's ext4_dir_entry struct. This is used in +// ext2, ext3 and sometimes in ext4. +// +// Note: This struct can be of variable size on disk. The one described below +// is of maximum size and the FileName beyond NameLength bytes might contain +// garbage. +type DirentOld struct { + InodeNumber uint32 + RecordLength uint16 + NameLength uint16 + FileNameRaw [MaxFileName]byte +} + +// Compiles only if DirentOld implements Dirent. +var _ Dirent = (*DirentOld)(nil) + +// Inode implements Dirent.Inode. +func (d *DirentOld) Inode() uint32 { return d.InodeNumber } + +// RecordSize implements Dirent.RecordSize. +func (d *DirentOld) RecordSize() uint16 { return d.RecordLength } + +// FileName implements Dirent.FileName. +func (d *DirentOld) FileName() string { + return string(d.FileNameRaw[:d.NameLength]) +} + +// FileType implements Dirent.FileType. +func (d *DirentOld) FileType() (fs.InodeType, bool) { + return fs.Anonymous, false +} diff --git a/pkg/sentry/fs/ext/disklayout/dirent_test.go b/pkg/sentry/fs/ext/disklayout/dirent_test.go new file mode 100644 index 000000000..cc6dff2c9 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/dirent_test.go @@ -0,0 +1,28 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "testing" +) + +// TestDirentSize tests that the dirent structs are of the correct +// size. +func TestDirentSize(t *testing.T) { + want := uintptr(263) + + assertSize(t, DirentOld{}, want) + assertSize(t, DirentNew{}, want) +} diff --git a/pkg/sentry/fs/ext/disklayout/disklayout.go b/pkg/sentry/fs/ext/disklayout/disklayout.go new file mode 100644 index 000000000..bdf4e2132 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/disklayout.go @@ -0,0 +1,50 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package disklayout provides Linux ext file system's disk level structures +// which can be directly read into from the underlying device. Structs aim to +// emulate structures `exactly` how they are layed out on disk. +// +// This library aims to be compatible with all ext(2/3/4) systems so it +// provides a generic interface for all major structures and various +// implementations (for different versions). The user code is responsible for +// using appropriate implementations based on the underlying device. +// +// Interfacing all major structures here serves a few purposes: +// - Abstracts away the complexity of the underlying structure from client +// code. The client only has to figure out versioning on set up and then +// can use these as black boxes and pass it higher up the stack. +// - Having pointer receivers forces the user to use pointers to these +// heavy structs. Hence, prevents the client code from unintentionally +// copying these by value while passing the interface around. +// - Version-based implementation selection is resolved on set up hence +// avoiding per call overhead of choosing implementation. +// - All interface methods are pretty light weight (do not take in any +// parameters by design). Passing pointer arguments to interface methods +// can lead to heap allocation as the compiler won't be able to perform +// escape analysis on an unknown implementation at compile time. +// +// Notes: +// - All fields in these structs are exported because binary.Read would +// panic otherwise. +// - All structures on disk are in little-endian order. Only jbd2 (journal) +// structures are in big-endian order. +// - All OS dependent fields in these structures will be interpretted using +// the Linux version of that field. +// - The suffix `Lo` in field names stands for lower bits of that field. +// - The suffix `Hi` in field names stands for upper bits of that field. +// - The suffix `Raw` has been added to indicate that the field is not split +// into Lo and Hi fields and also to resolve name collision with the +// respective interface. +package disklayout diff --git a/pkg/sentry/fs/ext/disklayout/inode.go b/pkg/sentry/fs/ext/disklayout/inode.go new file mode 100644 index 000000000..b48001910 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/inode.go @@ -0,0 +1,267 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/time" +) + +// The Inode interface must be implemented by structs representing ext inodes. +// The inode stores all the metadata pertaining to the file (except for the +// file name which is held by the directory entry). It does NOT expose all +// fields and should be extended if need be. +// +// Some file systems (e.g. FAT) use the directory entry to store all this +// information. Ext file systems do not so that they can support hard links. +// However, ext4 cheats a little bit and duplicates the file type in the +// directory entry for performance gains. +// +// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#index-nodes. +type Inode interface { + // Mode returns the linux file mode which is majorly used to extract + // information like: + // - File permissions (read/write/execute by user/group/others). + // - Sticky, set UID and GID bits. + // - File type. + // + // Masks to extract this information are provided in pkg/abi/linux/file.go. + Mode() linux.FileMode + + // UID returns the owner UID. + UID() auth.KUID + + // GID returns the owner GID. + GID() auth.KGID + + // Size returns the size of the file in bytes. + Size() uint64 + + // InodeSize returns the size of this inode struct in bytes. + // In ext2 and ext3, the inode struct and inode disk record size was fixed at + // 128 bytes. Ext4 makes it possible for the inode struct to be bigger. + // However, accessing any field beyond the 128 bytes marker must be verified + // using this method. + InodeSize() uint16 + + // AccessTime returns the last access time. Shows when the file was last read. + // + // If InExtendedAttr is set, then this should NOT be used because the + // underlying field is used to store the extended attribute value checksum. + AccessTime() time.Time + + // ChangeTime returns the last change time. Shows when the file meta data + // (like permissions) was last changed. + // + // If InExtendedAttr is set, then this should NOT be used because the + // underlying field is used to store the lower 32 bits of the attribute + // value’s reference count. + ChangeTime() time.Time + + // ModificationTime returns the last modification time. Shows when the file + // content was last modified. + // + // If InExtendedAttr is set, then this should NOT be used because + // the underlying field contains the number of the inode that owns the + // extended attribute. + ModificationTime() time.Time + + // DeletionTime returns the deletion time. Inodes are marked as deleted by + // writing to the underlying field. FS tools can restore files until they are + // actually overwritten. + DeletionTime() time.Time + + // LinksCount returns the number of hard links to this inode. + // + // Normally there is an upper limit on the number of hard links: + // - ext2/ext3 = 32,000 + // - ext4 = 65,000 + // + // This implies that an ext4 directory cannot have more than 64,998 + // subdirectories because each subdirectory will have a hard link to the + // directory via the `..` entry. The directory has hard link via the `.` entry + // of its own. And finally the inode is initiated with 1 hard link (itself). + // + // The underlying value is reset to 1 if all the following hold: + // - Inode is a directory. + // - SbDirNlink is enabled. + // - Number of hard links is incremented past 64,999. + // Hard link value of 1 for a directory would indicate that the number of hard + // links is unknown because a directory can have minimum 2 hard links (itself + // and `.` entry). + LinksCount() uint16 + + // Flags returns InodeFlags which represents the inode flags. + Flags() InodeFlags + + // Blocks returns the underlying inode.i_block array. This field is special + // and is used to store various kinds of things depending on the filesystem + // version and inode type. + // - In ext2/ext3, it contains the block map. + // - In ext4, it contains the extent tree. + // - For inline files, it contains the file contents. + // - For symlinks, it contains the link path (if it fits here). + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#the-contents-of-inode-i-block. + Blocks() [60]byte +} + +// Inode flags. This is not comprehensive and flags which were not used in +// the Linux kernel have been excluded. +const ( + // InSync indicates that all writes to the file must be synchronous. + InSync = 0x8 + + // InImmutable indicates that this file is immutable. + InImmutable = 0x10 + + // InAppend indicates that this file can only be appended to. + InAppend = 0x20 + + // InNoDump indicates that teh dump(1) utility should not dump this file. + InNoDump = 0x40 + + // InNoAccessTime indicates that the access time of this inode must not be + // updated. + InNoAccessTime = 0x80 + + // InIndex indicates that this directory has hashed indexes. + InIndex = 0x1000 + + // InJournalData indicates that file data must always be written through a + // journal device. + InJournalData = 0x4000 + + // InDirSync indicates that all the directory entiry data must be written + // synchronously. + InDirSync = 0x10000 + + // InTopDir indicates that this inode is at the top of the directory hierarchy. + InTopDir = 0x20000 + + // InHugeFile indicates that this is a huge file. + InHugeFile = 0x40000 + + // InExtents indicates that this inode uses extents. + InExtents = 0x80000 + + // InExtendedAttr indicates that this inode stores a large extended attribute + // value in its data blocks. + InExtendedAttr = 0x200000 + + // InInline indicates that this inode has inline data. + InInline = 0x10000000 + + // InReserved indicates that this inode is reserved for the ext4 library. + InReserved = 0x80000000 +) + +// InodeFlags represents all possible combinations of inode flags. It aims to +// cover the bit masks and provide a more user-friendly interface. +type InodeFlags struct { + Sync bool + Immutable bool + Append bool + NoDump bool + NoAccessTime bool + Index bool + JournalData bool + DirSync bool + TopDir bool + HugeFile bool + Extents bool + ExtendedAttr bool + Inline bool + Reserved bool +} + +// ToInt converts inode flags back to its 32-bit rep. +func (f InodeFlags) ToInt() uint32 { + var res uint32 + + if f.Sync { + res |= InSync + } + if f.Immutable { + res |= InImmutable + } + if f.Append { + res |= InAppend + } + if f.NoDump { + res |= InNoDump + } + if f.NoAccessTime { + res |= InNoAccessTime + } + if f.Index { + res |= InIndex + } + if f.JournalData { + res |= InJournalData + } + if f.DirSync { + res |= InDirSync + } + if f.TopDir { + res |= InTopDir + } + if f.HugeFile { + res |= InHugeFile + } + if f.Extents { + res |= InExtents + } + if f.ExtendedAttr { + res |= InExtendedAttr + } + if f.Inline { + res |= InInline + } + if f.Reserved { + res |= InReserved + } + + return res +} + +// InodeFlagsFromInt converts the integer representation of inode flags to +// a InodeFlags struct. +func InodeFlagsFromInt(f uint32) InodeFlags { + return InodeFlags{ + Sync: f&InSync > 0, + Immutable: f&InImmutable > 0, + Append: f&InAppend > 0, + NoDump: f&InNoDump > 0, + NoAccessTime: f&InNoAccessTime > 0, + Index: f&InIndex > 0, + JournalData: f&InJournalData > 0, + DirSync: f&InDirSync > 0, + TopDir: f&InTopDir > 0, + HugeFile: f&InHugeFile > 0, + Extents: f&InExtents > 0, + ExtendedAttr: f&InExtendedAttr > 0, + Inline: f&InInline > 0, + Reserved: f&InReserved > 0, + } +} + +// These masks define how users can view/modify inode flags. The rest of the +// flags are for internal kernel usage only. +const ( + InUserReadFlagMask = 0x4BDFFF + InUserWriteFlagMask = 0x4B80FF +) diff --git a/pkg/sentry/fs/ext/disklayout/inode_new.go b/pkg/sentry/fs/ext/disklayout/inode_new.go new file mode 100644 index 000000000..4f5348372 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/inode_new.go @@ -0,0 +1,96 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import "gvisor.dev/gvisor/pkg/sentry/kernel/time" + +// InodeNew represents ext4 inode structure which can be bigger than +// OldInodeSize. The actual size of this struct should be determined using +// inode.ExtraInodeSize. Accessing any field here should be verified with the +// actual size. The extra space between the end of the inode struct and end of +// the inode record can be used to store extended attr. +// +// If the TimeExtra fields are in scope, the lower 2 bits of those are used +// to extend their counter part to be 34 bits wide; the rest (upper) 30 bits +// are used to provide nanoscond precision. Hence, these timestamps will now +// overflow in May 2446. +// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#inode-timestamps. +type InodeNew struct { + InodeOld + + ExtraInodeSize uint16 + ChecksumHi uint16 + ChangeTimeExtra uint32 + ModificationTimeExtra uint32 + AccessTimeExtra uint32 + CreationTime uint32 + CreationTimeExtra uint32 + VersionHi uint32 + ProjectID uint32 +} + +// Compiles only if InodeNew implements Inode. +var _ Inode = (*InodeNew)(nil) + +// fromExtraTime decodes the extra time and constructs the kernel time struct +// with nanosecond precision. +func fromExtraTime(lo int32, extra uint32) time.Time { + // See description above InodeNew for format. + seconds := (int64(extra&0x3) << 32) + int64(lo) + nanoseconds := int64(extra >> 2) + return time.FromUnix(seconds, nanoseconds) +} + +// Only override methods which change due to ext4 specific fields. + +// Size implements Inode.Size. +func (in *InodeNew) Size() uint64 { + return (uint64(in.SizeHi) << 32) | uint64(in.SizeLo) +} + +// InodeSize implements Inode.InodeSize. +func (in *InodeNew) InodeSize() uint16 { + return oldInodeSize + in.ExtraInodeSize +} + +// ChangeTime implements Inode.ChangeTime. +func (in *InodeNew) ChangeTime() time.Time { + // Apply new timestamp logic if inode.ChangeTimeExtra is in scope. + if in.ExtraInodeSize >= 8 { + return fromExtraTime(in.ChangeTimeRaw, in.ChangeTimeExtra) + } + + return in.InodeOld.ChangeTime() +} + +// ModificationTime implements Inode.ModificationTime. +func (in *InodeNew) ModificationTime() time.Time { + // Apply new timestamp logic if inode.ModificationTimeExtra is in scope. + if in.ExtraInodeSize >= 12 { + return fromExtraTime(in.ModificationTimeRaw, in.ModificationTimeExtra) + } + + return in.InodeOld.ModificationTime() +} + +// AccessTime implements Inode.AccessTime. +func (in *InodeNew) AccessTime() time.Time { + // Apply new timestamp logic if inode.AccessTimeExtra is in scope. + if in.ExtraInodeSize >= 16 { + return fromExtraTime(in.AccessTimeRaw, in.AccessTimeExtra) + } + + return in.InodeOld.AccessTime() +} diff --git a/pkg/sentry/fs/ext/disklayout/inode_old.go b/pkg/sentry/fs/ext/disklayout/inode_old.go new file mode 100644 index 000000000..dc4c9d8e4 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/inode_old.go @@ -0,0 +1,117 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/kernel/time" +) + +const ( + // oldInodeSize is the inode size in ext2/ext3. + oldInodeSize = 128 +) + +// InodeOld implements Inode interface. It emulates ext2/ext3 inode struct. +// Inode struct size and record size are both 128 bytes for this. +// +// All fields representing time are in seconds since the epoch. Which means that +// they will overflow in January 2038. +type InodeOld struct { + ModeRaw uint16 + UIDLo uint16 + SizeLo uint32 + + // The time fields are signed integers because they could be negative to + // represent time before the epoch. + AccessTimeRaw int32 + ChangeTimeRaw int32 + ModificationTimeRaw int32 + DeletionTimeRaw int32 + + GIDLo uint16 + LinksCountRaw uint16 + BlocksCountLo uint32 + FlagsRaw uint32 + VersionLo uint32 // This is OS dependent. + BlocksRaw [60]byte + Generation uint32 + FileACLLo uint32 + SizeHi uint32 + ObsoFaddr uint32 + + // OS dependent fields have been inlined here. + BlocksCountHi uint16 + FileACLHi uint16 + UIDHi uint16 + GIDHi uint16 + ChecksumLo uint16 + _ uint16 +} + +// Compiles only if InodeOld implements Inode. +var _ Inode = (*InodeOld)(nil) + +// Mode implements Inode.Mode. +func (in *InodeOld) Mode() linux.FileMode { return linux.FileMode(in.ModeRaw) } + +// UID implements Inode.UID. +func (in *InodeOld) UID() auth.KUID { + return auth.KUID((uint32(in.UIDHi) << 16) | uint32(in.UIDLo)) +} + +// GID implements Inode.GID. +func (in *InodeOld) GID() auth.KGID { + return auth.KGID((uint32(in.GIDHi) << 16) | uint32(in.GIDLo)) +} + +// Size implements Inode.Size. +func (in *InodeOld) Size() uint64 { + // In ext2/ext3, in.SizeHi did not exist, it was instead named in.DirACL. + return uint64(in.SizeLo) +} + +// InodeSize implements Inode.InodeSize. +func (in *InodeOld) InodeSize() uint16 { return oldInodeSize } + +// AccessTime implements Inode.AccessTime. +func (in *InodeOld) AccessTime() time.Time { + return time.FromUnix(int64(in.AccessTimeRaw), 0) +} + +// ChangeTime implements Inode.ChangeTime. +func (in *InodeOld) ChangeTime() time.Time { + return time.FromUnix(int64(in.ChangeTimeRaw), 0) +} + +// ModificationTime implements Inode.ModificationTime. +func (in *InodeOld) ModificationTime() time.Time { + return time.FromUnix(int64(in.ModificationTimeRaw), 0) +} + +// DeletionTime implements Inode.DeletionTime. +func (in *InodeOld) DeletionTime() time.Time { + return time.FromUnix(int64(in.DeletionTimeRaw), 0) +} + +// LinksCount implements Inode.LinksCount. +func (in *InodeOld) LinksCount() uint16 { return in.LinksCountRaw } + +// Flags implements Inode.Flags. +func (in *InodeOld) Flags() InodeFlags { return InodeFlagsFromInt(in.FlagsRaw) } + +// Blocks implements Inode.Blocks. +func (in *InodeOld) Blocks() [60]byte { return in.BlocksRaw } diff --git a/pkg/sentry/fs/ext/disklayout/inode_test.go b/pkg/sentry/fs/ext/disklayout/inode_test.go new file mode 100644 index 000000000..9cae9e4f0 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/inode_test.go @@ -0,0 +1,222 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "fmt" + "strconv" + "testing" + + "gvisor.dev/gvisor/pkg/sentry/kernel/time" +) + +// TestInodeSize tests that the inode structs are of the correct size. +func TestInodeSize(t *testing.T) { + assertSize(t, InodeOld{}, oldInodeSize) + + // This was updated from 156 bytes to 160 bytes in Oct 2015. + assertSize(t, InodeNew{}, 160) +} + +// TestTimestampSeconds tests that the seconds part of [a/c/m] timestamps in +// ext4 inode structs are decoded correctly. +// +// These tests are derived from the table under https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#inode-timestamps. +func TestTimestampSeconds(t *testing.T) { + type timestampTest struct { + // msbSet tells if the most significant bit of InodeOld.[X]TimeRaw is set. + // If this is set then the 32-bit time is negative. + msbSet bool + + // lowerBound tells if we should take the lowest possible value of + // InodeOld.[X]TimeRaw while satisfying test.msbSet condition. If set to + // false it tells to take the highest possible value. + lowerBound bool + + // extraBits is InodeNew.[X]TimeExtra. + extraBits uint32 + + // want is the kernel time struct that is expected. + want time.Time + } + + tests := []timestampTest{ + // 1901-12-13 + { + msbSet: true, + lowerBound: true, + extraBits: 0, + want: time.FromUnix(int64(-0x80000000), 0), + }, + + // 1969-12-31 + { + msbSet: true, + lowerBound: false, + extraBits: 0, + want: time.FromUnix(int64(-1), 0), + }, + + // 1970-01-01 + { + msbSet: false, + lowerBound: true, + extraBits: 0, + want: time.FromUnix(int64(0), 0), + }, + + // 2038-01-19 + { + msbSet: false, + lowerBound: false, + extraBits: 0, + want: time.FromUnix(int64(0x7fffffff), 0), + }, + + // 2038-01-19 + { + msbSet: true, + lowerBound: true, + extraBits: 1, + want: time.FromUnix(int64(0x80000000), 0), + }, + + // 2106-02-07 + { + msbSet: true, + lowerBound: false, + extraBits: 1, + want: time.FromUnix(int64(0xffffffff), 0), + }, + + // 2106-02-07 + { + msbSet: false, + lowerBound: true, + extraBits: 1, + want: time.FromUnix(int64(0x100000000), 0), + }, + + // 2174-02-25 + { + msbSet: false, + lowerBound: false, + extraBits: 1, + want: time.FromUnix(int64(0x17fffffff), 0), + }, + + // 2174-02-25 + { + msbSet: true, + lowerBound: true, + extraBits: 2, + want: time.FromUnix(int64(0x180000000), 0), + }, + + // 2242-03-16 + { + msbSet: true, + lowerBound: false, + extraBits: 2, + want: time.FromUnix(int64(0x1ffffffff), 0), + }, + + // 2242-03-16 + { + msbSet: false, + lowerBound: true, + extraBits: 2, + want: time.FromUnix(int64(0x200000000), 0), + }, + + // 2310-04-04 + { + msbSet: false, + lowerBound: false, + extraBits: 2, + want: time.FromUnix(int64(0x27fffffff), 0), + }, + + // 2310-04-04 + { + msbSet: true, + lowerBound: true, + extraBits: 3, + want: time.FromUnix(int64(0x280000000), 0), + }, + + // 2378-04-22 + { + msbSet: true, + lowerBound: false, + extraBits: 3, + want: time.FromUnix(int64(0x2ffffffff), 0), + }, + + // 2378-04-22 + { + msbSet: false, + lowerBound: true, + extraBits: 3, + want: time.FromUnix(int64(0x300000000), 0), + }, + + // 2446-05-10 + { + msbSet: false, + lowerBound: false, + extraBits: 3, + want: time.FromUnix(int64(0x37fffffff), 0), + }, + } + + lowerMSB0 := int32(0) // binary: 00000000 00000000 00000000 00000000 + upperMSB0 := int32(0x7fffffff) // binary: 01111111 11111111 11111111 11111111 + lowerMSB1 := int32(-0x80000000) // binary: 10000000 00000000 00000000 00000000 + upperMSB1 := int32(-1) // binary: 11111111 11111111 11111111 11111111 + + get32BitTime := func(test timestampTest) int32 { + if test.msbSet { + if test.lowerBound { + return lowerMSB1 + } + + return upperMSB1 + } + + if test.lowerBound { + return lowerMSB0 + } + + return upperMSB0 + } + + getTestName := func(test timestampTest) string { + return fmt.Sprintf( + "Tests time decoding with epoch bits 0b%s and 32-bit raw time: MSB set=%t, lower bound=%t", + strconv.FormatInt(int64(test.extraBits), 2), + test.msbSet, + test.lowerBound, + ) + } + + for _, test := range tests { + t.Run(getTestName(test), func(t *testing.T) { + if got := fromExtraTime(get32BitTime(test), test.extraBits); got != test.want { + t.Errorf("Expected: %v, Got: %v", test.want, got) + } + }) + } +} diff --git a/pkg/sentry/fs/ext/disklayout/superblock.go b/pkg/sentry/fs/ext/disklayout/superblock.go new file mode 100644 index 000000000..e4b8f46fb --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/superblock.go @@ -0,0 +1,468 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// SuperBlock should be implemented by structs representing the ext superblock. +// The superblock holds a lot of information about the enclosing filesystem. +// This interface aims to provide access methods to important information held +// by the superblock. It does NOT expose all fields of the superblock, only the +// ones necessary. This can be expanded when need be. +// +// Location and replication: +// - The superblock is located at offset 1024 in block group 0. +// - Redundant copies of the superblock and group descriptors are kept in +// all groups if SbSparse feature flag is NOT set. If it is set, the +// replicas only exist in groups whose group number is either 0 or a +// power of 3, 5, or 7. +// - There is also a sparse superblock feature v2 in which there are just +// two replicas saved in the block groups pointed by sb.s_backup_bgs. +// +// Replicas should eventually be updated if the superblock is updated. +// +// See https://www.kernel.org/doc/html/latest/filesystems/ext4/globals.html#super-block. +type SuperBlock interface { + // InodesCount returns the total number of inodes in this filesystem. + InodesCount() uint32 + + // BlocksCount returns the total number of data blocks in this filesystem. + BlocksCount() uint64 + + // FreeBlocksCount returns the number of free blocks in this filesystem. + FreeBlocksCount() uint64 + + // FreeInodesCount returns the number of free inodes in this filesystem. + FreeInodesCount() uint32 + + // MountCount returns the number of mounts since the last fsck. + MountCount() uint16 + + // MaxMountCount returns the number of mounts allowed beyond which a fsck is + // needed. + MaxMountCount() uint16 + + // FirstDataBlock returns the absolute block number of the first data block, + // which contains the super block itself. + // + // If the filesystem has 1kb data blocks then this should return 1. For all + // other configurations, this typically returns 0. + // + // The first block group descriptor is in (FirstDataBlock() + 1)th block. + FirstDataBlock() uint32 + + // BlockSize returns the size of one data block in this filesystem. + // This can be calculated by 2^(10 + sb.s_log_block_size). This ensures that + // the smallest block size is 1kb. + BlockSize() uint64 + + // BlocksPerGroup returns the number of data blocks in a block group. + BlocksPerGroup() uint32 + + // ClusterSize returns block cluster size (set during mkfs time by admin). + // This can be calculated by 2^(10 + sb.s_log_cluster_size). This ensures that + // the smallest cluster size is 1kb. + // + // sb.s_log_cluster_size must equal sb.s_log_block_size if bigalloc feature + // is NOT set and consequently BlockSize() = ClusterSize() in that case. + ClusterSize() uint64 + + // ClustersPerGroup returns: + // - number of clusters per group if bigalloc is enabled. + // - BlocksPerGroup() otherwise. + ClustersPerGroup() uint32 + + // InodeSize returns the size of the inode disk record size in bytes. Use this + // to iterate over inode arrays on disk. + // + // In ext2 and ext3: + // - Each inode had a disk record of 128 bytes. + // - The inode struct size was fixed at 128 bytes. + // + // In ext4 its possible to allocate larger on-disk inodes: + // - Inode disk record size = sb.s_inode_size (function return value). + // = 256 (default) + // - Inode struct size = 128 + inode.i_extra_isize. + // = 128 + 32 = 160 (default) + InodeSize() uint16 + + // InodesPerGroup returns the number of inodes in a block group. + InodesPerGroup() uint32 + + // BgDescSize returns the size of the block group descriptor struct. + // + // In ext2, ext3, ext4 (without 64-bit feature), the block group descriptor + // is only 32 bytes long. + // In ext4 with 64-bit feature, the block group descriptor expands to AT LEAST + // 64 bytes. It might be bigger than that. + BgDescSize() uint16 + + // CompatibleFeatures returns the CompatFeatures struct which holds all the + // compatible features this fs supports. + CompatibleFeatures() CompatFeatures + + // IncompatibleFeatures returns the CompatFeatures struct which holds all the + // incompatible features this fs supports. + IncompatibleFeatures() IncompatFeatures + + // ReadOnlyCompatibleFeatures returns the CompatFeatures struct which holds all the + // readonly compatible features this fs supports. + ReadOnlyCompatibleFeatures() RoCompatFeatures + + // Magic() returns the magic signature which must be 0xef53. + Magic() uint16 + + // Revision returns the superblock revision. Superblock struct fields from + // offset 0x54 till 0x150 should only be used if superblock has DynamicRev. + Revision() SbRevision +} + +// SbRevision is the type for superblock revisions. +type SbRevision int + +// Super block revisions. +const ( + // OldRev is the good old (original) format. + OldRev SbRevision = 0 + + // DynamicRev is v2 format w/ dynamic inode sizes. + DynamicRev SbRevision = 1 +) + +// Superblock compatible features. +// This is not exhaustive, unused features are not listed. +const ( + // SbDirPrealloc indicates directory preallocation. + SbDirPrealloc = 0x1 + + // SbHasJournal indicates the presence of a journal. jbd2 should only work + // with this being set. + SbHasJournal = 0x4 + + // SbExtAttr indicates extended attributes support. + SbExtAttr = 0x8 + + // SbResizeInode indicates that the fs has reserved GDT blocks (right after + // group descriptors) for fs expansion. + SbResizeInode = 0x10 + + // SbDirIndex indicates that the fs has directory indices. + SbDirIndex = 0x20 + + // SbSparseV2 stands for Sparse superblock version 2. + SbSparseV2 = 0x200 +) + +// CompatFeatures represents a superblock's compatible feature set. If the +// kernel does not understand any of these feature, it can still read/write +// to this fs. +type CompatFeatures struct { + DirPrealloc bool + HasJournal bool + ExtAttr bool + ResizeInode bool + DirIndex bool + SparseV2 bool +} + +// ToInt converts superblock compatible features back to its 32-bit rep. +func (f CompatFeatures) ToInt() uint32 { + var res uint32 + + if f.DirPrealloc { + res |= SbDirPrealloc + } + if f.HasJournal { + res |= SbHasJournal + } + if f.ExtAttr { + res |= SbExtAttr + } + if f.ResizeInode { + res |= SbResizeInode + } + if f.DirIndex { + res |= SbDirIndex + } + if f.SparseV2 { + res |= SbSparseV2 + } + + return res +} + +// CompatFeaturesFromInt converts the integer representation of superblock +// compatible features to CompatFeatures struct. +func CompatFeaturesFromInt(f uint32) CompatFeatures { + return CompatFeatures{ + DirPrealloc: f&SbDirPrealloc > 0, + HasJournal: f&SbHasJournal > 0, + ExtAttr: f&SbExtAttr > 0, + ResizeInode: f&SbResizeInode > 0, + DirIndex: f&SbDirIndex > 0, + SparseV2: f&SbSparseV2 > 0, + } +} + +// Superblock incompatible features. +// This is not exhaustive, unused features are not listed. +const ( + // SbDirentFileType indicates that directory entries record the file type. + // We should use struct ext4_dir_entry_2 for dirents then. + SbDirentFileType = 0x2 + + // SbRecovery indicates that the filesystem needs recovery. + SbRecovery = 0x4 + + // SbJournalDev indicates that the filesystem has a separate journal device. + SbJournalDev = 0x8 + + // SbMetaBG indicates that the filesystem is using Meta block groups. Moves + // the group descriptors from the congested first block group into the first + // group of each metablock group to increase the maximum block groups limit + // and hence support much larger filesystems. + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/overview.html#meta-block-groups. + SbMetaBG = 0x10 + + // SbExtents indicates that the filesystem uses extents. Must be set in ext4 + // filesystems. + SbExtents = 0x40 + + // SbIs64Bit indicates that this filesystem addresses blocks with 64-bits. + // Hence can support 2^64 data blocks. + SbIs64Bit = 0x80 + + // SbMMP indicates that this filesystem has multiple mount protection. + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/globals.html#multiple-mount-protection. + SbMMP = 0x100 + + // SbFlexBg indicates that this filesystem has flexible block groups. Several + // block groups are tied into one logical block group so that all the metadata + // for the block groups (bitmaps and inode tables) are close together for + // faster loading. Consequently, large files will be continuous on disk. + // However, this does not affect the placement of redundant superblocks and + // group descriptors. + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/overview.html#flexible-block-groups. + SbFlexBg = 0x200 + + // SbLargeDir shows that large directory enabled. Directory htree can be 3 + // levels deep. Directory htrees are allowed to be 2 levels deep otherwise. + SbLargeDir = 0x4000 + + // SbInlineData allows inline data in inodes for really small files. + SbInlineData = 0x8000 + + // SbEncrypted indicates that this fs contains encrypted inodes. + SbEncrypted = 0x10000 +) + +// IncompatFeatures represents a superblock's incompatible feature set. If the +// kernel does not understand any of these feature, it should refuse to mount. +type IncompatFeatures struct { + DirentFileType bool + Recovery bool + JournalDev bool + MetaBG bool + Extents bool + Is64Bit bool + MMP bool + FlexBg bool + LargeDir bool + InlineData bool + Encrypted bool +} + +// ToInt converts superblock incompatible features back to its 32-bit rep. +func (f IncompatFeatures) ToInt() uint32 { + var res uint32 + + if f.DirentFileType { + res |= SbDirentFileType + } + if f.Recovery { + res |= SbRecovery + } + if f.JournalDev { + res |= SbJournalDev + } + if f.MetaBG { + res |= SbMetaBG + } + if f.Extents { + res |= SbExtents + } + if f.Is64Bit { + res |= SbIs64Bit + } + if f.MMP { + res |= SbMMP + } + if f.FlexBg { + res |= SbFlexBg + } + if f.LargeDir { + res |= SbLargeDir + } + if f.InlineData { + res |= SbInlineData + } + if f.Encrypted { + res |= SbEncrypted + } + + return res +} + +// IncompatFeaturesFromInt converts the integer representation of superblock +// incompatible features to IncompatFeatures struct. +func IncompatFeaturesFromInt(f uint32) IncompatFeatures { + return IncompatFeatures{ + DirentFileType: f&SbDirentFileType > 0, + Recovery: f&SbRecovery > 0, + JournalDev: f&SbJournalDev > 0, + MetaBG: f&SbMetaBG > 0, + Extents: f&SbExtents > 0, + Is64Bit: f&SbIs64Bit > 0, + MMP: f&SbMMP > 0, + FlexBg: f&SbFlexBg > 0, + LargeDir: f&SbLargeDir > 0, + InlineData: f&SbInlineData > 0, + Encrypted: f&SbEncrypted > 0, + } +} + +// Superblock readonly compatible features. +// This is not exhaustive, unused features are not listed. +const ( + // SbSparse indicates sparse superblocks. Only groups with number either 0 or + // a power of 3, 5, or 7 will have redundant copies of the superblock and + // block descriptors. + SbSparse = 0x1 + + // SbLargeFile indicates that this fs has been used to store a file >= 2GiB. + SbLargeFile = 0x2 + + // SbHugeFile indicates that this fs contains files whose sizes are + // represented in units of logicals blocks, not 512-byte sectors. + SbHugeFile = 0x8 + + // SbGdtCsum indicates that group descriptors have checksums. + SbGdtCsum = 0x10 + + // SbDirNlink indicates that the new subdirectory limit is 64,999. Ext3 has a + // 32,000 subdirectory limit. + SbDirNlink = 0x20 + + // SbExtraIsize indicates that large inodes exist on this filesystem. + SbExtraIsize = 0x40 + + // SbHasSnapshot indicates the existence of a snapshot. + SbHasSnapshot = 0x80 + + // SbQuota enables usage tracking for all quota types. + SbQuota = 0x100 + + // SbBigalloc maps to the bigalloc feature. When set, the minimum allocation + // unit becomes a cluster rather than a data block. Then block bitmaps track + // clusters, not data blocks. + // + // See https://www.kernel.org/doc/html/latest/filesystems/ext4/overview.html#bigalloc. + SbBigalloc = 0x200 + + // SbMetadataCsum indicates that the fs supports metadata checksumming. + SbMetadataCsum = 0x400 + + // SbReadOnly marks this filesystem as readonly. Should refuse to mount in + // read/write mode. + SbReadOnly = 0x1000 +) + +// RoCompatFeatures represents a superblock's readonly compatible feature set. +// If the kernel does not understand any of these feature, it can still mount +// readonly. But if the user wants to mount read/write, the kernel should +// refuse to mount. +type RoCompatFeatures struct { + Sparse bool + LargeFile bool + HugeFile bool + GdtCsum bool + DirNlink bool + ExtraIsize bool + HasSnapshot bool + Quota bool + Bigalloc bool + MetadataCsum bool + ReadOnly bool +} + +// ToInt converts superblock readonly compatible features to its 32-bit rep. +func (f RoCompatFeatures) ToInt() uint32 { + var res uint32 + + if f.Sparse { + res |= SbSparse + } + if f.LargeFile { + res |= SbLargeFile + } + if f.HugeFile { + res |= SbHugeFile + } + if f.GdtCsum { + res |= SbGdtCsum + } + if f.DirNlink { + res |= SbDirNlink + } + if f.ExtraIsize { + res |= SbExtraIsize + } + if f.HasSnapshot { + res |= SbHasSnapshot + } + if f.Quota { + res |= SbQuota + } + if f.Bigalloc { + res |= SbBigalloc + } + if f.MetadataCsum { + res |= SbMetadataCsum + } + if f.ReadOnly { + res |= SbReadOnly + } + + return res +} + +// RoCompatFeaturesFromInt converts the integer representation of superblock +// readonly compatible features to RoCompatFeatures struct. +func RoCompatFeaturesFromInt(f uint32) RoCompatFeatures { + return RoCompatFeatures{ + Sparse: f&SbSparse > 0, + LargeFile: f&SbLargeFile > 0, + HugeFile: f&SbHugeFile > 0, + GdtCsum: f&SbGdtCsum > 0, + DirNlink: f&SbDirNlink > 0, + ExtraIsize: f&SbExtraIsize > 0, + HasSnapshot: f&SbHasSnapshot > 0, + Quota: f&SbQuota > 0, + Bigalloc: f&SbBigalloc > 0, + MetadataCsum: f&SbMetadataCsum > 0, + ReadOnly: f&SbReadOnly > 0, + } +} diff --git a/pkg/sentry/fs/ext/disklayout/superblock_32.go b/pkg/sentry/fs/ext/disklayout/superblock_32.go new file mode 100644 index 000000000..587e4afaa --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/superblock_32.go @@ -0,0 +1,75 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// SuperBlock32Bit implements SuperBlock and represents the 32-bit version of +// the ext4_super_block struct in fs/ext4/ext4.h. +type SuperBlock32Bit struct { + // We embed the old superblock struct here because the 32-bit version is just + // an extension of the old version. + SuperBlockOld + + FirstInode uint32 + InodeSizeRaw uint16 + BlockGroupNumber uint16 + FeatureCompat uint32 + FeatureIncompat uint32 + FeatureRoCompat uint32 + UUID [16]byte + VolumeName [16]byte + LastMounted [64]byte + AlgoUsageBitmap uint32 + PreallocBlocks uint8 + PreallocDirBlocks uint8 + ReservedGdtBlocks uint16 + JournalUUID [16]byte + JournalInum uint32 + JournalDev uint32 + LastOrphan uint32 + HashSeed [4]uint32 + DefaultHashVersion uint8 + JnlBackupType uint8 + BgDescSizeRaw uint16 + DefaultMountOpts uint32 + FirstMetaBg uint32 + MkfsTime uint32 + JnlBlocks [17]uint32 +} + +// Compiles only if SuperBlock32Bit implements SuperBlock. +var _ SuperBlock = (*SuperBlock32Bit)(nil) + +// Only override methods which change based on the additional fields above. +// Not overriding SuperBlock.BgDescSize because it would still return 32 here. + +// InodeSize implements SuperBlock.InodeSize. +func (sb *SuperBlock32Bit) InodeSize() uint16 { + return sb.InodeSizeRaw +} + +// CompatibleFeatures implements SuperBlock.CompatibleFeatures. +func (sb *SuperBlock32Bit) CompatibleFeatures() CompatFeatures { + return CompatFeaturesFromInt(sb.FeatureCompat) +} + +// IncompatibleFeatures implements SuperBlock.IncompatibleFeatures. +func (sb *SuperBlock32Bit) IncompatibleFeatures() IncompatFeatures { + return IncompatFeaturesFromInt(sb.FeatureIncompat) +} + +// ReadOnlyCompatibleFeatures implements SuperBlock.ReadOnlyCompatibleFeatures. +func (sb *SuperBlock32Bit) ReadOnlyCompatibleFeatures() RoCompatFeatures { + return RoCompatFeaturesFromInt(sb.FeatureRoCompat) +} diff --git a/pkg/sentry/fs/ext/disklayout/superblock_64.go b/pkg/sentry/fs/ext/disklayout/superblock_64.go new file mode 100644 index 000000000..a2c2278fb --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/superblock_64.go @@ -0,0 +1,94 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// SuperBlock64Bit implements SuperBlock and represents the 64-bit version of +// the ext4_super_block struct in fs/ext4/ext4.h. This sums up to be exactly +// 1024 bytes (smallest possible block size) and hence the superblock always +// fits in no more than one data block. +type SuperBlock64Bit struct { + // We embed the 32-bit struct here because 64-bit version is just an extension + // of the 32-bit version. + SuperBlock32Bit + + BlocksCountHi uint32 + ReservedBlocksCountHi uint32 + FreeBlocksCountHi uint32 + MinInodeSize uint16 + WantInodeSize uint16 + Flags uint32 + RaidStride uint16 + MmpInterval uint16 + MmpBlock uint64 + RaidStripeWidth uint32 + LogGroupsPerFlex uint8 + ChecksumType uint8 + _ uint16 + KbytesWritten uint64 + SnapshotInum uint32 + SnapshotID uint32 + SnapshotRsrvBlocksCount uint64 + SnapshotList uint32 + ErrorCount uint32 + FirstErrorTime uint32 + FirstErrorInode uint32 + FirstErrorBlock uint64 + FirstErrorFunction [32]byte + FirstErrorLine uint32 + LastErrorTime uint32 + LastErrorInode uint32 + LastErrorLine uint32 + LastErrorBlock uint64 + LastErrorFunction [32]byte + MountOpts [64]byte + UserQuotaInum uint32 + GroupQuotaInum uint32 + OverheadBlocks uint32 + BackupBgs [2]uint32 + EncryptAlgos [4]uint8 + EncryptPwSalt [16]uint8 + LostFoundInode uint32 + ProjectQuotaInode uint32 + ChecksumSeed uint32 + WtimeHi uint8 + MtimeHi uint8 + MkfsTimeHi uint8 + LastCheckHi uint8 + FirstErrorTimeHi uint8 + LastErrorTimeHi uint8 + _ [2]uint8 + Encoding uint16 + EncodingFlags uint16 + _ [95]uint32 + Checksum uint32 +} + +// Compiles only if SuperBlock64Bit implements SuperBlock. +var _ SuperBlock = (*SuperBlock64Bit)(nil) + +// Only override methods which change based on the 64-bit feature. + +// BlocksCount implements SuperBlock.BlocksCount. +func (sb *SuperBlock64Bit) BlocksCount() uint64 { + return (uint64(sb.BlocksCountHi) << 32) | uint64(sb.BlocksCountLo) +} + +// FreeBlocksCount implements SuperBlock.FreeBlocksCount. +func (sb *SuperBlock64Bit) FreeBlocksCount() uint64 { + return (uint64(sb.FreeBlocksCountHi) << 32) | uint64(sb.FreeBlocksCountLo) +} + +// BgDescSize implements SuperBlock.BgDescSize. +func (sb *SuperBlock64Bit) BgDescSize() uint16 { return sb.BgDescSizeRaw } diff --git a/pkg/sentry/fs/ext/disklayout/superblock_old.go b/pkg/sentry/fs/ext/disklayout/superblock_old.go new file mode 100644 index 000000000..c74953610 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/superblock_old.go @@ -0,0 +1,102 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +// SuperBlockOld implements SuperBlock and represents the old version of the +// superblock struct in ext2 and ext3 systems. +type SuperBlockOld struct { + InodesCountRaw uint32 + BlocksCountLo uint32 + ReservedBlocksCount uint32 + FreeBlocksCountLo uint32 + FreeInodesCountRaw uint32 + FirstDataBlockRaw uint32 + LogBlockSize uint32 + LogClusterSize uint32 + BlocksPerGroupRaw uint32 + ClustersPerGroupRaw uint32 + InodesPerGroupRaw uint32 + Mtime uint32 + Wtime uint32 + MountCountRaw uint16 + MaxMountCountRaw uint16 + MagicRaw uint16 + State uint16 + Errors uint16 + MinorRevLevel uint16 + LastCheck uint32 + CheckInterval uint32 + CreatorOS uint32 + RevLevel uint32 + DefResUID uint16 + DefResGID uint16 +} + +// InodesCount implements SuperBlock.InodesCount. +func (sb *SuperBlockOld) InodesCount() uint32 { return sb.InodesCountRaw } + +// BlocksCount implements SuperBlock.BlocksCount. +func (sb *SuperBlockOld) BlocksCount() uint64 { return uint64(sb.BlocksCountLo) } + +// FreeBlocksCount implements SuperBlock.FreeBlocksCount. +func (sb *SuperBlockOld) FreeBlocksCount() uint64 { return uint64(sb.FreeBlocksCountLo) } + +// FreeInodesCount implements SuperBlock.FreeInodesCount. +func (sb *SuperBlockOld) FreeInodesCount() uint32 { return sb.FreeInodesCountRaw } + +// MountCount implements SuperBlock.MountCount. +func (sb *SuperBlockOld) MountCount() uint16 { return sb.MountCountRaw } + +// MaxMountCount implements SuperBlock.MaxMountCount. +func (sb *SuperBlockOld) MaxMountCount() uint16 { return sb.MaxMountCountRaw } + +// FirstDataBlock implements SuperBlock.FirstDataBlock. +func (sb *SuperBlockOld) FirstDataBlock() uint32 { return sb.FirstDataBlockRaw } + +// BlockSize implements SuperBlock.BlockSize. +func (sb *SuperBlockOld) BlockSize() uint64 { return 1 << (10 + sb.LogBlockSize) } + +// BlocksPerGroup implements SuperBlock.BlocksPerGroup. +func (sb *SuperBlockOld) BlocksPerGroup() uint32 { return sb.BlocksPerGroupRaw } + +// ClusterSize implements SuperBlock.ClusterSize. +func (sb *SuperBlockOld) ClusterSize() uint64 { return 1 << (10 + sb.LogClusterSize) } + +// ClustersPerGroup implements SuperBlock.ClustersPerGroup. +func (sb *SuperBlockOld) ClustersPerGroup() uint32 { return sb.ClustersPerGroupRaw } + +// InodeSize implements SuperBlock.InodeSize. +func (sb *SuperBlockOld) InodeSize() uint16 { return oldInodeSize } + +// InodesPerGroup implements SuperBlock.InodesPerGroup. +func (sb *SuperBlockOld) InodesPerGroup() uint32 { return sb.InodesPerGroupRaw } + +// BgDescSize implements SuperBlock.BgDescSize. +func (sb *SuperBlockOld) BgDescSize() uint16 { return 32 } + +// CompatibleFeatures implements SuperBlock.CompatibleFeatures. +func (sb *SuperBlockOld) CompatibleFeatures() CompatFeatures { return CompatFeatures{} } + +// IncompatibleFeatures implements SuperBlock.IncompatibleFeatures. +func (sb *SuperBlockOld) IncompatibleFeatures() IncompatFeatures { return IncompatFeatures{} } + +// ReadOnlyCompatibleFeatures implements SuperBlock.ReadOnlyCompatibleFeatures. +func (sb *SuperBlockOld) ReadOnlyCompatibleFeatures() RoCompatFeatures { return RoCompatFeatures{} } + +// Magic implements SuperBlock.Magic. +func (sb *SuperBlockOld) Magic() uint16 { return sb.MagicRaw } + +// Revision implements SuperBlock.Revision. +func (sb *SuperBlockOld) Revision() SbRevision { return SbRevision(sb.RevLevel) } diff --git a/pkg/sentry/fs/ext/disklayout/superblock_test.go b/pkg/sentry/fs/ext/disklayout/superblock_test.go new file mode 100644 index 000000000..463b5ba21 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/superblock_test.go @@ -0,0 +1,27 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "testing" +) + +// TestSuperBlockSize tests that the superblock structs are of the correct +// size. +func TestSuperBlockSize(t *testing.T) { + assertSize(t, SuperBlockOld{}, 84) + assertSize(t, SuperBlock32Bit{}, 336) + assertSize(t, SuperBlock64Bit{}, 1024) +} diff --git a/pkg/sentry/fs/ext/disklayout/test_utils.go b/pkg/sentry/fs/ext/disklayout/test_utils.go new file mode 100644 index 000000000..9c63f04c0 --- /dev/null +++ b/pkg/sentry/fs/ext/disklayout/test_utils.go @@ -0,0 +1,30 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package disklayout + +import ( + "reflect" + "testing" + + "gvisor.dev/gvisor/pkg/binary" +) + +func assertSize(t *testing.T, v interface{}, want uintptr) { + t.Helper() + + if got := binary.Size(v); got != want { + t.Errorf("struct %s should be exactly %d bytes but is %d bytes", reflect.TypeOf(v).Name(), want, got) + } +} diff --git a/pkg/sentry/fs/ext/ext.go b/pkg/sentry/fs/ext/ext.go new file mode 100644 index 000000000..7602e2bf0 --- /dev/null +++ b/pkg/sentry/fs/ext/ext.go @@ -0,0 +1,49 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package ext implements readonly ext(2/3/4) filesystems. +package ext + +import ( + "io" + "sync" + + "gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout" +) + +// Filesystem implements vfs.FilesystemImpl. +type Filesystem struct { + // dev is the ReadSeeker for the underlying fs device and is protected by mu. + dev io.ReadSeeker + + // mu synchronizes the usage of dev. The ext filesystems take locality into + // condsideration, i.e. data blocks of a file will tend to be placed close + // together. On a spinning disk, locality reduces the amount of movement of + // the head hence speeding up IO operations. On an SSD there are no moving + // parts but locality increases the size of each transer request. Hence, + // having mutual exclusion on the read seeker while reading a file *should* + // help in achieving the intended performance gains. + // + // Note: This synchronization was not coupled with the ReadSeeker itself + // because we want to synchronize across read/seek operations for the + // performance gains mentioned above. Helps enforcing one-file-at-a-time IO. + mu sync.Mutex + + // sb represents the filesystem superblock. Immutable after initialization. + sb disklayout.SuperBlock + + // bgs represents all the block group descriptors for the filesystem. + // Immutable after initialization. + bgs []disklayout.BlockGroup +} |