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-rw-r--r--pkg/sentry/fs/ext4/disklayout/BUILD5
-rw-r--r--pkg/sentry/fs/ext4/disklayout/block_group_32.go9
-rw-r--r--pkg/sentry/fs/ext4/disklayout/block_group_64.go6
-rw-r--r--pkg/sentry/fs/ext4/disklayout/disklayout.go50
-rw-r--r--pkg/sentry/fs/ext4/disklayout/inode_new.go96
-rw-r--r--pkg/sentry/fs/ext4/disklayout/inode_old.go117
-rw-r--r--pkg/sentry/fs/ext4/disklayout/inode_test.go222
-rw-r--r--pkg/sentry/fs/ext4/disklayout/superblock.go18
-rw-r--r--pkg/sentry/fs/ext4/disklayout/superblock_32.go7
-rw-r--r--pkg/sentry/fs/ext4/disklayout/superblock_64.go6
-rw-r--r--pkg/sentry/fs/ext4/disklayout/superblock_old.go8
11 files changed, 504 insertions, 40 deletions
diff --git a/pkg/sentry/fs/ext4/disklayout/BUILD b/pkg/sentry/fs/ext4/disklayout/BUILD
index e3d2f8d71..d1cbab275 100644
--- a/pkg/sentry/fs/ext4/disklayout/BUILD
+++ b/pkg/sentry/fs/ext4/disklayout/BUILD
@@ -8,7 +8,10 @@ go_library(
"block_group.go",
"block_group_32.go",
"block_group_64.go",
+ "disklayout.go",
"inode.go",
+ "inode_new.go",
+ "inode_old.go",
"superblock.go",
"superblock_32.go",
"superblock_64.go",
@@ -29,7 +32,9 @@ go_test(
size = "small",
srcs = [
"block_group_test.go",
+ "inode_test.go",
"superblock_test.go",
],
embed = [":disklayout"],
+ deps = ["//pkg/sentry/kernel/time"],
)
diff --git a/pkg/sentry/fs/ext4/disklayout/block_group_32.go b/pkg/sentry/fs/ext4/disklayout/block_group_32.go
index dadecb3e3..3e16c76db 100644
--- a/pkg/sentry/fs/ext4/disklayout/block_group_32.go
+++ b/pkg/sentry/fs/ext4/disklayout/block_group_32.go
@@ -17,12 +17,6 @@ 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.
-//
-// The suffix `Lo` here stands for lower bits because this is also used in the
-// 64-bit version where these fields represent the lower half of the fields.
-// The suffix `Raw` has been added to indicate that the field does not have a
-// counterpart in the 64-bit version and to resolve name collision with the
-// interface.
type BlockGroup32Bit struct {
BlockBitmapLo uint32
InodeBitmapLo uint32
@@ -38,6 +32,9 @@ type BlockGroup32Bit struct {
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) }
diff --git a/pkg/sentry/fs/ext4/disklayout/block_group_64.go b/pkg/sentry/fs/ext4/disklayout/block_group_64.go
index 27de3990d..9a809197a 100644
--- a/pkg/sentry/fs/ext4/disklayout/block_group_64.go
+++ b/pkg/sentry/fs/ext4/disklayout/block_group_64.go
@@ -18,9 +18,6 @@ package disklayout
// 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.
-//
-// The suffix `Hi` here stands for upper bits because they represent the upper
-// half of the fields.
type BlockGroup64Bit struct {
// We embed the 32-bit struct here because 64-bit version is just an extension
// of the 32-bit version.
@@ -40,6 +37,9 @@ type BlockGroup64Bit struct {
_ 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.
diff --git a/pkg/sentry/fs/ext4/disklayout/disklayout.go b/pkg/sentry/fs/ext4/disklayout/disklayout.go
new file mode 100644
index 000000000..bdf4e2132
--- /dev/null
+++ b/pkg/sentry/fs/ext4/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/ext4/disklayout/inode_new.go b/pkg/sentry/fs/ext4/disklayout/inode_new.go
new file mode 100644
index 000000000..4f5348372
--- /dev/null
+++ b/pkg/sentry/fs/ext4/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/ext4/disklayout/inode_old.go b/pkg/sentry/fs/ext4/disklayout/inode_old.go
new file mode 100644
index 000000000..dc4c9d8e4
--- /dev/null
+++ b/pkg/sentry/fs/ext4/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/ext4/disklayout/inode_test.go b/pkg/sentry/fs/ext4/disklayout/inode_test.go
new file mode 100644
index 000000000..9cae9e4f0
--- /dev/null
+++ b/pkg/sentry/fs/ext4/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/ext4/disklayout/superblock.go b/pkg/sentry/fs/ext4/disklayout/superblock.go
index 030c73410..e4b8f46fb 100644
--- a/pkg/sentry/fs/ext4/disklayout/superblock.go
+++ b/pkg/sentry/fs/ext4/disklayout/superblock.go
@@ -12,22 +12,6 @@
// 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. All structures
-// on disk are in little-endian order. Only jbd2 (journal) structures are in
-// big-endian order. 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.
-//
-// Notes:
-// - All fields in these structs are exported because binary.Read would
-// panic otherwise.
-// - All OS dependent fields in these structures will be interpretted using
-// the Linux version of that field.
package disklayout
// SuperBlock should be implemented by structs representing the ext superblock.
@@ -109,7 +93,7 @@ type SuperBlock interface {
// - Inode disk record size = sb.s_inode_size (function return value).
// = 256 (default)
// - Inode struct size = 128 + inode.i_extra_isize.
- // = 128 + 28 = 156 (default)
+ // = 128 + 32 = 160 (default)
InodeSize() uint16
// InodesPerGroup returns the number of inodes in a block group.
diff --git a/pkg/sentry/fs/ext4/disklayout/superblock_32.go b/pkg/sentry/fs/ext4/disklayout/superblock_32.go
index 4c3233eed..587e4afaa 100644
--- a/pkg/sentry/fs/ext4/disklayout/superblock_32.go
+++ b/pkg/sentry/fs/ext4/disklayout/superblock_32.go
@@ -16,10 +16,6 @@ package disklayout
// SuperBlock32Bit implements SuperBlock and represents the 32-bit version of
// the ext4_super_block struct in fs/ext4/ext4.h.
-//
-// The suffix `Raw` has been added to indicate that the field does not have a
-// counterpart in the 64-bit version and to resolve name collision with the
-// interface.
type SuperBlock32Bit struct {
// We embed the old superblock struct here because the 32-bit version is just
// an extension of the old version.
@@ -52,6 +48,9 @@ type SuperBlock32Bit struct {
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.
diff --git a/pkg/sentry/fs/ext4/disklayout/superblock_64.go b/pkg/sentry/fs/ext4/disklayout/superblock_64.go
index 2e945a7c7..a2c2278fb 100644
--- a/pkg/sentry/fs/ext4/disklayout/superblock_64.go
+++ b/pkg/sentry/fs/ext4/disklayout/superblock_64.go
@@ -18,9 +18,6 @@ package disklayout
// 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.
-//
-// The suffix `Hi` here stands for upper bits because they represent the upper
-// half of the fields.
type SuperBlock64Bit struct {
// We embed the 32-bit struct here because 64-bit version is just an extension
// of the 32-bit version.
@@ -78,6 +75,9 @@ type SuperBlock64Bit struct {
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.
diff --git a/pkg/sentry/fs/ext4/disklayout/superblock_old.go b/pkg/sentry/fs/ext4/disklayout/superblock_old.go
index 1f7425ba3..c74953610 100644
--- a/pkg/sentry/fs/ext4/disklayout/superblock_old.go
+++ b/pkg/sentry/fs/ext4/disklayout/superblock_old.go
@@ -16,12 +16,6 @@ package disklayout
// SuperBlockOld implements SuperBlock and represents the old version of the
// superblock struct in ext2 and ext3 systems.
-//
-// The suffix `Lo` here stands for lower bits because this is also used in the
-// 64-bit version where these fields represent the lower half of the fields.
-// The suffix `Raw` has been added to indicate that the field does not have a
-// counterpart in the 64-bit version and to resolve name collision with the
-// interface.
type SuperBlockOld struct {
InodesCountRaw uint32
BlocksCountLo uint32
@@ -84,7 +78,7 @@ func (sb *SuperBlockOld) ClusterSize() uint64 { return 1 << (10 + sb.LogClusterS
func (sb *SuperBlockOld) ClustersPerGroup() uint32 { return sb.ClustersPerGroupRaw }
// InodeSize implements SuperBlock.InodeSize.
-func (sb *SuperBlockOld) InodeSize() uint16 { return 128 }
+func (sb *SuperBlockOld) InodeSize() uint16 { return oldInodeSize }
// InodesPerGroup implements SuperBlock.InodesPerGroup.
func (sb *SuperBlockOld) InodesPerGroup() uint32 { return sb.InodesPerGroupRaw }