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-rw-r--r--pkg/sentry/vfs/BUILD2
-rw-r--r--pkg/sentry/vfs/README.md2
-rw-r--r--pkg/sentry/vfs/file_description.go18
-rw-r--r--pkg/sentry/vfs/file_description_impl_util.go25
-rw-r--r--pkg/sentry/vfs/lock.go (renamed from pkg/sentry/vfs/lock/lock.go)43
-rw-r--r--pkg/sentry/vfs/lock/BUILD13
-rw-r--r--pkg/sentry/vfs/permissions.go31
7 files changed, 93 insertions, 41 deletions
diff --git a/pkg/sentry/vfs/BUILD b/pkg/sentry/vfs/BUILD
index 16d9f3a28..642769e7c 100644
--- a/pkg/sentry/vfs/BUILD
+++ b/pkg/sentry/vfs/BUILD
@@ -44,6 +44,7 @@ go_library(
"filesystem_impl_util.go",
"filesystem_type.go",
"inotify.go",
+ "lock.go",
"mount.go",
"mount_unsafe.go",
"options.go",
@@ -72,7 +73,6 @@ go_library(
"//pkg/sentry/memmap",
"//pkg/sentry/socket/unix/transport",
"//pkg/sentry/uniqueid",
- "//pkg/sentry/vfs/lock",
"//pkg/sync",
"//pkg/syserror",
"//pkg/usermem",
diff --git a/pkg/sentry/vfs/README.md b/pkg/sentry/vfs/README.md
index 66f3105bd..4b9faf2ea 100644
--- a/pkg/sentry/vfs/README.md
+++ b/pkg/sentry/vfs/README.md
@@ -169,8 +169,6 @@ This construction, which is essentially a type-safe analogue to Linux's
- binder, which is similarly far too incomplete to use.
- - whitelistfs, which we are already actively attempting to remove.
-
- Save/restore. For instance, it is unclear if the current implementation of
the `state` package supports the inheritance pattern described above.
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 13c48824e..e0538ea53 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -438,14 +438,10 @@ type FileDescriptionImpl interface {
UnlockBSD(ctx context.Context, uid lock.UniqueID) error
// LockPOSIX tries to acquire a POSIX-style advisory file lock.
- //
- // TODO(gvisor.dev/issue/1480): POSIX-style file locking
- LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error
+ LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, start, length uint64, whence int16, block lock.Blocker) error
// UnlockPOSIX releases a POSIX-style advisory file lock.
- //
- // TODO(gvisor.dev/issue/1480): POSIX-style file locking
- UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error
+ UnlockPOSIX(ctx context.Context, uid lock.UniqueID, start, length uint64, whence int16) error
}
// Dirent holds the information contained in struct linux_dirent64.
@@ -764,3 +760,13 @@ func (fd *FileDescription) LockBSD(ctx context.Context, lockType lock.LockType,
func (fd *FileDescription) UnlockBSD(ctx context.Context) error {
return fd.impl.UnlockBSD(ctx, fd)
}
+
+// LockPOSIX locks a POSIX-style file range lock.
+func (fd *FileDescription) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, start, end uint64, whence int16, block lock.Blocker) error {
+ return fd.impl.LockPOSIX(ctx, uid, t, start, end, whence, block)
+}
+
+// UnlockPOSIX unlocks a POSIX-style file range lock.
+func (fd *FileDescription) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, start, end uint64, whence int16) error {
+ return fd.impl.UnlockPOSIX(ctx, uid, start, end, whence)
+}
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index af7213dfd..1e66997ce 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -23,7 +23,6 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
"gvisor.dev/gvisor/pkg/sentry/memmap"
- "gvisor.dev/gvisor/pkg/sentry/vfs/lock"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
@@ -369,14 +368,19 @@ func GenericConfigureMMap(fd *FileDescription, m memmap.Mappable, opts *memmap.M
// LockFD may be used by most implementations of FileDescriptionImpl.Lock*
// functions. Caller must call Init().
type LockFD struct {
- locks *lock.FileLocks
+ locks *FileLocks
}
// Init initializes fd with FileLocks to use.
-func (fd *LockFD) Init(locks *lock.FileLocks) {
+func (fd *LockFD) Init(locks *FileLocks) {
fd.locks = locks
}
+// Locks returns the locks associated with this file.
+func (fd *LockFD) Locks() *FileLocks {
+ return fd.locks
+}
+
// LockBSD implements vfs.FileDescriptionImpl.LockBSD.
func (fd *LockFD) LockBSD(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, block fslock.Blocker) error {
return fd.locks.LockBSD(uid, t, block)
@@ -388,17 +392,6 @@ func (fd *LockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
return nil
}
-// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
-func (fd *LockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error {
- return fd.locks.LockPOSIX(uid, t, rng, block)
-}
-
-// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
-func (fd *LockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, rng fslock.LockRange) error {
- fd.locks.UnlockPOSIX(uid, rng)
- return nil
-}
-
// NoLockFD implements Lock*/Unlock* portion of FileDescriptionImpl interface
// returning ENOLCK.
type NoLockFD struct{}
@@ -414,11 +407,11 @@ func (NoLockFD) UnlockBSD(ctx context.Context, uid fslock.UniqueID) error {
}
// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
-func (NoLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error {
+func (NoLockFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return syserror.ENOLCK
}
// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX.
-func (NoLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, rng fslock.LockRange) error {
+func (NoLockFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error {
return syserror.ENOLCK
}
diff --git a/pkg/sentry/vfs/lock/lock.go b/pkg/sentry/vfs/lock.go
index 724dfe743..6c7583a81 100644
--- a/pkg/sentry/vfs/lock/lock.go
+++ b/pkg/sentry/vfs/lock.go
@@ -17,9 +17,11 @@
//
// The actual implementations can be found in the lock package under
// sentry/fs/lock.
-package lock
+package vfs
import (
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock"
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -56,7 +58,11 @@ func (fl *FileLocks) UnlockBSD(uid fslock.UniqueID) {
}
// LockPOSIX tries to acquire a POSIX-style lock on a file region.
-func (fl *FileLocks) LockPOSIX(uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error {
+func (fl *FileLocks) LockPOSIX(ctx context.Context, fd *FileDescription, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
+ rng, err := computeRange(ctx, fd, start, length, whence)
+ if err != nil {
+ return err
+ }
if fl.posix.LockRegion(uid, t, rng, block) {
return nil
}
@@ -67,6 +73,37 @@ func (fl *FileLocks) LockPOSIX(uid fslock.UniqueID, t fslock.LockType, rng fsloc
//
// This operation is always successful, even if there did not exist a lock on
// the requested region held by uid in the first place.
-func (fl *FileLocks) UnlockPOSIX(uid fslock.UniqueID, rng fslock.LockRange) {
+func (fl *FileLocks) UnlockPOSIX(ctx context.Context, fd *FileDescription, uid fslock.UniqueID, start, length uint64, whence int16) error {
+ rng, err := computeRange(ctx, fd, start, length, whence)
+ if err != nil {
+ return err
+ }
fl.posix.UnlockRegion(uid, rng)
+ return nil
+}
+
+func computeRange(ctx context.Context, fd *FileDescription, start uint64, length uint64, whence int16) (fslock.LockRange, error) {
+ var off int64
+ switch whence {
+ case linux.SEEK_SET:
+ off = 0
+ case linux.SEEK_CUR:
+ // Note that Linux does not hold any mutexes while retrieving the file
+ // offset, see fs/locks.c:flock_to_posix_lock and fs/locks.c:fcntl_setlk.
+ curOff, err := fd.Seek(ctx, 0, linux.SEEK_CUR)
+ if err != nil {
+ return fslock.LockRange{}, err
+ }
+ off = curOff
+ case linux.SEEK_END:
+ stat, err := fd.Stat(ctx, StatOptions{Mask: linux.STATX_SIZE})
+ if err != nil {
+ return fslock.LockRange{}, err
+ }
+ off = int64(stat.Size)
+ default:
+ return fslock.LockRange{}, syserror.EINVAL
+ }
+
+ return fslock.ComputeRange(int64(start), int64(length), off)
}
diff --git a/pkg/sentry/vfs/lock/BUILD b/pkg/sentry/vfs/lock/BUILD
deleted file mode 100644
index d9ab063b7..000000000
--- a/pkg/sentry/vfs/lock/BUILD
+++ /dev/null
@@ -1,13 +0,0 @@
-load("//tools:defs.bzl", "go_library")
-
-package(licenses = ["notice"])
-
-go_library(
- name = "lock",
- srcs = ["lock.go"],
- visibility = ["//pkg/sentry:internal"],
- deps = [
- "//pkg/sentry/fs/lock",
- "//pkg/syserror",
- ],
-)
diff --git a/pkg/sentry/vfs/permissions.go b/pkg/sentry/vfs/permissions.go
index f9647f90e..afe2be8d7 100644
--- a/pkg/sentry/vfs/permissions.go
+++ b/pkg/sentry/vfs/permissions.go
@@ -94,6 +94,37 @@ func GenericCheckPermissions(creds *auth.Credentials, ats AccessTypes, mode linu
return syserror.EACCES
}
+// MayLink determines whether creating a hard link to a file with the given
+// mode, kuid, and kgid is permitted.
+//
+// This corresponds to Linux's fs/namei.c:may_linkat.
+func MayLink(creds *auth.Credentials, mode linux.FileMode, kuid auth.KUID, kgid auth.KGID) error {
+ // Source inode owner can hardlink all they like; otherwise, it must be a
+ // safe source.
+ if CanActAsOwner(creds, kuid) {
+ return nil
+ }
+
+ // Only regular files can be hard linked.
+ if mode.FileType() != linux.S_IFREG {
+ return syserror.EPERM
+ }
+
+ // Setuid files should not get pinned to the filesystem.
+ if mode&linux.S_ISUID != 0 {
+ return syserror.EPERM
+ }
+
+ // Executable setgid files should not get pinned to the filesystem, but we
+ // don't support S_IXGRP anyway.
+
+ // Hardlinking to unreadable or unwritable sources is dangerous.
+ if err := GenericCheckPermissions(creds, MayRead|MayWrite, mode, kuid, kgid); err != nil {
+ return syserror.EPERM
+ }
+ return nil
+}
+
// AccessTypesForOpenFlags returns the access types required to open a file
// with the given OpenOptions.Flags. Note that this is NOT the same thing as
// the set of accesses permitted for the opened file:
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 06:09:26 +0000