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-rw-r--r--pkg/sentry/fsimpl/gofer/filesystem.go2
-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go18
-rw-r--r--pkg/sentry/fsimpl/host/host.go7
-rw-r--r--pkg/sentry/fsimpl/kernfs/inode_impl_util.go2
-rw-r--r--pkg/sentry/fsimpl/overlay/filesystem.go2
-rw-r--r--pkg/sentry/fsimpl/overlay/non_directory.go2
-rw-r--r--pkg/sentry/fsimpl/tmpfs/filesystem.go2
-rw-r--r--pkg/sentry/fsimpl/tmpfs/tmpfs.go7
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/setstat.go5
-rw-r--r--pkg/sentry/vfs/options.go6
-rw-r--r--pkg/sentry/vfs/permissions.go8
11 files changed, 47 insertions, 14 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 491495b16..00e3c99cd 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -1334,7 +1334,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
fs.renameMuRUnlockAndCheckCaching(&ds)
return err
}
- if err := d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()); err != nil {
+ if err := d.setStat(ctx, rp.Credentials(), &opts, rp.Mount()); err != nil {
fs.renameMuRUnlockAndCheckCaching(&ds)
return err
}
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index ba7f650b3..e20de84b5 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -888,7 +888,8 @@ func (d *dentry) statTo(stat *linux.Statx) {
stat.DevMinor = d.fs.devMinor
}
-func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mnt *vfs.Mount) error {
+func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions, mnt *vfs.Mount) error {
+ stat := &opts.Stat
if stat.Mask == 0 {
return nil
}
@@ -896,7 +897,7 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
return syserror.EPERM
}
mode := linux.FileMode(atomic.LoadUint32(&d.mode))
- if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+ if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
return err
}
if err := mnt.CheckBeginWrite(); err != nil {
@@ -937,6 +938,17 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
}
if !d.isSynthetic() {
if stat.Mask != 0 {
+ if stat.Mask&linux.STATX_SIZE != 0 {
+ // Check whether to allow a truncate request to be made.
+ switch d.mode & linux.S_IFMT {
+ case linux.S_IFREG:
+ // Allow.
+ case linux.S_IFDIR:
+ return syserror.EISDIR
+ default:
+ return syserror.EINVAL
+ }
+ }
if err := d.file.setAttr(ctx, p9.SetAttrMask{
Permissions: stat.Mask&linux.STATX_MODE != 0,
UID: stat.Mask&linux.STATX_UID != 0,
@@ -1498,7 +1510,7 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
// SetStat implements vfs.FileDescriptionImpl.SetStat.
func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
- if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()); err != nil {
+ if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts, fd.vfsfd.Mount()); err != nil {
return err
}
if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go
index 1a88cb657..c894f2ca0 100644
--- a/pkg/sentry/fsimpl/host/host.go
+++ b/pkg/sentry/fsimpl/host/host.go
@@ -373,7 +373,7 @@ func (i *inode) fstat(fs *filesystem) (linux.Statx, error) {
// SetStat implements kernfs.Inode.
func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
- s := opts.Stat
+ s := &opts.Stat
m := s.Mask
if m == 0 {
@@ -386,7 +386,7 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
if err := syscall.Fstat(i.hostFD, &hostStat); err != nil {
return err
}
- if err := vfs.CheckSetStat(ctx, creds, &s, linux.FileMode(hostStat.Mode&linux.PermissionsMask), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil {
+ if err := vfs.CheckSetStat(ctx, creds, &opts, linux.FileMode(hostStat.Mode), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil {
return err
}
@@ -396,6 +396,9 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
}
}
if m&linux.STATX_SIZE != 0 {
+ if hostStat.Mode&linux.S_IFMT != linux.S_IFREG {
+ return syserror.EINVAL
+ }
if err := syscall.Ftruncate(i.hostFD, int64(s.Size)); err != nil {
return err
}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 2ab3f1761..579e627f0 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -267,7 +267,7 @@ func (a *InodeAttrs) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *aut
if opts.Stat.Mask&^(linux.STATX_MODE|linux.STATX_UID|linux.STATX_GID) != 0 {
return syserror.EPERM
}
- if err := vfs.CheckSetStat(ctx, creds, &opts.Stat, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil {
+ if err := vfs.CheckSetStat(ctx, creds, &opts, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil {
return err
}
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index ff82e1f20..6b705e955 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -1104,7 +1104,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
}
mode := linux.FileMode(atomic.LoadUint32(&d.mode))
- if err := vfs.CheckSetStat(ctx, rp.Credentials(), &opts.Stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+ if err := vfs.CheckSetStat(ctx, rp.Credentials(), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
return err
}
mnt := rp.Mount()
diff --git a/pkg/sentry/fsimpl/overlay/non_directory.go b/pkg/sentry/fsimpl/overlay/non_directory.go
index 6c8445ea1..c0749e711 100644
--- a/pkg/sentry/fsimpl/overlay/non_directory.go
+++ b/pkg/sentry/fsimpl/overlay/non_directory.go
@@ -151,7 +151,7 @@ func (fd *nonDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux
func (fd *nonDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
d := fd.dentry()
mode := linux.FileMode(atomic.LoadUint32(&d.mode))
- if err := vfs.CheckSetStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
+ if err := vfs.CheckSetStat(ctx, auth.CredentialsFromContext(ctx), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil {
return err
}
mnt := fd.vfsfd.Mount()
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index a0f20c2d4..ef210a69b 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -649,7 +649,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
fs.mu.RUnlock()
return err
}
- if err := d.inode.setStat(ctx, rp.Credentials(), &opts.Stat); err != nil {
+ if err := d.inode.setStat(ctx, rp.Credentials(), &opts); err != nil {
fs.mu.RUnlock()
return err
}
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index d7f4f0779..2545d88e9 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -452,7 +452,8 @@ func (i *inode) statTo(stat *linux.Statx) {
}
}
-func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx) error {
+func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions) error {
+ stat := &opts.Stat
if stat.Mask == 0 {
return nil
}
@@ -460,7 +461,7 @@ func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linu
return syserror.EPERM
}
mode := linux.FileMode(atomic.LoadUint32(&i.mode))
- if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil {
+ if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil {
return err
}
i.mu.Lock()
@@ -695,7 +696,7 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
creds := auth.CredentialsFromContext(ctx)
d := fd.dentry()
- if err := d.inode.setStat(ctx, creds, &opts.Stat); err != nil {
+ if err := d.inode.setStat(ctx, creds, &opts); err != nil {
return err
}
diff --git a/pkg/sentry/syscalls/linux/vfs2/setstat.go b/pkg/sentry/syscalls/linux/vfs2/setstat.go
index 09ecfed26..6daedd173 100644
--- a/pkg/sentry/syscalls/linux/vfs2/setstat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/setstat.go
@@ -178,6 +178,7 @@ func Truncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
Mask: linux.STATX_SIZE,
Size: uint64(length),
},
+ NeedWritePerm: true,
})
return 0, nil, handleSetSizeError(t, err)
}
@@ -197,6 +198,10 @@ func Ftruncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
}
defer file.DecRef()
+ if !file.IsWritable() {
+ return 0, nil, syserror.EINVAL
+ }
+
err := file.SetStat(t, vfs.SetStatOptions{
Stat: linux.Statx{
Mask: linux.STATX_SIZE,
diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go
index d37208a1f..dfc8573fd 100644
--- a/pkg/sentry/vfs/options.go
+++ b/pkg/sentry/vfs/options.go
@@ -164,6 +164,12 @@ type SetStatOptions struct {
// == UTIME_OMIT (VFS users must unset the corresponding bit in Stat.Mask
// instead).
Stat linux.Statx
+
+ // NeedWritePerm indicates that write permission on the file is needed for
+ // this operation. This is needed for truncate(2) (note that ftruncate(2)
+ // does not require the same check--instead, it checks that the fd is
+ // writable).
+ NeedWritePerm bool
}
// BoundEndpointOptions contains options to VirtualFilesystem.BoundEndpointAt()
diff --git a/pkg/sentry/vfs/permissions.go b/pkg/sentry/vfs/permissions.go
index 9cb050597..33389c1df 100644
--- a/pkg/sentry/vfs/permissions.go
+++ b/pkg/sentry/vfs/permissions.go
@@ -183,7 +183,8 @@ func MayWriteFileWithOpenFlags(flags uint32) bool {
// CheckSetStat checks that creds has permission to change the metadata of a
// file with the given permissions, UID, and GID as specified by stat, subject
// to the rules of Linux's fs/attr.c:setattr_prepare().
-func CheckSetStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mode linux.FileMode, kuid auth.KUID, kgid auth.KGID) error {
+func CheckSetStat(ctx context.Context, creds *auth.Credentials, opts *SetStatOptions, mode linux.FileMode, kuid auth.KUID, kgid auth.KGID) error {
+ stat := &opts.Stat
if stat.Mask&linux.STATX_SIZE != 0 {
limit, err := CheckLimit(ctx, 0, int64(stat.Size))
if err != nil {
@@ -215,6 +216,11 @@ func CheckSetStat(ctx context.Context, creds *auth.Credentials, stat *linux.Stat
return syserror.EPERM
}
}
+ if opts.NeedWritePerm && !creds.HasCapability(linux.CAP_DAC_OVERRIDE) {
+ if err := GenericCheckPermissions(creds, MayWrite, mode, kuid, kgid); err != nil {
+ return err
+ }
+ }
if stat.Mask&(linux.STATX_ATIME|linux.STATX_MTIME|linux.STATX_CTIME) != 0 {
if !CanActAsOwner(creds, kuid) {
if (stat.Mask&linux.STATX_ATIME != 0 && stat.Atime.Nsec != linux.UTIME_NOW) ||
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 10:56:42 +0000