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-rw-r--r--pkg/sentry/syscalls/linux/sys_file.go16
-rw-r--r--pkg/sentry/syscalls/linux/sys_stat.go5
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/setstat.go15
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/stat.go66
4 files changed, 88 insertions, 14 deletions
diff --git a/pkg/sentry/syscalls/linux/sys_file.go b/pkg/sentry/syscalls/linux/sys_file.go
index d10a9bed8..35a98212a 100644
--- a/pkg/sentry/syscalls/linux/sys_file.go
+++ b/pkg/sentry/syscalls/linux/sys_file.go
@@ -514,7 +514,7 @@ func (ac accessContext) Value(key interface{}) interface{} {
}
}
-func accessAt(t *kernel.Task, dirFD int32, addr usermem.Addr, resolve bool, mode uint) error {
+func accessAt(t *kernel.Task, dirFD int32, addr usermem.Addr, mode uint) error {
const rOK = 4
const wOK = 2
const xOK = 1
@@ -529,7 +529,7 @@ func accessAt(t *kernel.Task, dirFD int32, addr usermem.Addr, resolve bool, mode
return syserror.EINVAL
}
- return fileOpOn(t, dirFD, path, resolve, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
+ return fileOpOn(t, dirFD, path, true /* resolve */, func(root *fs.Dirent, d *fs.Dirent, _ uint) error {
// access(2) and faccessat(2) check permissions using real
// UID/GID, not effective UID/GID.
//
@@ -564,17 +564,23 @@ func Access(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
addr := args[0].Pointer()
mode := args[1].ModeT()
- return 0, nil, accessAt(t, linux.AT_FDCWD, addr, true, mode)
+ return 0, nil, accessAt(t, linux.AT_FDCWD, addr, mode)
}
// Faccessat implements linux syscall faccessat(2).
+//
+// Note that the faccessat() system call does not take a flags argument:
+// "The raw faccessat() system call takes only the first three arguments. The
+// AT_EACCESS and AT_SYMLINK_NOFOLLOW flags are actually implemented within
+// the glibc wrapper function for faccessat(). If either of these flags is
+// specified, then the wrapper function employs fstatat(2) to determine access
+// permissions." - faccessat(2)
func Faccessat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
dirFD := args[0].Int()
addr := args[1].Pointer()
mode := args[2].ModeT()
- flags := args[3].Int()
- return 0, nil, accessAt(t, dirFD, addr, flags&linux.AT_SYMLINK_NOFOLLOW == 0, mode)
+ return 0, nil, accessAt(t, dirFD, addr, mode)
}
// LINT.ThenChange(vfs2/filesystem.go)
diff --git a/pkg/sentry/syscalls/linux/sys_stat.go b/pkg/sentry/syscalls/linux/sys_stat.go
index 9bd2df104..a11a87cd1 100644
--- a/pkg/sentry/syscalls/linux/sys_stat.go
+++ b/pkg/sentry/syscalls/linux/sys_stat.go
@@ -136,7 +136,10 @@ func Statx(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
mask := args[3].Uint()
statxAddr := args[4].Pointer()
- if mask&linux.STATX__RESERVED > 0 {
+ if mask&linux.STATX__RESERVED != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+ if flags&^(linux.AT_SYMLINK_NOFOLLOW|linux.AT_EMPTY_PATH|linux.AT_STATX_SYNC_TYPE) != 0 {
return 0, nil, syserror.EINVAL
}
if flags&linux.AT_STATX_SYNC_TYPE == linux.AT_STATX_SYNC_TYPE {
diff --git a/pkg/sentry/syscalls/linux/vfs2/setstat.go b/pkg/sentry/syscalls/linux/vfs2/setstat.go
index 9250659ff..136453ccc 100644
--- a/pkg/sentry/syscalls/linux/vfs2/setstat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/setstat.go
@@ -173,12 +173,13 @@ func Truncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
return 0, nil, err
}
- return 0, nil, setstatat(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink, &vfs.SetStatOptions{
+ err = setstatat(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink, &vfs.SetStatOptions{
Stat: linux.Statx{
Mask: linux.STATX_SIZE,
Size: uint64(length),
},
})
+ return 0, nil, handleSetSizeError(t, err)
}
// Ftruncate implements Linux syscall ftruncate(2).
@@ -196,12 +197,13 @@ func Ftruncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
}
defer file.DecRef()
- return 0, nil, file.SetStat(t, vfs.SetStatOptions{
+ err := file.SetStat(t, vfs.SetStatOptions{
Stat: linux.Statx{
Mask: linux.STATX_SIZE,
Size: uint64(length),
},
})
+ return 0, nil, handleSetSizeError(t, err)
}
// Utime implements Linux syscall utime(2).
@@ -378,3 +380,12 @@ func setstatat(t *kernel.Task, dirfd int32, path fspath.Path, shouldAllowEmptyPa
FollowFinalSymlink: bool(shouldFollowFinalSymlink),
}, opts)
}
+
+func handleSetSizeError(t *kernel.Task, err error) error {
+ if err == syserror.ErrExceedsFileSizeLimit {
+ // Convert error to EFBIG and send a SIGXFSZ per setrlimit(2).
+ t.SendSignal(kernel.SignalInfoNoInfo(linux.SIGXFSZ, t, t))
+ return syserror.EFBIG
+ }
+ return err
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/stat.go b/pkg/sentry/syscalls/linux/vfs2/stat.go
index 12c532310..97eaedd66 100644
--- a/pkg/sentry/syscalls/linux/vfs2/stat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/stat.go
@@ -150,7 +150,11 @@ func Statx(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
mask := args[3].Uint()
statxAddr := args[4].Pointer()
- if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW) != 0 {
+ if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW|linux.AT_STATX_SYNC_TYPE) != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ if mask&linux.STATX__RESERVED != 0 {
return 0, nil, syserror.EINVAL
}
@@ -228,14 +232,64 @@ func Readlink(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
// Access implements Linux syscall access(2).
func Access(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
- // FIXME(jamieliu): actually implement
- return 0, nil, nil
+ addr := args[0].Pointer()
+ mode := args[1].ModeT()
+
+ return 0, nil, accessAt(t, linux.AT_FDCWD, addr, mode)
}
-// Faccessat implements Linux syscall access(2).
+// Faccessat implements Linux syscall faccessat(2).
+//
+// Note that the faccessat() system call does not take a flags argument:
+// "The raw faccessat() system call takes only the first three arguments. The
+// AT_EACCESS and AT_SYMLINK_NOFOLLOW flags are actually implemented within
+// the glibc wrapper function for faccessat(). If either of these flags is
+// specified, then the wrapper function employs fstatat(2) to determine access
+// permissions." - faccessat(2)
func Faccessat(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
- // FIXME(jamieliu): actually implement
- return 0, nil, nil
+ dirfd := args[0].Int()
+ addr := args[1].Pointer()
+ mode := args[2].ModeT()
+
+ return 0, nil, accessAt(t, dirfd, addr, mode)
+}
+
+func accessAt(t *kernel.Task, dirfd int32, pathAddr usermem.Addr, mode uint) error {
+ const rOK = 4
+ const wOK = 2
+ const xOK = 1
+
+ // Sanity check the mode.
+ if mode&^(rOK|wOK|xOK) != 0 {
+ return syserror.EINVAL
+ }
+
+ path, err := copyInPath(t, pathAddr)
+ if err != nil {
+ return err
+ }
+ tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, followFinalSymlink)
+ if err != nil {
+ return err
+ }
+
+ // access(2) and faccessat(2) check permissions using real
+ // UID/GID, not effective UID/GID.
+ //
+ // "access() needs to use the real uid/gid, not the effective
+ // uid/gid. We do this by temporarily clearing all FS-related
+ // capabilities and switching the fsuid/fsgid around to the
+ // real ones." -fs/open.c:faccessat
+ creds := t.Credentials().Fork()
+ creds.EffectiveKUID = creds.RealKUID
+ creds.EffectiveKGID = creds.RealKGID
+ if creds.EffectiveKUID.In(creds.UserNamespace) == auth.RootUID {
+ creds.EffectiveCaps = creds.PermittedCaps
+ } else {
+ creds.EffectiveCaps = 0
+ }
+
+ return t.Kernel().VFS().AccessAt(t, creds, vfs.AccessTypes(mode), &tpop.pop)
}
// Readlinkat implements Linux syscall mknodat(2).
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-14 18:29:20 +0000