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-rw-r--r--pkg/bits/bits_template.go8
-rw-r--r--pkg/bits/uint64_test.go18
-rw-r--r--pkg/sentry/fsimpl/gofer/filesystem.go16
-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go41
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/BUILD1
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/filesystem.go2
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/getdents.go4
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/stat.go7
-rw-r--r--pkg/sentry/vfs/resolving_path.go16
-rw-r--r--test/syscalls/linux/stat.cc11
10 files changed, 109 insertions, 15 deletions
diff --git a/pkg/bits/bits_template.go b/pkg/bits/bits_template.go
index 93a435b80..998645388 100644
--- a/pkg/bits/bits_template.go
+++ b/pkg/bits/bits_template.go
@@ -42,3 +42,11 @@ func Mask(is ...int) T {
func MaskOf(i int) T {
return T(1) << T(i)
}
+
+// IsPowerOfTwo returns true if v is power of 2.
+func IsPowerOfTwo(v T) bool {
+ if v == 0 {
+ return false
+ }
+ return v&(v-1) == 0
+}
diff --git a/pkg/bits/uint64_test.go b/pkg/bits/uint64_test.go
index 1b018d808..193d1ebcd 100644
--- a/pkg/bits/uint64_test.go
+++ b/pkg/bits/uint64_test.go
@@ -114,3 +114,21 @@ func TestIsOn(t *testing.T) {
}
}
}
+
+func TestIsPowerOfTwo(t *testing.T) {
+ for _, tc := range []struct {
+ v uint64
+ want bool
+ }{
+ {v: 0, want: false},
+ {v: 1, want: true},
+ {v: 2, want: true},
+ {v: 3, want: false},
+ {v: 4, want: true},
+ {v: 5, want: false},
+ } {
+ if got := IsPowerOfTwo64(tc.v); got != tc.want {
+ t.Errorf("IsPowerOfTwo(%d) = %t, want: %t", tc.v, got, tc.want)
+ }
+ }
+}
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 38e4cdbc5..26b492185 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -454,6 +454,9 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b
}
if fs.opts.interop != InteropModeShared {
parent.touchCMtime(ctx)
+ if dir {
+ parent.decLinks()
+ }
parent.cacheNegativeChildLocked(name)
parent.dirents = nil
}
@@ -569,8 +572,13 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, name string) error {
creds := rp.Credentials()
- _, err := parent.file.mkdir(ctx, name, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
- return err
+ if _, err := parent.file.mkdir(ctx, name, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID)); err != nil {
+ return err
+ }
+ if fs.opts.interop != InteropModeShared {
+ parent.incLinks()
+ }
+ return nil
})
}
@@ -962,6 +970,10 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
oldParent.dirents = nil
delete(newParent.negativeChildren, newName)
newParent.dirents = nil
+ if renamed.isDir() {
+ oldParent.decLinks()
+ newParent.incLinks()
+ }
}
vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, &newParent.vfsd, newName, replacedVFSD)
return nil
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 999485492..13928ce36 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -485,6 +485,11 @@ type dentry struct {
// locked to mutate it).
size uint64
+ // nlink counts the number of hard links to this dentry. It's updated and
+ // accessed using atomic operations. It's not protected by metadataMu like the
+ // other metadata fields.
+ nlink uint32
+
mapsMu sync.Mutex
// If this dentry represents a regular file, mappings tracks mappings of
@@ -604,6 +609,9 @@ func (fs *filesystem) newDentry(ctx context.Context, file p9file, qid p9.QID, ma
if mask.BTime {
d.btime = dentryTimestampFromP9(attr.BTimeSeconds, attr.BTimeNanoSeconds)
}
+ if mask.NLink {
+ d.nlink = uint32(attr.NLink)
+ }
d.vfsd.Init(d)
fs.syncMu.Lock()
@@ -645,6 +653,9 @@ func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) {
if mask.BTime {
atomic.StoreInt64(&d.btime, dentryTimestampFromP9(attr.BTimeSeconds, attr.BTimeNanoSeconds))
}
+ if mask.NLink {
+ atomic.StoreUint32(&d.nlink, uint32(attr.NLink))
+ }
if mask.Size {
d.dataMu.Lock()
atomic.StoreUint64(&d.size, attr.Size)
@@ -687,10 +698,7 @@ func (d *dentry) fileType() uint32 {
func (d *dentry) statTo(stat *linux.Statx) {
stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_INO | linux.STATX_SIZE | linux.STATX_BLOCKS | linux.STATX_BTIME
stat.Blksize = atomic.LoadUint32(&d.blockSize)
- stat.Nlink = 1
- if d.isDir() {
- stat.Nlink = 2
- }
+ stat.Nlink = atomic.LoadUint32(&d.nlink)
stat.UID = atomic.LoadUint32(&d.uid)
stat.GID = atomic.LoadUint32(&d.gid)
stat.Mode = uint16(atomic.LoadUint32(&d.mode))
@@ -703,7 +711,7 @@ func (d *dentry) statTo(stat *linux.Statx) {
stat.Btime = statxTimestampFromDentry(atomic.LoadInt64(&d.btime))
stat.Ctime = statxTimestampFromDentry(atomic.LoadInt64(&d.ctime))
stat.Mtime = statxTimestampFromDentry(atomic.LoadInt64(&d.mtime))
- // TODO(jamieliu): device number
+ // TODO(gvisor.dev/issue/1198): device number
}
func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mnt *vfs.Mount) error {
@@ -1094,6 +1102,26 @@ func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool
return nil
}
+// incLinks increments link count.
+//
+// Preconditions: d.nlink != 0 && d.nlink < math.MaxUint32.
+func (d *dentry) incLinks() {
+ v := atomic.AddUint32(&d.nlink, 1)
+ if v < 2 {
+ panic(fmt.Sprintf("dentry.nlink is invalid (was 0 or overflowed): %d", v))
+ }
+}
+
+// decLinks decrements link count.
+//
+// Preconditions: d.nlink > 1.
+func (d *dentry) decLinks() {
+ v := atomic.AddUint32(&d.nlink, ^uint32(0))
+ if v == 0 {
+ panic(fmt.Sprintf("dentry.nlink must be greater than 0: %d", v))
+ }
+}
+
// fileDescription is embedded by gofer implementations of
// vfs.FileDescriptionImpl.
type fileDescription struct {
@@ -1112,7 +1140,8 @@ func (fd *fileDescription) dentry() *dentry {
// Stat implements vfs.FileDescriptionImpl.Stat.
func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
d := fd.dentry()
- if d.fs.opts.interop == InteropModeShared && opts.Mask&(linux.STATX_MODE|linux.STATX_UID|linux.STATX_GID|linux.STATX_ATIME|linux.STATX_MTIME|linux.STATX_CTIME|linux.STATX_SIZE|linux.STATX_BLOCKS|linux.STATX_BTIME) != 0 && opts.Sync != linux.AT_STATX_DONT_SYNC {
+ const validMask = uint32(linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_SIZE | linux.STATX_BLOCKS | linux.STATX_BTIME)
+ if d.fs.opts.interop == InteropModeShared && opts.Mask&(validMask) != 0 && opts.Sync != linux.AT_STATX_DONT_SYNC {
// TODO(jamieliu): Use specialFileFD.handle.file for the getattr if
// available?
if err := d.updateFromGetattr(ctx); err != nil {
diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
index e7695e995..2eb210014 100644
--- a/pkg/sentry/syscalls/linux/vfs2/BUILD
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -31,6 +31,7 @@ go_library(
visibility = ["//:sandbox"],
deps = [
"//pkg/abi/linux",
+ "//pkg/bits",
"//pkg/fspath",
"//pkg/gohacks",
"//pkg/sentry/arch",
diff --git a/pkg/sentry/syscalls/linux/vfs2/filesystem.go b/pkg/sentry/syscalls/linux/vfs2/filesystem.go
index fc5ceea4c..a859095e2 100644
--- a/pkg/sentry/syscalls/linux/vfs2/filesystem.go
+++ b/pkg/sentry/syscalls/linux/vfs2/filesystem.go
@@ -250,7 +250,7 @@ func rmdirat(t *kernel.Task, dirfd int32, pathAddr usermem.Addr) error {
if err != nil {
return err
}
- tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, followFinalSymlink)
+ tpop, err := getTaskPathOperation(t, dirfd, path, disallowEmptyPath, nofollowFinalSymlink)
if err != nil {
return err
}
diff --git a/pkg/sentry/syscalls/linux/vfs2/getdents.go b/pkg/sentry/syscalls/linux/vfs2/getdents.go
index ddc140b65..a61cc5059 100644
--- a/pkg/sentry/syscalls/linux/vfs2/getdents.go
+++ b/pkg/sentry/syscalls/linux/vfs2/getdents.go
@@ -97,7 +97,7 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
// char d_name[]; /* Filename (null-terminated) */
// };
size := 8 + 8 + 2 + 1 + 1 + len(dirent.Name)
- if size < cb.remaining {
+ if size > cb.remaining {
return syserror.EINVAL
}
buf = cb.t.CopyScratchBuffer(size)
@@ -125,7 +125,7 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
panic(fmt.Sprintf("unsupported sizeof(unsigned long): %d", cb.t.Arch().Width()))
}
size := 8 + 8 + 2 + 1 + 1 + 1 + len(dirent.Name)
- if size < cb.remaining {
+ if size > cb.remaining {
return syserror.EINVAL
}
buf = cb.t.CopyScratchBuffer(size)
diff --git a/pkg/sentry/syscalls/linux/vfs2/stat.go b/pkg/sentry/syscalls/linux/vfs2/stat.go
index 068243132..fdfe49243 100644
--- a/pkg/sentry/syscalls/linux/vfs2/stat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/stat.go
@@ -16,6 +16,7 @@ package vfs2
import (
"gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/bits"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/gohacks"
"gvisor.dev/gvisor/pkg/sentry/arch"
@@ -153,7 +154,11 @@ func Statx(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
if flags&^(linux.AT_EMPTY_PATH|linux.AT_SYMLINK_NOFOLLOW|linux.AT_STATX_SYNC_TYPE) != 0 {
return 0, nil, syserror.EINVAL
}
-
+ // Make sure that only one sync type option is set.
+ syncType := uint32(flags & linux.AT_STATX_SYNC_TYPE)
+ if syncType != 0 && !bits.IsPowerOfTwo32(syncType) {
+ return 0, nil, syserror.EINVAL
+ }
if mask&linux.STATX__RESERVED != 0 {
return 0, nil, syserror.EINVAL
}
diff --git a/pkg/sentry/vfs/resolving_path.go b/pkg/sentry/vfs/resolving_path.go
index eb4ebb511..8f31495da 100644
--- a/pkg/sentry/vfs/resolving_path.go
+++ b/pkg/sentry/vfs/resolving_path.go
@@ -329,10 +329,22 @@ func (rp *ResolvingPath) ResolveComponent(d *Dentry) (*Dentry, error) {
// component in pcs represents a symbolic link, the symbolic link should be
// followed.
//
+// If path is terminated with '/', the '/' is considered the last element and
+// any symlink before that is followed:
+// - For most non-creating walks, the last path component is handled by
+// fs/namei.c:lookup_last(), which sets LOOKUP_FOLLOW if the first byte
+// after the path component is non-NULL (which is only possible if it's '/')
+// and the path component is of type LAST_NORM.
+//
+// - For open/openat/openat2 without O_CREAT, the last path component is
+// handled by fs/namei.c:do_last(), which does the same, though without the
+// LAST_NORM check.
+//
// Preconditions: !rp.Done().
func (rp *ResolvingPath) ShouldFollowSymlink() bool {
- // Non-final symlinks are always followed.
- return rp.flags&rpflagsFollowFinalSymlink != 0 || !rp.Final()
+ // Non-final symlinks are always followed. Paths terminated with '/' are also
+ // always followed.
+ return rp.flags&rpflagsFollowFinalSymlink != 0 || !rp.Final() || rp.MustBeDir()
}
// HandleSymlink is called when the current path component is a symbolic link
diff --git a/test/syscalls/linux/stat.cc b/test/syscalls/linux/stat.cc
index 513b9cd1c..2503960f3 100644
--- a/test/syscalls/linux/stat.cc
+++ b/test/syscalls/linux/stat.cc
@@ -34,6 +34,13 @@
#include "test/util/temp_path.h"
#include "test/util/test_util.h"
+#ifndef AT_STATX_FORCE_SYNC
+#define AT_STATX_FORCE_SYNC 0x2000
+#endif
+#ifndef AT_STATX_DONT_SYNC
+#define AT_STATX_DONT_SYNC 0x4000
+#endif
+
namespace gvisor {
namespace testing {
@@ -700,8 +707,10 @@ TEST_F(StatTest, StatxInvalidFlags) {
struct kernel_statx stx;
EXPECT_THAT(statx(AT_FDCWD, test_file_name_.c_str(), 12345, 0, &stx),
SyscallFailsWithErrno(EINVAL));
+
+ // Sync flags are mutually exclusive.
EXPECT_THAT(statx(AT_FDCWD, test_file_name_.c_str(),
- 0x6000 /* AT_STATX_SYNC_TYPE */, 0, &stx),
+ AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC, 0, &stx),
SyscallFailsWithErrno(EINVAL));
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 14:44:53 +0000