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-rw-r--r--pkg/sentry/fs/inode_overlay.go9
-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go42
-rw-r--r--pkg/sentry/fsimpl/overlay/copy_up.go52
-rw-r--r--pkg/sentry/fsimpl/overlay/filesystem.go120
-rw-r--r--pkg/sentry/fsimpl/overlay/overlay.go36
-rw-r--r--pkg/sentry/fsimpl/tmpfs/tmpfs.go46
-rw-r--r--pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go6
-rw-r--r--pkg/sentry/platform/ring0/defs_impl_arm64.go2
-rw-r--r--pkg/sentry/time/seqatomic_parameters_unsafe.go6
-rw-r--r--pkg/sentry/vfs/permissions.go38
10 files changed, 270 insertions, 87 deletions
diff --git a/pkg/sentry/fs/inode_overlay.go b/pkg/sentry/fs/inode_overlay.go
index dc2e353d9..0a2d64e3a 100644
--- a/pkg/sentry/fs/inode_overlay.go
+++ b/pkg/sentry/fs/inode_overlay.go
@@ -16,7 +16,6 @@ package fs
import (
"fmt"
- "strings"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
@@ -539,7 +538,7 @@ func overlayGetXattr(ctx context.Context, o *overlayEntry, name string, size uin
// Don't forward the value of the extended attribute if it would
// unexpectedly change the behavior of a wrapping overlay layer.
- if strings.HasPrefix(XattrOverlayPrefix, name) {
+ if isXattrOverlay(name) {
return "", syserror.ENODATA
}
@@ -555,7 +554,7 @@ func overlayGetXattr(ctx context.Context, o *overlayEntry, name string, size uin
func overlaySetxattr(ctx context.Context, o *overlayEntry, d *Dirent, name, value string, flags uint32) error {
// Don't allow changes to overlay xattrs through a setxattr syscall.
- if strings.HasPrefix(XattrOverlayPrefix, name) {
+ if isXattrOverlay(name) {
return syserror.EPERM
}
@@ -578,7 +577,7 @@ func overlayListXattr(ctx context.Context, o *overlayEntry, size uint64) (map[st
for name := range names {
// Same as overlayGetXattr, we shouldn't forward along
// overlay attributes.
- if strings.HasPrefix(XattrOverlayPrefix, name) {
+ if isXattrOverlay(name) {
delete(names, name)
}
}
@@ -587,7 +586,7 @@ func overlayListXattr(ctx context.Context, o *overlayEntry, size uint64) (map[st
func overlayRemoveXattr(ctx context.Context, o *overlayEntry, d *Dirent, name string) error {
// Don't allow changes to overlay xattrs through a removexattr syscall.
- if strings.HasPrefix(XattrOverlayPrefix, name) {
+ if isXattrOverlay(name) {
return syserror.EPERM
}
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 73d9e772d..78b07f1b3 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -1067,6 +1067,21 @@ func (d *dentry) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes)
return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid)))
}
+func (d *dentry) checkXattrPermissions(creds *auth.Credentials, name string, ats vfs.AccessTypes) error {
+ // We only support xattrs prefixed with "user." (see b/148380782). Currently,
+ // there is no need to expose any other xattrs through a gofer.
+ if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) {
+ return syserror.EOPNOTSUPP
+ }
+ mode := linux.FileMode(atomic.LoadUint32(&d.mode))
+ kuid := auth.KUID(atomic.LoadUint32(&d.uid))
+ kgid := auth.KGID(atomic.LoadUint32(&d.gid))
+ if err := vfs.GenericCheckPermissions(creds, ats, mode, kuid, kgid); err != nil {
+ return err
+ }
+ return vfs.CheckXattrPermissions(creds, ats, mode, kuid, name)
+}
+
func (d *dentry) mayDelete(creds *auth.Credentials, child *dentry) error {
return vfs.CheckDeleteSticky(creds, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&child.uid)))
}
@@ -1357,8 +1372,6 @@ func (d *dentry) setDeleted() {
atomic.StoreUint32(&d.deleted, 1)
}
-// We only support xattrs prefixed with "user." (see b/148380782). Currently,
-// there is no need to expose any other xattrs through a gofer.
func (d *dentry) listxattr(ctx context.Context, creds *auth.Credentials, size uint64) ([]string, error) {
if d.file.isNil() || !d.userXattrSupported() {
return nil, nil
@@ -1369,6 +1382,7 @@ func (d *dentry) listxattr(ctx context.Context, creds *auth.Credentials, size ui
}
xattrs := make([]string, 0, len(xattrMap))
for x := range xattrMap {
+ // We only support xattrs in the user.* namespace.
if strings.HasPrefix(x, linux.XATTR_USER_PREFIX) {
xattrs = append(xattrs, x)
}
@@ -1380,15 +1394,9 @@ func (d *dentry) getxattr(ctx context.Context, creds *auth.Credentials, opts *vf
if d.file.isNil() {
return "", syserror.ENODATA
}
- if err := d.checkPermissions(creds, vfs.MayRead); err != nil {
+ if err := d.checkXattrPermissions(creds, opts.Name, vfs.MayRead); err != nil {
return "", err
}
- if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) {
- return "", syserror.EOPNOTSUPP
- }
- if !d.userXattrSupported() {
- return "", syserror.ENODATA
- }
return d.file.getXattr(ctx, opts.Name, opts.Size)
}
@@ -1396,15 +1404,9 @@ func (d *dentry) setxattr(ctx context.Context, creds *auth.Credentials, opts *vf
if d.file.isNil() {
return syserror.EPERM
}
- if err := d.checkPermissions(creds, vfs.MayWrite); err != nil {
+ if err := d.checkXattrPermissions(creds, opts.Name, vfs.MayWrite); err != nil {
return err
}
- if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) {
- return syserror.EOPNOTSUPP
- }
- if !d.userXattrSupported() {
- return syserror.EPERM
- }
return d.file.setXattr(ctx, opts.Name, opts.Value, opts.Flags)
}
@@ -1412,15 +1414,9 @@ func (d *dentry) removexattr(ctx context.Context, creds *auth.Credentials, name
if d.file.isNil() {
return syserror.EPERM
}
- if err := d.checkPermissions(creds, vfs.MayWrite); err != nil {
+ if err := d.checkXattrPermissions(creds, name, vfs.MayWrite); err != nil {
return err
}
- if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) {
- return syserror.EOPNOTSUPP
- }
- if !d.userXattrSupported() {
- return syserror.EPERM
- }
return d.file.removeXattr(ctx, name)
}
diff --git a/pkg/sentry/fsimpl/overlay/copy_up.go b/pkg/sentry/fsimpl/overlay/copy_up.go
index 13735eb05..ba7b8495a 100644
--- a/pkg/sentry/fsimpl/overlay/copy_up.go
+++ b/pkg/sentry/fsimpl/overlay/copy_up.go
@@ -91,6 +91,10 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
if err != nil {
ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after copy-up error: %v", err)
}
+ if d.upperVD.Ok() {
+ d.upperVD.DecRef(ctx)
+ d.upperVD = vfs.VirtualDentry{}
+ }
}
switch ftype {
case linux.S_IFREG:
@@ -234,7 +238,10 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
panic(fmt.Sprintf("unexpected file type %o", ftype))
}
- // TODO(gvisor.dev/issue/1199): copy up xattrs
+ if err := d.copyXattrsLocked(ctx); err != nil {
+ cleanupUndoCopyUp()
+ return err
+ }
// Update the dentry's device and inode numbers (except for directories,
// for which these remain overlay-assigned).
@@ -246,14 +253,10 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
Mask: linux.STATX_INO,
})
if err != nil {
- d.upperVD.DecRef(ctx)
- d.upperVD = vfs.VirtualDentry{}
cleanupUndoCopyUp()
return err
}
if upperStat.Mask&linux.STATX_INO == 0 {
- d.upperVD.DecRef(ctx)
- d.upperVD = vfs.VirtualDentry{}
cleanupUndoCopyUp()
return syserror.EREMOTE
}
@@ -265,3 +268,42 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
atomic.StoreUint32(&d.copiedUp, 1)
return nil
}
+
+// copyXattrsLocked copies a subset of lower's extended attributes to upper.
+// Attributes that configure an overlay in the lower are not copied up.
+//
+// Preconditions: d.copyMu must be locked for writing.
+func (d *dentry) copyXattrsLocked(ctx context.Context) error {
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ lowerPop := &vfs.PathOperation{Root: d.lowerVDs[0], Start: d.lowerVDs[0]}
+ upperPop := &vfs.PathOperation{Root: d.upperVD, Start: d.upperVD}
+
+ lowerXattrs, err := vfsObj.ListxattrAt(ctx, d.fs.creds, lowerPop, 0)
+ if err != nil {
+ if err == syserror.EOPNOTSUPP {
+ // There are no guarantees as to the contents of lowerXattrs.
+ return nil
+ }
+ ctx.Warningf("failed to copy up xattrs because ListxattrAt failed: %v", err)
+ return err
+ }
+
+ for _, name := range lowerXattrs {
+ // Do not copy up overlay attributes.
+ if isOverlayXattr(name) {
+ continue
+ }
+
+ value, err := vfsObj.GetxattrAt(ctx, d.fs.creds, lowerPop, &vfs.GetxattrOptions{Name: name, Size: 0})
+ if err != nil {
+ ctx.Warningf("failed to copy up xattrs because GetxattrAt failed: %v", err)
+ return err
+ }
+
+ if err := vfsObj.SetxattrAt(ctx, d.fs.creds, upperPop, &vfs.SetxattrOptions{Name: name, Value: value}); err != nil {
+ ctx.Warningf("failed to copy up xattrs because SetxattrAt failed: %v", err)
+ return err
+ }
+ }
+ return nil
+}
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index 63df86481..46528c99c 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -15,6 +15,7 @@
package overlay
import (
+ "strings"
"sync/atomic"
"gvisor.dev/gvisor/pkg/abi/linux"
@@ -27,10 +28,15 @@ import (
"gvisor.dev/gvisor/pkg/syserror"
)
+// _OVL_XATTR_PREFIX is an extended attribute key prefix to identify overlayfs
+// attributes.
+// Linux: fs/overlayfs/overlayfs.h:OVL_XATTR_PREFIX
+const _OVL_XATTR_PREFIX = linux.XATTR_TRUSTED_PREFIX + "overlay."
+
// _OVL_XATTR_OPAQUE is an extended attribute key whose value is set to "y" for
// opaque directories.
// Linux: fs/overlayfs/overlayfs.h:OVL_XATTR_OPAQUE
-const _OVL_XATTR_OPAQUE = linux.XATTR_TRUSTED_PREFIX + "overlay.opaque"
+const _OVL_XATTR_OPAQUE = _OVL_XATTR_PREFIX + "opaque"
func isWhiteout(stat *linux.Statx) bool {
return stat.Mode&linux.S_IFMT == linux.S_IFCHR && stat.RdevMajor == 0 && stat.RdevMinor == 0
@@ -1347,18 +1353,42 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
return nil
}
+// isOverlayXattr returns whether the given extended attribute configures the
+// overlay.
+func isOverlayXattr(name string) bool {
+ return strings.HasPrefix(name, _OVL_XATTR_PREFIX)
+}
+
// ListxattrAt implements vfs.FilesystemImpl.ListxattrAt.
func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath, size uint64) ([]string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
- _, err := fs.resolveLocked(ctx, rp, &ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
}
- // TODO(gvisor.dev/issue/1199): Linux overlayfs actually allows listxattr,
- // but not any other xattr syscalls. For now we just reject all of them.
- return nil, syserror.ENOTSUP
+
+ return fs.listXattr(ctx, d, size)
+}
+
+func (fs *filesystem) listXattr(ctx context.Context, d *dentry, size uint64) ([]string, error) {
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ top := d.topLayer()
+ names, err := vfsObj.ListxattrAt(ctx, fs.creds, &vfs.PathOperation{Root: top, Start: top}, size)
+ if err != nil {
+ return nil, err
+ }
+
+ // Filter out all overlay attributes.
+ n := 0
+ for _, name := range names {
+ if !isOverlayXattr(name) {
+ names[n] = name
+ n++
+ }
+ }
+ return names[:n], err
}
// GetxattrAt implements vfs.FilesystemImpl.GetxattrAt.
@@ -1366,11 +1396,29 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
- _, err := fs.resolveLocked(ctx, rp, &ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return "", err
}
- return "", syserror.ENOTSUP
+
+ return fs.getXattr(ctx, d, rp.Credentials(), &opts)
+}
+
+func (fs *filesystem) getXattr(ctx context.Context, d *dentry, creds *auth.Credentials, opts *vfs.GetxattrOptions) (string, error) {
+ if err := d.checkXattrPermissions(creds, opts.Name, vfs.MayRead); err != nil {
+ return "", err
+ }
+
+ // Return EOPNOTSUPP when fetching an overlay attribute.
+ // See fs/overlayfs/super.c:ovl_own_xattr_get().
+ if isOverlayXattr(opts.Name) {
+ return "", syserror.EOPNOTSUPP
+ }
+
+ // Analogous to fs/overlayfs/super.c:ovl_other_xattr_get().
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ top := d.topLayer()
+ return vfsObj.GetxattrAt(ctx, fs.creds, &vfs.PathOperation{Root: top, Start: top}, opts)
}
// SetxattrAt implements vfs.FilesystemImpl.SetxattrAt.
@@ -1378,11 +1426,36 @@ func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
- _, err := fs.resolveLocked(ctx, rp, &ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return err
}
- return syserror.ENOTSUP
+
+ return fs.setXattrLocked(ctx, d, rp.Mount(), rp.Credentials(), &opts)
+}
+
+// Precondition: fs.renameMu must be locked.
+func (fs *filesystem) setXattrLocked(ctx context.Context, d *dentry, mnt *vfs.Mount, creds *auth.Credentials, opts *vfs.SetxattrOptions) error {
+ if err := d.checkXattrPermissions(creds, opts.Name, vfs.MayWrite); err != nil {
+ return err
+ }
+
+ // Return EOPNOTSUPP when setting an overlay attribute.
+ // See fs/overlayfs/super.c:ovl_own_xattr_set().
+ if isOverlayXattr(opts.Name) {
+ return syserror.EOPNOTSUPP
+ }
+
+ // Analogous to fs/overlayfs/super.c:ovl_other_xattr_set().
+ if err := mnt.CheckBeginWrite(); err != nil {
+ return err
+ }
+ defer mnt.EndWrite()
+ if err := d.copyUpLocked(ctx); err != nil {
+ return err
+ }
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ return vfsObj.SetxattrAt(ctx, fs.creds, &vfs.PathOperation{Root: d.upperVD, Start: d.upperVD}, opts)
}
// RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt.
@@ -1390,11 +1463,36 @@ func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
- _, err := fs.resolveLocked(ctx, rp, &ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return err
}
- return syserror.ENOTSUP
+
+ return fs.removeXattrLocked(ctx, d, rp.Mount(), rp.Credentials(), name)
+}
+
+// Precondition: fs.renameMu must be locked.
+func (fs *filesystem) removeXattrLocked(ctx context.Context, d *dentry, mnt *vfs.Mount, creds *auth.Credentials, name string) error {
+ if err := d.checkXattrPermissions(creds, name, vfs.MayWrite); err != nil {
+ return err
+ }
+
+ // Like SetxattrAt, return EOPNOTSUPP when removing an overlay attribute.
+ // Linux passes the remove request to xattr_handler->set.
+ // See fs/xattr.c:vfs_removexattr().
+ if isOverlayXattr(name) {
+ return syserror.EOPNOTSUPP
+ }
+
+ if err := mnt.CheckBeginWrite(); err != nil {
+ return err
+ }
+ defer mnt.EndWrite()
+ if err := d.copyUpLocked(ctx); err != nil {
+ return err
+ }
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ return vfsObj.RemovexattrAt(ctx, fs.creds, &vfs.PathOperation{Root: d.upperVD, Start: d.upperVD}, name)
}
// PrependPath implements vfs.FilesystemImpl.PrependPath.
diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go
index 00562667f..e706f9d4e 100644
--- a/pkg/sentry/fsimpl/overlay/overlay.go
+++ b/pkg/sentry/fsimpl/overlay/overlay.go
@@ -570,6 +570,16 @@ func (d *dentry) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes)
return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid)))
}
+func (d *dentry) checkXattrPermissions(creds *auth.Credentials, name string, ats vfs.AccessTypes) error {
+ mode := linux.FileMode(atomic.LoadUint32(&d.mode))
+ kuid := auth.KUID(atomic.LoadUint32(&d.uid))
+ kgid := auth.KGID(atomic.LoadUint32(&d.gid))
+ if err := vfs.GenericCheckPermissions(creds, ats, mode, kuid, kgid); err != nil {
+ return err
+ }
+ return vfs.CheckXattrPermissions(creds, ats, mode, kuid, name)
+}
+
// statInternalMask is the set of stat fields that is set by
// dentry.statInternalTo().
const statInternalMask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO
@@ -622,6 +632,32 @@ func (fd *fileDescription) dentry() *dentry {
return fd.vfsfd.Dentry().Impl().(*dentry)
}
+// Listxattr implements vfs.FileDescriptionImpl.Listxattr.
+func (fd *fileDescription) Listxattr(ctx context.Context, size uint64) ([]string, error) {
+ return fd.filesystem().listXattr(ctx, fd.dentry(), size)
+}
+
+// Getxattr implements vfs.FileDescriptionImpl.Getxattr.
+func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOptions) (string, error) {
+ return fd.filesystem().getXattr(ctx, fd.dentry(), auth.CredentialsFromContext(ctx), &opts)
+}
+
+// Setxattr implements vfs.FileDescriptionImpl.Setxattr.
+func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error {
+ fs := fd.filesystem()
+ fs.renameMu.RLock()
+ defer fs.renameMu.RUnlock()
+ return fs.setXattrLocked(ctx, fd.dentry(), fd.vfsfd.Mount(), auth.CredentialsFromContext(ctx), &opts)
+}
+
+// Removexattr implements vfs.FileDescriptionImpl.Removexattr.
+func (fd *fileDescription) Removexattr(ctx context.Context, name string) error {
+ fs := fd.filesystem()
+ fs.renameMu.RLock()
+ defer fs.renameMu.RUnlock()
+ return fs.removeXattrLocked(ctx, fd.dentry(), fd.vfsfd.Mount(), auth.CredentialsFromContext(ctx), name)
+}
+
// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX.
func (fd *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error {
return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block)
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index c4cec4130..d6074f20f 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -652,44 +652,18 @@ func (i *inode) removexattr(creds *auth.Credentials, name string) error {
}
func (i *inode) checkXattrPermissions(creds *auth.Credentials, name string, ats vfs.AccessTypes) error {
- switch {
- case ats&vfs.MayRead == vfs.MayRead:
- if err := i.checkPermissions(creds, vfs.MayRead); err != nil {
- return err
- }
- case ats&vfs.MayWrite == vfs.MayWrite:
- if err := i.checkPermissions(creds, vfs.MayWrite); err != nil {
- return err
- }
- default:
- panic(fmt.Sprintf("checkXattrPermissions called with impossible AccessTypes: %v", ats))
+ // We currently only support extended attributes in the user.* and
+ // trusted.* namespaces. See b/148380782.
+ if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) && !strings.HasPrefix(name, linux.XATTR_TRUSTED_PREFIX) {
+ return syserror.EOPNOTSUPP
}
-
- switch {
- case strings.HasPrefix(name, linux.XATTR_TRUSTED_PREFIX):
- // The trusted.* namespace can only be accessed by privileged
- // users.
- if creds.HasCapability(linux.CAP_SYS_ADMIN) {
- return nil
- }
- if ats&vfs.MayWrite == vfs.MayWrite {
- return syserror.EPERM
- }
- return syserror.ENODATA
- case strings.HasPrefix(name, linux.XATTR_USER_PREFIX):
- // Extended attributes in the user.* namespace are only
- // supported for regular files and directories.
- filetype := linux.S_IFMT & atomic.LoadUint32(&i.mode)
- if filetype == linux.S_IFREG || filetype == linux.S_IFDIR {
- return nil
- }
- if ats&vfs.MayWrite == vfs.MayWrite {
- return syserror.EPERM
- }
- return syserror.ENODATA
-
+ mode := linux.FileMode(atomic.LoadUint32(&i.mode))
+ kuid := auth.KUID(atomic.LoadUint32(&i.uid))
+ kgid := auth.KGID(atomic.LoadUint32(&i.gid))
+ if err := vfs.GenericCheckPermissions(creds, ats, mode, kuid, kgid); err != nil {
+ return err
}
- return syserror.EOPNOTSUPP
+ return vfs.CheckXattrPermissions(creds, ats, mode, kuid, name)
}
// fileDescription is embedded by tmpfs implementations of
diff --git a/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go b/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
index a0f2fe45c..90148bbb2 100644
--- a/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
+++ b/pkg/sentry/kernel/seqatomic_taskgoroutineschedinfo_unsafe.go
@@ -1,12 +1,12 @@
package kernel
import (
- "unsafe"
-
"fmt"
- "gvisor.dev/gvisor/pkg/sync"
"reflect"
"strings"
+ "unsafe"
+
+ "gvisor.dev/gvisor/pkg/sync"
)
// SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race
diff --git a/pkg/sentry/platform/ring0/defs_impl_arm64.go b/pkg/sentry/platform/ring0/defs_impl_arm64.go
index 2dac9ad14..424b66f76 100644
--- a/pkg/sentry/platform/ring0/defs_impl_arm64.go
+++ b/pkg/sentry/platform/ring0/defs_impl_arm64.go
@@ -3,11 +3,11 @@ package ring0
import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
- "reflect"
"fmt"
"gvisor.dev/gvisor/pkg/usermem"
"io"
+ "reflect"
)
// Useful bits.
diff --git a/pkg/sentry/time/seqatomic_parameters_unsafe.go b/pkg/sentry/time/seqatomic_parameters_unsafe.go
index f18440378..2cb001080 100644
--- a/pkg/sentry/time/seqatomic_parameters_unsafe.go
+++ b/pkg/sentry/time/seqatomic_parameters_unsafe.go
@@ -1,12 +1,12 @@
package time
import (
- "unsafe"
-
"fmt"
- "gvisor.dev/gvisor/pkg/sync"
"reflect"
"strings"
+ "unsafe"
+
+ "gvisor.dev/gvisor/pkg/sync"
)
// SeqAtomicLoad returns a copy of *ptr, ensuring that the read does not race
diff --git a/pkg/sentry/vfs/permissions.go b/pkg/sentry/vfs/permissions.go
index 014b928ed..00eeb8842 100644
--- a/pkg/sentry/vfs/permissions.go
+++ b/pkg/sentry/vfs/permissions.go
@@ -16,6 +16,7 @@ package vfs
import (
"math"
+ "strings"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
@@ -284,3 +285,40 @@ func CheckLimit(ctx context.Context, offset, size int64) (int64, error) {
}
return size, nil
}
+
+// CheckXattrPermissions checks permissions for extended attribute access.
+// This is analogous to fs/xattr.c:xattr_permission(). Some key differences:
+// * Does not check for read-only filesystem property.
+// * Does not check inode immutability or append only mode. In both cases EPERM
+// must be returned by filesystem implementations.
+// * Does not do inode permission checks. Filesystem implementations should
+// handle inode permission checks as they may differ across implementations.
+func CheckXattrPermissions(creds *auth.Credentials, ats AccessTypes, mode linux.FileMode, kuid auth.KUID, name string) error {
+ switch {
+ case strings.HasPrefix(name, linux.XATTR_TRUSTED_PREFIX):
+ // The trusted.* namespace can only be accessed by privileged
+ // users.
+ if creds.HasCapability(linux.CAP_SYS_ADMIN) {
+ return nil
+ }
+ if ats.MayWrite() {
+ return syserror.EPERM
+ }
+ return syserror.ENODATA
+ case strings.HasPrefix(name, linux.XATTR_USER_PREFIX):
+ // In the user.* namespace, only regular files and directories can have
+ // extended attributes. For sticky directories, only the owner and
+ // privileged users can write attributes.
+ filetype := mode.FileType()
+ if filetype != linux.ModeRegular && filetype != linux.ModeDirectory {
+ if ats.MayWrite() {
+ return syserror.EPERM
+ }
+ return syserror.ENODATA
+ }
+ if filetype == linux.ModeDirectory && mode&linux.ModeSticky != 0 && ats.MayWrite() && !CanActAsOwner(creds, kuid) {
+ return syserror.EPERM
+ }
+ }
+ return nil
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 08:08:31 +0000