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-rw-r--r--pkg/sentry/fsimpl/gofer/time.go3
-rw-r--r--pkg/sentry/fsimpl/tmpfs/tmpfs.go41
-rw-r--r--pkg/sentry/kernel/auth/credentials.go28
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/BUILD1
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/mount.go145
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/vfs2.go4
-rw-r--r--pkg/sentry/vfs/genericfstree/genericfstree.go3
-rw-r--r--pkg/sentry/vfs/mount.go34
-rw-r--r--pkg/sentry/vfs/options.go4
-rw-r--r--pkg/sentry/vfs/vfs.go2
10 files changed, 246 insertions, 19 deletions
diff --git a/pkg/sentry/fsimpl/gofer/time.go b/pkg/sentry/fsimpl/gofer/time.go
index 2608e7e1d..1d5aa82dc 100644
--- a/pkg/sentry/fsimpl/gofer/time.go
+++ b/pkg/sentry/fsimpl/gofer/time.go
@@ -38,6 +38,9 @@ func statxTimestampFromDentry(ns int64) linux.StatxTimestamp {
// Preconditions: fs.interop != InteropModeShared.
func (d *dentry) touchAtime(mnt *vfs.Mount) {
+ if mnt.Flags.NoATime {
+ return
+ }
if err := mnt.CheckBeginWrite(); err != nil {
return
}
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index f0e098702..3777ebdf2 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -30,6 +30,7 @@ package tmpfs
import (
"fmt"
"math"
+ "strconv"
"strings"
"sync/atomic"
@@ -124,14 +125,45 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
}
fs.vfsfs.Init(vfsObj, newFSType, &fs)
+ mopts := vfs.GenericParseMountOptions(opts.Data)
+
+ defaultMode := linux.FileMode(0777)
+ if modeStr, ok := mopts["mode"]; ok {
+ mode, err := strconv.ParseUint(modeStr, 8, 32)
+ if err != nil {
+ return nil, nil, fmt.Errorf("Mount option \"mode='%v'\" not parsable: %v", modeStr, err)
+ }
+ defaultMode = linux.FileMode(mode)
+ }
+
+ defaultOwnerCreds := creds.Fork()
+ if uidStr, ok := mopts["uid"]; ok {
+ uid, err := strconv.ParseInt(uidStr, 10, 32)
+ if err != nil {
+ return nil, nil, fmt.Errorf("Mount option \"uid='%v'\" not parsable: %v", uidStr, err)
+ }
+ if err := defaultOwnerCreds.SetUID(auth.UID(uid)); err != nil {
+ return nil, nil, fmt.Errorf("Error using mount option \"uid='%v'\": %v", uidStr, err)
+ }
+ }
+ if gidStr, ok := mopts["gid"]; ok {
+ gid, err := strconv.ParseInt(gidStr, 10, 32)
+ if err != nil {
+ return nil, nil, fmt.Errorf("Mount option \"gid='%v'\" not parsable: %v", gidStr, err)
+ }
+ if err := defaultOwnerCreds.SetGID(auth.GID(gid)); err != nil {
+ return nil, nil, fmt.Errorf("Error using mount option \"gid='%v'\": %v", gidStr, err)
+ }
+ }
+
var root *dentry
switch rootFileType {
case linux.S_IFREG:
- root = fs.newDentry(fs.newRegularFile(creds, 0777))
+ root = fs.newDentry(fs.newRegularFile(defaultOwnerCreds, defaultMode))
case linux.S_IFLNK:
- root = fs.newDentry(fs.newSymlink(creds, tmpfsOpts.RootSymlinkTarget))
+ root = fs.newDentry(fs.newSymlink(defaultOwnerCreds, tmpfsOpts.RootSymlinkTarget))
case linux.S_IFDIR:
- root = &fs.newDirectory(creds, 01777).dentry
+ root = &fs.newDirectory(defaultOwnerCreds, defaultMode).dentry
default:
fs.vfsfs.DecRef()
return nil, nil, fmt.Errorf("invalid tmpfs root file type: %#o", rootFileType)
@@ -562,6 +594,9 @@ func (i *inode) isDir() bool {
}
func (i *inode) touchAtime(mnt *vfs.Mount) {
+ if mnt.Flags.NoATime {
+ return
+ }
if err := mnt.CheckBeginWrite(); err != nil {
return
}
diff --git a/pkg/sentry/kernel/auth/credentials.go b/pkg/sentry/kernel/auth/credentials.go
index e057d2c6d..6862f2ef5 100644
--- a/pkg/sentry/kernel/auth/credentials.go
+++ b/pkg/sentry/kernel/auth/credentials.go
@@ -232,3 +232,31 @@ func (c *Credentials) UseGID(gid GID) (KGID, error) {
}
return NoID, syserror.EPERM
}
+
+// SetUID translates the provided uid to the root user namespace and updates c's
+// uids to it. This performs no permissions or capabilities checks, the caller
+// is responsible for ensuring the calling context is permitted to modify c.
+func (c *Credentials) SetUID(uid UID) error {
+ kuid := c.UserNamespace.MapToKUID(uid)
+ if !kuid.Ok() {
+ return syserror.EINVAL
+ }
+ c.RealKUID = kuid
+ c.EffectiveKUID = kuid
+ c.SavedKUID = kuid
+ return nil
+}
+
+// SetGID translates the provided gid to the root user namespace and updates c's
+// gids to it. This performs no permissions or capabilities checks, the caller
+// is responsible for ensuring the calling context is permitted to modify c.
+func (c *Credentials) SetGID(gid GID) error {
+ kgid := c.UserNamespace.MapToKGID(gid)
+ if !kgid.Ok() {
+ return syserror.EINVAL
+ }
+ c.RealKGID = kgid
+ c.EffectiveKGID = kgid
+ c.SavedKGID = kgid
+ return nil
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
index 9c8b44f64..c0d005247 100644
--- a/pkg/sentry/syscalls/linux/vfs2/BUILD
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -16,6 +16,7 @@ go_library(
"ioctl.go",
"memfd.go",
"mmap.go",
+ "mount.go",
"path.go",
"pipe.go",
"poll.go",
diff --git a/pkg/sentry/syscalls/linux/vfs2/mount.go b/pkg/sentry/syscalls/linux/vfs2/mount.go
new file mode 100644
index 000000000..adeaa39cc
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/mount.go
@@ -0,0 +1,145 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs2
+
+import (
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/sentry/arch"
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
+)
+
+// Mount implements Linux syscall mount(2).
+func Mount(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ sourceAddr := args[0].Pointer()
+ targetAddr := args[1].Pointer()
+ typeAddr := args[2].Pointer()
+ flags := args[3].Uint64()
+ dataAddr := args[4].Pointer()
+
+ // For null-terminated strings related to mount(2), Linux copies in at most
+ // a page worth of data. See fs/namespace.c:copy_mount_string().
+ fsType, err := t.CopyInString(typeAddr, usermem.PageSize)
+ if err != nil {
+ return 0, nil, err
+ }
+ source, err := t.CopyInString(sourceAddr, usermem.PageSize)
+ if err != nil {
+ return 0, nil, err
+ }
+
+ targetPath, err := copyInPath(t, targetAddr)
+ if err != nil {
+ return 0, nil, err
+ }
+
+ data := ""
+ if dataAddr != 0 {
+ // In Linux, a full page is always copied in regardless of null
+ // character placement, and the address is passed to each file system.
+ // Most file systems always treat this data as a string, though, and so
+ // do all of the ones we implement.
+ data, err = t.CopyInString(dataAddr, usermem.PageSize)
+ if err != nil {
+ return 0, nil, err
+ }
+ }
+
+ // Ignore magic value that was required before Linux 2.4.
+ if flags&linux.MS_MGC_MSK == linux.MS_MGC_VAL {
+ flags = flags &^ linux.MS_MGC_MSK
+ }
+
+ // Must have CAP_SYS_ADMIN in the current mount namespace's associated user
+ // namespace.
+ creds := t.Credentials()
+ if !creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, t.MountNamespaceVFS2().Owner) {
+ return 0, nil, syserror.EPERM
+ }
+
+ const unsupportedOps = linux.MS_REMOUNT | linux.MS_BIND |
+ linux.MS_SHARED | linux.MS_PRIVATE | linux.MS_SLAVE |
+ linux.MS_UNBINDABLE | linux.MS_MOVE
+
+ // Silently allow MS_NOSUID, since we don't implement set-id bits
+ // anyway.
+ const unsupportedFlags = linux.MS_NODEV |
+ linux.MS_NODIRATIME | linux.MS_STRICTATIME
+
+ // Linux just allows passing any flags to mount(2) - it won't fail when
+ // unknown or unsupported flags are passed. Since we don't implement
+ // everything, we fail explicitly on flags that are unimplemented.
+ if flags&(unsupportedOps|unsupportedFlags) != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ var opts vfs.MountOptions
+ if flags&linux.MS_NOATIME == linux.MS_NOATIME {
+ opts.Flags.NoATime = true
+ }
+ if flags&linux.MS_NOEXEC == linux.MS_NOEXEC {
+ opts.Flags.NoExec = true
+ }
+ if flags&linux.MS_RDONLY == linux.MS_RDONLY {
+ opts.ReadOnly = true
+ }
+ opts.GetFilesystemOptions.Data = data
+
+ target, err := getTaskPathOperation(t, linux.AT_FDCWD, targetPath, disallowEmptyPath, nofollowFinalSymlink)
+ if err != nil {
+ return 0, nil, err
+ }
+ defer target.Release()
+
+ return 0, nil, t.Kernel().VFS().MountAt(t, creds, source, &target.pop, fsType, &opts)
+}
+
+// Umount2 implements Linux syscall umount2(2).
+func Umount2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ addr := args[0].Pointer()
+ flags := args[1].Int()
+
+ // Must have CAP_SYS_ADMIN in the mount namespace's associated user
+ // namespace.
+ //
+ // Currently, this is always the init task's user namespace.
+ creds := t.Credentials()
+ if !creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, t.MountNamespaceVFS2().Owner) {
+ return 0, nil, syserror.EPERM
+ }
+
+ const unsupported = linux.MNT_FORCE | linux.MNT_EXPIRE
+ if flags&unsupported != 0 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ path, err := copyInPath(t, addr)
+ if err != nil {
+ return 0, nil, err
+ }
+ tpop, err := getTaskPathOperation(t, linux.AT_FDCWD, path, disallowEmptyPath, nofollowFinalSymlink)
+ if err != nil {
+ return 0, nil, err
+ }
+ defer tpop.Release()
+
+ opts := vfs.UmountOptions{
+ Flags: uint32(flags),
+ }
+
+ return 0, nil, t.Kernel().VFS().UmountAt(t, creds, &tpop.pop, &opts)
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/vfs2.go b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
index ef8358b8a..7b6e7571a 100644
--- a/pkg/sentry/syscalls/linux/vfs2/vfs2.go
+++ b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
@@ -90,8 +90,8 @@ func Override() {
s.Table[138] = syscalls.Supported("fstatfs", Fstatfs)
s.Table[161] = syscalls.Supported("chroot", Chroot)
s.Table[162] = syscalls.Supported("sync", Sync)
- delete(s.Table, 165) // mount
- delete(s.Table, 166) // umount2
+ s.Table[165] = syscalls.Supported("mount", Mount)
+ s.Table[166] = syscalls.Supported("umount2", Umount2)
delete(s.Table, 187) // readahead
s.Table[188] = syscalls.Supported("setxattr", Setxattr)
s.Table[189] = syscalls.Supported("lsetxattr", Lsetxattr)
diff --git a/pkg/sentry/vfs/genericfstree/genericfstree.go b/pkg/sentry/vfs/genericfstree/genericfstree.go
index 286510195..8882fa84a 100644
--- a/pkg/sentry/vfs/genericfstree/genericfstree.go
+++ b/pkg/sentry/vfs/genericfstree/genericfstree.go
@@ -43,7 +43,7 @@ type Dentry struct {
// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
// either d2's parent or an ancestor of d2's parent.
func IsAncestorDentry(d, d2 *Dentry) bool {
- for {
+ for d2 != nil { // Stop at root, where d2.parent == nil.
if d2.parent == d {
return true
}
@@ -52,6 +52,7 @@ func IsAncestorDentry(d, d2 *Dentry) bool {
}
d2 = d2.parent
}
+ return false
}
// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index 3adb7c97d..32f901bd8 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -55,6 +55,10 @@ type Mount struct {
// ID is the immutable mount ID.
ID uint64
+ // Flags contains settings as specified for mount(2), e.g. MS_NOEXEC, except
+ // for MS_RDONLY which is tracked in "writers". Immutable.
+ Flags MountFlags
+
// key is protected by VirtualFilesystem.mountMu and
// VirtualFilesystem.mounts.seq, and may be nil. References are held on
// key.parent and key.point if they are not nil.
@@ -81,10 +85,6 @@ type Mount struct {
// umounted is true. umounted is protected by VirtualFilesystem.mountMu.
umounted bool
- // flags contains settings as specified for mount(2), e.g. MS_NOEXEC, except
- // for MS_RDONLY which is tracked in "writers".
- flags MountFlags
-
// The lower 63 bits of writers is the number of calls to
// Mount.CheckBeginWrite() that have not yet been paired with a call to
// Mount.EndWrite(). The MSB of writers is set if MS_RDONLY is in effect.
@@ -95,10 +95,10 @@ type Mount struct {
func newMount(vfs *VirtualFilesystem, fs *Filesystem, root *Dentry, mntns *MountNamespace, opts *MountOptions) *Mount {
mnt := &Mount{
ID: atomic.AddUint64(&vfs.lastMountID, 1),
+ Flags: opts.Flags,
vfs: vfs,
fs: fs,
root: root,
- flags: opts.Flags,
ns: mntns,
refs: 1,
}
@@ -113,13 +113,12 @@ func (mnt *Mount) Options() MountOptions {
mnt.vfs.mountMu.Lock()
defer mnt.vfs.mountMu.Unlock()
return MountOptions{
- Flags: mnt.flags,
+ Flags: mnt.Flags,
ReadOnly: mnt.readOnly(),
}
}
-// A MountNamespace is a collection of Mounts.
-//
+// A MountNamespace is a collection of Mounts.//
// MountNamespaces are reference-counted. Unless otherwise specified, all
// MountNamespace methods require that a reference is held.
//
@@ -127,6 +126,9 @@ func (mnt *Mount) Options() MountOptions {
//
// +stateify savable
type MountNamespace struct {
+ // Owner is the usernamespace that owns this mount namespace.
+ Owner *auth.UserNamespace
+
// root is the MountNamespace's root mount. root is immutable.
root *Mount
@@ -163,6 +165,7 @@ func (vfs *VirtualFilesystem) NewMountNamespace(ctx context.Context, creds *auth
return nil, err
}
mntns := &MountNamespace{
+ Owner: creds.UserNamespace,
refs: 1,
mountpoints: make(map[*Dentry]uint32),
}
@@ -279,6 +282,9 @@ func (vfs *VirtualFilesystem) UmountAt(ctx context.Context, creds *auth.Credenti
}
// MNT_FORCE is currently unimplemented except for the permission check.
+ // Force unmounting specifically requires CAP_SYS_ADMIN in the root user
+ // namespace, and not in the owner user namespace for the target mount. See
+ // fs/namespace.c:SYSCALL_DEFINE2(umount, ...)
if opts.Flags&linux.MNT_FORCE != 0 && creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, creds.UserNamespace.Root()) {
return syserror.EPERM
}
@@ -753,7 +759,10 @@ func (vfs *VirtualFilesystem) GenerateProcMounts(ctx context.Context, taskRootDi
if mnt.readOnly() {
opts = "ro"
}
- if mnt.flags.NoExec {
+ if mnt.Flags.NoATime {
+ opts = ",noatime"
+ }
+ if mnt.Flags.NoExec {
opts += ",noexec"
}
@@ -838,11 +847,12 @@ func (vfs *VirtualFilesystem) GenerateProcMountInfo(ctx context.Context, taskRoo
if mnt.readOnly() {
opts = "ro"
}
- if mnt.flags.NoExec {
+ if mnt.Flags.NoATime {
+ opts = ",noatime"
+ }
+ if mnt.Flags.NoExec {
opts += ",noexec"
}
- // TODO(gvisor.dev/issue/1193): Add "noatime" if MS_NOATIME is
- // set.
fmt.Fprintf(buf, "%s ", opts)
// (7) Optional fields: zero or more fields of the form "tag[:value]".
diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go
index 53d364c5c..f223aeda8 100644
--- a/pkg/sentry/vfs/options.go
+++ b/pkg/sentry/vfs/options.go
@@ -75,6 +75,10 @@ type MknodOptions struct {
type MountFlags struct {
// NoExec is equivalent to MS_NOEXEC.
NoExec bool
+
+ // NoATime is equivalent to MS_NOATIME and indicates that the
+ // filesystem should not update access time in-place.
+ NoATime bool
}
// MountOptions contains options to VirtualFilesystem.MountAt().
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 52643a7c5..9acca8bc7 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -405,7 +405,7 @@ func (vfs *VirtualFilesystem) OpenAt(ctx context.Context, creds *auth.Credential
vfs.putResolvingPath(rp)
if opts.FileExec {
- if fd.Mount().flags.NoExec {
+ if fd.Mount().Flags.NoExec {
fd.DecRef()
return nil, syserror.EACCES
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-26 20:20:30 +0000