diff options
| -rw-r--r-- | pkg/sentry/vfs/mount.go | 26 | ||||
| -rw-r--r-- | runsc/boot/vfs.go | 4 |
2 files changed, 28 insertions, 2 deletions
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go index 09fea3628..cd5456eef 100644 --- a/pkg/sentry/vfs/mount.go +++ b/pkg/sentry/vfs/mount.go @@ -18,12 +18,14 @@ import ( "bytes" "fmt" "math" + "path" "sort" "strings" "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fspath" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/syserror" ) @@ -888,6 +890,30 @@ func (vfs *VirtualFilesystem) GenerateProcMountInfo(ctx context.Context, taskRoo } } +// MakeSyntheticMountpoint creates parent directories of target if they do not +// exist and attempts to create a directory for the mountpoint. If a +// non-directory file already exists there then we allow it. +func (vfs *VirtualFilesystem) MakeSyntheticMountpoint(ctx context.Context, target string, root VirtualDentry, creds *auth.Credentials) error { + mkdirOpts := &MkdirOptions{Mode: 0777, ForSyntheticMountpoint: true} + + // Make sure the parent directory of target exists. + if err := vfs.MkdirAllAt(ctx, path.Dir(target), root, creds, mkdirOpts); err != nil { + return fmt.Errorf("failed to create parent directory of mountpoint %q: %w", target, err) + } + + // Attempt to mkdir the final component. If a file (of any type) exists + // then we let allow mounting on top of that because we do not require the + // target to be an existing directory, unlike Linux mount(2). + if err := vfs.MkdirAt(ctx, creds, &PathOperation{ + Root: root, + Start: root, + Path: fspath.Parse(target), + }, mkdirOpts); err != nil && err != syserror.EEXIST { + return fmt.Errorf("failed to create mountpoint %q: %w", target, err) + } + return nil +} + // manglePath replaces ' ', '\t', '\n', and '\\' with their octal equivalents. // See Linux fs/seq_file.c:mangle_path. func manglePath(p string) string { diff --git a/runsc/boot/vfs.go b/runsc/boot/vfs.go index fb200e988..66b6cf19b 100644 --- a/runsc/boot/vfs.go +++ b/runsc/boot/vfs.go @@ -292,7 +292,7 @@ func (c *containerMounter) mountSubmountVFS2(ctx context.Context, conf *config.C return nil, nil } - if err := c.k.VFS().MkdirAllAt(ctx, submount.Destination, root, creds, &vfs.MkdirOptions{Mode: 0777, ForSyntheticMountpoint: true}); err != nil { + if err := c.k.VFS().MakeSyntheticMountpoint(ctx, submount.Destination, root, creds); err != nil { return nil, err } mnt, err := c.k.VFS().MountAt(ctx, creds, "", target, fsName, opts) @@ -496,7 +496,7 @@ func (c *containerMounter) mountSharedSubmountVFS2(ctx context.Context, conf *co root := mns.Root() defer root.DecRef(ctx) - if err := c.k.VFS().MkdirAllAt(ctx, mount.Destination, root, creds, &vfs.MkdirOptions{Mode: 0777, ForSyntheticMountpoint: true}); err != nil { + if err := c.k.VFS().MakeSyntheticMountpoint(ctx, mount.Destination, root, creds); err != nil { return nil, err } |