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Diffstat (limited to 'pkg/sentry/fs/mounts.go')
-rw-r--r--pkg/sentry/fs/mounts.go134
1 files changed, 28 insertions, 106 deletions
diff --git a/pkg/sentry/fs/mounts.go b/pkg/sentry/fs/mounts.go
index ac0398bd9..d741c4339 100644
--- a/pkg/sentry/fs/mounts.go
+++ b/pkg/sentry/fs/mounts.go
@@ -17,16 +17,12 @@ package fs
import (
"fmt"
"math"
- "path"
- "strings"
- "sync"
"syscall"
- "gvisor.dev/gvisor/pkg/abi/linux"
- "gvisor.dev/gvisor/pkg/log"
+ "gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/refs"
- "gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+ "gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -100,10 +96,14 @@ func newUndoMount(d *Dirent) *Mount {
}
}
-// Root returns the root dirent of this mount. Callers must call DecRef on the
-// returned dirent.
+// Root returns the root dirent of this mount.
+//
+// This may return nil if the mount has already been free. Callers must handle this
+// case appropriately. If non-nil, callers must call DecRef on the returned *Dirent.
func (m *Mount) Root() *Dirent {
- m.root.IncRef()
+ if !m.root.TryIncRef() {
+ return nil
+ }
return m.root
}
@@ -234,7 +234,7 @@ func (mns *MountNamespace) flushMountSourceRefsLocked() {
// After destroy is called, the MountNamespace may continue to be referenced (for
// example via /proc/mounts), but should free all resources and shouldn't have
// Find* methods called.
-func (mns *MountNamespace) destroy() {
+func (mns *MountNamespace) destroy(ctx context.Context) {
mns.mu.Lock()
defer mns.mu.Unlock()
@@ -247,13 +247,13 @@ func (mns *MountNamespace) destroy() {
for _, mp := range mns.mounts {
// Drop the mount reference on all mounted dirents.
for ; mp != nil; mp = mp.previous {
- mp.root.DecRef()
+ mp.root.DecRef(ctx)
}
}
mns.mounts = nil
// Drop reference on the root.
- mns.root.DecRef()
+ mns.root.DecRef(ctx)
// Ensure that root cannot be accessed via this MountNamespace any
// more.
@@ -265,21 +265,8 @@ func (mns *MountNamespace) destroy() {
}
// DecRef implements RefCounter.DecRef with destructor mns.destroy.
-func (mns *MountNamespace) DecRef() {
- mns.DecRefWithDestructor(mns.destroy)
-}
-
-// Freeze freezes the entire mount tree.
-func (mns *MountNamespace) Freeze() {
- mns.mu.Lock()
- defer mns.mu.Unlock()
-
- // We only want to freeze Dirents with active references, not Dirents referenced
- // by a mount's MountSource.
- mns.flushMountSourceRefsLocked()
-
- // Freeze the entire shebang.
- mns.root.Freeze()
+func (mns *MountNamespace) DecRef(ctx context.Context) {
+ mns.DecRefWithDestructor(ctx, mns.destroy)
}
// withMountLocked prevents further walks to `node`, because `node` is about to
@@ -325,7 +312,7 @@ func (mns *MountNamespace) Mount(ctx context.Context, mountPoint *Dirent, inode
if err != nil {
return err
}
- defer replacement.DecRef()
+ defer replacement.DecRef(ctx)
// Set the mount's root dirent and id.
parentMnt := mns.findMountLocked(mountPoint)
@@ -407,7 +394,7 @@ func (mns *MountNamespace) Unmount(ctx context.Context, node *Dirent, detachOnly
panic(fmt.Sprintf("Last mount in the chain must be a undo mount: %+v", prev))
}
// Drop mount reference taken at the end of MountNamespace.Mount.
- prev.root.DecRef()
+ prev.root.DecRef(ctx)
} else {
mns.mounts[prev.root] = prev
}
@@ -509,11 +496,11 @@ func (mns *MountNamespace) FindLink(ctx context.Context, root, wd *Dirent, path
// non-directory root is hopeless.
if current != root {
if !IsDir(current.Inode.StableAttr) {
- current.DecRef() // Drop reference from above.
+ current.DecRef(ctx) // Drop reference from above.
return nil, syserror.ENOTDIR
}
if err := current.Inode.CheckPermission(ctx, PermMask{Execute: true}); err != nil {
- current.DecRef() // Drop reference from above.
+ current.DecRef(ctx) // Drop reference from above.
return nil, err
}
}
@@ -524,12 +511,12 @@ func (mns *MountNamespace) FindLink(ctx context.Context, root, wd *Dirent, path
// Allow failed walks to cache the dirent, because no
// children will acquire a reference at the end.
current.maybeExtendReference()
- current.DecRef()
+ current.DecRef(ctx)
return nil, err
}
// Drop old reference.
- current.DecRef()
+ current.DecRef(ctx)
if remainder != "" {
// Ensure it's resolved, unless it's the last level.
@@ -583,11 +570,11 @@ func (mns *MountNamespace) resolve(ctx context.Context, root, node *Dirent, rema
case nil:
// Make sure we didn't exhaust the traversal budget.
if *remainingTraversals == 0 {
- target.DecRef()
+ target.DecRef(ctx)
return nil, syscall.ELOOP
}
- node.DecRef() // Drop the original reference.
+ node.DecRef(ctx) // Drop the original reference.
return target, nil
case syscall.ENOLINK:
@@ -595,7 +582,7 @@ func (mns *MountNamespace) resolve(ctx context.Context, root, node *Dirent, rema
return node, nil
case ErrResolveViaReadlink:
- defer node.DecRef() // See above.
+ defer node.DecRef(ctx) // See above.
// First, check if we should traverse.
if *remainingTraversals == 0 {
@@ -609,8 +596,11 @@ func (mns *MountNamespace) resolve(ctx context.Context, root, node *Dirent, rema
}
// Find the node; we resolve relative to the current symlink's parent.
+ renameMu.RLock()
+ parent := node.parent
+ renameMu.RUnlock()
*remainingTraversals--
- d, err := mns.FindInode(ctx, root, node.parent, targetPath, remainingTraversals)
+ d, err := mns.FindInode(ctx, root, parent, targetPath, remainingTraversals)
if err != nil {
return nil, err
}
@@ -618,7 +608,7 @@ func (mns *MountNamespace) resolve(ctx context.Context, root, node *Dirent, rema
return d, err
default:
- node.DecRef() // Drop for err; see above.
+ node.DecRef(ctx) // Drop for err; see above.
// Propagate the error.
return nil, err
@@ -631,71 +621,3 @@ func (mns *MountNamespace) SyncAll(ctx context.Context) {
defer mns.mu.Unlock()
mns.root.SyncAll(ctx)
}
-
-// ResolveExecutablePath resolves the given executable name given a set of
-// paths that might contain it.
-func (mns *MountNamespace) ResolveExecutablePath(ctx context.Context, wd, name string, paths []string) (string, error) {
- // Absolute paths can be used directly.
- if path.IsAbs(name) {
- return name, nil
- }
-
- // Paths with '/' in them should be joined to the working directory, or
- // to the root if working directory is not set.
- if strings.IndexByte(name, '/') > 0 {
- if wd == "" {
- wd = "/"
- }
- if !path.IsAbs(wd) {
- return "", fmt.Errorf("working directory %q must be absolute", wd)
- }
- return path.Join(wd, name), nil
- }
-
- // Otherwise, We must lookup the name in the paths, starting from the
- // calling context's root directory.
- root := RootFromContext(ctx)
- if root == nil {
- // Caller has no root. Don't bother traversing anything.
- return "", syserror.ENOENT
- }
- defer root.DecRef()
- for _, p := range paths {
- binPath := path.Join(p, name)
- traversals := uint(linux.MaxSymlinkTraversals)
- d, err := mns.FindInode(ctx, root, nil, binPath, &traversals)
- if err == syserror.ENOENT || err == syserror.EACCES {
- // Didn't find it here.
- continue
- }
- if err != nil {
- return "", err
- }
- defer d.DecRef()
-
- // Check that it is a regular file.
- if !IsRegular(d.Inode.StableAttr) {
- continue
- }
-
- // Check whether we can read and execute the found file.
- if err := d.Inode.CheckPermission(ctx, PermMask{Read: true, Execute: true}); err != nil {
- log.Infof("Found executable at %q, but user cannot execute it: %v", binPath, err)
- continue
- }
- return path.Join("/", p, name), nil
- }
- return "", syserror.ENOENT
-}
-
-// GetPath returns the PATH as a slice of strings given the environment
-// variables.
-func GetPath(env []string) []string {
- const prefix = "PATH="
- for _, e := range env {
- if strings.HasPrefix(e, prefix) {
- return strings.Split(strings.TrimPrefix(e, prefix), ":")
- }
- }
- return nil
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 15:01:45 +0000