diff options
| -rw-r--r-- | fs/namei.c | 31 | ||||
| -rw-r--r-- | include/linux/namei.h | 1 |
2 files changed, 28 insertions, 4 deletions
diff --git a/fs/namei.c b/fs/namei.c index 7fd801af7e50..a9ca46e4f82c 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -838,6 +838,11 @@ static inline void path_to_nameidata(const struct path *path, static int nd_jump_root(struct nameidata *nd) { + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { + /* Absolute path arguments to path_init() are allowed. */ + if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) + return -EXDEV; + } if (!nd->root.mnt) { int error = set_root(nd); if (error) @@ -873,6 +878,12 @@ int nd_jump_link(struct path *path) if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) goto err; + error = -EXDEV; + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { + if (nd->path.mnt != path->mnt) + goto err; + } + path_put(&nd->path); nd->path = *path; nd->inode = nd->path.dentry->d_inode; @@ -1284,10 +1295,14 @@ static int follow_managed(struct path *path, struct nameidata *nd) break; } - if (need_mntput && path->mnt == mnt) - mntput(path->mnt); - if (need_mntput) - nd->flags |= LOOKUP_JUMPED; + if (need_mntput) { + if (path->mnt == mnt) + mntput(path->mnt); + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) + ret = -EXDEV; + else + nd->flags |= LOOKUP_JUMPED; + } if (ret == -EISDIR || !ret) ret = 1; if (ret > 0 && unlikely(d_flags_negative(flags))) @@ -1348,6 +1363,8 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, mounted = __lookup_mnt(path->mnt, path->dentry); if (!mounted) break; + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) + return false; path->mnt = &mounted->mnt; path->dentry = mounted->mnt.mnt_root; nd->flags |= LOOKUP_JUMPED; @@ -1394,6 +1411,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) return -ECHILD; if (&mparent->mnt == nd->path.mnt) break; + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) + return -ECHILD; /* we know that mountpoint was pinned */ nd->path.dentry = mountpoint; nd->path.mnt = &mparent->mnt; @@ -1408,6 +1427,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) return -ECHILD; if (!mounted) break; + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) + return -ECHILD; nd->path.mnt = &mounted->mnt; nd->path.dentry = mounted->mnt.mnt_root; inode = nd->path.dentry->d_inode; @@ -1506,6 +1527,8 @@ static int follow_dotdot(struct nameidata *nd) } if (!follow_up(&nd->path)) break; + if (unlikely(nd->flags & LOOKUP_NO_XDEV)) + return -EXDEV; } follow_mount(&nd->path); nd->inode = nd->path.dentry->d_inode; diff --git a/include/linux/namei.h b/include/linux/namei.h index f8acec81cf03..edb4562b5c4e 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -42,6 +42,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; /* Scoping flags for lookup. */ #define LOOKUP_NO_SYMLINKS 0x010000 /* No symlink crossing. */ #define LOOKUP_NO_MAGICLINKS 0x020000 /* No nd_jump_link() crossing. */ +#define LOOKUP_NO_XDEV 0x040000 /* No mountpoint crossing. */ extern int path_pts(struct path *path); |