diff options
| -rw-r--r-- | fs/namei.c | 29 |
1 files changed, 27 insertions, 2 deletions
@@ -398,6 +398,24 @@ void path_put(struct path *path) } EXPORT_SYMBOL(path_put); +/** + * path_connected - Verify that a path->dentry is below path->mnt.mnt_root + * @path: nameidate to verify + * + * Rename can sometimes move a file or directory outside of a bind + * mount, path_connected allows those cases to be detected. + */ +static bool path_connected(const struct path *path) +{ + struct vfsmount *mnt = path->mnt; + + /* Only bind mounts can have disconnected paths */ + if (mnt->mnt_root == mnt->mnt_sb->s_root) + return true; + + return is_subdir(path->dentry, mnt->mnt_root); +} + /* * Path walking has 2 modes, rcu-walk and ref-walk (see * Documentation/filesystems/path-lookup.txt). In situations when we can't @@ -933,6 +951,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) goto failed; nd->path.dentry = parent; nd->seq = seq; + if (unlikely(!path_connected(&nd->path))) + goto failed; break; } if (!follow_up_rcu(&nd->path)) @@ -1027,7 +1047,7 @@ static void follow_mount(struct path *path) } } -static void follow_dotdot(struct nameidata *nd) +static int follow_dotdot(struct nameidata *nd) { if (!nd->root.mnt) set_root(nd); @@ -1043,6 +1063,10 @@ static void follow_dotdot(struct nameidata *nd) /* rare case of legitimate dget_parent()... */ nd->path.dentry = dget_parent(nd->path.dentry); dput(old); + if (unlikely(!path_connected(&nd->path))) { + path_put(&nd->path); + return -ENOENT; + } break; } if (!follow_up(&nd->path)) @@ -1050,6 +1074,7 @@ static void follow_dotdot(struct nameidata *nd) } follow_mount(&nd->path); nd->inode = nd->path.dentry->d_inode; + return 0; } /* @@ -1241,7 +1266,7 @@ static inline int handle_dots(struct nameidata *nd, int type) if (follow_dotdot_rcu(nd)) return -ECHILD; } else - follow_dotdot(nd); + return follow_dotdot(nd); } return 0; } |