diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/fs/namei.c b/fs/namei.c index 1c2105ed2..36df4818a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -560,6 +560,24 @@ static int __nd_alloc_stack(struct nameidata *nd) return 0; } +/** + * 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); +} + static inline int nd_alloc_stack(struct nameidata *nd) { if (likely(nd->depth != EMBEDDED_LEVELS)) @@ -1296,6 +1314,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) return -ECHILD; nd->path.dentry = parent; nd->seq = seq; + if (unlikely(!path_connected(&nd->path))) + return -ENOENT; break; } else { struct mount *mnt = real_mount(nd->path.mnt); @@ -1396,7 +1416,7 @@ 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); @@ -1412,6 +1432,8 @@ 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))) + return -ENOENT; break; } if (!follow_up(&nd->path)) @@ -1419,6 +1441,7 @@ static void follow_dotdot(struct nameidata *nd) } follow_mount(&nd->path); nd->inode = nd->path.dentry->d_inode; + return 0; } /* @@ -1535,8 +1558,6 @@ static int lookup_fast(struct nameidata *nd, negative = d_is_negative(dentry); if (read_seqcount_retry(&dentry->d_seq, seq)) return -ECHILD; - if (negative) - return -ENOENT; /* * This sequence count validates that the parent had no @@ -1557,6 +1578,12 @@ static int lookup_fast(struct nameidata *nd, goto unlazy; } } + /* + * Note: do negative dentry check after revalidation in + * case that drops it. + */ + if (negative) + return -ENOENT; path->mnt = mnt; path->dentry = dentry; if (likely(__follow_mount_rcu(nd, path, inode, seqp))) @@ -1634,7 +1661,7 @@ static inline int handle_dots(struct nameidata *nd, int type) if (nd->flags & LOOKUP_RCU) { return follow_dotdot_rcu(nd); } else - follow_dotdot(nd); + return follow_dotdot(nd); } return 0; } |