diff options
| -rw-r--r-- | fs/namei.c | 45 |
1 files changed, 45 insertions, 0 deletions
@@ -414,6 +414,46 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd) } /* + * force_reval_path - force revalidation of a dentry + * + * In some situations the path walking code will trust dentries without + * revalidating them. This causes problems for filesystems that depend on + * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set + * (which indicates that it's possible for the dentry to go stale), force + * a d_revalidate call before proceeding. + * + * Returns 0 if the revalidation was successful. If the revalidation fails, + * either return the error returned by d_revalidate or -ESTALE if the + * revalidation it just returned 0. If d_revalidate returns 0, we attempt to + * invalidate the dentry. It's up to the caller to handle putting references + * to the path if necessary. + */ +static int +force_reval_path(struct path *path, struct nameidata *nd) +{ + int status; + struct dentry *dentry = path->dentry; + + /* + * only check on filesystems where it's possible for the dentry to + * become stale. It's assumed that if this flag is set then the + * d_revalidate op will also be defined. + */ + if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) + return 0; + + status = dentry->d_op->d_revalidate(dentry, nd); + if (status > 0) + return 0; + + if (!status) { + d_invalidate(dentry); + status = -ESTALE; + } + return status; +} + +/* * Short-cut version of permission(), for calling on directories * during pathname resolution. Combines parts of permission() * and generic_permission(), and tests ONLY for MAY_EXEC permission. @@ -529,6 +569,11 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata error = 0; if (s) error = __vfs_follow_link(nd, s); + else if (nd->last_type == LAST_BIND) { + error = force_reval_path(&nd->path, nd); + if (error) + path_put(&nd->path); + } if (dentry->d_inode->i_op->put_link) dentry->d_inode->i_op->put_link(dentry, nd, cookie); } |
