From 4f0d844bad2b3c705767e3df85978aae2ca5beb7 Mon Sep 17 00:00:00 2001 From: Andy Whitcroft Date: Wed, 2 Nov 2011 09:44:39 +0100 Subject: readlinkat: ensure we return ENOENT for the empty pathname for normal lookups commit 1fa1e7f615f4d3ae436fa319af6e4eebdd4026a8 upstream. Since the commit below which added O_PATH support to the *at() calls, the error return for readlink/readlinkat for the empty pathname has switched from ENOENT to EINVAL: commit 65cfc6722361570bfe255698d9cd4dccaf47570d Author: Al Viro Date: Sun Mar 13 15:56:26 2011 -0400 readlinkat(), fchownat() and fstatat() with empty relative pathnames This is both unexpected for userspace and makes readlink/readlinkat inconsistant with all other interfaces; and inconsistant with our stated return for these pathnames. As the readlinkat call does not have a flags parameter we cannot use the AT_EMPTY_PATH approach used in the other calls. Therefore expose whether the original path is infact entry via a new user_path_at_empty() path lookup function. Use this to determine whether to default to EINVAL or ENOENT for failures. Addresses http://bugs.launchpad.net/bugs/817187 [akpm@linux-foundation.org: remove unused getname_flags()] Signed-off-by: Andy Whitcroft Cc: Christoph Hellwig Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Christoph Hellwig Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 0b3138de2a3b..12f086519d9e 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -137,7 +137,7 @@ static int do_getname(const char __user *filename, char *page) return retval; } -static char *getname_flags(const char __user * filename, int flags) +static char *getname_flags(const char __user *filename, int flags, int *empty) { char *tmp, *result; @@ -148,6 +148,8 @@ static char *getname_flags(const char __user * filename, int flags) result = tmp; if (retval < 0) { + if (retval == -ENOENT && empty) + *empty = 1; if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { __putname(tmp); result = ERR_PTR(retval); @@ -160,7 +162,7 @@ static char *getname_flags(const char __user * filename, int flags) char *getname(const char __user * filename) { - return getname_flags(filename, 0); + return getname_flags(filename, 0, 0); } #ifdef CONFIG_AUDITSYSCALL @@ -1798,11 +1800,11 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) return __lookup_hash(&this, base, NULL); } -int user_path_at(int dfd, const char __user *name, unsigned flags, - struct path *path) +int user_path_at_empty(int dfd, const char __user *name, unsigned flags, + struct path *path, int *empty) { struct nameidata nd; - char *tmp = getname_flags(name, flags); + char *tmp = getname_flags(name, flags, empty); int err = PTR_ERR(tmp); if (!IS_ERR(tmp)) { @@ -1816,6 +1818,12 @@ int user_path_at(int dfd, const char __user *name, unsigned flags, return err; } +int user_path_at(int dfd, const char __user *name, unsigned flags, + struct path *path) +{ + return user_path_at_empty(dfd, name, flags, path, 0); +} + static int user_path_parent(int dfd, const char __user *path, struct nameidata *nd, char **name) { -- cgit v1.2.3