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authorAndy Whitcroft <apw@canonical.com>2011-11-02 09:44:39 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2011-11-11 09:43:35 -0800
commit4f0d844bad2b3c705767e3df85978aae2ca5beb7 (patch)
tree475c19f9a1c77c850fdbdbcc5704bdf7ec9b09a4 /fs
parent02e66bee63c63c2bec1947553e6c5b58b3f0c67d (diff)
downloadlinux-linaro-precise-4f0d844bad2b3c705767e3df85978aae2ca5beb7.tar.gz
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 <viro@zeniv.linux.org.uk> 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 <apw@canonical.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c18
-rw-r--r--fs/stat.c5
2 files changed, 16 insertions, 7 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 0b3138de2a3..12f086519d9 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)
{
diff --git a/fs/stat.c b/fs/stat.c
index 78a3aa83c7e..8806b8997d2 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -294,15 +294,16 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
{
struct path path;
int error;
+ int empty = 0;
if (bufsiz <= 0)
return -EINVAL;
- error = user_path_at(dfd, pathname, LOOKUP_EMPTY, &path);
+ error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
if (!error) {
struct inode *inode = path.dentry->d_inode;
- error = -EINVAL;
+ error = empty ? -ENOENT : -EINVAL;
if (inode->i_op->readlink) {
error = security_inode_readlink(path.dentry);
if (!error) {