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author | Andy Whitcroft <apw@canonical.com> | 2011-11-02 09:44:39 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-11 09:36:19 -0800 |
commit | b0917c31699319f0b0ce0747e26bd66e8ed83491 (patch) | |
tree | 357f87260c815d39f7efdd36f072ccd64a017a46 | |
parent | 5f0d9e03e7e0792fbd36ba9fb9859f0ef7956a20 (diff) | |
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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>
-rw-r--r-- | fs/namei.c | 18 | ||||
-rw-r--r-- | fs/stat.c | 5 | ||||
-rw-r--r-- | include/linux/namei.h | 1 |
3 files changed, 17 insertions, 7 deletions
@@ -136,7 +136,7 @@ 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; @@ -147,6 +147,8 @@ 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); @@ -159,7 +161,7 @@ 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 @@ -1747,11 +1749,11 @@ 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)) { @@ -1765,6 +1767,12 @@ 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) { @@ -296,15 +296,16 @@ 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) { diff --git a/include/linux/namei.h b/include/linux/namei.h index eba45ea..549b7d2 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -67,6 +67,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND}; #define LOOKUP_EMPTY 0x4000 extern int user_path_at(int, const char __user *, unsigned, struct path *); +extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty); #define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path) #define user_lpath(name, path) user_path_at(AT_FDCWD, name, 0, path) |