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authorAl Viro <viro@zeniv.linux.org.uk>2011-03-13 15:56:26 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-03-15 02:21:45 -0400
commit65cfc6722361570bfe255698d9cd4dccaf47570d (patch)
treed98ac0a392cf9abc1bbc3363448c8e072504c6a4
parentbcda76524cd1fa32af748536f27f674a13e56700 (diff)
downloadlinux-65cfc6722361570bfe255698d9cd4dccaf47570d.tar.bz2
readlinkat(), fchownat() and fstatat() with empty relative pathnames
For readlinkat() we simply allow empty pathname; it will fail unless we have dfd equal to O_PATH-opened symlink, so we are outside of POSIX scope here. For fchownat() and fstatat() we allow AT_EMPTY_PATH; let the caller explicitly ask for such behaviour. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/open.c10
-rw-r--r--fs/stat.c7
2 files changed, 11 insertions, 6 deletions
diff --git a/fs/open.c b/fs/open.c
index 14a51de01f54..3cac0bda46df 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -573,13 +573,15 @@ SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
{
struct path path;
int error = -EINVAL;
- int follow;
+ int lookup_flags;
- if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
+ if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
goto out;
- follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
- error = user_path_at(dfd, filename, follow, &path);
+ lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+ if (flag & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+ error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
goto out;
error = mnt_want_write(path.mnt);
diff --git a/fs/stat.c b/fs/stat.c
index d5c61cf2b703..961039121cb8 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -75,13 +75,16 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
int error = -EINVAL;
int lookup_flags = 0;
- if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)) != 0)
+ if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+ AT_EMPTY_PATH)) != 0)
goto out;
if (!(flag & AT_SYMLINK_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
if (flag & AT_NO_AUTOMOUNT)
lookup_flags |= LOOKUP_NO_AUTOMOUNT;
+ if (flag & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
error = user_path_at(dfd, filename, lookup_flags, &path);
if (error)
@@ -297,7 +300,7 @@ SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
if (bufsiz <= 0)
return -EINVAL;
- error = user_path_at(dfd, pathname, 0, &path);
+ error = user_path_at(dfd, pathname, LOOKUP_EMPTY, &path);
if (!error) {
struct inode *inode = path.dentry->d_inode;