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authorJeff Layton <jlayton@redhat.com>2014-03-04 10:30:23 -0500
committerJeff Layton <jlayton@redhat.com>2014-03-31 08:24:43 -0400
commit90478939dce096ed5b239cad16237dca0a59d66f (patch)
tree743b3d825bc56bd1c0ab4d9487abba7b6883af86 /fs/locks.c
parent5d50ffd7c31dab47c6b828841ca1ec70a1b40169 (diff)
downloadlinux-90478939dce096ed5b239cad16237dca0a59d66f.tar.bz2
locks: require that flock->l_pid be set to 0 for file-private locks
Neil Brown suggested potentially overloading the l_pid value as a "lock context" field for file-private locks. While I don't think we will probably want to do that here, it's probably a good idea to ensure that in the future we could extend this API without breaking existing callers. Typically the l_pid value is ignored for incoming struct flock arguments, serving mainly as a place to return the pid of the owner if there is a conflicting lock. For file-private locks, require that it currently be set to 0 and return EINVAL if it isn't. If we eventually want to make a non-zero l_pid mean something, then this will help ensure that we don't break legacy programs that are using file-private locks. Cc: Neil Brown <neilb@suse.de> Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 3b54b98236ee..09d6c8c33c81 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1931,6 +1931,10 @@ int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
goto out;
if (cmd == F_GETLKP) {
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_GETLK;
file_lock.fl_flags |= FL_FILE_PVT;
file_lock.fl_owner = (fl_owner_t)filp;
@@ -2062,11 +2066,19 @@ again:
*/
switch (cmd) {
case F_SETLKP:
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_SETLK;
file_lock->fl_flags |= FL_FILE_PVT;
file_lock->fl_owner = (fl_owner_t)filp;
break;
case F_SETLKPW:
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_SETLKW;
file_lock->fl_flags |= FL_FILE_PVT;
file_lock->fl_owner = (fl_owner_t)filp;
@@ -2121,6 +2133,10 @@ int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
goto out;
if (cmd == F_GETLKP) {
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_GETLK64;
file_lock.fl_flags |= FL_FILE_PVT;
file_lock.fl_owner = (fl_owner_t)filp;
@@ -2185,11 +2201,19 @@ again:
*/
switch (cmd) {
case F_SETLKP:
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_SETLK64;
file_lock->fl_flags |= FL_FILE_PVT;
file_lock->fl_owner = (fl_owner_t)filp;
break;
case F_SETLKPW:
+ error = -EINVAL;
+ if (flock.l_pid != 0)
+ goto out;
+
cmd = F_SETLKW64;
file_lock->fl_flags |= FL_FILE_PVT;
file_lock->fl_owner = (fl_owner_t)filp;