ipc/mqueue: switch back to using non-max values on create

Commit b231cca4381ee15e ("message queues: increase range limits") changed
how we create a queue that does not include an attr struct passed to open
so that it creates the queue with whatever the maximum values are.
However, if the admin has set the maximums to allow flexibility in
creating a queue (aka, both a large size and large queue are allowed, but
combined they create a queue too large for the RLIMIT_MSGQUEUE of the
user), then attempts to create a queue without an attr struct will fail.
Switch back to using acceptable defaults regardless of what the maximums
are.

Signed-off-by: Doug Ledford <dledford@redhat.com>
Cc: Amerigo Wang <amwang@redhat.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Joe Korty <joe.korty@ccur.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 1372b566e1e13abba37c9c1110887c4aa7a6533e..bde094ee7b0e518239fb43b6be7fbfaed80d55ff 100644 (file)
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -95,9 +95,11 @@ extern int mq_init_ns(struct ipc_namespace *ns);
 #define DFLT_QUEUESMAX 256     /* max number of message queues */
 #define HARD_QUEUESMAX 1024
 #define MIN_MSGMAX     1
+#define DFLT_MSG       10U
 #define DFLT_MSGMAX    10      /* max number of messages in each queue */
 #define HARD_MSGMAX    (32768*sizeof(void *)/4)
 #define MIN_MSGSIZEMAX  128
+#define DFLT_MSGSIZE    8192U
 #define DFLT_MSGSIZEMAX 8192   /* max message size */
 #define HARD_MSGSIZEMAX (8192*128)
 #else

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index ed049ea568f45ee6026941b5d8335853c33efcd8..c6597fc42861aba688583415448a2adda59a11a2 100644 (file)
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -142,8 +142,9 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
                info->qsize = 0;
                info->user = NULL;      /* set when all is ok */
                memset(&info->attr, 0, sizeof(info->attr));
-               info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
-               info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
+               info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, DFLT_MSG);
+               info->attr.mq_msgsize =
+                       min(ipc_ns->mq_msgsize_max, DFLT_MSGSIZE);
                if (attr) {
                        info->attr.mq_maxmsg = attr->mq_maxmsg;
                        info->attr.mq_msgsize = attr->mq_msgsize;