libceph: store timeouts in jiffies, verify user input

There are currently three libceph-level timeouts that the user can
specify on mount: mount_timeout, osd_idle_ttl and osdkeepalive.  All of
these are in seconds and no checking is done on user input: negative
values are accepted, we multiply them all by HZ which may or may not
overflow, arbitrarily large jiffies then get added together, etc.

There is also a bug in the way mount_timeout=0 is handled.  It's
supposed to mean "infinite timeout", but that's not how wait.h APIs
treat it and so __ceph_open_session() for example will busy loop
without much chance of being interrupted if none of ceph-mons are
there.

Fix all this by verifying user input, storing timeouts capped by
msecs_to_jiffies() in jiffies and using the new ceph_timeout_jiffies()
helper for all user-specified waits to handle infinite timeouts
correctly.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Alex Elder <elder@linaro.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index 85ae9a889a3f..d73a569f9bf5 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -43,9 +43,9 @@ struct ceph_options {
         int flags;
         struct ceph_fsid fsid;
         struct ceph_entity_addr my_addr;
-        int mount_timeout;
-        int osd_idle_ttl;
-        int osd_keepalive_timeout;
+        unsigned long mount_timeout;            /* jiffies */
+        unsigned long osd_idle_ttl;             /* jiffies */
+        unsigned long osd_keepalive_timeout;    /* jiffies */
 
         /*
          * any type that can't be simply compared or doesn't need need
@@ -63,9 +63,9 @@ struct ceph_options {
 /*
  * defaults
  */
-#define CEPH_MOUNT_TIMEOUT_DEFAULT  60
-#define CEPH_OSD_KEEPALIVE_DEFAULT  5
-#define CEPH_OSD_IDLE_TTL_DEFAULT    60
+#define CEPH_MOUNT_TIMEOUT_DEFAULT      msecs_to_jiffies(60 * 1000)
+#define CEPH_OSD_KEEPALIVE_DEFAULT      msecs_to_jiffies(5 * 1000)
+#define CEPH_OSD_IDLE_TTL_DEFAULT       msecs_to_jiffies(60 * 1000)
 
 #define CEPH_MSG_MAX_FRONT_LEN  (16*1024*1024)
 #define CEPH_MSG_MAX_MIDDLE_LEN (16*1024*1024)
@@ -93,6 +93,11 @@ enum {
         CEPH_MOUNT_SHUTDOWN,
 };
 
+static inline unsigned long ceph_timeout_jiffies(unsigned long timeout)
+{
+        return timeout ?: MAX_SCHEDULE_TIMEOUT;
+}
+
 struct ceph_mds_client;
 
 /*