libceph: tolerate addrvecs with multiple entries of the same type

ceph_decode_entity_addrvec() rejects any addrvec containing more than
one entry that matches the requested msgr type (LEGACY or MSGR2),
logging "another match of type N in addrvec" and returning -EINVAL.

Some admin tooling (e.g. pveceph mon create from Proxmox VE) generates
addrvecs with multiple same-type entries when public_network lists more
than one CIDR: it picks one local IP per subnet and emits both a v2 and
a v1 entry for each IP.  Monmaps shaped this way cause:

  libceph: mon0 (1)10.10.10.15:6789 session established
  libceph: another match of type 1 in addrvec
  libceph: problem decoding monmap, -22

No Ceph code uses the extra entries: since Nautilus, the userspace
messenger (AsyncMessenger) unconditionally picks the first address of
the requested type and ignores any subsequent matches.

Match that behavior: use the first matching entry and silently skip any
subsequent ones.  This is a compatibility fix for existing deployments
and does not enable dual-stack or multi-subnet address selection.

[ idryomov: tweak ceph_decode_entity_addrvec() comment ]

Cc: stable@vger.kernel.org
Fixes: a5cbd5fc22d5 ("libceph, ceph: get and handle cluster maps with addrvecs")
Link: https://bugzilla.proxmox.com/show_bug.cgi?id=7518
Signed-off-by: Kefu Chai <k.chai@proxmox.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/net/ceph/decode.c b/net/ceph/decode.c
index bc109a1a4616faa21ce2774a5e6e8d0383405a0f..2f21af38cd9a5b282f6aedd24b6804e24f1e2b0f 100644 (file)
--- a/net/ceph/decode.c
+++ b/net/ceph/decode.c
@@ -87,8 +87,9 @@ bad:
 EXPORT_SYMBOL(ceph_decode_entity_addr);
 
 /*
- * Return addr of desired type (MSGR2 or LEGACY) or error.
- * Make sure there is only one match.
+ * Return addr of desired type (MSGR2 or LEGACY) or error.  In case of
+ * multiple matches, use the first one for compatibility with userspace
+ * messenger.
  *
  * Assume encoding with MSG_ADDR2.
  */
@@ -121,14 +122,13 @@ int ceph_decode_entity_addrvec(void **p, void *end, bool msgr2,
 
                dout("%s i %d addr %s\n", __func__, i, ceph_pr_addr(&tmp_addr));
                if (tmp_addr.type == my_type) {
-                       if (found) {
-                               pr_err("another match of type %d in addrvec\n",
-                                      le32_to_cpu(my_type));
-                               return -EINVAL;
+                       if (!found) {
+                               memcpy(addr, &tmp_addr, sizeof(*addr));
+                               found = true;
+                       } else {
+                               dout("%s skipping extra match of type %d in addrvec\n",
+                                    __func__, le32_to_cpu(my_type));
                        }
-
-                       memcpy(addr, &tmp_addr, sizeof(*addr));
-                       found = true;
                }
        }