ceph: fix authenticator buffer size calculation

The buffer size was incorrectly calculated for the ceph_x_encrypt()
encapsulated ticket blob.  Use a helper (with correct arithmetic) and
BUG out if we were wrong.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 13 insertions, 6 deletions

diff --git a/fs/ceph/auth_x.c b/fs/ceph/auth_x.c
index f0318427b6da..96e7aaa77678 100644
--- a/fs/ceph/auth_x.c
+++ b/fs/ceph/auth_x.c
@@ -28,6 +28,12 @@ static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
         return (ac->want_keys & xi->have_keys) == ac->want_keys;
 }
 
+static int ceph_x_encrypt_buflen(int ilen)
+{
+        return sizeof(struct ceph_x_encrypt_header) + ilen + 16 +
+                sizeof(u32);
+}
+
 static int ceph_x_encrypt(struct ceph_crypto_key *secret,
                           void *ibuf, int ilen, void *obuf, size_t olen)
 {
@@ -242,7 +248,7 @@ static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
                                    struct ceph_x_ticket_handler *th,
                                    struct ceph_x_authorizer *au)
 {
-        int len;
+        int maxlen;
         struct ceph_x_authorize_a *msg_a;
         struct ceph_x_authorize_b msg_b;
         void *p, *end;
@@ -253,15 +259,15 @@ static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
         dout("build_authorizer for %s %p\n",
              ceph_entity_type_name(th->service), au);
 
-        len = sizeof(*msg_a) + sizeof(msg_b) + sizeof(u32) +
-                ticket_blob_len + 16;
-        dout("  need len %d\n", len);
-        if (au->buf && au->buf->alloc_len < len) {
+        maxlen = sizeof(*msg_a) + sizeof(msg_b) +
+                ceph_x_encrypt_buflen(ticket_blob_len);
+        dout("  need len %d\n", maxlen);
+        if (au->buf && au->buf->alloc_len < maxlen) {
                 ceph_buffer_put(au->buf);
                 au->buf = NULL;
         }
         if (!au->buf) {
-                au->buf = ceph_buffer_new(len, GFP_NOFS);
+                au->buf = ceph_buffer_new(maxlen, GFP_NOFS);
                 if (!au->buf)
                         return -ENOMEM;
         }
@@ -296,6 +302,7 @@ static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
         au->buf->vec.iov_len = p - au->buf->vec.iov_base;
         dout(" built authorizer nonce %llx len %d\n", au->nonce,
              (int)au->buf->vec.iov_len);
+        BUG_ON(au->buf->vec.iov_len > maxlen);
         return 0;
 
 out_buf: