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>

diff --git a/fs/ceph/auth_x.c b/fs/ceph/auth_x.c
index f031842..96e7aaa 100644 (file)
--- 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: