rxrpc: Fix rxkad token xdr encoding

The session key should be encoded with just the 8 data bytes and
no length; ENCODE_DATA precedes it with a 4 byte length, which
confuses some existing tools that try to parse this format.

Add an ENCODE_BYTES macro that does not include a length, and use
it for the key.  Also adjust the expected length.

Note that commit 774521f353e1d ("rxrpc: Fix an assertion in
rxrpc_read()") had fixed a BUG by changing the length rather than
fixing the encoding.  The original length was correct.

Fixes: 99455153d067 ("RxRPC: Parse security index 5 keys (Kerberos 5)")
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
index 94c3df392651b90cd59a7e3bab73d0313b1110bb..8f7d7a6187db7973ed7cabde509156d5625fd649 100644 (file)
--- a/net/rxrpc/key.c
+++ b/net/rxrpc/key.c
@@ -1072,7 +1072,7 @@ static long rxrpc_read(const struct key *key,
 
                switch (token->security_index) {
                case RXRPC_SECURITY_RXKAD:
-                       toksize += 9 * 4;       /* viceid, kvno, key*2 + len, begin,
+                       toksize += 8 * 4;       /* viceid, kvno, key*2, begin,
                                                 * end, primary, tktlen */
                        toksize += RND(token->kad->ticket_len);
                        break;
@@ -1138,6 +1138,14 @@ static long rxrpc_read(const struct key *key,
                        memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3));    \
                xdr += (_l + 3) >> 2;                                   \
        } while(0)
+#define ENCODE_BYTES(l, s)                                             \
+       do {                                                            \
+               u32 _l = (l);                                           \
+               memcpy(xdr, (s), _l);                                   \
+               if (_l & 3)                                             \
+                       memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3));    \
+               xdr += (_l + 3) >> 2;                                   \
+       } while(0)
 #define ENCODE64(x)                                    \
        do {                                            \
                __be64 y = cpu_to_be64(x);              \
@@ -1165,7 +1173,7 @@ static long rxrpc_read(const struct key *key,
                case RXRPC_SECURITY_RXKAD:
                        ENCODE(token->kad->vice_id);
                        ENCODE(token->kad->kvno);
-                       ENCODE_DATA(8, token->kad->session_key);
+                       ENCODE_BYTES(8, token->kad->session_key);
                        ENCODE(token->kad->start);
                        ENCODE(token->kad->expiry);
                        ENCODE(token->kad->primary_flag);