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    Subject[PATCH 4.19 42/49] rxrpc: Fix rxkad token xdr encoding
    Date
    From: Marc Dionne <marc.dionne@auristor.com>

    [ Upstream commit 56305118e05b2db8d0395bba640ac9a3aee92624 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/rxrpc/key.c | 12 ++++++++++--
    1 file changed, 10 insertions(+), 2 deletions(-)

    diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c
    index ad9d1b21cb0ba..fead67b42a993 100644
    --- a/net/rxrpc/key.c
    +++ b/net/rxrpc/key.c
    @@ -1075,7 +1075,7 @@ 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;
    @@ -1141,6 +1141,14 @@ 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); \
    @@ -1168,7 +1176,7 @@ 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);
    --
    2.25.1


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