Kernel(2.6.23.1-42.fc8) is not identifying the SADB_ACQUIRE(PF_KEY) message to indicate key management failure

[ramaswamy]

Hi all,

I'm receiving the SADB_ACQUIRE message from the kernel to establish the
required SA, as i have registered my pfkey socket with the kernel. 
The Key management in my application is failing to get the require key
information from the server, so I'm sending the same SADB_ACQUIRE message to
the kernel with same sequence number which have received in the SADB_ACQUIRE
message with errno set to ENOENT to indicate the Key management has failed. 

Here i'm constructing only the base header (struct sadb_msg) as described in
the RFC 2367. As per the RFC 2367 it has to return me the SADB_ACQUIRE
message with the same errno set. 

The problem here I'm facing is, the kernel is dropping the message which i
have sent to the kernel to indicate the Key management has failed. The
Kernel is sending the same (last SADB_ACQUIRE for which key management is
failed) SADB_ACQUIRE message with errno set to ZERO.  The OS i'm using is
Fedora core 8 (2.6.23.1-42.fc8).

Is this handled in the above mentioned Linux Kernel version ?

can any please let me know what is wrong i'm doing here. It will be very
helpful for me.

This is code snippet which i'm sending to kernel.

/*
 * send error against acquire message to kenrel.
 */
int
send_acquire_msg_fail(struct acquire *acquire)
{
    struct sadb_msg *newmsg;
    int len;

    len = sizeof(struct sadb_msg);
    newmsg = calloc(1, len);
    if (newmsg == NULL) {
        ERROR_RETURN("failed to get buffer to send acquire.\n");
        return -1;
    }

    memset(newmsg, 0, len);
    newmsg->sadb_msg_version = PF_KEY_V2;  
    newmsg->sadb_msg_type = SADB_ACQUIRE;
    newmsg->sadb_msg_errno = ENOENT;   
    newmsg->sadb_msg_satype = SADB_SATYPE_ESP;
    newmsg->sadb_msg_len = (len/8);
    newmsg->sadb_msg_reserved = 0;
    newmsg->sadb_msg_seq = acquire->seq;
    newmsg->sadb_msg_pid = (u_int32_t)getpid();

    /* send message */
    if (len != write(pfkey_socket, (void*)msg, len)) {
          ERROR_RETURN (("SORRY, failed to write the SADB_ACQUIRE message to
the kernel\n"));
     }
     free(newmsg);
     return 0;
}

-- 
Regards,
Ram