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socket: clear port when unable to generate local port

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When running out of local ports, _nl_socket_generate_local_port_no_release()
would leave the socket with port UINT32_MAX. That means if nl_connect()
fails due to out-of-ports, it would leave the port id assigned to an
invalid port and the socket instance was not re-usable until the user
called nl_socket_set_local_port(). Fix that by resetting the local port
to zero.

Thereby, also change generate_local_port() to return zero when
running out of ports. zero is a more natural value for ~no port found~.
It also matches the port that _nl_socket_generate_local_port_no_release()
uses when failing to generate a port.

Also ensure that zero cannot be returned as valid port by generate_local_port().
Arguably, that would only be possible if (getpid() & 0x3FFFFF)
returns zero. Just be extra cautious.

Signed-off-by: Thomas Haller <thaller@redhat.com>
This commit is contained in:
Thomas Haller 2015-07-10 14:58:50 +02:00
parent c38022898a
commit f78c3e8239
2 changed files with 23 additions and 9 deletions
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2
lib/nl.c
View File

@ -134,7 +134,7 @@ int nl_connect(struct nl_sock *sk, int protocol)
while (1) {
port = _nl_socket_generate_local_port_no_release(sk);
if (port == UINT32_MAX) {
if (port == 0) {
NL_DBG(4, "nl_connect(%p): no more unused local ports.\n", sk);
_nl_socket_used_ports_release_all(used_ports);
err = -NLE_EXIST;

30
lib/socket.c
View File

@ -108,7 +108,9 @@ static uint32_t generate_local_port(void)
nl_write_unlock(&port_map_lock);
return pid + (((uint32_t)n) << 22);
/* ensure we don't return zero. */
pid = pid + (((uint32_t)n) << 22);
return pid ? pid : 1024;
}
}
@ -116,7 +118,7 @@ static uint32_t generate_local_port(void)
/* Out of sockets in our own PID namespace, what to do? FIXME */
NL_DBG(1, "Warning: Ran out of unique local port namespace\n");
return UINT32_MAX;
return 0;
}
static void release_local_port(uint32_t port)
@ -124,9 +126,6 @@ static void release_local_port(uint32_t port)
int nr;
uint32_t mask;
if (port == UINT32_MAX)
return;
BUG_ON(port == 0);
nr = port >> 22;
@ -167,7 +166,7 @@ void _nl_socket_used_ports_set(uint32_t *used_ports, uint32_t port)
nr /= 32;
/*
BUG_ON(port == UINT32_MAX || port == 0 || (getpid() & 0x3FFFFF) != (port & 0x3FFFFF));
BUG_ON(port == 0 || (getpid() & 0x3FFFFF) != (port & 0x3FFFFF));
BUG_ON(used_ports[nr] & mask);
*/
@ -345,8 +344,13 @@ uint32_t _nl_socket_generate_local_port_no_release(struct nl_sock *sk)
* the previously generated port. */
port = generate_local_port();
sk->s_flags &= ~NL_OWN_PORT;
sk->s_local.nl_pid = port;
if (port == 0) {
/* failed to find an unsed port. Restore the socket to have an
* unspecified port. */
sk->s_flags |= NL_OWN_PORT;
} else
sk->s_flags &= ~NL_OWN_PORT;
return port;
}
/** \endcond */
@ -359,6 +363,8 @@ uint32_t _nl_socket_generate_local_port_no_release(struct nl_sock *sk)
uint32_t nl_socket_get_local_port(const struct nl_sock *sk)
{
if (sk->s_local.nl_pid == 0) {
struct nl_sock *sk_mutable = (struct nl_sock *) sk;
/* modify the const argument sk. This is justified, because
* nobody ever saw the local_port from externally. So, we
* initilize it on first use.
@ -368,7 +374,15 @@ uint32_t nl_socket_get_local_port(const struct nl_sock *sk)
* is not automatically threadsafe anyway, so the user is not
* allowed to do that.
*/
return _nl_socket_generate_local_port_no_release((struct nl_sock *) sk);
sk_mutable->s_local.nl_pid = generate_local_port();
if (sk_mutable->s_local.nl_pid == 0) {
/* could not generate a local port. Assign UINT32_MAX to preserve
* backward compatibility. A user who cares can clear that anyway
* with nl_socket_set_local_port(). */
sk_mutable->s_local.nl_pid = UINT32_MAX;
sk_mutable->s_flags |= NL_OWN_PORT;
} else
sk_mutable->s_flags &= ~NL_OWN_PORT;
}
return sk->s_local.nl_pid;
}