From f78c3e82398a505ccf7e297b4021f23559ad8977 Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Fri, 10 Jul 2015 14:58:50 +0200 Subject: socket: clear port when unable to generate local port 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 --- lib/nl.c | 2 +- lib/socket.c | 30 ++++++++++++++++++++++-------- 2 files changed, 23 insertions(+), 9 deletions(-) diff --git a/lib/nl.c b/lib/nl.c index 1e1b1ed..3dee873 100644 --- a/lib/nl.c +++ b/lib/nl.c @@ -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; diff --git a/lib/socket.c b/lib/socket.c index b29d1da..a1e0873 100644 --- a/lib/socket.c +++ b/lib/socket.c @@ -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; } -- cgit v0.12