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Fixes mixed-up messages on netlink socket

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Under specific circumstances there might be two mixed-up
netlink sessions (one for scan, the other for route change
request). This patch separates netlink scans and requests
to two fds (and seq counters).

This should fix http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=428865
This commit is contained in:
Ondrej Zajicek 2009-04-17 18:43:11 +02:00
parent c8a6b9a3d1
commit e366625c0e
1 changed files with 34 additions and 19 deletions
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53
sysdep/linux/netlink/netlink.c
View file

@ -38,8 +38,14 @@
* Synchronous Netlink interface * Synchronous Netlink interface
*/ */
static int nl_sync_fd = -1; /* Unix socket for synchronous netlink actions */ struct nl_sock
static u32 nl_sync_seq; /* Sequence number of last request sent */ {
int fd;
u32 seq;
};
static struct nl_sock nl_scan = {-1, 0}; /* Netlink socket for synchronous scan */
static struct nl_sock nl_req = {-1, 0}; /* Netlink socket for requests */
static byte *nl_rx_buffer; /* Receive buffer */ static byte *nl_rx_buffer; /* Receive buffer */
#define NL_RX_SIZE 8192 #define NL_RX_SIZE 8192
@ -48,28 +54,37 @@ static struct nlmsghdr *nl_last_hdr; /* Recently received packet */
static unsigned int nl_last_size; static unsigned int nl_last_size;
static void static void
nl_open(void) nl_open_sock(struct nl_sock *nl)
{ {
if (nl_sync_fd < 0) if (nl->fd < 0)
{ {
nl_sync_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE); nl->fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (nl_sync_fd < 0) if (nl->fd < 0)
die("Unable to open rtnetlink socket: %m"); die("Unable to open rtnetlink socket: %m");
nl_sync_seq = now; nl->seq = now;
nl_rx_buffer = xmalloc(NL_RX_SIZE);
} }
} }
static void static void
nl_send(struct nlmsghdr *nh) nl_open(void)
{
nl_open_sock(&nl_scan);
nl_open_sock(&nl_req);
if (nl_rx_buffer == NULL)
nl_rx_buffer = xmalloc(NL_RX_SIZE);
}
static void
nl_send(struct nl_sock *nl, struct nlmsghdr *nh)
{ {
struct sockaddr_nl sa; struct sockaddr_nl sa;
memset(&sa, 0, sizeof(sa)); memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK; sa.nl_family = AF_NETLINK;
nh->nlmsg_pid = 0; nh->nlmsg_pid = 0;
nh->nlmsg_seq = ++nl_sync_seq; nh->nlmsg_seq = ++(nl->seq);
if (sendto(nl_sync_fd, nh, nh->nlmsg_len, 0, (struct sockaddr *)&sa, sizeof(sa)) < 0) if (sendto(nl->fd, nh, nh->nlmsg_len, 0, (struct sockaddr *)&sa, sizeof(sa)) < 0)
die("rtnetlink sendto: %m"); die("rtnetlink sendto: %m");
nl_last_hdr = NULL; nl_last_hdr = NULL;
} }
@ -85,11 +100,11 @@ nl_request_dump(int cmd)
req.nh.nlmsg_len = sizeof(req); req.nh.nlmsg_len = sizeof(req);
req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP; req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
req.g.rtgen_family = BIRD_PF; req.g.rtgen_family = BIRD_PF;
nl_send(&req.nh); nl_send(&nl_scan, &req.nh);
} }
static struct nlmsghdr * static struct nlmsghdr *
nl_get_reply(void) nl_get_reply(struct nl_sock *nl)
{ {
for(;;) for(;;)
{ {
@ -98,7 +113,7 @@ nl_get_reply(void)
struct iovec iov = { nl_rx_buffer, NL_RX_SIZE }; struct iovec iov = { nl_rx_buffer, NL_RX_SIZE };
struct sockaddr_nl sa; struct sockaddr_nl sa;
struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 }; struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
int x = recvmsg(nl_sync_fd, &m, 0); int x = recvmsg(nl->fd, &m, 0);
if (x < 0) if (x < 0)
die("nl_get_reply: %m"); die("nl_get_reply: %m");
if (sa.nl_pid) /* It isn't from the kernel */ if (sa.nl_pid) /* It isn't from the kernel */
@ -115,10 +130,10 @@ nl_get_reply(void)
{ {
struct nlmsghdr *h = nl_last_hdr; struct nlmsghdr *h = nl_last_hdr;
nl_last_hdr = NLMSG_NEXT(h, nl_last_size); nl_last_hdr = NLMSG_NEXT(h, nl_last_size);
if (h->nlmsg_seq != nl_sync_seq) if (h->nlmsg_seq != nl->seq)
{ {
log(L_WARN "nl_get_reply: Ignoring out of sequence netlink packet (%x != %x)", log(L_WARN "nl_get_reply: Ignoring out of sequence netlink packet (%x != %x)",
h->nlmsg_seq, nl_sync_seq); h->nlmsg_seq, nl->seq);
continue; continue;
} }
return h; return h;
@ -152,7 +167,7 @@ nl_error(struct nlmsghdr *h)
static struct nlmsghdr * static struct nlmsghdr *
nl_get_scan(void) nl_get_scan(void)
{ {
struct nlmsghdr *h = nl_get_reply(); struct nlmsghdr *h = nl_get_reply(&nl_scan);
if (h->nlmsg_type == NLMSG_DONE) if (h->nlmsg_type == NLMSG_DONE)
return NULL; return NULL;
@ -169,10 +184,10 @@ nl_exchange(struct nlmsghdr *pkt)
{ {
struct nlmsghdr *h; struct nlmsghdr *h;
nl_send(pkt); nl_send(&nl_req, pkt);
for(;;) for(;;)
{ {
h = nl_get_reply(); h = nl_get_reply(&nl_req);
if (h->nlmsg_type == NLMSG_ERROR) if (h->nlmsg_type == NLMSG_ERROR)
break; break;
log(L_WARN "nl_exchange: Unexpected reply received"); log(L_WARN "nl_exchange: Unexpected reply received");