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[zebra/linux] Use BPF to filter out responses, to try avoid netlink overruns

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2008-05-29 Stephen Hemminger <stephen.hemminger@vyatta.com>

	* rt_netlink.c: (netlink_install_filter) BPF filter to catch and
	  drop responses to zebra's own route messages.
	  (kernel_init) add BPF filter on the netlink socket.
This commit is contained in:
Paul Jakma 2008-05-29 18:23:08 +00:00
parent 311064ddc5
commit 768a27ea7b
3 changed files with 62 additions and 1 deletions
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2
lib/zebra.h
View File

@ -162,6 +162,8 @@ typedef int socklen_t;
#ifdef HAVE_NETLINK
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/filter.h>
#include <stddef.h>
#else
#define RT_TABLE_MAIN 0
#endif /* HAVE_NETLINK */

6
zebra/ChangeLog
View File

@ -1,3 +1,9 @@
2008-05-29 Stephen Hemminger <stephen.hemminger@vyatta.com>
* rt_netlink.c: (netlink_install_filter) BPF filter to catch and
drop responses to zebra's own route messages.
(kernel_init) add BPF filter on the netlink socket.
2008-02-26 Denis Ovsienko
* zebra_rib.[ch]: (rib_lookup_and_pushup) New function, which makes sure,
that if_set_prefix() has nothing in its way of assigning an address.

55
zebra/rt_netlink.c
View File

@ -1938,6 +1938,56 @@ kernel_read (struct thread *thread)
return 0;
}
/* Filter out messages from self that occur on listener socket */
static void netlink_install_filter (int sock)
{
/*
* Filter is equivalent to netlink_route_change
*
* if (h->nlmsg_type == RTM_DELROUTE || h->nlmsg_type == RTM_NEWROUTE) {
* if (rtm->rtm_type != RTM_UNICAST)
* return 0;
* if (rtm->rtm_flags & RTM_F_CLONED)
* return 0;
* if (rtm->rtm_protocol == RTPROT_REDIRECT)
* return 0;
* if (rtm->rtm_protocol == RTPROT_KERNEL)
* return 0;
* if (rtm->rtm_protocol == RTPROT_ZEBRA && h->nlmsg_type == RTM_NEWROUTE)
* return 0;
* }
* return 0xffff;
*/
struct sock_filter filter[] = {
/* 0*/ BPF_STMT(BPF_LD|BPF_ABS|BPF_H, offsetof(struct nlmsghdr, nlmsg_type)),
/* 1*/ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htons(RTM_DELROUTE), 1, 0),
/* 2*/ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htons(RTM_NEWROUTE), 0, 11),
/* 3*/ BPF_STMT(BPF_LD|BPF_ABS|BPF_B,
sizeof(struct nlmsghdr) + offsetof(struct rtmsg, rtm_type)),
/* 4*/ BPF_JUMP(BPF_JMP|BPF_B, RTN_UNICAST, 0, 8),
/* 5*/ BPF_STMT(BPF_LD|BPF_ABS|BPF_B,
sizeof(struct nlmsghdr) + offsetof(struct rtmsg, rtm_flags)),
/* 6*/ BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, RTM_F_CLONED, 6, 0),
/* 7*/ BPF_STMT(BPF_LD|BPF_ABS|BPF_B,
sizeof(struct nlmsghdr) + offsetof(struct rtmsg, rtm_protocol)),
/* 8*/ BPF_JUMP(BPF_JMP+ BPF_B, RTPROT_REDIRECT, 4, 0),
/* 9*/ BPF_JUMP(BPF_JMP+ BPF_B, RTPROT_KERNEL, 0, 1),
/*10*/ BPF_JUMP(BPF_JMP+ BPF_B, RTPROT_ZEBRA, 0, 3),
/*11*/ BPF_STMT(BPF_LD|BPF_ABS|BPF_H, offsetof(struct nlmsghdr, nlmsg_type)),
/*12*/ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htons(RTM_NEWROUTE), 0, 1),
/*13*/ BPF_STMT(BPF_RET|BPF_K, 0), /* drop */
/*14*/ BPF_STMT(BPF_RET|BPF_K, 0xffff), /* keep */
};
struct sock_fprog prog = {
.len = sizeof(filter) / sizeof(filter[0]),
.filter = filter,
};
if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &prog, sizeof(prog)) < 0)
zlog_warn ("Can't install socket filter: %s\n", safe_strerror(errno));
}
/* Exported interface function. This function simply calls
netlink_socket (). */
void
@ -1954,5 +2004,8 @@ kernel_init (void)
/* Register kernel socket. */
if (netlink.sock > 0)
thread_add_read (zebrad.master, kernel_read, NULL, netlink.sock);
{
netlink_install_filter (netlink.sock);
thread_add_read (zebrad.master, kernel_read, NULL, netlink.sock);
}
}