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Fix regression from r310655, which broke operation of bsnmpd if it is bound

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to a non-wildcard address.  As documented in ip(4), doing sendmsg(2) with
IP_SENDSRCADDR on a socket that is bound to non-wildcard address is
completely different to using this control message on a wildcard one.

A fix is to add a bool to mark whether we did setsockopt(IP_RECVDSTADDR)
on the socket, and use IP_SENDSRCADDR control message only if we did.

While here, garbage collect absolutely useless udp_recv() function that
establishes some structures on stack to never use them later.
This commit is contained in:
Gleb Smirnoff 2017-01-17 03:52:57 +00:00
parent 489b7fc0a4
commit 1897a4f168
2 changed files with 30 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
contrib/bsnmp/snmpd/trans_udp.c
View File

@ -34,6 +34,7 @@
#include <sys/queue.h>
#include <sys/ucred.h>
#include <stdbool.h>
#include <stdlib.h>
#include <syslog.h>
#include <string.h>
@ -119,13 +120,15 @@ udp_init_port(struct tport *tp)
addr.sin_port = htons(p->port);
addr.sin_family = AF_INET;
addr.sin_len = sizeof(addr);
if (addr.sin_addr.s_addr == INADDR_ANY &&
setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
sizeof(on)) == -1) {
syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
close(p->input.fd);
p->input.fd = -1;
return (SNMP_ERR_GENERR);
if (addr.sin_addr.s_addr == INADDR_ANY) {
if (setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
sizeof(on)) == -1) {
syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
close(p->input.fd);
p->input.fd = -1;
return (SNMP_ERR_GENERR);
}
p->recvdstaddr = true;
}
if (bind(p->input.fd, (struct sockaddr *)&addr, sizeof(addr))) {
if (errno == EADDRNOTAVAIL) {
@ -218,7 +221,6 @@ udp_send(struct tport *tp, const u_char *buf, size_t len,
{
struct udp_port *p = (struct udp_port *)tp;
struct cmsghdr *cmsg;
struct in_addr *src_addr;
struct msghdr msg;
char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
struct iovec iov;
@ -231,15 +233,20 @@ udp_send(struct tport *tp, const u_char *buf, size_t len,
msg.msg_iovlen = 1;
msg.msg_name = __DECONST(void *, addr);
msg.msg_namelen = addrlen;
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = IPPROTO_IP;
cmsg->cmsg_type = IP_SENDSRCADDR;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
src_addr = (struct in_addr *)(void*)CMSG_DATA(cmsg);
memcpy(src_addr, &p->recv_addr, sizeof(struct in_addr));
if (p->recvdstaddr) {
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = IPPROTO_IP;
cmsg->cmsg_type = IP_SENDSRCADDR;
cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
memcpy(CMSG_DATA(cmsg), &p->dstaddr, sizeof(struct in_addr));
} else {
msg.msg_control = NULL;
msg.msg_controllen = 0;
}
return (sendmsg(p->input.fd, &msg, 0));
}
@ -260,11 +267,12 @@ check_priv_dgram(struct port_input *pi, struct sockcred *cred)
* Each receive should return one datagram.
*/
static ssize_t
recv_dgram(struct port_input *pi, struct in_addr *laddr)
udp_recv(struct tport *tp, struct port_input *pi)
{
u_char embuf[1000];
char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
CMSG_SPACE(sizeof(struct in_addr))];
struct udp_port *p = (struct udp_port *)tp;
struct msghdr msg;
struct iovec iov[1];
ssize_t len;
@ -316,7 +324,8 @@ recv_dgram(struct port_input *pi, struct in_addr *laddr)
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == IPPROTO_IP &&
cmsg->cmsg_type == IP_RECVDSTADDR)
memcpy(laddr, CMSG_DATA(cmsg), sizeof(struct in_addr));
memcpy(&p->dstaddr, CMSG_DATA(cmsg),
sizeof(struct in_addr));
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDS)
cred = (struct sockcred *)CMSG_DATA(cmsg);
@ -328,42 +337,6 @@ recv_dgram(struct port_input *pi, struct in_addr *laddr)
return (0);
}
/*
* Receive something
*/
static ssize_t
udp_recv(struct tport *tp, struct port_input *pi)
{
struct udp_port *p = (struct udp_port *)tp;
struct cmsghdr *cmsgp;
struct in_addr *laddr;
struct msghdr msg;
char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
ssize_t ret;
memset(cbuf, 0, sizeof(cbuf));
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsgp = CMSG_FIRSTHDR(&msg);
cmsgp->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
cmsgp->cmsg_level = IPPROTO_IP;
cmsgp->cmsg_type = IP_SENDSRCADDR;
laddr = (struct in_addr *)CMSG_DATA(cmsgp);
ret = recv_dgram(pi, laddr);
memcpy(&p->recv_addr, laddr, sizeof(struct in_addr));
if (laddr->s_addr == INADDR_ANY) {
msg.msg_control = NULL;
msg.msg_controllen = 0;
}
return (ret);
}
/*
* Port table
*/

4
contrib/bsnmp/snmpd/trans_udp.h
View File

@ -39,7 +39,9 @@ struct udp_port {
struct port_input input; /* common input stuff */
struct sockaddr_in ret; /* the return address */
struct in_addr recv_addr; /* the address the request was sent to */
bool recvdstaddr; /* IP_RECVDSTADDR is on */
struct in_addr dstaddr; /* address the request was sent to */
};
/* argument for open call */