On Mon, 13 Jun 2016 16:49:01 +0200
Vincent Gross <[email protected]> wrote:
>
> While validating source address inside selection functions is the
> right direction, I don't think it would be a good thing to extend
> further in_selectsrc() prototype. However it is easy to add a check
> while processing cmsg.
>
> rev2 below. Ok ?
>
rev3 below.
I fixed the line length, the useless bzero(), and also the wording in
ip.4
Ok ?
Index: sys/netinet/in.h
===================================================================
RCS file: /cvs/src/sys/netinet/in.h,v
retrieving revision 1.115
diff -u -p -r1.115 in.h
--- sys/netinet/in.h 20 Oct 2015 20:22:42 -0000 1.115
+++ sys/netinet/in.h 15 Jun 2016 17:37:11 -0000
@@ -307,6 +307,7 @@ struct ip_opts {
#define IP_RECVRTABLE 35 /* bool; receive rdomain w/dgram */
#define IP_IPSECFLOWINFO 36 /* bool; IPsec flow info for dgram */
#define IP_IPDEFTTL 37 /* int; IP TTL system default */
+#define IP_SENDSRCADDR 38 /* struct in_addr; source address to use */
#define IP_RTABLE 0x1021 /* int; routing table, see SO_RTABLE */
#define IP_DIVERTFL 0x1022 /* int; divert direction flag opt */
Index: sys/netinet/udp_usrreq.c
===================================================================
RCS file: /cvs/src/sys/netinet/udp_usrreq.c,v
retrieving revision 1.212
diff -u -p -r1.212 udp_usrreq.c
--- sys/netinet/udp_usrreq.c 15 Jun 2016 16:06:35 -0000 1.212
+++ sys/netinet/udp_usrreq.c 15 Jun 2016 17:37:11 -0000
@@ -888,6 +888,7 @@ udp_output(struct inpcb *inp, struct mbu
struct sockaddr_in *sin = NULL;
struct udpiphdr *ui;
u_int32_t ipsecflowinfo = 0;
+ struct sockaddr_in src_sin;
int len = m->m_pkthdr.len;
struct in_addr *laddr;
int error = 0;
@@ -906,6 +907,8 @@ udp_output(struct inpcb *inp, struct mbu
goto release;
}
+ memset(&src_sin, 0, sizeof(src_sin));
+
if (control) {
u_int clen;
struct cmsghdr *cm;
@@ -939,9 +942,20 @@ udp_output(struct inpcb *inp, struct mbu
cm->cmsg_level == IPPROTO_IP &&
cm->cmsg_type == IP_IPSECFLOWINFO) {
ipsecflowinfo = *(u_int32_t *)CMSG_DATA(cm);
- break;
- }
+ } else
#endif
+ if (cm->cmsg_len == CMSG_LEN(sizeof(struct in_addr)) &&
+ cm->cmsg_level == IPPROTO_IP &&
+ cm->cmsg_type == IP_SENDSRCADDR) {
+ memcpy(&src_sin.sin_addr, CMSG_DATA(cm),
+ sizeof(struct in_addr));
+ src_sin.sin_family = AF_INET;
+ src_sin.sin_len = sizeof(src_sin);
+ /* no check on reuse when sin->sin_port == 0 */
+ if ((error = in_pcbaddrisavail(inp, &src_sin,
+ 0, curproc)))
+ goto release;
+ }
clen -= CMSG_ALIGN(cm->cmsg_len);
cmsgs += CMSG_ALIGN(cm->cmsg_len);
} while (clen);
@@ -979,6 +993,17 @@ udp_output(struct inpcb *inp, struct mbu
splx(s);
if (error)
goto release;
+ }
+
+ if (src_sin.sin_len > 0 &&
+ src_sin.sin_addr.s_addr != INADDR_ANY &&
+ src_sin.sin_addr.s_addr != inp->inp_laddr.s_addr) {
+ src_sin.sin_port = inp->inp_lport;
+ if (inp->inp_laddr.s_addr != INADDR_ANY &&
+ (error =
+ in_pcbaddrisavail(inp, &src_sin, 0, curproc)))
+ goto release;
+ laddr = &src_sin.sin_addr;
}
} else {
if (inp->inp_faddr.s_addr == INADDR_ANY) {
Index: share/man/man4/ip.4
===================================================================
RCS file: /cvs/src/share/man/man4/ip.4,v
retrieving revision 1.38
diff -u -p -r1.38 ip.4
--- share/man/man4/ip.4 20 Oct 2015 22:08:19 -0000 1.38
+++ share/man/man4/ip.4 15 Jun 2016 17:37:12 -0000
@@ -290,6 +290,34 @@ cmsg_len = CMSG_LEN(sizeof(u_int))
cmsg_level = IPPROTO_IP
cmsg_type = IP_RECVRTABLE
.Ed
+.Pp
+When sending on a
+.Dv SOCK_DGRAM
+socket with
+.Xr sendmsg 2
+, the source address to be used can be passed as ancillary data with a type
code of
+.Dv IP_SENDSRCADDR .
+The
+.Va msg_control
+field in the
+.Vt msghdr
+structure should point to a buffer that contains a
+.Vt cmsghdr
+structure followed by the requested source address.
+The
+.Vt cmsghdr
+fields should have the following values:
+.Bd -literal -offset indent
+cmsg_len = CMSG_LEN(sizeof(struct in_addr))
+cmsg_level = IPPROTO_IP
+cmsg_type = IP_SENDSRCADDR
+.Ed
+.Pp
+The same checks and restrictions as for
+.Xr bind 2
+apply, unless the socket is bound to
+.Dv INADDR_ANY .
+In this case, there is no source address overlap check.
.Ss "Multicast Options"
.Tn IP
multicasting is supported only on
