Module Name: src
Committed By: ryo
Date: Sun Oct 17 04:14:49 UTC 2021
Modified Files:
src/usr.sbin/inetd: inetd.c
Log Message:
To an alias address, or in a multihoming environment, the internal dgram
server may respond from a different address than the destination address
sent by the client.
To solve this problem, I introduce sendfromto() and recvfromto() so that
the server can reply from the correct address, i.e., the destination address
used in the request.
This change also has the aspect of a reference implementation using the
RECVDSTADDR and PKTINFO socket options.
To generate a diff of this commit:
cvs rdiff -u -r1.138 -r1.139 src/usr.sbin/inetd/inetd.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/usr.sbin/inetd/inetd.c
diff -u src/usr.sbin/inetd/inetd.c:1.138 src/usr.sbin/inetd/inetd.c:1.139
--- src/usr.sbin/inetd/inetd.c:1.138 Tue Oct 12 22:51:28 2021
+++ src/usr.sbin/inetd/inetd.c Sun Oct 17 04:14:49 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: inetd.c,v 1.138 2021/10/12 22:51:28 rillig Exp $ */
+/* $NetBSD: inetd.c,v 1.139 2021/10/17 04:14:49 ryo Exp $ */
/*-
* Copyright (c) 1998, 2003 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@ __COPYRIGHT("@(#) Copyright (c) 1983, 19
#if 0
static char sccsid[] = "@(#)inetd.c 8.4 (Berkeley) 4/13/94";
#else
-__RCSID("$NetBSD: inetd.c,v 1.138 2021/10/12 22:51:28 rillig Exp $");
+__RCSID("$NetBSD: inetd.c,v 1.139 2021/10/17 04:14:49 ryo Exp $");
#endif
#endif /* not lint */
@@ -269,6 +269,11 @@ size_t changes;
struct servtab *servtab;
+static ssize_t recvfromto(int, void * restrict, size_t, int,
+ struct sockaddr * restrict, socklen_t * restrict,
+ struct sockaddr * restrict, socklen_t * restrict);
+static ssize_t sendfromto(int, const void *, size_t, int,
+ const struct sockaddr *, socklen_t, const struct sockaddr *, socklen_t);
static void chargen_dg(int, struct servtab *);
static void chargen_stream(int, struct servtab *);
static void daytime_dg(int, struct servtab *);
@@ -809,6 +814,26 @@ setsockopt(fd, SOL_SOCKET, opt, &on, (so
if (sep->se_socktype == SOCK_STREAM)
listen(sep->se_fd, 10);
+ /* for internal dgram, setsockopt() is required for recvfromto() */
+ if (sep->se_socktype == SOCK_DGRAM && sep->se_bi != NULL) {
+ switch (sep->se_family) {
+ case AF_INET:
+ if (setsockopt(sep->se_fd, IPPROTO_IP,
+ IP_RECVDSTADDR, &on, sizeof(on)) < 0)
+ syslog(LOG_ERR,
+ "setsockopt (IP_RECVDSTADDR): %m");
+ break;
+#ifdef INET6
+ case AF_INET6:
+ if (setsockopt(sep->se_fd, IPPROTO_IPV6,
+ IPV6_RECVPKTINFO, &on, sizeof(on)) < 0)
+ syslog(LOG_ERR,
+ "setsockopt (IPV6_RECVPKTINFO): %m");
+ break;
+#endif
+ }
+ }
+
/* Set the accept filter, if specified. To be done after listen.*/
if (sep->se_accf.af_name[0] != 0 && setsockopt(sep->se_fd, SOL_SOCKET,
SO_ACCEPTFILTER, &sep->se_accf,
@@ -955,6 +980,189 @@ bump_nofile(void)
}
/*
+ * In order to get the destination address (`to') with recvfromto(),
+ * IP_RECVDSTADDR or IP_RECVPKTINFO for AF_INET, or IPV6_RECVPKTINFO
+ * for AF_INET6, must be enabled with setsockopt(2).
+ *
+ * .sin_port and .sin6_port in 'to' are always stored as zero.
+ * If necessary, extract them using getsockname(2).
+ */
+static ssize_t
+recvfromto(int s, void * restrict buf, size_t len, int flags,
+ struct sockaddr * restrict from, socklen_t * restrict fromlen,
+ struct sockaddr * restrict to, socklen_t * restrict tolen)
+{
+ struct msghdr msg;
+ struct iovec vec;
+ struct cmsghdr *cmsg;
+ struct sockaddr_storage ss;
+ char cmsgbuf[1024];
+ ssize_t rc;
+
+ if (to == NULL)
+ return recvfrom(s, buf, len, flags, from, fromlen);
+
+ if (tolen == NULL || fromlen == NULL) {
+ errno = EFAULT;
+ return -1;
+ }
+
+ vec.iov_base = buf;
+ vec.iov_len = len;
+ msg.msg_name = from;
+ msg.msg_namelen = *fromlen;
+ msg.msg_iov = &vec;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cmsgbuf;
+ msg.msg_controllen = sizeof(cmsgbuf);
+
+ rc = recvmsg(s, &msg, flags);
+ if (rc < 0)
+ return rc;
+ *fromlen = msg.msg_namelen;
+
+ memset(&ss, 0, sizeof(ss));
+ for (cmsg = (struct cmsghdr *)CMSG_FIRSTHDR(&msg); cmsg != NULL;
+ cmsg = (struct cmsghdr *)CMSG_NXTHDR(&msg, cmsg)) {
+ if (cmsg->cmsg_level == IPPROTO_IP &&
+ cmsg->cmsg_type == IP_RECVDSTADDR) {
+ struct in_addr *dst = (struct in_addr *)CMSG_DATA(cmsg);
+ struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
+
+ sin->sin_len = sizeof(*sin);
+ sin->sin_family = AF_INET;
+ sin->sin_addr = *dst;
+ break;
+ }
+ if (cmsg->cmsg_level == IPPROTO_IP &&
+ cmsg->cmsg_type == IP_PKTINFO) {
+ struct in_pktinfo *pi =
+ (struct in_pktinfo *)CMSG_DATA(cmsg);
+ struct sockaddr_in *sin = (struct sockaddr_in *)&ss;
+
+ sin->sin_len = sizeof(*sin);
+ sin->sin_family = AF_INET;
+ sin->sin_addr = pi->ipi_addr;
+ break;
+ }
+#ifdef INET6
+ if (cmsg->cmsg_level == IPPROTO_IPV6 &&
+ cmsg->cmsg_type == IPV6_PKTINFO) {
+ struct in6_pktinfo *pi6 =
+ (struct in6_pktinfo *)CMSG_DATA(cmsg);
+ struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&ss;
+
+ sin6->sin6_len = sizeof(*sin6);
+ sin6->sin6_family = AF_INET6;
+ sin6->sin6_addr = pi6->ipi6_addr;
+ if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) ||
+ IN6_IS_ADDR_MC_LINKLOCAL(&sin6->sin6_addr))
+ sin6->sin6_scope_id = pi6->ipi6_ifindex;
+ else
+ sin6->sin6_scope_id = 0;
+ break;
+ }
+#endif /* INET6 */
+ }
+
+ socklen_t sslen = (*tolen < ss.ss_len) ? *tolen : ss.ss_len;
+ if (sslen > 0)
+ memcpy(to, &ss, sslen);
+ *tolen = sslen;
+
+ return rc;
+}
+
+/*
+ * When sending, the source port is selected as the one bind(2)'ed
+ * to the socket.
+ * .sin_port and .sin6_port in `from' are always ignored.
+ */
+static ssize_t
+sendfromto(int s, const void *buf, size_t len, int flags,
+ const struct sockaddr *from, socklen_t fromlen,
+ const struct sockaddr *to, socklen_t tolen)
+{
+ struct msghdr msg;
+ struct iovec vec;
+ struct cmsghdr *cmsg;
+ char cmsgbuf[256];
+ __CTASSERT(sizeof(cmsgbuf) > CMSG_SPACE(sizeof(struct in_pktinfo)));
+#ifdef INET6
+ __CTASSERT(sizeof(cmsgbuf) > CMSG_SPACE(sizeof(struct in6_pktinfo)));
+#endif
+
+ if (from == NULL || fromlen == 0)
+ return sendto(s, buf, len, flags, to, tolen);
+
+ vec.iov_base = __UNCONST(buf);
+ vec.iov_len = len;
+ msg.msg_name = __UNCONST(to);
+ msg.msg_namelen = tolen;
+ msg.msg_iov = &vec;
+ msg.msg_iovlen = 1;
+ msg.msg_control = cmsgbuf;
+ msg.msg_controllen = 0;
+
+ if (fromlen < 2) { /* sa_len + sa_family */
+ errno = EINVAL;
+ return -1;
+ }
+
+ cmsg = (struct cmsghdr *)cmsgbuf;
+ if (from->sa_family == AF_INET) {
+ const struct sockaddr_in *from4 =
+ (const struct sockaddr_in *)from;
+ struct in_pktinfo *pi;
+
+ if (fromlen != sizeof(struct sockaddr_in) ||
+ from4->sin_family != AF_INET) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ msg.msg_controllen += CMSG_SPACE(sizeof(struct in_pktinfo));
+ cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+ cmsg->cmsg_level = IPPROTO_IP;
+ cmsg->cmsg_type = IP_PKTINFO;
+
+ pi = (struct in_pktinfo *)CMSG_DATA(cmsg);
+ pi->ipi_addr = from4->sin_addr;
+ pi->ipi_ifindex = 0;
+#ifdef INET6
+ } else if (from->sa_family == AF_INET6) {
+ const struct sockaddr_in6 *from6 =
+ (const struct sockaddr_in6 *)from;
+ struct in6_pktinfo *pi6;
+
+ if (fromlen != sizeof(struct sockaddr_in6) ||
+ from6->sin6_family != AF_INET6) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ msg.msg_controllen += CMSG_SPACE(sizeof(struct in6_pktinfo));
+ cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+ cmsg->cmsg_level = IPPROTO_IPV6;
+ cmsg->cmsg_type = IPV6_PKTINFO;
+
+ pi6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
+ pi6->ipi6_addr = from6->sin6_addr;
+ if (IN6_IS_ADDR_LINKLOCAL(&from6->sin6_addr) ||
+ IN6_IS_ADDR_MC_LINKLOCAL(&from6->sin6_addr)) {
+ pi6->ipi6_ifindex = from6->sin6_scope_id;
+ } else {
+ pi6->ipi6_ifindex = 0;
+ }
+#endif /* INET6 */
+ } else {
+ return sendto(s, buf, len, flags, to, tolen);
+ }
+
+ return sendmsg(s, &msg, flags);
+}
+
+/*
* Internet services provided internally by inetd:
*/
#define BUFSIZE 4096
@@ -978,16 +1186,20 @@ echo_dg(int s, struct servtab *sep) /* E
{
char buffer[BUFSIZE];
ssize_t i;
- socklen_t size;
- struct sockaddr_storage ss;
- struct sockaddr *sa;
-
- sa = (struct sockaddr *)(void *)&ss;
- size = sizeof(ss);
- if ((i = recvfrom(s, buffer, sizeof(buffer), 0, sa, &size)) < 0)
+ socklen_t rsize, lsize;
+ struct sockaddr_storage remote, local;
+ struct sockaddr *lsa, *rsa;
+
+ rsa = (struct sockaddr *)(void *)&remote;
+ lsa = (struct sockaddr *)(void *)&local;
+ rsize = sizeof(remote);
+ lsize = sizeof(local);
+ if ((i = recvfromto(s, buffer, sizeof(buffer), 0,
+ rsa, &rsize, lsa, &lsize)) < 0)
return;
- if (port_good_dg(sa))
- (void) sendto(s, buffer, (size_t)i, 0, sa, size);
+ if (port_good_dg(rsa))
+ (void) sendfromto(s, buffer, (size_t)i, 0,
+ lsa, lsize, rsa, rsize);
}
/* ARGSUSED */
@@ -1062,11 +1274,11 @@ chargen_stream(int s, struct servtab *se
static void
chargen_dg(int s, struct servtab *sep) /* Character generator */
{
- struct sockaddr_storage ss;
- struct sockaddr *sa;
+ struct sockaddr_storage remote, local;
+ struct sockaddr *rsa, *lsa;
static char *rs;
size_t len;
- socklen_t size;
+ socklen_t rsize, lsize;
char text[LINESIZ+2];
if (endring == 0) {
@@ -1074,12 +1286,15 @@ chargen_dg(int s, struct servtab *sep)
rs = ring;
}
- sa = (struct sockaddr *)(void *)&ss;
- size = sizeof(ss);
- if (recvfrom(s, text, sizeof(text), 0, sa, &size) < 0)
+ rsa = (struct sockaddr *)(void *)&remote;
+ lsa = (struct sockaddr *)(void *)&local;
+ rsize = sizeof(remote);
+ lsize = sizeof(local);
+ if (recvfromto(s, text, sizeof(text), 0,
+ rsa, &rsize, lsa, &lsize) < 0)
return;
- if (!port_good_dg(sa))
+ if (!port_good_dg(rsa))
return;
if ((len = (size_t)(endring - rs)) >= LINESIZ)
@@ -1092,7 +1307,7 @@ chargen_dg(int s, struct servtab *sep)
rs = ring;
text[LINESIZ] = '\r';
text[LINESIZ + 1] = '\n';
- (void) sendto(s, text, sizeof(text), 0, sa, size);
+ (void) sendfromto(s, text, sizeof(text), 0, lsa, lsize, rsa, rsize);
}
/*
@@ -1132,18 +1347,21 @@ void
machtime_dg(int s, struct servtab *sep)
{
uint32_t result;
- struct sockaddr_storage ss;
- struct sockaddr *sa;
- socklen_t size;
-
- sa = (struct sockaddr *)(void *)&ss;
- size = sizeof(ss);
- if (recvfrom(s, &result, sizeof(result), 0, sa, &size) < 0)
+ struct sockaddr_storage remote, local;
+ struct sockaddr *rsa, *lsa;
+ socklen_t rsize, lsize;
+
+ rsa = (struct sockaddr *)(void *)&remote;
+ lsa = (struct sockaddr *)(void *)&local;
+ rsize = sizeof(remote);
+ lsize = sizeof(local);
+ if (recvfromto(s, &result, sizeof(result), 0,
+ rsa, &rsize, lsa, &lsize) < 0)
return;
- if (!port_good_dg(sa))
+ if (!port_good_dg(rsa))
return;
result = machtime();
- (void)sendto(s, &result, sizeof(result), 0, sa, size);
+ (void)sendfromto(s, &result, sizeof(result), 0, lsa, lsize, rsa, rsize);
}
/* ARGSUSED */
@@ -1168,21 +1386,24 @@ daytime_dg(int s, struct servtab *sep)
{
char buffer[256];
time_t clk;
- struct sockaddr_storage ss;
- struct sockaddr *sa;
- socklen_t size;
+ struct sockaddr_storage remote, local;
+ struct sockaddr *rsa, *lsa;
+ socklen_t rsize, lsize;
int len;
clk = time((time_t *) 0);
- sa = (struct sockaddr *)(void *)&ss;
- size = sizeof(ss);
- if (recvfrom(s, buffer, sizeof(buffer), 0, sa, &size) < 0)
+ rsa = (struct sockaddr *)(void *)&remote;
+ lsa = (struct sockaddr *)(void *)&local;
+ rsize = sizeof(remote);
+ lsize = sizeof(local);
+ if (recvfromto(s, buffer, sizeof(buffer), 0,
+ rsa, &rsize, lsa, &lsize) < 0)
return;
- if (!port_good_dg(sa))
+ if (!port_good_dg(rsa))
return;
len = snprintf(buffer, sizeof buffer, "%.24s\r\n", ctime(&clk));
- (void) sendto(s, buffer, (size_t)len, 0, sa, size);
+ (void) sendfromto(s, buffer, (size_t)len, 0, lsa, lsize, rsa, rsize);
}
static void
