- (dtucker) OpenBSD CVS Sync

   - djm@cvs.openbsd.org 2008/06/10 03:57:27
     [servconf.c match.h sshd_config.5]
     support CIDR address matching in sshd_config "Match address" blocks, with
     full support for negation and fall-back to classic wildcard matching.
     For example:
     Match address 192.0.2.0/24,3ffe:ffff::/32,!10.*
         PasswordAuthentication yes
     addrmatch.c code mostly lifted from flowd's addr.c
     feedback and ok dtucker@

1 files changed, 420 insertions, 0 deletions

diff --git a/addrmatch.c b/addrmatch.c
new file mode 100644
index 00000000..a0559efa
--- /dev/null
+++ b/addrmatch.c
@@ -0,0 +1,420 @@
+/*	$OpenBSD: addrmatch.c,v 1.2 2008/06/10 05:22:45 djm Exp $ */
+
+/*
+ * Copyright (c) 2004-2008 Damien Miller <djm@mindrot.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "match.h"
+#include "log.h"
+
+struct xaddr {
+	sa_family_t	af;
+	union {
+		struct in_addr		v4;
+		struct in6_addr		v6;
+		u_int8_t		addr8[16];
+		u_int32_t		addr32[4];
+	} xa;		    /* 128-bit address */
+	u_int32_t	scope_id;	/* iface scope id for v6 */
+#define v4	xa.v4
+#define v6	xa.v6
+#define addr8	xa.addr8
+#define addr32	xa.addr32
+};
+
+static int
+addr_unicast_masklen(int af)
+{
+	switch (af) {
+	case AF_INET:
+		return 32;
+	case AF_INET6:
+		return 128;
+	default:
+		return -1;
+	}
+}
+
+static inline int
+masklen_valid(int af, u_int masklen)
+{
+	switch (af) {
+	case AF_INET:
+		return masklen <= 32 ? 0 : -1;
+	case AF_INET6:
+		return masklen <= 128 ? 0 : -1;
+	default:
+		return -1;
+	}
+}
+
+/*
+ * Convert struct sockaddr to struct xaddr
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_sa_to_xaddr(struct sockaddr *sa, socklen_t slen, struct xaddr *xa)
+{
+	struct sockaddr_in *in4 = (struct sockaddr_in *)sa;
+	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)sa;
+
+	memset(xa, '\0', sizeof(*xa));
+
+	switch (sa->sa_family) {
+	case AF_INET:
+		if (slen < sizeof(*in4))
+			return -1;
+		xa->af = AF_INET;
+		memcpy(&xa->v4, &in4->sin_addr, sizeof(xa->v4));
+		break;
+	case AF_INET6:
+		if (slen < sizeof(*in6))
+			return -1;
+		xa->af = AF_INET6;
+		memcpy(&xa->v6, &in6->sin6_addr, sizeof(xa->v6));
+		xa->scope_id = in6->sin6_scope_id;
+		break;
+	default:
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Calculate a netmask of length 'l' for address family 'af' and
+ * store it in 'n'.
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_netmask(int af, u_int l, struct xaddr *n)
+{
+	int i;
+
+	if (masklen_valid(af, l) != 0 || n == NULL)
+		return -1;
+
+	memset(n, '\0', sizeof(*n));
+	switch (af) {
+	case AF_INET:
+		n->af = AF_INET;
+		n->v4.s_addr = htonl((0xffffffff << (32 - l)) & 0xffffffff);
+		return 0;
+	case AF_INET6:
+		n->af = AF_INET6;
+		for (i = 0; i < 4 && l >= 32; i++, l -= 32)
+			n->addr32[i] = 0xffffffffU;
+		if (i < 4 && l != 0)
+			n->addr32[i] = htonl((0xffffffff << (32 - l)) &
+			    0xffffffff);
+		return 0;
+	default:
+		return -1;
+	}
+}
+
+/*
+ * Perform logical AND of addresses 'a' and 'b', storing result in 'dst'.
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_and(struct xaddr *dst, const struct xaddr *a, const struct xaddr *b)
+{
+	int i;
+
+	if (dst == NULL || a == NULL || b == NULL || a->af != b->af)
+		return -1;
+
+	memcpy(dst, a, sizeof(*dst));
+	switch (a->af) {
+	case AF_INET:
+		dst->v4.s_addr &= b->v4.s_addr;
+		return 0;
+	case AF_INET6:
+		dst->scope_id = a->scope_id;
+		for (i = 0; i < 4; i++)
+			dst->addr32[i] &= b->addr32[i];
+		return 0;
+	default:
+		return -1;
+	}
+}
+
+/*
+ * Compare addresses 'a' and 'b'
+ * Return 0 if addresses are identical, -1 if (a < b) or 1 if (a > b)
+ */
+static int
+addr_cmp(const struct xaddr *a, const struct xaddr *b)
+{
+	int i;
+
+	if (a->af != b->af)
+		return a->af == AF_INET6 ? 1 : -1;
+
+	switch (a->af) {
+	case AF_INET:
+		if (a->v4.s_addr == b->v4.s_addr)
+			return 0;
+		return ntohl(a->v4.s_addr) > ntohl(b->v4.s_addr) ? 1 : -1;
+	case AF_INET6:
+		for (i = 0; i < 16; i++)
+			if (a->addr8[i] - b->addr8[i] != 0)
+				return a->addr8[i] > b->addr8[i] ? 1 : -1;
+		if (a->scope_id == b->scope_id)
+			return 0;
+		return a->scope_id > b->scope_id ? 1 : -1;
+	default:
+		return -1;
+	}
+}
+
+/*
+ * Parse string address 'p' into 'n'
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_pton(const char *p, struct xaddr *n)
+{
+	struct addrinfo hints, *ai;
+
+	memset(&hints, '\0', sizeof(hints));
+	hints.ai_flags = AI_NUMERICHOST;
+
+	if (p == NULL || getaddrinfo(p, NULL, &hints, &ai) != 0)
+		return -1;
+
+	if (ai == NULL || ai->ai_addr == NULL)
+		return -1;
+
+	if (n != NULL &&
+	    addr_sa_to_xaddr(ai->ai_addr, ai->ai_addrlen, n) == -1) {
+		freeaddrinfo(ai);
+		return -1;
+	}
+
+	freeaddrinfo(ai);
+	return 0;
+}
+
+/*
+ * Perform bitwise negation of address
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_invert(struct xaddr *n)
+{
+	int i;
+
+	if (n == NULL)
+		return (-1);
+
+	switch (n->af) {
+	case AF_INET:
+		n->v4.s_addr = ~n->v4.s_addr;
+		return (0);
+	case AF_INET6:
+		for (i = 0; i < 4; i++)
+			n->addr32[i] = ~n->addr32[i];
+		return (0);
+	default:
+		return (-1);
+	}
+}
+
+/*
+ * Calculate a netmask of length 'l' for address family 'af' and
+ * store it in 'n'.
+ * Returns 0 on success, -1 on failure.
+ */
+static int
+addr_hostmask(int af, u_int l, struct xaddr *n)
+{
+	if (addr_netmask(af, l, n) == -1 || addr_invert(n) == -1)
+		return (-1);
+	return (0);
+}
+
+/*
+ * Test whether address 'a' is all zeros (i.e. 0.0.0.0 or ::)
+ * Returns 0 on if address is all-zeros, -1 if not all zeros or on failure.
+ */
+static int
+addr_is_all0s(const struct xaddr *a)
+{
+	int i;
+
+	switch (a->af) {
+	case AF_INET:
+		return (a->v4.s_addr == 0 ? 0 : -1);
+	case AF_INET6:;
+		for (i = 0; i < 4; i++)
+			if (a->addr32[i] != 0)
+				return (-1);
+		return (0);
+	default:
+		return (-1);
+	}
+}
+
+/*
+ * Test whether host portion of address 'a', as determined by 'masklen'
+ * is all zeros.
+ * Returns 0 on if host portion of address is all-zeros,
+ * -1 if not all zeros or on failure.
+ */
+static int
+addr_host_is_all0s(const struct xaddr *a, u_int masklen)
+{
+	struct xaddr tmp_addr, tmp_mask, tmp_result;
+
+	memcpy(&tmp_addr, a, sizeof(tmp_addr));
+	if (addr_hostmask(a->af, masklen, &tmp_mask) == -1)
+		return (-1);
+	if (addr_and(&tmp_result, &tmp_addr, &tmp_mask) == -1)
+		return (-1);
+	return (addr_is_all0s(&tmp_result));
+}
+
+/*
+ * Parse a CIDR address (x.x.x.x/y or xxxx:yyyy::/z).
+ * Return -1 on parse error, -2 on inconsistency or 0 on success.
+ */
+static int
+addr_pton_cidr(const char *p, struct xaddr *n, u_int *l)
+{
+	struct xaddr tmp;
+	long unsigned int masklen = 999;
+	char addrbuf[64], *mp, *cp;
+
+	/* Don't modify argument */
+	if (p == NULL || strlcpy(addrbuf, p, sizeof(addrbuf)) > sizeof(addrbuf))
+		return -1;
+
+	if ((mp = strchr(addrbuf, '/')) != NULL) {
+		*mp = '\0';
+		mp++;
+		masklen = strtoul(mp, &cp, 10);
+		if (*mp == '\0' || *cp != '\0' || masklen > 128)
+			return -1;
+	}
+
+	if (addr_pton(addrbuf, &tmp) == -1)
+		return -1;
+
+	if (mp == NULL)
+		masklen = addr_unicast_masklen(tmp.af);
+	if (masklen_valid(tmp.af, masklen) == -1)
+		return -2;
+	if (addr_host_is_all0s(&tmp, masklen) != 0)
+		return -2;
+
+	if (n != NULL)
+		memcpy(n, &tmp, sizeof(*n));
+	if (l != NULL)
+		*l = masklen;
+
+	return 0;
+}
+
+static int
+addr_netmatch(const struct xaddr *host, const struct xaddr *net, u_int masklen)
+{
+	struct xaddr tmp_mask, tmp_result;
+
+	if (host->af != net->af)
+		return -1;
+
+	if (addr_netmask(host->af, masklen, &tmp_mask) == -1)
+		return -1;
+	if (addr_and(&tmp_result, host, &tmp_mask) == -1)
+		return -1;
+	return addr_cmp(&tmp_result, net);
+}
+
+/*
+ * Match "addr" against list pattern list "_list", which may contain a
+ * mix of CIDR addresses and old-school wildcards.
+ *
+ * If addr is NULL, then no matching is performed, but _list is parsed
+ * and checked for well-formedness.
+ *
+ * Returns 1 on match found (never returned when addr == NULL).
+ * Returns 0 on if no match found, or no errors found when addr == NULL.
+ * Returns -1 on invalid list entry.
+ */
+int
+addr_match_list(const char *addr, const char *_list)
+{
+	char *list, *cp, *o;
+	struct xaddr try_addr, match_addr;
+	u_int masklen, neg;
+	int ret = 0, r;
+
+	if (addr != NULL && addr_pton(addr, &try_addr) != 0) {
+		debug2("%s: couldn't parse address %.100s", __func__, addr);
+		return 0;
+	}
+	if ((o = list = strdup(_list)) == NULL)
+		return -1;
+	while ((cp = strsep(&list, ",")) != NULL) {
+		neg = *cp == '!';
+		if (neg)
+			cp++;
+		if (*cp == '\0') {
+			ret = -1;
+			break;
+		}
+		/* Prefer CIDR address matching */
+		r = addr_pton_cidr(cp, &match_addr, &masklen);
+		if (r == -2) {
+			error("Inconsistent mask length for "
+			    "network \"%.100s\"", cp);
+			ret = -1;
+			break;
+		} else if (r == 0) {
+			if (addr != NULL && addr_netmatch(&try_addr,
+                           &match_addr, masklen) == 0) {
+ foundit:
+				if (neg) {
+					ret = 0;
+					break;
+				}
+				ret = 1;
+			}
+			continue;
+		} else {
+			/* If CIDR parse failed, try wildcard string match */
+			if (addr != NULL && match_pattern(addr, cp) == 1)
+				goto foundit;
+		}
+	}
+	free(o);
+
+	return ret;
+}