Merge pull request #41 from bwhacks/security-fixes

Security fixes

4 files changed, 57 insertions, 29 deletions

diff --git a/src/dhcpv6.c b/src/dhcpv6.c
index cfa3f29..e27d899 100644
--- a/src/dhcpv6.c
+++ b/src/dhcpv6.c
@@ -23,6 +23,7 @@
 #include <unistd.h>
 #include <syslog.h>
 #include <stdbool.h>
+#include <ctype.h>
 #include <sys/time.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
@@ -812,7 +813,8 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
 			if (inf_max_rt >= DHCPV6_INF_MAX_RT_MIN &&
 					inf_max_rt <= DHCPV6_INF_MAX_RT_MAX)
 				cand.inf_max_rt = inf_max_rt;
-		} else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
+		} else if (otype == DHCPV6_OPT_IA_PD && request_prefix &&
+					olen >= -4 + sizeof(struct dhcpv6_ia_hdr)) {
 			struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 			uint8_t *oend = odata + olen, *d;
 			dhcpv6_for_each_option(&h[1], oend, otype, olen, d) {
@@ -822,7 +824,8 @@ static int dhcpv6_handle_advert(enum dhcpv6_msg orig, const int rc,
 					have_pd = p->prefix;
 				}
 			}
-		} else if (otype == DHCPV6_OPT_IA_NA) {
+		} else if (otype == DHCPV6_OPT_IA_NA &&
+					olen >= -4 + sizeof(struct dhcpv6_ia_hdr)) {
 			struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 			uint8_t *oend = odata + olen, *d;
 			dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
@@ -1185,7 +1188,7 @@ static int dhcpv6_parse_ia(void *opt, void *end)
 				if (elen > 64)
 					elen = 64;
 
-				if (elen <= 32 || elen <= entry.length) {
+				if (entry.length < 32 || elen <= entry.length) {
 					ok = false;
 					continue;
 				}
@@ -1290,16 +1293,22 @@ static int dhcpv6_calc_refresh_timers(void)
 
 
 static void dhcpv6_log_status_code(const uint16_t code, const char *scope,
-		const void *status_msg, const int len)
+		const void *status_msg, int len)
 {
-	uint8_t buf[len + 3];
+	const char *src = status_msg;
+	char buf[len + 3];
+	char *dst = buf;
 
-	memset(buf, 0, sizeof(buf));
 	if (len) {
-		buf[0] = '(';
-		memcpy(&buf[1], status_msg, len);
-		buf[len + 1] = ')';
+		*dst++ = '(';
+		while (len--) {
+			*dst = isprint((unsigned char)*src) ? *src : '?';
+			src++;
+			dst++;
+		}
+		*dst++ = ')';
 	}
+	*dst = 0;
 
 	syslog(LOG_WARNING, "Server returned %s status %i %s",
 		scope, code, buf);
@@ -1362,6 +1371,7 @@ static void dhcpv6_handle_ia_status_code(const enum dhcpv6_msg orig,
 	}
 }
 
+// Note this always takes ownership of cand->ia_na and cand->ia_pd
 static void dhcpv6_add_server_cand(const struct dhcpv6_server_cand *cand)
 {
 	size_t cand_len, i;
@@ -1384,7 +1394,10 @@ static void dhcpv6_add_server_cand(const struct dhcpv6_server_cand *cand)
 			break;
 	}
 
-	odhcp6c_insert_state(STATE_SERVER_CAND, i * sizeof(*c), cand, sizeof(*cand));
+	if (odhcp6c_insert_state(STATE_SERVER_CAND, i * sizeof(*c), cand, sizeof(*cand))) {
+		free(cand->ia_na);
+		free(cand->ia_pd);
+	}
 }
 
 static void dhcpv6_clear_all_server_cand(void)
diff --git a/src/odhcp6c.c b/src/odhcp6c.c
index 133ade7..1714d62 100644
--- a/src/odhcp6c.c
+++ b/src/odhcp6c.c
@@ -516,11 +516,11 @@ void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len)
 		memcpy(n, data, len);
 }
 
-void odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *data, size_t len)
+int odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *data, size_t len)
 {
 	ssize_t len_after = state_len[state] - offset;
 	if (len_after < 0)
-		return;
+		return -1;
 
 	uint8_t *n = odhcp6c_resize_state(state, len);
 	if (n) {
@@ -529,6 +529,8 @@ void odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *d
 		memmove(sdata + offset + len, sdata + offset, len_after);
 		memcpy(sdata + offset, data, len);
 	}
+
+	return 0;
 }
 
 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len)
diff --git a/src/odhcp6c.h b/src/odhcp6c.h
index d202790..928f82f 100644
--- a/src/odhcp6c.h
+++ b/src/odhcp6c.h
@@ -335,7 +335,7 @@ bool odhcp6c_is_bound(void);
 void odhcp6c_clear_state(enum odhcp6c_state state);
 void odhcp6c_add_state(enum odhcp6c_state state, const void *data, size_t len);
 void odhcp6c_append_state(enum odhcp6c_state state, const void *data, size_t len);
-void odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *data, size_t len);
+int odhcp6c_insert_state(enum odhcp6c_state state, size_t offset, const void *data, size_t len);
 size_t odhcp6c_remove_state(enum odhcp6c_state state, size_t offset, size_t len);
 void* odhcp6c_move_state(enum odhcp6c_state state, size_t *len);
 void* odhcp6c_get_state(enum odhcp6c_state state, size_t *len);
diff --git a/src/script.c b/src/script.c
index f272c19..3579331 100644
--- a/src/script.c
+++ b/src/script.c
@@ -118,9 +118,10 @@ static void fqdn_to_env(const char *name, const uint8_t *fqdn, size_t len)
 	char *buf = realloc(NULL, len + buf_len + 2);
 	memcpy(buf, name, buf_len);
 	buf[buf_len++] = '=';
-	int l = 1;
-	while (l > 0 && fqdn < fqdn_end) {
-		l = dn_expand(fqdn, fqdn_end, fqdn, &buf[buf_len], buf_size - buf_len);
+	while (fqdn < fqdn_end) {
+		int l = dn_expand(fqdn, fqdn_end, fqdn, &buf[buf_len], buf_size - buf_len);
+		if (l <= 0)
+			break;
 		fqdn += l;
 		buf_len += strlen(&buf[buf_len]);
 		buf[buf_len++] = ' ';
@@ -156,7 +157,10 @@ static void entry_to_env(const char *name, const void *data, size_t len, enum en
 {
 	size_t buf_len = strlen(name);
 	const struct odhcp6c_entry *e = data;
-	char *buf = realloc(NULL, buf_len + 2 + (len / sizeof(*e)) * 144);
+	// Worst case: ENTRY_PREFIX with iaid != 1 and exclusion
+	const size_t max_entry_len = (INET6_ADDRSTRLEN-1 + 5 + 22 + 15 + 10 +
+				      INET6_ADDRSTRLEN-1 + 11 + 1);
+	char *buf = realloc(NULL, buf_len + 2 + (len / sizeof(*e)) * max_entry_len);
 	memcpy(buf, name, buf_len);
 	buf[buf_len++] = '=';
 
@@ -164,28 +168,34 @@ static void entry_to_env(const char *name, const void *data, size_t len, enum en
 		inet_ntop(AF_INET6, &e[i].target, &buf[buf_len], INET6_ADDRSTRLEN);
 		buf_len += strlen(&buf[buf_len]);
 		if (type != ENTRY_HOST) {
-			buf_len += snprintf(&buf[buf_len], 6, "/%"PRIu16, e[i].length);
+			snprintf(&buf[buf_len], 6, "/%"PRIu16, e[i].length);
+			buf += strlen(&buf[buf_len]);
 			if (type == ENTRY_ROUTE) {
 				buf[buf_len++] = ',';
 				if (!IN6_IS_ADDR_UNSPECIFIED(&e[i].router)) {
 					inet_ntop(AF_INET6, &e[i].router, &buf[buf_len], INET6_ADDRSTRLEN);
 					buf_len += strlen(&buf[buf_len]);
 				}
-				buf_len += snprintf(&buf[buf_len], 24, ",%u", e[i].valid);
-				buf_len += snprintf(&buf[buf_len], 12, ",%u", e[i].priority);
+				snprintf(&buf[buf_len], 23, ",%u,%u", e[i].valid, e[i].priority);
+				buf += strlen(&buf[buf_len]);
 			} else {
-				buf_len += snprintf(&buf[buf_len], 24, ",%u,%u", e[i].preferred, e[i].valid);
+				snprintf(&buf[buf_len], 23, ",%u,%u", e[i].preferred, e[i].valid);
+				buf += strlen(&buf[buf_len]);
 			}
 
-			if (type == ENTRY_PREFIX && ntohl(e[i].iaid) != 1)
-				buf_len += snprintf(&buf[buf_len], 16, ",class=%08x", ntohl(e[i].iaid));
+			if (type == ENTRY_PREFIX && ntohl(e[i].iaid) != 1) {
+				snprintf(&buf[buf_len], 16, ",class=%08x", ntohl(e[i].iaid));
+				buf += strlen(&buf[buf_len]);
+			}
 
 			if (type == ENTRY_PREFIX && e[i].priority) {
 				// priority and router are abused for prefix exclusion
-				buf_len += snprintf(&buf[buf_len], 12, ",excluded=");
+				snprintf(&buf[buf_len], 11, ",excluded=");
+				buf_len += strlen(&buf[buf_len]);
 				inet_ntop(AF_INET6, &e[i].router, &buf[buf_len], INET6_ADDRSTRLEN);
 				buf_len += strlen(&buf[buf_len]);
-				buf_len += snprintf(&buf[buf_len], 24, "/%u", e[i].priority);
+				snprintf(&buf[buf_len], 12, "/%u", e[i].priority);
+				buf_len += strlen(&buf[buf_len]);
 			}
 		}
 		buf[buf_len++] = ' ';
@@ -217,7 +227,7 @@ static void search_to_env(const char *name, const uint8_t *start, size_t len)
 
 static void int_to_env(const char *name, int value)
 {
-	size_t len = 12 + strlen(name);
+	size_t len = 13 + strlen(name);
 	char *buf = realloc(NULL, len);
 	snprintf(buf, len, "%s=%d", name, value);
 	putenv(buf);
@@ -272,7 +282,8 @@ static void s46_to_env(enum odhcp6c_state state, const uint8_t *data, size_t len
 			size_t prefix6len = rule->prefix6_len;
 			prefix6len = (prefix6len % 8 == 0) ? prefix6len / 8 : prefix6len / 8 + 1;
 
-			if (olen < sizeof(struct dhcpv6_s46_rule) + prefix6len)
+			if (prefix6len > sizeof(in6) ||
+			    olen < sizeof(struct dhcpv6_s46_rule) + prefix6len)
 				continue;
 
 			memcpy(&in6, rule->ipv6_prefix, prefix6len);
@@ -301,7 +312,8 @@ static void s46_to_env(enum odhcp6c_state state, const uint8_t *data, size_t len
 					size_t prefix6len = dmr->dmr_prefix6_len;
 					prefix6len = (prefix6len % 8 == 0) ? prefix6len / 8 : prefix6len / 8 + 1;
 
-					if (olen < sizeof(struct dhcpv6_s46_dmr) + prefix6len)
+					if (prefix6len > sizeof(in6) ||
+					    olen < sizeof(struct dhcpv6_s46_dmr) + prefix6len)
 						continue;
 
 					memcpy(&in6, dmr->dmr_ipv6_prefix, prefix6len);
@@ -320,7 +332,8 @@ static void s46_to_env(enum odhcp6c_state state, const uint8_t *data, size_t len
 			size_t prefix6len = bind->bindprefix6_len;
 			prefix6len = (prefix6len % 8 == 0) ? prefix6len / 8 : prefix6len / 8 + 1;
 
-			if (olen < sizeof(struct dhcpv6_s46_v4v6bind) + prefix6len)
+			if (prefix6len > sizeof(in6) ||
+			    olen < sizeof(struct dhcpv6_s46_v4v6bind) + prefix6len)
 				continue;
 
 			memcpy(&in6, bind->bind_ipv6_prefix, prefix6len);