git: 46d7b45a267b - main - ping: Fix handling of IP packet sizes

The branch main has been updated by gordon:

URL: https://cgit.FreeBSD.org/src/commit/?id=46d7b45a267b3d78c5054b210ff7b6c55bfca42b

commit 46d7b45a267b3d78c5054b210ff7b6c55bfca42b
Author:     Tom Jones <thj@FreeBSD.org>
AuthorDate: 2022-11-17 10:31:38 +0000
Commit:     Gordon Tetlow <gordon@FreeBSD.org>
CommitDate: 2022-11-29 22:51:50 +0000

    ping: Fix handling of IP packet sizes
    
    Ping reads raw IP packets to parse ICMP responses. When reading the
    IP Header Len (IHL) ping was was taking the value from the provided
    packet without any validation. This could lead to remotely triggerable
    stack corruption.
    
    Validate the IHL against expected and recieved data sizes when reading
    from the received packet and when reading any quoted packets from within
    the ICMP response.
    
    Approved by:    so
    Reviewed by:    markj, asomers
    Security:       FreeBSD-SA-22:15.ping
    Security:       CVE-2022-23093
    Sponsored by:   NetApp, Inc.
    Sponsored by:   Klara, Inc.
    X-NetApp-PR:    #77
    Differential Revision: https://reviews.freebsd.org/D37195
---
 sbin/ping/ping.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 60 insertions(+), 9 deletions(-)

diff --git a/sbin/ping/ping.c b/sbin/ping/ping.c
index 4c4326f98f61..6956b9a68ad2 100644
--- a/sbin/ping/ping.c
+++ b/sbin/ping/ping.c
@@ -963,6 +963,9 @@ ping(int argc, char *const *argv)
 				warn("recvmsg");
 				continue;
 			}
+			/* If we have a 0 byte read from recvfrom continue */
+			if (cc == 0)
+				continue;
 #ifdef SO_TIMESTAMP
 			if (cmsg != NULL &&
 			    cmsg->cmsg_level == SOL_SOCKET &&
@@ -1144,8 +1147,10 @@ pr_pack(char *buf, ssize_t cc, struct sockaddr_in *from, struct timespec *tv)
 	struct icmp icp;
 	struct ip ip;
 	const u_char *icmp_data_raw;
+	ssize_t icmp_data_raw_len;
 	double triptime;
-	int dupflag, hlen, i, j, recv_len;
+	int dupflag, i, j, recv_len;
+	uint8_t hlen;
 	uint16_t seq;
 	static int old_rrlen;
 	static char old_rr[MAX_IPOPTLEN];
@@ -1155,15 +1160,27 @@ pr_pack(char *buf, ssize_t cc, struct sockaddr_in *from, struct timespec *tv)
 	const u_char *oicmp_raw;
 
 	/*
-	 * Get size of IP header of the received packet. The
-	 * information is contained in the lower four bits of the
-	 * first byte.
+	 * Get size of IP header of the received packet.
+	 * The header length is contained in the lower four bits of the first
+	 * byte and represents the number of 4 byte octets the header takes up.
+	 *
+	 * The IHL minimum value is 5 (20 bytes) and its maximum value is 15
+	 * (60 bytes).
 	 */
 	memcpy(&l, buf, sizeof(l));
 	hlen = (l & 0x0f) << 2;
-	memcpy(&ip, buf, hlen);
 
-	/* Check the IP header */
+	/* Reject IP packets with a short header */
+	if (hlen < sizeof(struct ip)) {
+		if (options & F_VERBOSE)
+			warn("IHL too short (%d bytes) from %s", hlen,
+			     inet_ntoa(from->sin_addr));
+		return;
+	}
+
+	memcpy(&ip, buf, sizeof(struct ip));
+
+	/* Check packet has enough data to carry a valid ICMP header */
 	recv_len = cc;
 	if (cc < hlen + ICMP_MINLEN) {
 		if (options & F_VERBOSE)
@@ -1175,6 +1192,7 @@ pr_pack(char *buf, ssize_t cc, struct sockaddr_in *from, struct timespec *tv)
 #ifndef icmp_data
 	icmp_data_raw = buf + hlen + offsetof(struct icmp, icmp_ip);
 #else
+	icmp_data_raw_len = cc - (hlen + offsetof(struct icmp, icmp_data));
 	icmp_data_raw = buf + hlen + offsetof(struct icmp, icmp_data);
 #endif
 
@@ -1304,12 +1322,45 @@ pr_pack(char *buf, ssize_t cc, struct sockaddr_in *from, struct timespec *tv)
 		 * as root to avoid leaking information not normally
 		 * available to those not running as root.
 		 */
+
+		/*
+		 * If we don't have enough bytes for a quoted IP header and an
+		 * ICMP header then stop.
+		 */
+		if (icmp_data_raw_len <
+				(ssize_t)(sizeof(struct ip) + sizeof(struct icmp))) {
+			if (options & F_VERBOSE)
+				warnx("quoted data too short (%zd bytes) from %s",
+					icmp_data_raw_len, inet_ntoa(from->sin_addr));
+			return;
+		}
+
 		memcpy(&oip_header_len, icmp_data_raw, sizeof(oip_header_len));
 		oip_header_len = (oip_header_len & 0x0f) << 2;
-		memcpy(&oip, icmp_data_raw, oip_header_len);
+
+		/* Reject IP packets with a short header */
+		if (oip_header_len < sizeof(struct ip)) {
+			if (options & F_VERBOSE)
+				warnx("inner IHL too short (%d bytes) from %s",
+					oip_header_len, inet_ntoa(from->sin_addr));
+			return;
+		}
+
+		/*
+		 * Check against the actual IHL length, to protect against
+		 * quoated packets carrying IP options.
+		 */
+		if (icmp_data_raw_len <
+				(ssize_t)(oip_header_len + sizeof(struct icmp))) {
+			if (options & F_VERBOSE)
+				warnx("inner packet too short (%zd bytes) from %s",
+				     icmp_data_raw_len, inet_ntoa(from->sin_addr));
+			return;
+		}
+
+		memcpy(&oip, icmp_data_raw, sizeof(struct ip));
 		oicmp_raw = icmp_data_raw + oip_header_len;
-		memcpy(&oicmp, oicmp_raw, offsetof(struct icmp, icmp_id) +
-		    sizeof(oicmp.icmp_id));
+		memcpy(&oicmp, oicmp_raw, sizeof(struct icmp));
 
 		if (((options & F_VERBOSE) && uid == 0) ||
 		    (!(options & F_QUIET2) &&