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ping: Fix handling of IP packet sizes

Browse source 
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
This commit is contained in:
Tom Jones 2022-11-17 10:31:38 +00:00 committed by Gordon Tetlow
parent a6d40b0ad2
commit 46d7b45a26
1 changed files with 60 additions and 9 deletions
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69
sbin/ping/ping.c
View file

@ -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) &&