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icmp ping response: fix invalid checksum (and possible assertion failure) when ip header contains options (is it correct that we mirror back all options)

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This commit is contained in:
goldsimon 2016-06-17 10:07:49 +02:00
parent 61e067b98a
commit 6d95a34971
1 changed files with 12 additions and 9 deletions
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21
src/core/ipv4/icmp.c
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@ -148,7 +148,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
} }
#endif #endif
#if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN #if LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN
if (pbuf_header(p, (PBUF_IP_HLEN + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) { if (pbuf_header(p, (hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) {
/* p is not big enough to contain link headers /* p is not big enough to contain link headers
* allocate a new one and copy p into it * allocate a new one and copy p into it
*/ */
@ -159,11 +159,14 @@ icmp_input(struct pbuf *p, struct netif *inp)
LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n")); LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
goto icmperr; goto icmperr;
} }
LWIP_ASSERT("check that first pbuf can hold struct the ICMP header", if (r->len < hlen + sizeof(struct icmp_echo_hdr)) {
(r->len >= hlen + sizeof(struct icmp_echo_hdr))); LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("first pbuf cannot hold the ICMP header"));
pbuf_free(r);
goto icmperr;
}
/* copy the ip header */ /* copy the ip header */
MEMCPY(r->payload, iphdr_in, hlen); MEMCPY(r->payload, iphdr_in, hlen);
/* switch r->payload back to icmp header */ /* switch r->payload back to icmp header (cannot fail) */
if (pbuf_header(r, -hlen)) { if (pbuf_header(r, -hlen)) {
LWIP_ASSERT("icmp_input: moving r->payload to icmp header failed\n", 0); LWIP_ASSERT("icmp_input: moving r->payload to icmp header failed\n", 0);
pbuf_free(r); pbuf_free(r);
@ -171,7 +174,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
} }
/* copy the rest of the packet without ip header */ /* copy the rest of the packet without ip header */
if (pbuf_copy(r, p) != ERR_OK) { if (pbuf_copy(r, p) != ERR_OK) {
LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0); LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("icmp_input: copying to new pbuf failed"));
pbuf_free(r); pbuf_free(r);
goto icmperr; goto icmperr;
} }
@ -180,8 +183,8 @@ icmp_input(struct pbuf *p, struct netif *inp)
/* we now have an identical copy of p that has room for link headers */ /* we now have an identical copy of p that has room for link headers */
p = r; p = r;
} else { } else {
/* restore p->payload to point to icmp header */ /* restore p->payload to point to icmp header (cannot fail) */
if (pbuf_header(p, -(s16_t)(PBUF_IP_HLEN + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) { if (pbuf_header(p, -(s16_t)(hlen + PBUF_LINK_HLEN + PBUF_LINK_ENCAPSULATION_HLEN))) {
LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0); LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
goto icmperr; goto icmperr;
} }
@ -192,7 +195,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
* setting the icmp type to ECHO_RESPONSE and updating the checksum. */ * setting the icmp type to ECHO_RESPONSE and updating the checksum. */
iecho = (struct icmp_echo_hdr *)p->payload; iecho = (struct icmp_echo_hdr *)p->payload;
if (pbuf_header(p, hlen)) { if (pbuf_header(p, hlen)) {
LWIP_ASSERT("Can't move over header in packet", 0); LWIP_DEBUGF(ICMP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Can't move over header in packet"));
} else { } else {
err_t ret; err_t ret;
struct ip_hdr *iphdr = (struct ip_hdr*)p->payload; struct ip_hdr *iphdr = (struct ip_hdr*)p->payload;
@ -222,7 +225,7 @@ icmp_input(struct pbuf *p, struct netif *inp)
IPH_CHKSUM_SET(iphdr, 0); IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP #if CHECKSUM_GEN_IP
IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_IP) { IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_GEN_IP) {
IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN)); IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, hlen));
} }
#endif /* CHECKSUM_GEN_IP */ #endif /* CHECKSUM_GEN_IP */