u_int32_t dest,
u_int32_t nextmtu)
{
- struct ip *oip, *nip;
- struct icmp *icp;
- struct mbuf *m;
- u_int32_t oiphlen, icmplen, icmpelen, nlen;
-
+ struct ip *oip = NULL;
+ struct ip *nip = NULL;
+ struct icmp *icp = NULL;
+ struct mbuf *m = NULL;
+ u_int32_t oiphlen = 0;
+ u_int32_t icmplen = 0;
+ u_int32_t icmpelen = 0;
+ u_int32_t nlen = 0;
+
+ VERIFY((u_int)type <= ICMP_MAXTYPE);
/* Expect 32-bit aligned data pointer on strict-align platforms */
MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(n);
+ if (type != ICMP_REDIRECT)
+ icmpstat.icps_error++;
+ /*
+ * Don't send error:
+ * if not the first fragment of message
+ * if original packet was a multicast or broadcast packet
+ * if the old packet protocol was ICMP
+ * error message, only known informational types.
+ */
+ if (n->m_flags & (M_BCAST|M_MCAST))
+ goto freeit;
+
+ /*
+ * Drop if IP header plus ICMP_MINLEN bytes are not contiguous
+ * in first mbuf.
+ */
+ if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
+ goto freeit;
+
oip = mtod(n, struct ip *);
oiphlen = IP_VHL_HL(oip->ip_vhl) << 2;
+ if (n->m_len < oiphlen + ICMP_MINLEN)
+ goto freeit;
#if (DEBUG | DEVELOPMENT)
if (icmpprintfs > 1)
printf("icmp_error(0x%llx, %x, %d)\n",
(uint64_t)VM_KERNEL_ADDRPERM(oip), type, code);
#endif
- if (type != ICMP_REDIRECT)
- icmpstat.icps_error++;
- /*
- * Don't send error if not the first fragment of message.
- * Don't error if the old packet protocol was ICMP
- * error message, only known informational types.
- */
+
if (oip->ip_off & ~(IP_MF|IP_DF))
goto freeit;
if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
- n->m_len >= oiphlen + ICMP_MINLEN &&
- !ICMP_INFOTYPE(((struct icmp *)(void *)((caddr_t)oip + oiphlen))->
- icmp_type)) {
+ n->m_len >= oiphlen + ICMP_MINLEN &&
+ !ICMP_INFOTYPE(((struct icmp *)(void *)((caddr_t)oip + oiphlen))->
+ icmp_type)) {
icmpstat.icps_oldicmp++;
goto freeit;
}
- /*
- * Don't send error in response to a multicast or
- * broadcast packet
- */
- if (n->m_flags & (M_BCAST|M_MCAST))
- goto freeit;
/*
* Calculate the length to quote from original packet and prevent
* the ICMP mbuf from overflowing.
+ * Unfortunatly this is non-trivial since ip_forward()
+ * sends us truncated packets.
*/
nlen = m_length(n);
if (oip->ip_p == IPPROTO_TCP) {
- struct tcphdr *th;
- u_int16_t tcphlen;
+ struct tcphdr *th = NULL;
+ u_int16_t tcphlen = 0;
+ /*
+ * If the packet got truncated and TCP header
+ * is not contained in the packet, send out
+ * standard reply with only IP header as payload
+ */
if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
n->m_next == NULL)
goto stdreply;
+
+ /*
+ * Otherwise, pull up to get IP and TCP headers
+ * together
+ */
if (n->m_len < (oiphlen + sizeof(struct tcphdr)) &&
(n = m_pullup(n, (oiphlen + sizeof(struct tcphdr)))) == NULL)
goto freeit;
sizeof(u_int32_t))))
goto freeit;
tcphlen = th->th_off << 2;
+
+ /* Sanity checks */
if (tcphlen < sizeof(struct tcphdr))
goto freeit;
if (oip->ip_len < (oiphlen + tcphlen))
stdreply: icmpelen = max(ICMP_MINLEN, min(icmp_datalen,
(oip->ip_len - oiphlen)));
- icmplen = min(oiphlen + icmpelen, min(nlen, oip->ip_len));
+ icmplen = min(oiphlen + icmpelen, nlen);
if (icmplen < sizeof(struct ip))
goto freeit;
+
/*
* First, formulate icmp message
+ * Allocate enough space for the IP header, ICMP header
+ * and the payload (part of the original message to be sent back).
*/
if (MHLEN > (sizeof(struct ip) + ICMP_MINLEN + icmplen))
m = m_gethdr(M_DONTWAIT, MT_HEADER); /* MAC-OK */
if (m == NULL)
goto freeit;
- if (n->m_flags & M_SKIP_FIREWALL) {
- /*
- * set M_SKIP_FIREWALL to skip firewall check, since
- * we're called from firewall
- */
- m->m_flags |= M_SKIP_FIREWALL;
- }
-
#if CONFIG_MACF_NET
mac_mbuf_label_associate_netlayer(n, m);
#endif
- m->m_len = icmplen + ICMP_MINLEN; /* for ICMP header and data */
- MH_ALIGN(m, m->m_len);
+ /*
+ * Further refine the payload length to the space
+ * remaining in mbuf after including the IP header and ICMP
+ * header.
+ */
+ icmplen = min(icmplen, M_TRAILINGSPACE(m) -
+ sizeof(struct ip) - ICMP_MINLEN);
+ m_align(m, ICMP_MINLEN + icmplen);
+ m->m_len = ICMP_MINLEN + icmplen; /* for ICMP header and data */
+
icp = mtod(m, struct icmp *);
- if ((u_int)type > ICMP_MAXTYPE) {
- m_freem(m);
- goto freeit;
- }
icmpstat.icps_outhist[type]++;
icp->icmp_type = type;
if (type == ICMP_REDIRECT)
}
icp->icmp_code = code;
+
+ /*
+ * Copy icmplen worth of content from original
+ * mbuf (n) to the new packet after ICMP header.
+ */
m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
nip = &icp->icmp_ip;
HTONS(nip->ip_off);
#endif
/*
- * Now, copy old ip header (without options)
- * in front of icmp message.
- */
- if (m->m_data - sizeof(struct ip) < m->m_pktdat) {
- m_freem(m);
- goto freeit;
- }
+ * Set up ICMP message mbuf and copy old IP header (without options
+ * in front of ICMP message.
+ * If the original mbuf was meant to bypass the firewall, the error
+ * reply should bypass as well.
+ */
+ m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
m->m_data -= sizeof(struct ip);
m->m_len += sizeof(struct ip);
m->m_pkthdr.len = m->m_len;
nip->ip_tos = 0;
nip->ip_off = 0;
icmp_reflect(m);
-
freeit:
m_freem(n);
}
projects / apple / xnu.git / blobdiff