Author: cieciwa Date: Thu Sep 15 08:47:16 2005 GMT
Module: SOURCES Tag: LINUX_2_6
---- Log message:
- [extra] unclean - kernel patch.
---- Files affected:
SOURCES:
linux-2.6-nf-unclean.patch (NONE -> 1.1.2.1) (NEW)
---- Diffs:
================================================================
Index: SOURCES/linux-2.6-nf-unclean.patch
diff -u /dev/null SOURCES/linux-2.6-nf-unclean.patch:1.1.2.1
--- /dev/null Thu Sep 15 10:47:16 2005
+++ SOURCES/linux-2.6-nf-unclean.patch Thu Sep 15 10:47:11 2005
@@ -0,0 +1,648 @@
+ Kconfig | 14 +
+ Makefile | 1
+ ipt_unclean.c | 611
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ 3 files changed, 626 insertions(+)
+
+diff -Nur --exclude '*.orig' linux-2.6.13.1.org/net/ipv4/netfilter/Kconfig
linux-2.6.13.1/net/ipv4/netfilter/Kconfig
+--- linux-2.6.13.1.org/net/ipv4/netfilter/Kconfig 2005-09-10
04:42:58.000000000 +0200
++++ linux-2.6.13.1/net/ipv4/netfilter/Kconfig 2005-09-15 10:39:29.000000000
+0200
+@@ -692,5 +692,19 @@
+ Allows altering the ARP packet payload: source and destination
+ hardware and network addresses.
+
++config IP_NF_MATCH_UNCLEAN
++ tristate 'Unclean match support (DANGEROUS)'
++ depends on EXPERIMENTAL && IP_NF_IPTABLES
++ help
++ Unclean packet matching matches any strange or invalid packets, by
++ looking at a series of fields in the IP, TCP, UDP and ICMP headers.
++
++ Please note that this kind of matching is considered dangerous and
++ might harm the future compatibility of your packet filter.
++
++ It has happened before, search on the net for ECN blackholes :(
++
++
++
+ endmenu
+
+diff -Nur --exclude '*.orig' linux-2.6.13.1.org/net/ipv4/netfilter/Makefile
linux-2.6.13.1/net/ipv4/netfilter/Makefile
+--- linux-2.6.13.1.org/net/ipv4/netfilter/Makefile 2005-09-10
04:42:58.000000000 +0200
++++ linux-2.6.13.1/net/ipv4/netfilter/Makefile 2005-09-15 10:39:29.000000000
+0200
+@@ -0,0 +0,1 @@
++obj-$(CONFIG_IP_NF_MATCH_UNCLEAN) += ipt_unclean.o
+diff -Nur --exclude '*.orig'
linux-2.6.13.1.org/net/ipv4/netfilter/ipt_unclean.c
linux-2.6.13.1/net/ipv4/netfilter/ipt_unclean.c
+--- linux-2.6.13.1.org/net/ipv4/netfilter/ipt_unclean.c 1970-01-01
01:00:00.000000000 +0100
++++ linux-2.6.13.1/net/ipv4/netfilter/ipt_unclean.c 2005-09-15
10:39:29.000000000 +0200
+@@ -0,0 +1,611 @@
++/* Kernel module to match suspect packets. */
++#include <linux/module.h>
++#include <linux/skbuff.h>
++#include <linux/ip.h>
++#include <linux/udp.h>
++#include <linux/tcp.h>
++#include <linux/icmp.h>
++#include <net/checksum.h>
++#include <net/ip.h>
++
++#include <linux/netfilter_ipv4/ip_tables.h>
++
++#define limpk(format, args...)
\
++do { \
++ if (net_ratelimit()) \
++ printk("ipt_unclean: %s" format, \
++ embedded ? "(embedded packet) " : "" , ## args); \
++} while(0)
++
++enum icmp_error_status
++{
++ ICMP_MAY_BE_ERROR,
++ ICMP_IS_ERROR,
++ ICMP_NOT_ERROR
++};
++
++struct icmp_info
++{
++ size_t min_len, max_len;
++ enum icmp_error_status err;
++ u_int8_t min_code, max_code;
++};
++
++static int
++check_ip(const struct sk_buff *skb, unsigned int offset);
++
++/* ICMP-specific checks. */
++static int
++check_icmp(const struct sk_buff *skb,
++ unsigned int offset,
++ unsigned int fragoff,
++ int more_frags,
++ int embedded)
++{
++ struct icmphdr icmph;
++ static struct icmp_info info[]
++ = { [ICMP_ECHOREPLY]
++ = { 8, 65536, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_DEST_UNREACH]
++ = { 8 + 28, 65536, ICMP_IS_ERROR, 0, 15 },
++ [ICMP_SOURCE_QUENCH]
++ = { 8 + 28, 65536, ICMP_IS_ERROR, 0, 0 },
++ [ICMP_REDIRECT]
++ = { 8 + 28, 65536, ICMP_IS_ERROR, 0, 3 },
++ [ICMP_ECHO]
++ = { 8, 65536, ICMP_NOT_ERROR, 0, 0 },
++ /* Router advertisement. */
++ [9]
++ = { 8, 8 + 255 * 8, ICMP_NOT_ERROR, 0, 0 },
++ /* Router solicitation. */
++ [10]
++ = { 8, 8, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_TIME_EXCEEDED]
++ = { 8 + 28, 65536, ICMP_IS_ERROR, 0, 1 },
++ [ICMP_PARAMETERPROB]
++ = { 8 + 28, 65536, ICMP_IS_ERROR, 0, 1 },
++ [ICMP_TIMESTAMP]
++ = { 20, 20, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_TIMESTAMPREPLY]
++ = { 20, 20, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_INFO_REQUEST]
++ = { 8, 65536, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_INFO_REPLY]
++ = { 8, 65536, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_ADDRESS]
++ = { 12, 12, ICMP_NOT_ERROR, 0, 0 },
++ [ICMP_ADDRESSREPLY]
++ = { 12, 12, ICMP_NOT_ERROR, 0, 0 } };
++
++ /* Can't do anything if it's a fragment. */
++ if (fragoff)
++ return 1;
++
++ /* CHECK: Must have whole header.. */
++ if (skb_copy_bits(skb, offset, &icmph, sizeof(icmph)) < 0) {
++ limpk("ICMP len=%u too short\n", skb->len - offset);
++ return 0;
++ }
++
++ /* If not embedded in an ICMP error already. */
++ if (!embedded) {
++ /* CHECK: Truncated ICMP (even if first fragment). */
++ if (icmph.type < sizeof(info)/sizeof(struct icmp_info)
++ && info[icmph.type].min_len != 0
++ && skb->len - offset < info[icmph.type].min_len) {
++ limpk("ICMP type %u len %u too short\n",
++ icmph.type, skb->len - offset);
++ return 0;
++ }
++
++ /* CHECK: Check within known error ICMPs. */
++ if (icmph.type < sizeof(info)/sizeof(struct icmp_info)
++ && info[icmph.type].err == ICMP_IS_ERROR) {
++ /* Max IP header size = 60 */
++ char inner[60 + 8];
++ struct iphdr *inner_ip = (struct iphdr *)inner;
++
++ /* CHECK: Embedded packet must be at least
++ length of iph + 8 bytes. */
++ if (skb_copy_bits(skb, offset + sizeof(icmph),
++ inner, sizeof(struct iphdr)+8) < 0) {
++ limpk("ICMP error internal way too short\n");
++ return 0;
++ }
++
++ /* iphhdr may actually be longer: still need 8
++ actual protocol bytes. */
++ if (offset + sizeof(icmph) + inner_ip->ihl*4 + 8
++ > skb->len) {
++ limpk("ICMP error internal too short\n");
++ return 0;
++ }
++ if (!check_ip(skb, offset + sizeof(icmph)))
++ return 0;
++ }
++ } else {
++ /* CHECK: Can't embed ICMP unless known non-error. */
++ if (icmph.type >= sizeof(info)/sizeof(struct icmp_info)
++ || info[icmph.type].err != ICMP_NOT_ERROR) {
++ limpk("ICMP type %u not embeddable\n",
++ icmph.type);
++ return 0;
++ }
++ }
++
++ /* CHECK: Invalid ICMP codes. */
++ if (icmph.type < sizeof(info)/sizeof(struct icmp_info)
++ && (icmph.code < info[icmph.type].min_code
++ || icmph.code > info[icmph.type].max_code)) {
++ limpk("ICMP type=%u code=%u\n",
++ icmph.type, icmph.code);
++ return 0;
++ }
++
++ /* CHECK: Above maximum length. */
++ if (icmph.type < sizeof(info)/sizeof(struct icmp_info)
++ && info[icmph.type].max_len != 0
++ && skb->len - offset > info[icmph.type].max_len) {
++ limpk("ICMP type=%u too long: %u bytes\n",
++ icmph.type, skb->len - offset);
++ return 0;
++ }
++
++ switch (icmph.type) {
++ case ICMP_PARAMETERPROB: {
++ /* CHECK: Problem param must be within error packet's
++ * IP header. */
++ u_int32_t arg = ntohl(icmph.un.gateway);
++
++ if (icmph.code == 0) {
++ /* We've already made sure it's long enough. */
++ struct iphdr iph;
++ skb_copy_bits(skb, offset + sizeof(icmph), &iph,
++ sizeof(iph));
++ /* Code 0 means that upper 8 bits is pointer
++ to problem. */
++ if ((arg >> 24) >= iph.ihl*4) {
++ limpk("ICMP PARAMETERPROB ptr = %u\n",
++ ntohl(icmph.un.gateway) >> 24);
++ return 0;
++ }
++ arg &= 0x00FFFFFF;
++ }
++
++ /* CHECK: Rest must be zero. */
++ if (arg) {
++ limpk("ICMP PARAMETERPROB nonzero arg = %u\n",
++ arg);
++ return 0;
++ }
++ break;
++ }
++
++ case ICMP_TIME_EXCEEDED:
++ case ICMP_SOURCE_QUENCH:
++ /* CHECK: Unused must be zero. */
++ if (icmph.un.gateway != 0) {
++ limpk("ICMP type=%u unused = %u\n",
++ icmph.type, ntohl(icmph.un.gateway));
++ return 0;
++ }
++ break;
++ }
++
++ return 1;
++}
++
++/* UDP-specific checks. */
++static int
++check_udp(const struct sk_buff *skb,
++ unsigned int offset,
++ unsigned int fragoff,
++ int more_frags,
++ int embedded)
++{
++ struct udphdr udph;
++
++ /* Can't do anything if it's a fragment. */
++ if (fragoff)
++ return 1;
++
++ /* CHECK: Must cover UDP header. */
++ if (skb_copy_bits(skb, offset, &udph, sizeof(udph)) < 0) {
++ limpk("UDP len=%u too short\n", skb->len - offset);
++ return 0;
++ }
++
++ /* CHECK: Destination port can't be zero. */
++ if (!udph.dest) {
++ limpk("UDP zero destination port\n");
++ return 0;
++ }
++
++ if (!more_frags) {
++ if (!embedded) {
++ /* CHECK: UDP length must match. */
++ if (ntohs(udph.len) != skb->len - offset) {
++ limpk("UDP len too short %u vs %u\n",
++ ntohs(udph.len), skb->len - offset);
++ return 0;
++ }
++ } else {
++ /* CHECK: UDP length be >= this truncated pkt. */
++ if (ntohs(udph.len) < skb->len - offset) {
++ limpk("UDP len too long %u vs %u\n",
++ ntohs(udph.len), skb->len - offset);
++ return 0;
++ }
++ }
++ } else {
++ /* CHECK: UDP length must be > this frag's length. */
++ if (ntohs(udph.len) <= skb->len - offset) {
++ limpk("UDP fragment len too short %u vs %u\n",
++ ntohs(udph.len), skb->len - offset);
++ return 0;
++ }
++ }
++
++ return 1;
++}
++
++/* TCP-specific checks. */
++static int
++check_tcp(const struct sk_buff *skb,
++ unsigned int offset,
++ unsigned int fragoff,
++ int more_frags,
++ int embedded)
++{
++ struct tcphdr tcph;
++ unsigned char opt[15 * 4 - sizeof(struct tcphdr)];
++ u32 tcpflags;
++ int end_of_options = 0;
++ unsigned int i, optlen;
++
++ /* CHECK: Can't have offset=1: used to override TCP syn-checks. */
++ /* In fact, this is caught below (offset < 516). */
++
++ /* Can't do anything if it's a fragment. */
++ if (fragoff)
++ return 1;
++
++ /* CHECK: Smaller than minimal TCP hdr. */
++ if (skb_copy_bits(skb, offset, &tcph, sizeof(tcph)) < 0) {
++ u16 ports[2];
++
++ if (!embedded) {
++ limpk("Packet length %u < TCP header.\n",
++ skb->len - offset);
++ return 0;
++ }
++
++ /* Must have ports available (datalen >= 8), from
++ check_icmp which set embedded = 1 */
++ /* CHECK: TCP ports inside ICMP error */
++ skb_copy_bits(skb, offset, ports, sizeof(ports));
++ if (!ports[0] || !ports[1]) {
++ limpk("Zero TCP ports %u/%u.\n",
++ htons(ports[0]), htons(ports[1]));
++ return 0;
++ }
++ return 1;
++ }
++
++ /* CHECK: TCP header claims tiny size. */
++ if (tcph.doff * 4 < sizeof(tcph)) {
++ limpk("TCP header claims tiny size %u\n", tcph.doff * 4);
++ return 0;
++ }
++
++ /* CHECK: Packet smaller than actual TCP hdr. */
++ optlen = tcph.doff*4 - sizeof(tcph);
++ if (skb_copy_bits(skb, offset + sizeof(tcph), opt, optlen) < 0) {
++ if (!embedded) {
++ limpk("Packet length %u < actual TCP header.\n",
++ skb->len - offset);
++ return 0;
++ } else
++ return 1;
++ }
++
++ /* CHECK: TCP ports non-zero */
++ if (!tcph.source || !tcph.dest) {
++ limpk("Zero TCP ports %u/%u.\n",
++ htons(tcph.source), htons(tcph.dest));
++ return 0;
++ }
++
++ tcpflags = tcp_flag_word(&tcph);
++
++ /* CHECK: TCP reserved bits zero. */
++ if (tcpflags & TCP_RESERVED_BITS) {
++ limpk("TCP reserved bits not zero\n");
++ return 0;
++ }
++
++ tcpflags &= ~(TCP_DATA_OFFSET | TCP_FLAG_CWR | TCP_FLAG_ECE
++ | __constant_htonl(0x0000FFFF));
++
++ /* CHECK: TCP flags. */
++ if (tcpflags != TCP_FLAG_SYN
++ && tcpflags != (TCP_FLAG_SYN|TCP_FLAG_ACK)
++ && tcpflags != TCP_FLAG_RST
++ && tcpflags != (TCP_FLAG_RST|TCP_FLAG_ACK)
++ && tcpflags != (TCP_FLAG_RST|TCP_FLAG_ACK|TCP_FLAG_PSH)
++ && tcpflags != (TCP_FLAG_FIN|TCP_FLAG_ACK)
++ && tcpflags != TCP_FLAG_ACK
++ && tcpflags != (TCP_FLAG_ACK|TCP_FLAG_PSH)
++ && tcpflags != (TCP_FLAG_ACK|TCP_FLAG_URG)
++ && tcpflags != (TCP_FLAG_ACK|TCP_FLAG_URG|TCP_FLAG_PSH)
++ && tcpflags != (TCP_FLAG_FIN|TCP_FLAG_ACK|TCP_FLAG_PSH)
++ && tcpflags != (TCP_FLAG_FIN|TCP_FLAG_ACK|TCP_FLAG_URG)
++ && tcpflags != (TCP_FLAG_FIN|TCP_FLAG_ACK|TCP_FLAG_URG
++ |TCP_FLAG_PSH)) {
++ limpk("TCP flags bad: 0x%04X\n", ntohl(tcpflags) >> 16);
++ return 0;
++ }
++
++ for (i = 0; i < optlen; ) {
++ switch (opt[i]) {
++ case 0:
++ end_of_options = 1;
++ i++;
++ break;
++ case 1:
++ i++;
++ break;
++ default:
++ /* CHECK: options after EOO. */
++ if (end_of_options) {
++ limpk("TCP option %u after end\n",
++ opt[i]);
++ return 0;
++ }
++ /* CHECK: options at tail. */
++ else if (i+1 >= optlen) {
++ limpk("TCP option %u at tail\n",
++ opt[i]);
++ return 0;
++ }
++ /* CHECK: zero-length options. */
++ else if (opt[i+1] == 0) {
++ limpk("TCP option %u 0 len\n",
++ opt[i]);
++ return 0;
++ }
++ /* CHECK: oversize options. */
++ else if (i + opt[i+1] > optlen) {
++ limpk("TCP option %u at %u too long\n",
++ (unsigned int) opt[i], i);
++ return 0;
++ }
++ /* Move to next option */
++ i += opt[i+1];
++ }
++ }
++
++ return 1;
++}
++
++/* Returns 1 if ok */
++/* Standard IP checks. */
++static int
++check_ip(const struct sk_buff *skb, unsigned int offset)
++{
++ int end_of_options = 0;
++ unsigned int datalen, optlen;
++ unsigned int i;
++ unsigned int fragoff;
++ struct iphdr iph;
++ unsigned char opt[15 * 4 - sizeof(struct iphdr)];
++ int embedded = offset;
++
++ /* Should only happen for local outgoing raw-socket packets. */
++ /* CHECK: length >= ip header. */
++ if (skb_copy_bits(skb, offset, &iph, sizeof(iph)) < 0) {
++ limpk("Packet length %u < IP header.\n", skb->len - offset);
++ return 0;
++ }
++ if (iph.ihl * 4 < sizeof(iph)) {
++ limpk("IP len %u < minimum IP header.\n", iph.ihl*4);
++ return 0;
++ }
++
++ optlen = iph.ihl * 4 - sizeof(iph);
++ if (skb_copy_bits(skb, offset+sizeof(struct iphdr), opt, optlen)<0) {
++ limpk("Packet length %u < IP header %u.\n",
++ skb->len - offset, iph.ihl * 4);
++ return 0;
++ }
++
++ fragoff = (ntohs(iph.frag_off) & IP_OFFSET);
++ datalen = skb->len - (offset + sizeof(struct iphdr) + optlen);
++
++ /* CHECK: Embedded fragment. */
++ if (offset && fragoff) {
++ limpk("Embedded fragment.\n");
++ return 0;
++ }
++
++ for (i = 0; i < optlen; ) {
++ switch (opt[i]) {
++ case 0:
++ end_of_options = 1;
++ i++;
++ break;
++ case 1:
++ i++;
++ break;
++ default:
++ /* CHECK: options after EOO. */
++ if (end_of_options) {
++ limpk("IP option %u after end\n",
++ opt[i]);
++ return 0;
++ }
++ /* CHECK: options at tail. */
++ else if (i+1 >= optlen) {
++ limpk("IP option %u at tail\n",
++ opt[i]);
++ return 0;
++ }
++ /* CHECK: zero-length or one-length options. */
++ else if (opt[i+1] < 2) {
++ limpk("IP option %u %u len\n",
++ opt[i], opt[i+1]);
++ return 0;
++ }
++ /* CHECK: oversize options. */
++ else if (i + opt[i+1] > optlen) {
++ limpk("IP option %u at %u too long\n",
++ opt[i], i);
++ return 0;
++ }
++ /* Move to next option */
++ i += opt[i+1];
++ }
++ }
++
++ /* Fragment checks. */
++
++ /* CHECK: More fragments, but doesn't fill 8-byte boundary. */
++ if ((ntohs(iph.frag_off) & IP_MF)
++ && (ntohs(iph.tot_len) % 8) != 0) {
++ limpk("Truncated fragment %u long.\n", ntohs(iph.tot_len));
++ return 0;
++ }
++
++ /* CHECK: Oversize fragment a-la Ping of Death. */
++ if (fragoff * 8 + datalen > 65535) {
++ limpk("Oversize fragment to %u.\n", fragoff * 8);
++ return 0;
++ }
++
++ /* CHECK: DF set and fragoff or MF set. */
++ if ((ntohs(iph.frag_off) & IP_DF)
++ && (fragoff || (ntohs(iph.frag_off) & IP_MF))) {
++ limpk("DF set and offset=%u, MF=%u.\n",
++ fragoff, ntohs(iph.frag_off) & IP_MF);
++ return 0;
++ }
++
++ /* CHECK: Zero-sized fragments. */
++ if ((fragoff || (ntohs(iph.frag_off) & IP_MF))
++ && datalen == 0) {
++ limpk("Zero size fragment offset=%u\n", fragoff);
++ return 0;
++ }
++
++ /* Note: we can have even middle fragments smaller than this:
++ consider a large packet passing through a 600MTU then
++ 576MTU link: this gives a fragment of 24 data bytes. But
++ everyone packs fragments largest first, hence a fragment
++ can't START before 576 - MAX_IP_HEADER_LEN. */
++
++ /* Used to be min-size 576: I recall Alan Cox saying ax25 goes
++ down to 128 (576 taken from RFC 791: All hosts must be
++ prepared to accept datagrams of up to 576 octets). Use 128
++ here. */
++#define MIN_LIKELY_MTU 128
++ /* CHECK: Min size of first frag = 128. */
++ if ((ntohs(iph.frag_off) & IP_MF)
++ && fragoff == 0
++ && ntohs(iph.tot_len) < MIN_LIKELY_MTU) {
++ limpk("First fragment size %u < %u\n", ntohs(iph.tot_len),
++ MIN_LIKELY_MTU);
++ return 0;
++ }
++
++ /* CHECK: Min offset of frag = 128 - IP hdr len. */
++ if (fragoff && fragoff * 8 < MIN_LIKELY_MTU - iph.ihl * 4) {
++ limpk("Fragment starts at %u < %u\n", fragoff * 8,
++ MIN_LIKELY_MTU - iph.ihl * 4);
++ return 0;
++ }
++
++ /* CHECK: Protocol specification non-zero. */
++ if (iph.protocol == 0) {
++ limpk("Zero protocol\n");
++ return 0;
++ }
++
++ /* FIXME: This is already checked for in "Oversize fragment"
++ above --RR */
++ /* CHECK: Do not use what is unused.
++ * First bit of fragmentation flags should be unused.
++ * May be used by OS fingerprinting tools.
++ * 04 Jun 2002, Maciej Soltysiak, [EMAIL PROTECTED]
++ */
++ if (ntohs(iph.frag_off)>>15) {
++ limpk("IP unused bit set\n");
++ return 0;
++ }
++
++ /* Per-protocol checks. */
++ switch (iph.protocol) {
++ case IPPROTO_ICMP:
++ return check_icmp(skb, offset + iph.ihl*4, fragoff,
++ (ntohs(iph.frag_off) & IP_MF),
++ embedded);
++
++ case IPPROTO_UDP:
++ return check_udp(skb, offset + iph.ihl*4, fragoff,
++ (ntohs(iph.frag_off) & IP_MF),
<<Diff was trimmed, longer than 597 lines>>
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