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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /net/netfilter/xt_tcpudp.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'net/netfilter/xt_tcpudp.c')
-rw-r--r-- | net/netfilter/xt_tcpudp.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/net/netfilter/xt_tcpudp.c b/net/netfilter/xt_tcpudp.c new file mode 100644 index 0000000000..e8991130a3 --- /dev/null +++ b/net/netfilter/xt_tcpudp.c @@ -0,0 +1,342 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/types.h> +#include <linux/module.h> +#include <net/ip.h> +#include <linux/ipv6.h> +#include <linux/icmp.h> +#include <net/ipv6.h> +#include <net/tcp.h> +#include <net/udp.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_tcpudp.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> + +MODULE_DESCRIPTION("Xtables: TCP, UDP and UDP-Lite match"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("xt_tcp"); +MODULE_ALIAS("xt_udp"); +MODULE_ALIAS("ipt_udp"); +MODULE_ALIAS("ipt_tcp"); +MODULE_ALIAS("ip6t_udp"); +MODULE_ALIAS("ip6t_tcp"); +MODULE_ALIAS("ipt_icmp"); +MODULE_ALIAS("ip6t_icmp6"); + +/* Returns 1 if the port is matched by the range, 0 otherwise */ +static inline bool +port_match(u_int16_t min, u_int16_t max, u_int16_t port, bool invert) +{ + return (port >= min && port <= max) ^ invert; +} + +static bool +tcp_find_option(u_int8_t option, + const struct sk_buff *skb, + unsigned int protoff, + unsigned int optlen, + bool invert, + bool *hotdrop) +{ + /* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */ + const u_int8_t *op; + u_int8_t _opt[60 - sizeof(struct tcphdr)]; + unsigned int i; + + pr_debug("finding option\n"); + + if (!optlen) + return invert; + + /* If we don't have the whole header, drop packet. */ + op = skb_header_pointer(skb, protoff + sizeof(struct tcphdr), + optlen, _opt); + if (op == NULL) { + *hotdrop = true; + return false; + } + + for (i = 0; i < optlen; ) { + if (op[i] == option) return !invert; + if (op[i] < 2) i++; + else i += op[i+1]?:1; + } + + return invert; +} + +static bool tcp_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct tcphdr *th; + struct tcphdr _tcph; + const struct xt_tcp *tcpinfo = par->matchinfo; + + if (par->fragoff != 0) { + /* To quote Alan: + + Don't allow a fragment of TCP 8 bytes in. Nobody normal + causes this. Its a cracker trying to break in by doing a + flag overwrite to pass the direction checks. + */ + if (par->fragoff == 1) { + pr_debug("Dropping evil TCP offset=1 frag.\n"); + par->hotdrop = true; + } + /* Must not be a fragment. */ + return false; + } + + th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph); + if (th == NULL) { + /* We've been asked to examine this packet, and we + can't. Hence, no choice but to drop. */ + pr_debug("Dropping evil TCP offset=0 tinygram.\n"); + par->hotdrop = true; + return false; + } + + if (!port_match(tcpinfo->spts[0], tcpinfo->spts[1], + ntohs(th->source), + !!(tcpinfo->invflags & XT_TCP_INV_SRCPT))) + return false; + if (!port_match(tcpinfo->dpts[0], tcpinfo->dpts[1], + ntohs(th->dest), + !!(tcpinfo->invflags & XT_TCP_INV_DSTPT))) + return false; + if (!NF_INVF(tcpinfo, XT_TCP_INV_FLAGS, + (((unsigned char *)th)[13] & tcpinfo->flg_mask) == tcpinfo->flg_cmp)) + return false; + if (tcpinfo->option) { + if (th->doff * 4 < sizeof(_tcph)) { + par->hotdrop = true; + return false; + } + if (!tcp_find_option(tcpinfo->option, skb, par->thoff, + th->doff*4 - sizeof(_tcph), + tcpinfo->invflags & XT_TCP_INV_OPTION, + &par->hotdrop)) + return false; + } + return true; +} + +static int tcp_mt_check(const struct xt_mtchk_param *par) +{ + const struct xt_tcp *tcpinfo = par->matchinfo; + + /* Must specify no unknown invflags */ + return (tcpinfo->invflags & ~XT_TCP_INV_MASK) ? -EINVAL : 0; +} + +static bool udp_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct udphdr *uh; + struct udphdr _udph; + const struct xt_udp *udpinfo = par->matchinfo; + + /* Must not be a fragment. */ + if (par->fragoff != 0) + return false; + + uh = skb_header_pointer(skb, par->thoff, sizeof(_udph), &_udph); + if (uh == NULL) { + /* We've been asked to examine this packet, and we + can't. Hence, no choice but to drop. */ + pr_debug("Dropping evil UDP tinygram.\n"); + par->hotdrop = true; + return false; + } + + return port_match(udpinfo->spts[0], udpinfo->spts[1], + ntohs(uh->source), + !!(udpinfo->invflags & XT_UDP_INV_SRCPT)) + && port_match(udpinfo->dpts[0], udpinfo->dpts[1], + ntohs(uh->dest), + !!(udpinfo->invflags & XT_UDP_INV_DSTPT)); +} + +static int udp_mt_check(const struct xt_mtchk_param *par) +{ + const struct xt_udp *udpinfo = par->matchinfo; + + /* Must specify no unknown invflags */ + return (udpinfo->invflags & ~XT_UDP_INV_MASK) ? -EINVAL : 0; +} + +/* Returns 1 if the type and code is matched by the range, 0 otherwise */ +static bool type_code_in_range(u8 test_type, u8 min_code, u8 max_code, + u8 type, u8 code) +{ + return type == test_type && code >= min_code && code <= max_code; +} + +static bool icmp_type_code_match(u8 test_type, u8 min_code, u8 max_code, + u8 type, u8 code, bool invert) +{ + return (test_type == 0xFF || + type_code_in_range(test_type, min_code, max_code, type, code)) + ^ invert; +} + +static bool icmp6_type_code_match(u8 test_type, u8 min_code, u8 max_code, + u8 type, u8 code, bool invert) +{ + return type_code_in_range(test_type, min_code, max_code, type, code) ^ invert; +} + +static bool +icmp_match(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct icmphdr *ic; + struct icmphdr _icmph; + const struct ipt_icmp *icmpinfo = par->matchinfo; + + /* Must not be a fragment. */ + if (par->fragoff != 0) + return false; + + ic = skb_header_pointer(skb, par->thoff, sizeof(_icmph), &_icmph); + if (!ic) { + /* We've been asked to examine this packet, and we + * can't. Hence, no choice but to drop. + */ + par->hotdrop = true; + return false; + } + + return icmp_type_code_match(icmpinfo->type, + icmpinfo->code[0], + icmpinfo->code[1], + ic->type, ic->code, + !!(icmpinfo->invflags & IPT_ICMP_INV)); +} + +static bool +icmp6_match(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct icmp6hdr *ic; + struct icmp6hdr _icmph; + const struct ip6t_icmp *icmpinfo = par->matchinfo; + + /* Must not be a fragment. */ + if (par->fragoff != 0) + return false; + + ic = skb_header_pointer(skb, par->thoff, sizeof(_icmph), &_icmph); + if (!ic) { + /* We've been asked to examine this packet, and we + * can't. Hence, no choice but to drop. + */ + par->hotdrop = true; + return false; + } + + return icmp6_type_code_match(icmpinfo->type, + icmpinfo->code[0], + icmpinfo->code[1], + ic->icmp6_type, ic->icmp6_code, + !!(icmpinfo->invflags & IP6T_ICMP_INV)); +} + +static int icmp_checkentry(const struct xt_mtchk_param *par) +{ + const struct ipt_icmp *icmpinfo = par->matchinfo; + + return (icmpinfo->invflags & ~IPT_ICMP_INV) ? -EINVAL : 0; +} + +static int icmp6_checkentry(const struct xt_mtchk_param *par) +{ + const struct ip6t_icmp *icmpinfo = par->matchinfo; + + return (icmpinfo->invflags & ~IP6T_ICMP_INV) ? -EINVAL : 0; +} + +static struct xt_match tcpudp_mt_reg[] __read_mostly = { + { + .name = "tcp", + .family = NFPROTO_IPV4, + .checkentry = tcp_mt_check, + .match = tcp_mt, + .matchsize = sizeof(struct xt_tcp), + .proto = IPPROTO_TCP, + .me = THIS_MODULE, + }, + { + .name = "tcp", + .family = NFPROTO_IPV6, + .checkentry = tcp_mt_check, + .match = tcp_mt, + .matchsize = sizeof(struct xt_tcp), + .proto = IPPROTO_TCP, + .me = THIS_MODULE, + }, + { + .name = "udp", + .family = NFPROTO_IPV4, + .checkentry = udp_mt_check, + .match = udp_mt, + .matchsize = sizeof(struct xt_udp), + .proto = IPPROTO_UDP, + .me = THIS_MODULE, + }, + { + .name = "udp", + .family = NFPROTO_IPV6, + .checkentry = udp_mt_check, + .match = udp_mt, + .matchsize = sizeof(struct xt_udp), + .proto = IPPROTO_UDP, + .me = THIS_MODULE, + }, + { + .name = "udplite", + .family = NFPROTO_IPV4, + .checkentry = udp_mt_check, + .match = udp_mt, + .matchsize = sizeof(struct xt_udp), + .proto = IPPROTO_UDPLITE, + .me = THIS_MODULE, + }, + { + .name = "udplite", + .family = NFPROTO_IPV6, + .checkentry = udp_mt_check, + .match = udp_mt, + .matchsize = sizeof(struct xt_udp), + .proto = IPPROTO_UDPLITE, + .me = THIS_MODULE, + }, + { + .name = "icmp", + .match = icmp_match, + .matchsize = sizeof(struct ipt_icmp), + .checkentry = icmp_checkentry, + .proto = IPPROTO_ICMP, + .family = NFPROTO_IPV4, + .me = THIS_MODULE, + }, + { + .name = "icmp6", + .match = icmp6_match, + .matchsize = sizeof(struct ip6t_icmp), + .checkentry = icmp6_checkentry, + .proto = IPPROTO_ICMPV6, + .family = NFPROTO_IPV6, + .me = THIS_MODULE, + }, +}; + +static int __init tcpudp_mt_init(void) +{ + return xt_register_matches(tcpudp_mt_reg, ARRAY_SIZE(tcpudp_mt_reg)); +} + +static void __exit tcpudp_mt_exit(void) +{ + xt_unregister_matches(tcpudp_mt_reg, ARRAY_SIZE(tcpudp_mt_reg)); +} + +module_init(tcpudp_mt_init); +module_exit(tcpudp_mt_exit); |