// SPDX-License-Identifier: GPL-2.0-only
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/* Xtables module to match packets using a BPF filter.
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* Copyright 2013 Google Inc.
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* Written by Willem de Bruijn <willemb@google.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/syscalls.h>
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#include <linux/skbuff.h>
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#include <linux/filter.h>
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#include <linux/bpf.h>
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#include <linux/netfilter/xt_bpf.h>
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#include <linux/netfilter/x_tables.h>
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MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
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MODULE_DESCRIPTION("Xtables: BPF filter match");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_bpf");
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MODULE_ALIAS("ip6t_bpf");
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static int __bpf_mt_check_bytecode(struct sock_filter *insns, __u16 len,
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struct bpf_prog **ret)
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{
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struct sock_fprog_kern program;
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if (len > XT_BPF_MAX_NUM_INSTR)
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return -EINVAL;
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program.len = len;
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program.filter = insns;
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if (bpf_prog_create(ret, &program)) {
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pr_info_ratelimited("check failed: parse error\n");
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return -EINVAL;
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}
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return 0;
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}
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static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
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{
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struct bpf_prog *prog;
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prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
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if (IS_ERR(prog))
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return PTR_ERR(prog);
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*ret = prog;
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return 0;
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}
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static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
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{
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if (strnlen(path, XT_BPF_PATH_MAX) == XT_BPF_PATH_MAX)
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return -EINVAL;
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*ret = bpf_prog_get_type_path(path, BPF_PROG_TYPE_SOCKET_FILTER);
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return PTR_ERR_OR_ZERO(*ret);
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}
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static int bpf_mt_check(const struct xt_mtchk_param *par)
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{
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struct xt_bpf_info *info = par->matchinfo;
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return __bpf_mt_check_bytecode(info->bpf_program,
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info->bpf_program_num_elem,
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&info->filter);
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}
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static int bpf_mt_check_v1(const struct xt_mtchk_param *par)
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{
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struct xt_bpf_info_v1 *info = par->matchinfo;
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if (info->mode == XT_BPF_MODE_BYTECODE)
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return __bpf_mt_check_bytecode(info->bpf_program,
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info->bpf_program_num_elem,
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&info->filter);
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else if (info->mode == XT_BPF_MODE_FD_ELF)
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return __bpf_mt_check_fd(info->fd, &info->filter);
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else if (info->mode == XT_BPF_MODE_PATH_PINNED)
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return __bpf_mt_check_path(info->path, &info->filter);
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else
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return -EINVAL;
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}
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static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_bpf_info *info = par->matchinfo;
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return BPF_PROG_RUN(info->filter, skb);
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}
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static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_bpf_info_v1 *info = par->matchinfo;
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return !!bpf_prog_run_save_cb(info->filter, (struct sk_buff *) skb);
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}
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static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
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{
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const struct xt_bpf_info *info = par->matchinfo;
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bpf_prog_destroy(info->filter);
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}
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static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par)
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{
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const struct xt_bpf_info_v1 *info = par->matchinfo;
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bpf_prog_destroy(info->filter);
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}
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static struct xt_match bpf_mt_reg[] __read_mostly = {
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{
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.name = "bpf",
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.revision = 0,
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.family = NFPROTO_UNSPEC,
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.checkentry = bpf_mt_check,
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.match = bpf_mt,
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.destroy = bpf_mt_destroy,
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.matchsize = sizeof(struct xt_bpf_info),
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.usersize = offsetof(struct xt_bpf_info, filter),
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.me = THIS_MODULE,
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},
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{
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.name = "bpf",
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.revision = 1,
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.family = NFPROTO_UNSPEC,
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.checkentry = bpf_mt_check_v1,
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.match = bpf_mt_v1,
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.destroy = bpf_mt_destroy_v1,
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.matchsize = sizeof(struct xt_bpf_info_v1),
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.usersize = offsetof(struct xt_bpf_info_v1, filter),
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.me = THIS_MODULE,
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},
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};
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static int __init bpf_mt_init(void)
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{
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return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
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}
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static void __exit bpf_mt_exit(void)
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{
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xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
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}
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module_init(bpf_mt_init);
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module_exit(bpf_mt_exit);
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