net/netfilter/xt_bpf.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Xtables module to match packets using a BPF filter.
0003  * Copyright 2013 Google Inc.
0004  * Written by Willem de Bruijn <willemb@google.com>
0005  */
0006
0007 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0008
0009 #include <linux/module.h>
0010 #include <linux/syscalls.h>
0011 #include <linux/skbuff.h>
0012 #include <linux/filter.h>
0013 #include <linux/bpf.h>
0014
0015 #include <linux/netfilter/xt_bpf.h>
0016 #include <linux/netfilter/x_tables.h>
0017
0018 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
0019 MODULE_DESCRIPTION("Xtables: BPF filter match");
0020 MODULE_LICENSE("GPL");
0021 MODULE_ALIAS("ipt_bpf");
0022 MODULE_ALIAS("ip6t_bpf");
0023
0024 static int __bpf_mt_check_bytecode(struct sock_filter *insns, __u16 len,
0025                    struct bpf_prog **ret)
0026 {
0027     struct sock_fprog_kern program;
0028
0029     if (len > XT_BPF_MAX_NUM_INSTR)
0030         return -EINVAL;
0031
0032     program.len = len;
0033     program.filter = insns;
0034
0035     if (bpf_prog_create(ret, &program)) {
0036         pr_info_ratelimited("check failed: parse error\n");
0037         return -EINVAL;
0038     }
0039
0040     return 0;
0041 }
0042
0043 static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
0044 {
0045     struct bpf_prog *prog;
0046
0047     prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
0048     if (IS_ERR(prog))
0049         return PTR_ERR(prog);
0050
0051     *ret = prog;
0052     return 0;
0053 }
0054
0055 static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
0056 {
0057     if (strnlen(path, XT_BPF_PATH_MAX) == XT_BPF_PATH_MAX)
0058         return -EINVAL;
0059
0060     *ret = bpf_prog_get_type_path(path, BPF_PROG_TYPE_SOCKET_FILTER);
0061     return PTR_ERR_OR_ZERO(*ret);
0062 }
0063
0064 static int bpf_mt_check(const struct xt_mtchk_param *par)
0065 {
0066     struct xt_bpf_info *info = par->matchinfo;
0067
0068     return __bpf_mt_check_bytecode(info->bpf_program,
0069                        info->bpf_program_num_elem,
0070                        &info->filter);
0071 }
0072
0073 static int bpf_mt_check_v1(const struct xt_mtchk_param *par)
0074 {
0075     struct xt_bpf_info_v1 *info = par->matchinfo;
0076
0077     if (info->mode == XT_BPF_MODE_BYTECODE)
0078         return __bpf_mt_check_bytecode(info->bpf_program,
0079                            info->bpf_program_num_elem,
0080                            &info->filter);
0081     else if (info->mode == XT_BPF_MODE_FD_ELF)
0082         return __bpf_mt_check_fd(info->fd, &info->filter);
0083     else if (info->mode == XT_BPF_MODE_PATH_PINNED)
0084         return __bpf_mt_check_path(info->path, &info->filter);
0085     else
0086         return -EINVAL;
0087 }
0088
0089 static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par)
0090 {
0091     const struct xt_bpf_info *info = par->matchinfo;
0092
0093     return bpf_prog_run(info->filter, skb);
0094 }
0095
0096 static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
0097 {
0098     const struct xt_bpf_info_v1 *info = par->matchinfo;
0099
0100     return !!bpf_prog_run_save_cb(info->filter, (struct sk_buff *) skb);
0101 }
0102
0103 static void bpf_mt_destroy(const struct xt_mtdtor_param *par)
0104 {
0105     const struct xt_bpf_info *info = par->matchinfo;
0106
0107     bpf_prog_destroy(info->filter);
0108 }
0109
0110 static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par)
0111 {
0112     const struct xt_bpf_info_v1 *info = par->matchinfo;
0113
0114     bpf_prog_destroy(info->filter);
0115 }
0116
0117 static struct xt_match bpf_mt_reg[] __read_mostly = {
0118     {
0119         .name       = "bpf",
0120         .revision   = 0,
0121         .family     = NFPROTO_UNSPEC,
0122         .checkentry = bpf_mt_check,
0123         .match      = bpf_mt,
0124         .destroy    = bpf_mt_destroy,
0125         .matchsize  = sizeof(struct xt_bpf_info),
0126         .usersize   = offsetof(struct xt_bpf_info, filter),
0127         .me     = THIS_MODULE,
0128     },
0129     {
0130         .name       = "bpf",
0131         .revision   = 1,
0132         .family     = NFPROTO_UNSPEC,
0133         .checkentry = bpf_mt_check_v1,
0134         .match      = bpf_mt_v1,
0135         .destroy    = bpf_mt_destroy_v1,
0136         .matchsize  = sizeof(struct xt_bpf_info_v1),
0137         .usersize   = offsetof(struct xt_bpf_info_v1, filter),
0138         .me     = THIS_MODULE,
0139     },
0140 };
0141
0142 static int __init bpf_mt_init(void)
0143 {
0144     return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
0145 }
0146
0147 static void __exit bpf_mt_exit(void)
0148 {
0149     xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
0150 }
0151
0152 module_init(bpf_mt_init);
0153 module_exit(bpf_mt_exit);