1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Xtables module to match packets using a BPF filter. |
3 | * Copyright 2013 Google Inc. |
4 | * Written by Willem de Bruijn <willemb@google.com> |
5 | */ |
6 | |
7 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
8 | |
9 | #include <linux/module.h> |
10 | #include <linux/syscalls.h> |
11 | #include <linux/skbuff.h> |
12 | #include <linux/filter.h> |
13 | #include <linux/bpf.h> |
14 | |
15 | #include <linux/netfilter/xt_bpf.h> |
16 | #include <linux/netfilter/x_tables.h> |
17 | |
18 | MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>" ); |
19 | MODULE_DESCRIPTION("Xtables: BPF filter match" ); |
20 | MODULE_LICENSE("GPL" ); |
21 | MODULE_ALIAS("ipt_bpf" ); |
22 | MODULE_ALIAS("ip6t_bpf" ); |
23 | |
24 | static int __bpf_mt_check_bytecode(struct sock_filter *insns, __u16 len, |
25 | struct bpf_prog **ret) |
26 | { |
27 | struct sock_fprog_kern program; |
28 | |
29 | if (len > XT_BPF_MAX_NUM_INSTR) |
30 | return -EINVAL; |
31 | |
32 | program.len = len; |
33 | program.filter = insns; |
34 | |
35 | if (bpf_prog_create(pfp: ret, fprog: &program)) { |
36 | pr_info_ratelimited("check failed: parse error\n" ); |
37 | return -EINVAL; |
38 | } |
39 | |
40 | return 0; |
41 | } |
42 | |
43 | static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret) |
44 | { |
45 | struct bpf_prog *prog; |
46 | |
47 | prog = bpf_prog_get_type(ufd: fd, type: BPF_PROG_TYPE_SOCKET_FILTER); |
48 | if (IS_ERR(ptr: prog)) |
49 | return PTR_ERR(ptr: prog); |
50 | |
51 | *ret = prog; |
52 | return 0; |
53 | } |
54 | |
55 | static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret) |
56 | { |
57 | if (strnlen(p: path, XT_BPF_PATH_MAX) == XT_BPF_PATH_MAX) |
58 | return -EINVAL; |
59 | |
60 | *ret = bpf_prog_get_type_path(name: path, type: BPF_PROG_TYPE_SOCKET_FILTER); |
61 | return PTR_ERR_OR_ZERO(ptr: *ret); |
62 | } |
63 | |
64 | static int bpf_mt_check(const struct xt_mtchk_param *par) |
65 | { |
66 | struct xt_bpf_info *info = par->matchinfo; |
67 | |
68 | return __bpf_mt_check_bytecode(insns: info->bpf_program, |
69 | len: info->bpf_program_num_elem, |
70 | ret: &info->filter); |
71 | } |
72 | |
73 | static int bpf_mt_check_v1(const struct xt_mtchk_param *par) |
74 | { |
75 | struct xt_bpf_info_v1 *info = par->matchinfo; |
76 | |
77 | if (info->mode == XT_BPF_MODE_BYTECODE) |
78 | return __bpf_mt_check_bytecode(insns: info->bpf_program, |
79 | len: info->bpf_program_num_elem, |
80 | ret: &info->filter); |
81 | else if (info->mode == XT_BPF_MODE_FD_ELF) |
82 | return __bpf_mt_check_fd(fd: info->fd, ret: &info->filter); |
83 | else if (info->mode == XT_BPF_MODE_PATH_PINNED) |
84 | return __bpf_mt_check_path(path: info->path, ret: &info->filter); |
85 | else |
86 | return -EINVAL; |
87 | } |
88 | |
89 | static bool bpf_mt(const struct sk_buff *skb, struct xt_action_param *par) |
90 | { |
91 | const struct xt_bpf_info *info = par->matchinfo; |
92 | |
93 | return bpf_prog_run(prog: info->filter, ctx: skb); |
94 | } |
95 | |
96 | static bool bpf_mt_v1(const struct sk_buff *skb, struct xt_action_param *par) |
97 | { |
98 | const struct xt_bpf_info_v1 *info = par->matchinfo; |
99 | |
100 | return !!bpf_prog_run_save_cb(prog: info->filter, skb: (struct sk_buff *) skb); |
101 | } |
102 | |
103 | static void bpf_mt_destroy(const struct xt_mtdtor_param *par) |
104 | { |
105 | const struct xt_bpf_info *info = par->matchinfo; |
106 | |
107 | bpf_prog_destroy(fp: info->filter); |
108 | } |
109 | |
110 | static void bpf_mt_destroy_v1(const struct xt_mtdtor_param *par) |
111 | { |
112 | const struct xt_bpf_info_v1 *info = par->matchinfo; |
113 | |
114 | bpf_prog_destroy(fp: info->filter); |
115 | } |
116 | |
117 | static struct xt_match bpf_mt_reg[] __read_mostly = { |
118 | { |
119 | .name = "bpf" , |
120 | .revision = 0, |
121 | .family = NFPROTO_UNSPEC, |
122 | .checkentry = bpf_mt_check, |
123 | .match = bpf_mt, |
124 | .destroy = bpf_mt_destroy, |
125 | .matchsize = sizeof(struct xt_bpf_info), |
126 | .usersize = offsetof(struct xt_bpf_info, filter), |
127 | .me = THIS_MODULE, |
128 | }, |
129 | { |
130 | .name = "bpf" , |
131 | .revision = 1, |
132 | .family = NFPROTO_UNSPEC, |
133 | .checkentry = bpf_mt_check_v1, |
134 | .match = bpf_mt_v1, |
135 | .destroy = bpf_mt_destroy_v1, |
136 | .matchsize = sizeof(struct xt_bpf_info_v1), |
137 | .usersize = offsetof(struct xt_bpf_info_v1, filter), |
138 | .me = THIS_MODULE, |
139 | }, |
140 | }; |
141 | |
142 | static int __init bpf_mt_init(void) |
143 | { |
144 | return xt_register_matches(match: bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg)); |
145 | } |
146 | |
147 | static void __exit bpf_mt_exit(void) |
148 | { |
149 | xt_unregister_matches(match: bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg)); |
150 | } |
151 | |
152 | module_init(bpf_mt_init); |
153 | module_exit(bpf_mt_exit); |
154 | |