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
__bpf_mt_check_bytecode(struct sock_filter * insns,__u16 len,struct bpf_prog ** ret)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(ret, &program)) {
36 pr_info_ratelimited("check failed: parse error\n");
37 return -EINVAL;
38 }
39
40 return 0;
41 }
42
__bpf_mt_check_fd(int fd,struct bpf_prog ** ret)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(fd, BPF_PROG_TYPE_SOCKET_FILTER);
48 if (IS_ERR(prog))
49 return PTR_ERR(prog);
50
51 *ret = prog;
52 return 0;
53 }
54
__bpf_mt_check_path(const char * path,struct bpf_prog ** ret)55 static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
56 {
57 if (strnlen(path, XT_BPF_PATH_MAX) == XT_BPF_PATH_MAX)
58 return -EINVAL;
59
60 *ret = bpf_prog_get_type_path(path, BPF_PROG_TYPE_SOCKET_FILTER);
61 return PTR_ERR_OR_ZERO(*ret);
62 }
63
bpf_mt_check(const struct xt_mtchk_param * par)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(info->bpf_program,
69 info->bpf_program_num_elem,
70 &info->filter);
71 }
72
bpf_mt_check_v1(const struct xt_mtchk_param * par)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(info->bpf_program,
79 info->bpf_program_num_elem,
80 &info->filter);
81 else if (info->mode == XT_BPF_MODE_FD_ELF)
82 return __bpf_mt_check_fd(info->fd, &info->filter);
83 else if (info->mode == XT_BPF_MODE_PATH_PINNED)
84 return __bpf_mt_check_path(info->path, &info->filter);
85 else
86 return -EINVAL;
87 }
88
bpf_mt(const struct sk_buff * skb,struct xt_action_param * par)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(info->filter, skb);
94 }
95
bpf_mt_v1(const struct sk_buff * skb,struct xt_action_param * par)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(info->filter, (struct sk_buff *) skb);
101 }
102
bpf_mt_destroy(const struct xt_mtdtor_param * par)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(info->filter);
108 }
109
bpf_mt_destroy_v1(const struct xt_mtdtor_param * par)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(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
bpf_mt_init(void)142 static int __init bpf_mt_init(void)
143 {
144 return xt_register_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
145 }
146
bpf_mt_exit(void)147 static void __exit bpf_mt_exit(void)
148 {
149 xt_unregister_matches(bpf_mt_reg, ARRAY_SIZE(bpf_mt_reg));
150 }
151
152 module_init(bpf_mt_init);
153 module_exit(bpf_mt_exit);
154