1 /* Xtables module to match packets using a BPF filter.
2 * Copyright 2013 Google Inc.
3 * Written by Willem de Bruijn <willemb@google.com>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/module.h>
11 #include <linux/syscalls.h>
12 #include <linux/skbuff.h>
13 #include <linux/filter.h>
14 #include <linux/bpf.h>
16 #include <linux/netfilter/xt_bpf.h>
17 #include <linux/netfilter/x_tables.h>
19 MODULE_AUTHOR("Willem de Bruijn <willemb@google.com>");
20 MODULE_DESCRIPTION("Xtables: BPF filter match");
21 MODULE_LICENSE("GPL");
22 MODULE_ALIAS("ipt_bpf");
23 MODULE_ALIAS("ip6t_bpf");
25 static int __bpf_mt_check_bytecode(struct sock_filter
*insns
, __u16 len
,
26 struct bpf_prog
**ret
)
28 struct sock_fprog_kern program
;
31 program
.filter
= insns
;
33 if (bpf_prog_create(ret
, &program
)) {
34 pr_info("bpf: check failed: parse error\n");
41 static int __bpf_mt_check_fd(int fd
, struct bpf_prog
**ret
)
43 struct bpf_prog
*prog
;
45 prog
= bpf_prog_get_type(fd
, BPF_PROG_TYPE_SOCKET_FILTER
);
53 static int __bpf_mt_check_path(const char *path
, struct bpf_prog
**ret
)
55 mm_segment_t oldfs
= get_fs();
59 fd
= bpf_obj_get_user(path
, 0);
64 retval
= __bpf_mt_check_fd(fd
, ret
);
69 static int bpf_mt_check(const struct xt_mtchk_param
*par
)
71 struct xt_bpf_info
*info
= par
->matchinfo
;
73 return __bpf_mt_check_bytecode(info
->bpf_program
,
74 info
->bpf_program_num_elem
,
78 static int bpf_mt_check_v1(const struct xt_mtchk_param
*par
)
80 struct xt_bpf_info_v1
*info
= par
->matchinfo
;
82 if (info
->mode
== XT_BPF_MODE_BYTECODE
)
83 return __bpf_mt_check_bytecode(info
->bpf_program
,
84 info
->bpf_program_num_elem
,
86 else if (info
->mode
== XT_BPF_MODE_FD_ELF
)
87 return __bpf_mt_check_fd(info
->fd
, &info
->filter
);
88 else if (info
->mode
== XT_BPF_MODE_PATH_PINNED
)
89 return __bpf_mt_check_path(info
->path
, &info
->filter
);
94 static bool bpf_mt(const struct sk_buff
*skb
, struct xt_action_param
*par
)
96 const struct xt_bpf_info
*info
= par
->matchinfo
;
98 return BPF_PROG_RUN(info
->filter
, skb
);
101 static bool bpf_mt_v1(const struct sk_buff
*skb
, struct xt_action_param
*par
)
103 const struct xt_bpf_info_v1
*info
= par
->matchinfo
;
105 return !!bpf_prog_run_save_cb(info
->filter
, (struct sk_buff
*) skb
);
108 static void bpf_mt_destroy(const struct xt_mtdtor_param
*par
)
110 const struct xt_bpf_info
*info
= par
->matchinfo
;
112 bpf_prog_destroy(info
->filter
);
115 static void bpf_mt_destroy_v1(const struct xt_mtdtor_param
*par
)
117 const struct xt_bpf_info_v1
*info
= par
->matchinfo
;
119 bpf_prog_destroy(info
->filter
);
122 static struct xt_match bpf_mt_reg
[] __read_mostly
= {
126 .family
= NFPROTO_UNSPEC
,
127 .checkentry
= bpf_mt_check
,
129 .destroy
= bpf_mt_destroy
,
130 .matchsize
= sizeof(struct xt_bpf_info
),
131 .usersize
= offsetof(struct xt_bpf_info
, filter
),
137 .family
= NFPROTO_UNSPEC
,
138 .checkentry
= bpf_mt_check_v1
,
140 .destroy
= bpf_mt_destroy_v1
,
141 .matchsize
= sizeof(struct xt_bpf_info_v1
),
142 .usersize
= offsetof(struct xt_bpf_info_v1
, filter
),
147 static int __init
bpf_mt_init(void)
149 return xt_register_matches(bpf_mt_reg
, ARRAY_SIZE(bpf_mt_reg
));
152 static void __exit
bpf_mt_exit(void)
154 xt_unregister_matches(bpf_mt_reg
, ARRAY_SIZE(bpf_mt_reg
));
157 module_init(bpf_mt_init
);
158 module_exit(bpf_mt_exit
);