ec23189049
In matches and targets that define a kernel-only tail to their xt_match and xt_target data structs, add a field .usersize that specifies up to where data is to be shared with userspace. Performed a search for comment "Used internally by the kernel" to find relevant matches and targets. Manually inspected the structs to derive a valid offsetof. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
141 lines
3.4 KiB
C
141 lines
3.4 KiB
C
/* 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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.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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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("bpf: 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(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_PINNED ||
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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
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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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