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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Module for modifying the secmark field of the skb, for use by
4 * security subsystems.
5 *
6 * Based on the nfmark match by:
7 * (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
8 *
9 * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
10 */
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12#include <linux/module.h>
13#include <linux/security.h>
14#include <linux/skbuff.h>
15#include <linux/netfilter/x_tables.h>
16#include <linux/netfilter/xt_SECMARK.h>
17
18MODULE_LICENSE("GPL");
19MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
20MODULE_DESCRIPTION("Xtables: packet security mark modification");
21MODULE_ALIAS("ipt_SECMARK");
22MODULE_ALIAS("ip6t_SECMARK");
23
24static u8 mode;
25
26static unsigned int
27secmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
28{
29 u32 secmark = 0;
30 const struct xt_secmark_target_info *info = par->targinfo;
31
32 switch (mode) {
33 case SECMARK_MODE_SEL:
34 secmark = info->secid;
35 break;
36 default:
37 BUG();
38 }
39
40 skb->secmark = secmark;
41 return XT_CONTINUE;
42}
43
44static int checkentry_lsm(struct xt_secmark_target_info *info)
45{
46 int err;
47
48 info->secctx[SECMARK_SECCTX_MAX - 1] = '\0';
49 info->secid = 0;
50
51 err = security_secctx_to_secid(info->secctx, strlen(info->secctx),
52 &info->secid);
53 if (err) {
54 if (err == -EINVAL)
55 pr_info_ratelimited("invalid security context \'%s\'\n",
56 info->secctx);
57 return err;
58 }
59
60 if (!info->secid) {
61 pr_info_ratelimited("unable to map security context \'%s\'\n",
62 info->secctx);
63 return -ENOENT;
64 }
65
66 err = security_secmark_relabel_packet(info->secid);
67 if (err) {
68 pr_info_ratelimited("unable to obtain relabeling permission\n");
69 return err;
70 }
71
72 security_secmark_refcount_inc();
73 return 0;
74}
75
76static int secmark_tg_check(const struct xt_tgchk_param *par)
77{
78 struct xt_secmark_target_info *info = par->targinfo;
79 int err;
80
81 if (strcmp(par->table, "mangle") != 0 &&
82 strcmp(par->table, "security") != 0) {
83 pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
84 par->table);
85 return -EINVAL;
86 }
87
88 if (mode && mode != info->mode) {
89 pr_info_ratelimited("mode already set to %hu cannot mix with rules for mode %hu\n",
90 mode, info->mode);
91 return -EINVAL;
92 }
93
94 switch (info->mode) {
95 case SECMARK_MODE_SEL:
96 break;
97 default:
98 pr_info_ratelimited("invalid mode: %hu\n", info->mode);
99 return -EINVAL;
100 }
101
102 err = checkentry_lsm(info);
103 if (err)
104 return err;
105
106 if (!mode)
107 mode = info->mode;
108 return 0;
109}
110
111static void secmark_tg_destroy(const struct xt_tgdtor_param *par)
112{
113 switch (mode) {
114 case SECMARK_MODE_SEL:
115 security_secmark_refcount_dec();
116 }
117}
118
119static struct xt_target secmark_tg_reg __read_mostly = {
120 .name = "SECMARK",
121 .revision = 0,
122 .family = NFPROTO_UNSPEC,
123 .checkentry = secmark_tg_check,
124 .destroy = secmark_tg_destroy,
125 .target = secmark_tg,
126 .targetsize = sizeof(struct xt_secmark_target_info),
127 .me = THIS_MODULE,
128};
129
130static int __init secmark_tg_init(void)
131{
132 return xt_register_target(&secmark_tg_reg);
133}
134
135static void __exit secmark_tg_exit(void)
136{
137 xt_unregister_target(&secmark_tg_reg);
138}
139
140module_init(secmark_tg_init);
141module_exit(secmark_tg_exit);