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_secmark_target_info_v1 *info)
28{
29 u32 secmark = 0;
30
31 switch (mode) {
32 case SECMARK_MODE_SEL:
33 secmark = info->secid;
34 break;
35 default:
36 BUG();
37 }
38
39 skb->secmark = secmark;
40 return XT_CONTINUE;
41}
42
43static int checkentry_lsm(struct xt_secmark_target_info_v1 *info)
44{
45 int err;
46
47 info->secctx[SECMARK_SECCTX_MAX - 1] = '\0';
48 info->secid = 0;
49
50 err = security_secctx_to_secid(secdata: info->secctx, seclen: strlen(info->secctx),
51 secid: &info->secid);
52 if (err) {
53 if (err == -EINVAL)
54 pr_info_ratelimited("invalid security context \'%s\'\n",
55 info->secctx);
56 return err;
57 }
58
59 if (!info->secid) {
60 pr_info_ratelimited("unable to map security context \'%s\'\n",
61 info->secctx);
62 return -ENOENT;
63 }
64
65 err = security_secmark_relabel_packet(secid: info->secid);
66 if (err) {
67 pr_info_ratelimited("unable to obtain relabeling permission\n");
68 return err;
69 }
70
71 security_secmark_refcount_inc();
72 return 0;
73}
74
75static int
76secmark_tg_check(const char *table, struct xt_secmark_target_info_v1 *info)
77{
78 int err;
79
80 if (strcmp(table, "mangle") != 0 &&
81 strcmp(table, "security") != 0) {
82 pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
83 table);
84 return -EINVAL;
85 }
86
87 if (mode && mode != info->mode) {
88 pr_info_ratelimited("mode already set to %hu cannot mix with rules for mode %hu\n",
89 mode, info->mode);
90 return -EINVAL;
91 }
92
93 switch (info->mode) {
94 case SECMARK_MODE_SEL:
95 break;
96 default:
97 pr_info_ratelimited("invalid mode: %hu\n", info->mode);
98 return -EINVAL;
99 }
100
101 err = checkentry_lsm(info);
102 if (err)
103 return err;
104
105 if (!mode)
106 mode = info->mode;
107 return 0;
108}
109
110static void secmark_tg_destroy(const struct xt_tgdtor_param *par)
111{
112 switch (mode) {
113 case SECMARK_MODE_SEL:
114 security_secmark_refcount_dec();
115 }
116}
117
118static int secmark_tg_check_v0(const struct xt_tgchk_param *par)
119{
120 struct xt_secmark_target_info *info = par->targinfo;
121 struct xt_secmark_target_info_v1 newinfo = {
122 .mode = info->mode,
123 };
124 int ret;
125
126 memcpy(to: newinfo.secctx, from: info->secctx, SECMARK_SECCTX_MAX);
127
128 ret = secmark_tg_check(table: par->table, info: &newinfo);
129 info->secid = newinfo.secid;
130
131 return ret;
132}
133
134static unsigned int
135secmark_tg_v0(struct sk_buff *skb, const struct xt_action_param *par)
136{
137 const struct xt_secmark_target_info *info = par->targinfo;
138 struct xt_secmark_target_info_v1 newinfo = {
139 .secid = info->secid,
140 };
141
142 return secmark_tg(skb, info: &newinfo);
143}
144
145static int secmark_tg_check_v1(const struct xt_tgchk_param *par)
146{
147 return secmark_tg_check(table: par->table, info: par->targinfo);
148}
149
150static unsigned int
151secmark_tg_v1(struct sk_buff *skb, const struct xt_action_param *par)
152{
153 return secmark_tg(skb, info: par->targinfo);
154}
155
156static struct xt_target secmark_tg_reg[] __read_mostly = {
157 {
158 .name = "SECMARK",
159 .revision = 0,
160 .family = NFPROTO_IPV4,
161 .checkentry = secmark_tg_check_v0,
162 .destroy = secmark_tg_destroy,
163 .target = secmark_tg_v0,
164 .targetsize = sizeof(struct xt_secmark_target_info),
165 .me = THIS_MODULE,
166 },
167 {
168 .name = "SECMARK",
169 .revision = 1,
170 .family = NFPROTO_IPV4,
171 .checkentry = secmark_tg_check_v1,
172 .destroy = secmark_tg_destroy,
173 .target = secmark_tg_v1,
174 .targetsize = sizeof(struct xt_secmark_target_info_v1),
175 .usersize = offsetof(struct xt_secmark_target_info_v1, secid),
176 .me = THIS_MODULE,
177 },
178#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
179 {
180 .name = "SECMARK",
181 .revision = 0,
182 .family = NFPROTO_IPV6,
183 .checkentry = secmark_tg_check_v0,
184 .destroy = secmark_tg_destroy,
185 .target = secmark_tg_v0,
186 .targetsize = sizeof(struct xt_secmark_target_info),
187 .me = THIS_MODULE,
188 },
189 {
190 .name = "SECMARK",
191 .revision = 1,
192 .family = NFPROTO_IPV6,
193 .checkentry = secmark_tg_check_v1,
194 .destroy = secmark_tg_destroy,
195 .target = secmark_tg_v1,
196 .targetsize = sizeof(struct xt_secmark_target_info_v1),
197 .usersize = offsetof(struct xt_secmark_target_info_v1, secid),
198 .me = THIS_MODULE,
199 },
200#endif
201};
202
203static int __init secmark_tg_init(void)
204{
205 return xt_register_targets(target: secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg));
206}
207
208static void __exit secmark_tg_exit(void)
209{
210 xt_unregister_targets(target: secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg));
211}
212
213module_init(secmark_tg_init);
214module_exit(secmark_tg_exit);
215