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
18 MODULE_LICENSE("GPL");
19 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
20 MODULE_DESCRIPTION("Xtables: packet security mark modification");
21 MODULE_ALIAS("ipt_SECMARK");
22 MODULE_ALIAS("ip6t_SECMARK");
23
24 static u8 mode;
25
26 static unsigned int
27 secmark_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
43 static 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(info->secctx, strlen(info->secctx),
51 &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(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
75 static int
76 secmark_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
110 static 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
118 static 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(newinfo.secctx, info->secctx, SECMARK_SECCTX_MAX);
127
128 ret = secmark_tg_check(par->table, &newinfo);
129 info->secid = newinfo.secid;
130
131 return ret;
132 }
133
134 static unsigned int
135 secmark_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, &newinfo);
143 }
144
145 static int secmark_tg_check_v1(const struct xt_tgchk_param *par)
146 {
147 return secmark_tg_check(par->table, par->targinfo);
148 }
149
150 static unsigned int
151 secmark_tg_v1(struct sk_buff *skb, const struct xt_action_param *par)
152 {
153 return secmark_tg(skb, par->targinfo);
154 }
155
156 static struct xt_target secmark_tg_reg[] __read_mostly = {
157 {
158 .name = "SECMARK",
159 .revision = 0,
160 .family = NFPROTO_UNSPEC,
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_UNSPEC,
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 };
179
180 static int __init secmark_tg_init(void)
181 {
182 return xt_register_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg));
183 }
184
185 static void __exit secmark_tg_exit(void)
186 {
187 xt_unregister_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg));
188 }
189
190 module_init(secmark_tg_init);
191 module_exit(secmark_tg_exit);
192
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