1 /*
2 * Module for modifying the secmark field of the skb, for use by
3 * security subsystems.
4 *
5 * Based on the nfmark match by:
6 * (C) 1999-2001 Marc Boucher <marc@mbsi.ca>
7 *
8 * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16 #include <linux/module.h>
17 #include <linux/security.h>
18 #include <linux/skbuff.h>
19 #include <linux/netfilter/x_tables.h>
20 #include <linux/netfilter/xt_SECMARK.h>
21
22 MODULE_LICENSE("GPL");
23 MODULE_AUTHOR("James Morris <jmorris@redhat.com>");
24 MODULE_DESCRIPTION("Xtables: packet security mark modification");
25 MODULE_ALIAS("ipt_SECMARK");
26 MODULE_ALIAS("ip6t_SECMARK");
27
28 #define PFX "SECMARK: "
29
30 static u8 mode;
31
32 static unsigned int
secmark_tg(struct sk_buff * skb,const struct xt_action_param * par)33 secmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
34 {
35 u32 secmark = 0;
36 const struct xt_secmark_target_info *info = par->targinfo;
37
38 BUG_ON(info->mode != mode);
39
40 switch (mode) {
41 case SECMARK_MODE_SEL:
42 secmark = info->secid;
43 break;
44 default:
45 BUG();
46 }
47
48 skb->secmark = secmark;
49 return XT_CONTINUE;
50 }
51
checkentry_lsm(struct xt_secmark_target_info * info)52 static int checkentry_lsm(struct xt_secmark_target_info *info)
53 {
54 int err;
55
56 info->secctx[SECMARK_SECCTX_MAX - 1] = '\0';
57 info->secid = 0;
58
59 err = security_secctx_to_secid(info->secctx, strlen(info->secctx),
60 &info->secid);
61 if (err) {
62 if (err == -EINVAL)
63 pr_info_ratelimited("invalid security context \'%s\'\n",
64 info->secctx);
65 return err;
66 }
67
68 if (!info->secid) {
69 pr_info_ratelimited("unable to map security context \'%s\'\n",
70 info->secctx);
71 return -ENOENT;
72 }
73
74 err = security_secmark_relabel_packet(info->secid);
75 if (err) {
76 pr_info_ratelimited("unable to obtain relabeling permission\n");
77 return err;
78 }
79
80 security_secmark_refcount_inc();
81 return 0;
82 }
83
secmark_tg_check(const struct xt_tgchk_param * par)84 static int secmark_tg_check(const struct xt_tgchk_param *par)
85 {
86 struct xt_secmark_target_info *info = par->targinfo;
87 int err;
88
89 if (strcmp(par->table, "mangle") != 0 &&
90 strcmp(par->table, "security") != 0) {
91 pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n",
92 par->table);
93 return -EINVAL;
94 }
95
96 if (mode && mode != info->mode) {
97 pr_info_ratelimited("mode already set to %hu cannot mix with rules for mode %hu\n",
98 mode, info->mode);
99 return -EINVAL;
100 }
101
102 switch (info->mode) {
103 case SECMARK_MODE_SEL:
104 break;
105 default:
106 pr_info_ratelimited("invalid mode: %hu\n", info->mode);
107 return -EINVAL;
108 }
109
110 err = checkentry_lsm(info);
111 if (err)
112 return err;
113
114 if (!mode)
115 mode = info->mode;
116 return 0;
117 }
118
secmark_tg_destroy(const struct xt_tgdtor_param * par)119 static void secmark_tg_destroy(const struct xt_tgdtor_param *par)
120 {
121 switch (mode) {
122 case SECMARK_MODE_SEL:
123 security_secmark_refcount_dec();
124 }
125 }
126
127 static struct xt_target secmark_tg_reg __read_mostly = {
128 .name = "SECMARK",
129 .revision = 0,
130 .family = NFPROTO_UNSPEC,
131 .checkentry = secmark_tg_check,
132 .destroy = secmark_tg_destroy,
133 .target = secmark_tg,
134 .targetsize = sizeof(struct xt_secmark_target_info),
135 .me = THIS_MODULE,
136 };
137
secmark_tg_init(void)138 static int __init secmark_tg_init(void)
139 {
140 return xt_register_target(&secmark_tg_reg);
141 }
142
secmark_tg_exit(void)143 static void __exit secmark_tg_exit(void)
144 {
145 xt_unregister_target(&secmark_tg_reg);
146 }
147
148 module_init(secmark_tg_init);
149 module_exit(secmark_tg_exit);
150
