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 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 switch (mode) { 39 case SECMARK_MODE_SEL: 40 secmark = info->secid; 41 break; 42 default: 43 BUG(); 44 } 45 46 skb->secmark = secmark; 47 return XT_CONTINUE; 48 } 49 50 static int checkentry_lsm(struct xt_secmark_target_info *info) 51 { 52 int err; 53 54 info->secctx[SECMARK_SECCTX_MAX - 1] = '\0'; 55 info->secid = 0; 56 57 err = security_secctx_to_secid(info->secctx, strlen(info->secctx), 58 &info->secid); 59 if (err) { 60 if (err == -EINVAL) 61 pr_info_ratelimited("invalid security context \'%s\'\n", 62 info->secctx); 63 return err; 64 } 65 66 if (!info->secid) { 67 pr_info_ratelimited("unable to map security context \'%s\'\n", 68 info->secctx); 69 return -ENOENT; 70 } 71 72 err = security_secmark_relabel_packet(info->secid); 73 if (err) { 74 pr_info_ratelimited("unable to obtain relabeling permission\n"); 75 return err; 76 } 77 78 security_secmark_refcount_inc(); 79 return 0; 80 } 81 82 static int secmark_tg_check(const struct xt_tgchk_param *par) 83 { 84 struct xt_secmark_target_info *info = par->targinfo; 85 int err; 86 87 if (strcmp(par->table, "mangle") != 0 && 88 strcmp(par->table, "security") != 0) { 89 pr_info_ratelimited("only valid in \'mangle\' or \'security\' table, not \'%s\'\n", 90 par->table); 91 return -EINVAL; 92 } 93 94 if (mode && mode != info->mode) { 95 pr_info_ratelimited("mode already set to %hu cannot mix with rules for mode %hu\n", 96 mode, info->mode); 97 return -EINVAL; 98 } 99 100 switch (info->mode) { 101 case SECMARK_MODE_SEL: 102 break; 103 default: 104 pr_info_ratelimited("invalid mode: %hu\n", info->mode); 105 return -EINVAL; 106 } 107 108 err = checkentry_lsm(info); 109 if (err) 110 return err; 111 112 if (!mode) 113 mode = info->mode; 114 return 0; 115 } 116 117 static void secmark_tg_destroy(const struct xt_tgdtor_param *par) 118 { 119 switch (mode) { 120 case SECMARK_MODE_SEL: 121 security_secmark_refcount_dec(); 122 } 123 } 124 125 static struct xt_target secmark_tg_reg __read_mostly = { 126 .name = "SECMARK", 127 .revision = 0, 128 .family = NFPROTO_UNSPEC, 129 .checkentry = secmark_tg_check, 130 .destroy = secmark_tg_destroy, 131 .target = secmark_tg, 132 .targetsize = sizeof(struct xt_secmark_target_info), 133 .me = THIS_MODULE, 134 }; 135 136 static int __init secmark_tg_init(void) 137 { 138 return xt_register_target(&secmark_tg_reg); 139 } 140 141 static void __exit secmark_tg_exit(void) 142 { 143 xt_unregister_target(&secmark_tg_reg); 144 } 145 146 module_init(secmark_tg_init); 147 module_exit(secmark_tg_exit); 148