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 #include <linux/module.h> 16 #include <linux/skbuff.h> 17 #include <linux/selinux.h> 18 #include <linux/netfilter/x_tables.h> 19 #include <linux/netfilter/xt_SECMARK.h> 20 21 MODULE_LICENSE("GPL"); 22 MODULE_AUTHOR("James Morris <jmorris@redhat.com>"); 23 MODULE_DESCRIPTION("Xtables: packet security mark modification"); 24 MODULE_ALIAS("ipt_SECMARK"); 25 MODULE_ALIAS("ip6t_SECMARK"); 26 27 #define PFX "SECMARK: " 28 29 static u8 mode; 30 31 static unsigned int 32 secmark_tg(struct sk_buff *skb, const struct net_device *in, 33 const struct net_device *out, unsigned int hooknum, 34 const struct xt_target *target, const void *targinfo) 35 { 36 u32 secmark = 0; 37 const struct xt_secmark_target_info *info = targinfo; 38 39 BUG_ON(info->mode != mode); 40 41 switch (mode) { 42 case SECMARK_MODE_SEL: 43 secmark = info->u.sel.selsid; 44 break; 45 46 default: 47 BUG(); 48 } 49 50 skb->secmark = secmark; 51 return XT_CONTINUE; 52 } 53 54 static bool checkentry_selinux(struct xt_secmark_target_info *info) 55 { 56 int err; 57 struct xt_secmark_target_selinux_info *sel = &info->u.sel; 58 59 sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0'; 60 61 err = selinux_string_to_sid(sel->selctx, &sel->selsid); 62 if (err) { 63 if (err == -EINVAL) 64 printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n", 65 sel->selctx); 66 return false; 67 } 68 69 if (!sel->selsid) { 70 printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n", 71 sel->selctx); 72 return false; 73 } 74 75 err = selinux_secmark_relabel_packet_permission(sel->selsid); 76 if (err) { 77 printk(KERN_INFO PFX "unable to obtain relabeling permission\n"); 78 return false; 79 } 80 81 selinux_secmark_refcount_inc(); 82 return true; 83 } 84 85 static bool 86 secmark_tg_check(const char *tablename, const void *entry, 87 const struct xt_target *target, void *targinfo, 88 unsigned int hook_mask) 89 { 90 struct xt_secmark_target_info *info = targinfo; 91 92 if (strcmp(tablename, "mangle") && strcmp(tablename, "security")) { 93 printk(KERN_INFO PFX "target only valid in the \'mangle\' " 94 "or \'security\' tables, not \'%s\'.\n", tablename); 95 return false; 96 } 97 98 if (mode && mode != info->mode) { 99 printk(KERN_INFO PFX "mode already set to %hu cannot mix with " 100 "rules for mode %hu\n", mode, info->mode); 101 return false; 102 } 103 104 switch (info->mode) { 105 case SECMARK_MODE_SEL: 106 if (!checkentry_selinux(info)) 107 return false; 108 break; 109 110 default: 111 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode); 112 return false; 113 } 114 115 if (!mode) 116 mode = info->mode; 117 return true; 118 } 119 120 static void secmark_tg_destroy(const struct xt_target *target, void *targinfo) 121 { 122 switch (mode) { 123 case SECMARK_MODE_SEL: 124 selinux_secmark_refcount_dec(); 125 } 126 } 127 128 static struct xt_target secmark_tg_reg[] __read_mostly = { 129 { 130 .name = "SECMARK", 131 .family = NFPROTO_IPV4, 132 .checkentry = secmark_tg_check, 133 .destroy = secmark_tg_destroy, 134 .target = secmark_tg, 135 .targetsize = sizeof(struct xt_secmark_target_info), 136 .me = THIS_MODULE, 137 }, 138 { 139 .name = "SECMARK", 140 .family = NFPROTO_IPV6, 141 .checkentry = secmark_tg_check, 142 .destroy = secmark_tg_destroy, 143 .target = secmark_tg, 144 .targetsize = sizeof(struct xt_secmark_target_info), 145 .me = THIS_MODULE, 146 }, 147 }; 148 149 static int __init secmark_tg_init(void) 150 { 151 return xt_register_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg)); 152 } 153 154 static void __exit secmark_tg_exit(void) 155 { 156 xt_unregister_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg)); 157 } 158 159 module_init(secmark_tg_init); 160 module_exit(secmark_tg_exit); 161