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 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_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 return true; 82 } 83 84 static bool 85 secmark_tg_check(const char *tablename, const void *entry, 86 const struct xt_target *target, void *targinfo, 87 unsigned int hook_mask) 88 { 89 struct xt_secmark_target_info *info = targinfo; 90 91 if (mode && mode != info->mode) { 92 printk(KERN_INFO PFX "mode already set to %hu cannot mix with " 93 "rules for mode %hu\n", mode, info->mode); 94 return false; 95 } 96 97 switch (info->mode) { 98 case SECMARK_MODE_SEL: 99 if (!checkentry_selinux(info)) 100 return false; 101 break; 102 103 default: 104 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode); 105 return false; 106 } 107 108 if (!mode) 109 mode = info->mode; 110 return true; 111 } 112 113 static struct xt_target secmark_tg_reg[] __read_mostly = { 114 { 115 .name = "SECMARK", 116 .family = AF_INET, 117 .checkentry = secmark_tg_check, 118 .target = secmark_tg, 119 .targetsize = sizeof(struct xt_secmark_target_info), 120 .table = "mangle", 121 .me = THIS_MODULE, 122 }, 123 { 124 .name = "SECMARK", 125 .family = AF_INET6, 126 .checkentry = secmark_tg_check, 127 .target = secmark_tg, 128 .targetsize = sizeof(struct xt_secmark_target_info), 129 .table = "mangle", 130 .me = THIS_MODULE, 131 }, 132 }; 133 134 static int __init secmark_tg_init(void) 135 { 136 return xt_register_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg)); 137 } 138 139 static void __exit secmark_tg_exit(void) 140 { 141 xt_unregister_targets(secmark_tg_reg, ARRAY_SIZE(secmark_tg_reg)); 142 } 143 144 module_init(secmark_tg_init); 145 module_exit(secmark_tg_exit); 146