net/netfilter/xt_SECMARK.c

   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("ip[6]tables SECMARK modification module");
  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 target(struct sk_buff **pskb, const struct net_device *in,
  32                            const struct net_device *out, unsigned int hooknum,
  33                            const struct xt_target *target,
  34                            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         if ((*pskb)->secmark != secmark)
  51                 (*pskb)->secmark = secmark;
  52
  53         return XT_CONTINUE;
  54 }
  55
  56 static int checkentry_selinux(struct xt_secmark_target_info *info)
  57 {
  58         int err;
  59         struct xt_secmark_target_selinux_info *sel = &info->u.sel;
  60
  61         sel->selctx[SECMARK_SELCTX_MAX - 1] = '\0';
  62
  63         err = selinux_string_to_sid(sel->selctx, &sel->selsid);
  64         if (err) {
  65                 if (err == -EINVAL)
  66                         printk(KERN_INFO PFX "invalid SELinux context \'%s\'\n",
  67                                sel->selctx);
  68                 return 0;
  69         }
  70
  71         if (!sel->selsid) {
  72                 printk(KERN_INFO PFX "unable to map SELinux context \'%s\'\n",
  73                        sel->selctx);
  74                 return 0;
  75         }
  76
  77         err = selinux_relabel_packet_permission(sel->selsid);
  78         if (err) {
  79                 printk(KERN_INFO PFX "unable to obtain relabeling permission\n");
  80                 return 0;
  81         }
  82
  83         return 1;
  84 }
  85
  86 static int checkentry(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 (mode && mode != info->mode) {
  93                 printk(KERN_INFO PFX "mode already set to %hu cannot mix with "
  94                        "rules for mode %hu\n", mode, info->mode);
  95                 return 0;
  96         }
  97
  98         switch (info->mode) {
  99         case SECMARK_MODE_SEL:
 100                 if (!checkentry_selinux(info))
 101                         return 0;
 102                 break;
 103
 104         default:
 105                 printk(KERN_INFO PFX "invalid mode: %hu\n", info->mode);
 106                 return 0;
 107         }
 108
 109         if (!mode)
 110                 mode = info->mode;
 111         return 1;
 112 }
 113
 114 static struct xt_target xt_secmark_target[] = {
 115         {
 116                 .name           = "SECMARK",
 117                 .family         = AF_INET,
 118                 .checkentry     = checkentry,
 119                 .target         = target,
 120                 .targetsize     = sizeof(struct xt_secmark_target_info),
 121                 .table          = "mangle",
 122                 .me             = THIS_MODULE,
 123         },
 124         {
 125                 .name           = "SECMARK",
 126                 .family         = AF_INET6,
 127                 .checkentry     = checkentry,
 128                 .target         = target,
 129                 .targetsize     = sizeof(struct xt_secmark_target_info),
 130                 .table          = "mangle",
 131                 .me             = THIS_MODULE,
 132         },
 133 };
 134
 135 static int __init xt_secmark_init(void)
 136 {
 137         return xt_register_targets(xt_secmark_target,
 138                                    ARRAY_SIZE(xt_secmark_target));
 139 }
 140
 141 static void __exit xt_secmark_fini(void)
 142 {
 143         xt_unregister_targets(xt_secmark_target, ARRAY_SIZE(xt_secmark_target));
 144 }
 145
 146 module_init(xt_secmark_init);
 147 module_exit(xt_secmark_fini);