net/sched/act_pedit.c

   1 /*
   2  * net/sched/act_pedit.c        Generic packet editor
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Jamal Hadi Salim (2002-4)
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/string.h>
  15 #include <linux/errno.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <net/netlink.h>
  22 #include <net/pkt_sched.h>
  23 #include <linux/tc_act/tc_pedit.h>
  24 #include <net/tc_act/tc_pedit.h>
  25
  26 #define PEDIT_TAB_MASK  15
  27
  28 static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
  29         [TCA_PEDIT_PARMS]       = { .len = sizeof(struct tc_pedit) },
  30 };
  31
  32 static int tcf_pedit_init(struct net *net, struct nlattr *nla,
  33                           struct nlattr *est, struct tc_action *a,
  34                           int ovr, int bind)
  35 {
  36         struct nlattr *tb[TCA_PEDIT_MAX + 1];
  37         struct tc_pedit *parm;
  38         int ret = 0, err;
  39         struct tcf_pedit *p;
  40         struct tc_pedit_key *keys = NULL;
  41         int ksize;
  42
  43         if (nla == NULL)
  44                 return -EINVAL;
  45
  46         err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy);
  47         if (err < 0)
  48                 return err;
  49
  50         if (tb[TCA_PEDIT_PARMS] == NULL)
  51                 return -EINVAL;
  52         parm = nla_data(tb[TCA_PEDIT_PARMS]);
  53         ksize = parm->nkeys * sizeof(struct tc_pedit_key);
  54         if (nla_len(tb[TCA_PEDIT_PARMS]) < sizeof(*parm) + ksize)
  55                 return -EINVAL;
  56
  57         if (!tcf_hash_check(parm->index, a, bind)) {
  58                 if (!parm->nkeys)
  59                         return -EINVAL;
  60                 ret = tcf_hash_create(parm->index, est, a, sizeof(*p),
  61                                       bind, false);
  62                 if (ret)
  63                         return ret;
  64                 p = to_pedit(a);
  65                 keys = kmalloc(ksize, GFP_KERNEL);
  66                 if (keys == NULL) {
  67                         tcf_hash_cleanup(a, est);
  68                         return -ENOMEM;
  69                 }
  70                 ret = ACT_P_CREATED;
  71         } else {
  72                 if (bind)
  73                         return 0;
  74                 tcf_hash_release(a, bind);
  75                 if (!ovr)
  76                         return -EEXIST;
  77                 p = to_pedit(a);
  78                 if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {
  79                         keys = kmalloc(ksize, GFP_KERNEL);
  80                         if (keys == NULL)
  81                                 return -ENOMEM;
  82                 }
  83         }
  84
  85         spin_lock_bh(&p->tcf_lock);
  86         p->tcfp_flags = parm->flags;
  87         p->tcf_action = parm->action;
  88         if (keys) {
  89                 kfree(p->tcfp_keys);
  90                 p->tcfp_keys = keys;
  91                 p->tcfp_nkeys = parm->nkeys;
  92         }
  93         memcpy(p->tcfp_keys, parm->keys, ksize);
  94         spin_unlock_bh(&p->tcf_lock);
  95         if (ret == ACT_P_CREATED)
  96                 tcf_hash_insert(a);
  97         return ret;
  98 }
  99
 100 static void tcf_pedit_cleanup(struct tc_action *a, int bind)
 101 {
 102         struct tcf_pedit *p = a->priv;
 103         struct tc_pedit_key *keys = p->tcfp_keys;
 104         kfree(keys);
 105 }
 106
 107 static bool offset_valid(struct sk_buff *skb, int offset)
 108 {
 109         if (offset > 0 && offset > skb->len)
 110                 return false;
 111
 112         if  (offset < 0 && -offset > skb_headroom(skb))
 113                 return false;
 114
 115         return true;
 116 }
 117
 118 static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
 119                      struct tcf_result *res)
 120 {
 121         struct tcf_pedit *p = a->priv;
 122         int i;
 123         unsigned int off;
 124
 125         if (skb_unclone(skb, GFP_ATOMIC))
 126                 return p->tcf_action;
 127
 128         off = skb_network_offset(skb);
 129
 130         spin_lock(&p->tcf_lock);
 131
 132         p->tcf_tm.lastuse = jiffies;
 133
 134         if (p->tcfp_nkeys > 0) {
 135                 struct tc_pedit_key *tkey = p->tcfp_keys;
 136
 137                 for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
 138                         u32 *ptr, _data;
 139                         int offset = tkey->off;
 140
 141                         if (tkey->offmask) {
 142                                 char *d, _d;
 143
 144                                 if (!offset_valid(skb, off + tkey->at)) {
 145                                         pr_info("tc filter pedit 'at' offset %d out of bounds\n",
 146                                                 off + tkey->at);
 147                                         goto bad;
 148                                 }
 149                                 d = skb_header_pointer(skb, off + tkey->at, 1,
 150                                                        &_d);
 151                                 if (!d)
 152                                         goto bad;
 153                                 offset += (*d & tkey->offmask) >> tkey->shift;
 154                         }
 155
 156                         if (offset % 4) {
 157                                 pr_info("tc filter pedit"
 158                                         " offset must be on 32 bit boundaries\n");
 159                                 goto bad;
 160                         }
 161
 162                         if (!offset_valid(skb, off + offset)) {
 163                                 pr_info("tc filter pedit offset %d out of bounds\n",
 164                                         offset);
 165                                 goto bad;
 166                         }
 167
 168                         ptr = skb_header_pointer(skb, off + offset, 4, &_data);
 169                         if (!ptr)
 170                                 goto bad;
 171                         /* just do it, baby */
 172                         *ptr = ((*ptr & tkey->mask) ^ tkey->val);
 173                         if (ptr == &_data)
 174                                 skb_store_bits(skb, off + offset, ptr, 4);
 175                 }
 176
 177                 goto done;
 178         } else
 179                 WARN(1, "pedit BUG: index %d\n", p->tcf_index);
 180
 181 bad:
 182         p->tcf_qstats.overlimits++;
 183 done:
 184         bstats_update(&p->tcf_bstats, skb);
 185         spin_unlock(&p->tcf_lock);
 186         return p->tcf_action;
 187 }
 188
 189 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 190                           int bind, int ref)
 191 {
 192         unsigned char *b = skb_tail_pointer(skb);
 193         struct tcf_pedit *p = a->priv;
 194         struct tc_pedit *opt;
 195         struct tcf_t t;
 196         int s;
 197
 198         s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
 199
 200         /* netlink spinlocks held above us - must use ATOMIC */
 201         opt = kzalloc(s, GFP_ATOMIC);
 202         if (unlikely(!opt))
 203                 return -ENOBUFS;
 204
 205         memcpy(opt->keys, p->tcfp_keys,
 206                p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 207         opt->index = p->tcf_index;
 208         opt->nkeys = p->tcfp_nkeys;
 209         opt->flags = p->tcfp_flags;
 210         opt->action = p->tcf_action;
 211         opt->refcnt = p->tcf_refcnt - ref;
 212         opt->bindcnt = p->tcf_bindcnt - bind;
 213
 214         if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
 215                 goto nla_put_failure;
 216         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 217         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 218         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 219         if (nla_put(skb, TCA_PEDIT_TM, sizeof(t), &t))
 220                 goto nla_put_failure;
 221         kfree(opt);
 222         return skb->len;
 223
 224 nla_put_failure:
 225         nlmsg_trim(skb, b);
 226         kfree(opt);
 227         return -1;
 228 }
 229
 230 static struct tc_action_ops act_pedit_ops = {
 231         .kind           =       "pedit",
 232         .type           =       TCA_ACT_PEDIT,
 233         .owner          =       THIS_MODULE,
 234         .act            =       tcf_pedit,
 235         .dump           =       tcf_pedit_dump,
 236         .cleanup        =       tcf_pedit_cleanup,
 237         .init           =       tcf_pedit_init,
 238 };
 239
 240 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 241 MODULE_DESCRIPTION("Generic Packet Editor actions");
 242 MODULE_LICENSE("GPL");
 243
 244 static int __init pedit_init_module(void)
 245 {
 246         return tcf_register_action(&act_pedit_ops, PEDIT_TAB_MASK);
 247 }
 248
 249 static void __exit pedit_cleanup_module(void)
 250 {
 251         tcf_unregister_action(&act_pedit_ops);
 252 }
 253
 254 module_init(pedit_init_module);
 255 module_exit(pedit_cleanup_module);
 256