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         if (!parm->nkeys)
  54                 return -EINVAL;
  55
  56         ksize = parm->nkeys * sizeof(struct tc_pedit_key);
  57         if (nla_len(tb[TCA_PEDIT_PARMS]) < sizeof(*parm) + ksize)
  58                 return -EINVAL;
  59
  60         if (!tcf_hash_check(parm->index, a, bind)) {
  61                 ret = tcf_hash_create(parm->index, est, a, sizeof(*p),
  62                                       bind, false);
  63                 if (ret)
  64                         return ret;
  65                 p = to_pedit(a);
  66                 keys = kmalloc(ksize, GFP_KERNEL);
  67                 if (keys == NULL) {
  68                         tcf_hash_cleanup(a, est);
  69                         return -ENOMEM;
  70                 }
  71                 ret = ACT_P_CREATED;
  72         } else {
  73                 if (bind)
  74                         return 0;
  75                 tcf_hash_release(a, bind);
  76                 if (!ovr)
  77                         return -EEXIST;
  78                 p = to_pedit(a);
  79                 if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {
  80                         keys = kmalloc(ksize, GFP_KERNEL);
  81                         if (keys == NULL)
  82                                 return -ENOMEM;
  83                 }
  84         }
  85
  86         spin_lock_bh(&p->tcf_lock);
  87         p->tcfp_flags = parm->flags;
  88         p->tcf_action = parm->action;
  89         if (keys) {
  90                 kfree(p->tcfp_keys);
  91                 p->tcfp_keys = keys;
  92                 p->tcfp_nkeys = parm->nkeys;
  93         }
  94         memcpy(p->tcfp_keys, parm->keys, ksize);
  95         spin_unlock_bh(&p->tcf_lock);
  96         if (ret == ACT_P_CREATED)
  97                 tcf_hash_insert(a);
  98         return ret;
  99 }
 100
 101 static void tcf_pedit_cleanup(struct tc_action *a, int bind)
 102 {
 103         struct tcf_pedit *p = a->priv;
 104         struct tc_pedit_key *keys = p->tcfp_keys;
 105         kfree(keys);
 106 }
 107
 108 static bool offset_valid(struct sk_buff *skb, int offset)
 109 {
 110         if (offset > 0 && offset > skb->len)
 111                 return false;
 112
 113         if  (offset < 0 && -offset > skb_headroom(skb))
 114                 return false;
 115
 116         return true;
 117 }
 118
 119 static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
 120                      struct tcf_result *res)
 121 {
 122         struct tcf_pedit *p = a->priv;
 123         int i;
 124         unsigned int off;
 125
 126         if (skb_unclone(skb, GFP_ATOMIC))
 127                 return p->tcf_action;
 128
 129         off = skb_network_offset(skb);
 130
 131         spin_lock(&p->tcf_lock);
 132
 133         p->tcf_tm.lastuse = jiffies;
 134
 135         if (p->tcfp_nkeys > 0) {
 136                 struct tc_pedit_key *tkey = p->tcfp_keys;
 137
 138                 for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
 139                         u32 *ptr, _data;
 140                         int offset = tkey->off;
 141
 142                         if (tkey->offmask) {
 143                                 char *d, _d;
 144
 145                                 if (!offset_valid(skb, off + tkey->at)) {
 146                                         pr_info("tc filter pedit 'at' offset %d out of bounds\n",
 147                                                 off + tkey->at);
 148                                         goto bad;
 149                                 }
 150                                 d = skb_header_pointer(skb, off + tkey->at, 1,
 151                                                        &_d);
 152                                 if (!d)
 153                                         goto bad;
 154                                 offset += (*d & tkey->offmask) >> tkey->shift;
 155                         }
 156
 157                         if (offset % 4) {
 158                                 pr_info("tc filter pedit"
 159                                         " offset must be on 32 bit boundaries\n");
 160                                 goto bad;
 161                         }
 162
 163                         if (!offset_valid(skb, off + offset)) {
 164                                 pr_info("tc filter pedit offset %d out of bounds\n",
 165                                         offset);
 166                                 goto bad;
 167                         }
 168
 169                         ptr = skb_header_pointer(skb, off + offset, 4, &_data);
 170                         if (!ptr)
 171                                 goto bad;
 172                         /* just do it, baby */
 173                         *ptr = ((*ptr & tkey->mask) ^ tkey->val);
 174                         if (ptr == &_data)
 175                                 skb_store_bits(skb, off + offset, ptr, 4);
 176                 }
 177
 178                 goto done;
 179         } else
 180                 WARN(1, "pedit BUG: index %d\n", p->tcf_index);
 181
 182 bad:
 183         p->tcf_qstats.overlimits++;
 184 done:
 185         bstats_update(&p->tcf_bstats, skb);
 186         spin_unlock(&p->tcf_lock);
 187         return p->tcf_action;
 188 }
 189
 190 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 191                           int bind, int ref)
 192 {
 193         unsigned char *b = skb_tail_pointer(skb);
 194         struct tcf_pedit *p = a->priv;
 195         struct tc_pedit *opt;
 196         struct tcf_t t;
 197         int s;
 198
 199         s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
 200
 201         /* netlink spinlocks held above us - must use ATOMIC */
 202         opt = kzalloc(s, GFP_ATOMIC);
 203         if (unlikely(!opt))
 204                 return -ENOBUFS;
 205
 206         memcpy(opt->keys, p->tcfp_keys,
 207                p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 208         opt->index = p->tcf_index;
 209         opt->nkeys = p->tcfp_nkeys;
 210         opt->flags = p->tcfp_flags;
 211         opt->action = p->tcf_action;
 212         opt->refcnt = p->tcf_refcnt - ref;
 213         opt->bindcnt = p->tcf_bindcnt - bind;
 214
 215         if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
 216                 goto nla_put_failure;
 217         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 218         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 219         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 220         if (nla_put(skb, TCA_PEDIT_TM, sizeof(t), &t))
 221                 goto nla_put_failure;
 222         kfree(opt);
 223         return skb->len;
 224
 225 nla_put_failure:
 226         nlmsg_trim(skb, b);
 227         kfree(opt);
 228         return -1;
 229 }
 230
 231 static struct tc_action_ops act_pedit_ops = {
 232         .kind           =       "pedit",
 233         .type           =       TCA_ACT_PEDIT,
 234         .owner          =       THIS_MODULE,
 235         .act            =       tcf_pedit,
 236         .dump           =       tcf_pedit_dump,
 237         .cleanup        =       tcf_pedit_cleanup,
 238         .init           =       tcf_pedit_init,
 239 };
 240
 241 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 242 MODULE_DESCRIPTION("Generic Packet Editor actions");
 243 MODULE_LICENSE("GPL");
 244
 245 static int __init pedit_init_module(void)
 246 {
 247         return tcf_register_action(&act_pedit_ops, PEDIT_TAB_MASK);
 248 }
 249
 250 static void __exit pedit_cleanup_module(void)
 251 {
 252         tcf_unregister_action(&act_pedit_ops);
 253 }
 254
 255 module_init(pedit_init_module);
 256 module_exit(pedit_cleanup_module);
 257