net/sched/act_pedit.c

   1 /*
   2  * net/sched/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 static struct tcf_common *tcf_pedit_ht[PEDIT_TAB_MASK + 1];
  28 static u32 pedit_idx_gen;
  29 static DEFINE_RWLOCK(pedit_lock);
  30
  31 static struct tcf_hashinfo pedit_hash_info = {
  32         .htab   =       tcf_pedit_ht,
  33         .hmask  =       PEDIT_TAB_MASK,
  34         .lock   =       &pedit_lock,
  35 };
  36
  37 static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
  38         [TCA_PEDIT_PARMS]       = { .len = sizeof(struct tc_pedit) },
  39 };
  40
  41 static int tcf_pedit_init(struct nlattr *nla, struct nlattr *est,
  42                           struct tc_action *a, int ovr, int bind)
  43 {
  44         struct nlattr *tb[TCA_PEDIT_MAX + 1];
  45         struct tc_pedit *parm;
  46         int ret = 0, err;
  47         struct tcf_pedit *p;
  48         struct tcf_common *pc;
  49         struct tc_pedit_key *keys = NULL;
  50         int ksize;
  51
  52         if (nla == NULL)
  53                 return -EINVAL;
  54
  55         err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy);
  56         if (err < 0)
  57                 return err;
  58
  59         if (tb[TCA_PEDIT_PARMS] == NULL)
  60                 return -EINVAL;
  61         parm = nla_data(tb[TCA_PEDIT_PARMS]);
  62         ksize = parm->nkeys * sizeof(struct tc_pedit_key);
  63         if (nla_len(tb[TCA_PEDIT_PARMS]) < sizeof(*parm) + ksize)
  64                 return -EINVAL;
  65
  66         pc = tcf_hash_check(parm->index, a, bind, &pedit_hash_info);
  67         if (!pc) {
  68                 if (!parm->nkeys)
  69                         return -EINVAL;
  70                 pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
  71                                      &pedit_idx_gen, &pedit_hash_info);
  72                 if (IS_ERR(pc))
  73                     return PTR_ERR(pc);
  74                 p = to_pedit(pc);
  75                 keys = kmalloc(ksize, GFP_KERNEL);
  76                 if (keys == NULL) {
  77                         kfree(pc);
  78                         return -ENOMEM;
  79                 }
  80                 ret = ACT_P_CREATED;
  81         } else {
  82                 p = to_pedit(pc);
  83                 if (!ovr) {
  84                         tcf_hash_release(pc, bind, &pedit_hash_info);
  85                         return -EEXIST;
  86                 }
  87                 if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {
  88                         keys = kmalloc(ksize, GFP_KERNEL);
  89                         if (keys == NULL)
  90                                 return -ENOMEM;
  91                 }
  92         }
  93
  94         spin_lock_bh(&p->tcf_lock);
  95         p->tcfp_flags = parm->flags;
  96         p->tcf_action = parm->action;
  97         if (keys) {
  98                 kfree(p->tcfp_keys);
  99                 p->tcfp_keys = keys;
 100                 p->tcfp_nkeys = parm->nkeys;
 101         }
 102         memcpy(p->tcfp_keys, parm->keys, ksize);
 103         spin_unlock_bh(&p->tcf_lock);
 104         if (ret == ACT_P_CREATED)
 105                 tcf_hash_insert(pc, &pedit_hash_info);
 106         return ret;
 107 }
 108
 109 static int tcf_pedit_cleanup(struct tc_action *a, int bind)
 110 {
 111         struct tcf_pedit *p = a->priv;
 112
 113         if (p) {
 114                 struct tc_pedit_key *keys = p->tcfp_keys;
 115                 if (tcf_hash_release(&p->common, bind, &pedit_hash_info)) {
 116                         kfree(keys);
 117                         return 1;
 118                 }
 119         }
 120         return 0;
 121 }
 122
 123 static int tcf_pedit(struct sk_buff *skb, struct tc_action *a,
 124                      struct tcf_result *res)
 125 {
 126         struct tcf_pedit *p = a->priv;
 127         int i, munged = 0;
 128         unsigned int off;
 129
 130         if (!(skb->tc_verd & TC_OK2MUNGE)) {
 131                 /* should we set skb->cloned? */
 132                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
 133                         return p->tcf_action;
 134                 }
 135         }
 136
 137         off = skb_network_offset(skb);
 138
 139         spin_lock(&p->tcf_lock);
 140
 141         p->tcf_tm.lastuse = jiffies;
 142
 143         if (p->tcfp_nkeys > 0) {
 144                 struct tc_pedit_key *tkey = p->tcfp_keys;
 145
 146                 for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
 147                         u32 *ptr, _data;
 148                         int offset = tkey->off;
 149
 150                         if (tkey->offmask) {
 151                                 char *d, _d;
 152
 153                                 d = skb_header_pointer(skb, off + tkey->at, 1,
 154                                                        &_d);
 155                                 if (!d)
 156                                         goto bad;
 157                                 offset += (*d & tkey->offmask) >> tkey->shift;
 158                         }
 159
 160                         if (offset % 4) {
 161                                 pr_info("tc filter pedit"
 162                                         " offset must be on 32 bit boundaries\n");
 163                                 goto bad;
 164                         }
 165                         if (offset > 0 && offset > skb->len) {
 166                                 pr_info("tc filter pedit"
 167                                         " offset %d cant exceed pkt length %d\n",
 168                                        offset, skb->len);
 169                                 goto bad;
 170                         }
 171
 172                         ptr = skb_header_pointer(skb, off + offset, 4, &_data);
 173                         if (!ptr)
 174                                 goto bad;
 175                         /* just do it, baby */
 176                         *ptr = ((*ptr & tkey->mask) ^ tkey->val);
 177                         if (ptr == &_data)
 178                                 skb_store_bits(skb, off + offset, ptr, 4);
 179                         munged++;
 180                 }
 181
 182                 if (munged)
 183                         skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
 184                 goto done;
 185         } else
 186                 WARN(1, "pedit BUG: index %d\n", p->tcf_index);
 187
 188 bad:
 189         p->tcf_qstats.overlimits++;
 190 done:
 191         p->tcf_bstats.bytes += qdisc_pkt_len(skb);
 192         p->tcf_bstats.packets++;
 193         spin_unlock(&p->tcf_lock);
 194         return p->tcf_action;
 195 }
 196
 197 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 198                           int bind, int ref)
 199 {
 200         unsigned char *b = skb_tail_pointer(skb);
 201         struct tcf_pedit *p = a->priv;
 202         struct tc_pedit *opt;
 203         struct tcf_t t;
 204         int s;
 205
 206         s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
 207
 208         /* netlink spinlocks held above us - must use ATOMIC */
 209         opt = kzalloc(s, GFP_ATOMIC);
 210         if (unlikely(!opt))
 211                 return -ENOBUFS;
 212
 213         memcpy(opt->keys, p->tcfp_keys,
 214                p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 215         opt->index = p->tcf_index;
 216         opt->nkeys = p->tcfp_nkeys;
 217         opt->flags = p->tcfp_flags;
 218         opt->action = p->tcf_action;
 219         opt->refcnt = p->tcf_refcnt - ref;
 220         opt->bindcnt = p->tcf_bindcnt - bind;
 221
 222         NLA_PUT(skb, TCA_PEDIT_PARMS, s, opt);
 223         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 224         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 225         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 226         NLA_PUT(skb, TCA_PEDIT_TM, sizeof(t), &t);
 227         kfree(opt);
 228         return skb->len;
 229
 230 nla_put_failure:
 231         nlmsg_trim(skb, b);
 232         kfree(opt);
 233         return -1;
 234 }
 235
 236 static struct tc_action_ops act_pedit_ops = {
 237         .kind           =       "pedit",
 238         .hinfo          =       &pedit_hash_info,
 239         .type           =       TCA_ACT_PEDIT,
 240         .capab          =       TCA_CAP_NONE,
 241         .owner          =       THIS_MODULE,
 242         .act            =       tcf_pedit,
 243         .dump           =       tcf_pedit_dump,
 244         .cleanup        =       tcf_pedit_cleanup,
 245         .lookup         =       tcf_hash_search,
 246         .init           =       tcf_pedit_init,
 247         .walk           =       tcf_generic_walker
 248 };
 249
 250 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 251 MODULE_DESCRIPTION("Generic Packet Editor actions");
 252 MODULE_LICENSE("GPL");
 253
 254 static int __init pedit_init_module(void)
 255 {
 256         return tcf_register_action(&act_pedit_ops);
 257 }
 258
 259 static void __exit pedit_cleanup_module(void)
 260 {
 261         tcf_unregister_action(&act_pedit_ops);
 262 }
 263
 264 module_init(pedit_init_module);
 265 module_exit(pedit_cleanup_module);
 266