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 bool offset_valid(struct sk_buff *skb, int offset)
 124 {
 125         if (offset > 0 && offset > skb->len)
 126                 return false;
 127
 128         if  (offset < 0 && -offset > skb_headroom(skb))
 129                 return false;
 130
 131         return true;
 132 }
 133
 134 static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
 135                      struct tcf_result *res)
 136 {
 137         struct tcf_pedit *p = a->priv;
 138         int i, munged = 0;
 139         unsigned int off;
 140
 141         if (skb_cloned(skb) &&
 142             pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
 143                 return p->tcf_action;
 144
 145         off = skb_network_offset(skb);
 146
 147         spin_lock(&p->tcf_lock);
 148
 149         p->tcf_tm.lastuse = jiffies;
 150
 151         if (p->tcfp_nkeys > 0) {
 152                 struct tc_pedit_key *tkey = p->tcfp_keys;
 153
 154                 for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
 155                         u32 *ptr, _data;
 156                         int offset = tkey->off;
 157
 158                         if (tkey->offmask) {
 159                                 char *d, _d;
 160
 161                                 if (!offset_valid(skb, off + tkey->at)) {
 162                                         pr_info("tc filter pedit 'at' offset %d out of bounds\n",
 163                                                 off + tkey->at);
 164                                         goto bad;
 165                                 }
 166                                 d = skb_header_pointer(skb, off + tkey->at, 1,
 167                                                        &_d);
 168                                 if (!d)
 169                                         goto bad;
 170                                 offset += (*d & tkey->offmask) >> tkey->shift;
 171                         }
 172
 173                         if (offset % 4) {
 174                                 pr_info("tc filter pedit"
 175                                         " offset must be on 32 bit boundaries\n");
 176                                 goto bad;
 177                         }
 178
 179                         if (!offset_valid(skb, off + offset)) {
 180                                 pr_info("tc filter pedit offset %d out of bounds\n",
 181                                         offset);
 182                                 goto bad;
 183                         }
 184
 185                         ptr = skb_header_pointer(skb, off + offset, 4, &_data);
 186                         if (!ptr)
 187                                 goto bad;
 188                         /* just do it, baby */
 189                         *ptr = ((*ptr & tkey->mask) ^ tkey->val);
 190                         if (ptr == &_data)
 191                                 skb_store_bits(skb, off + offset, ptr, 4);
 192                         munged++;
 193                 }
 194
 195                 if (munged)
 196                         skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
 197                 goto done;
 198         } else
 199                 WARN(1, "pedit BUG: index %d\n", p->tcf_index);
 200
 201 bad:
 202         p->tcf_qstats.overlimits++;
 203 done:
 204         bstats_update(&p->tcf_bstats, skb);
 205         spin_unlock(&p->tcf_lock);
 206         return p->tcf_action;
 207 }
 208
 209 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 210                           int bind, int ref)
 211 {
 212         unsigned char *b = skb_tail_pointer(skb);
 213         struct tcf_pedit *p = a->priv;
 214         struct tc_pedit *opt;
 215         struct tcf_t t;
 216         int s;
 217
 218         s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
 219
 220         /* netlink spinlocks held above us - must use ATOMIC */
 221         opt = kzalloc(s, GFP_ATOMIC);
 222         if (unlikely(!opt))
 223                 return -ENOBUFS;
 224
 225         memcpy(opt->keys, p->tcfp_keys,
 226                p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 227         opt->index = p->tcf_index;
 228         opt->nkeys = p->tcfp_nkeys;
 229         opt->flags = p->tcfp_flags;
 230         opt->action = p->tcf_action;
 231         opt->refcnt = p->tcf_refcnt - ref;
 232         opt->bindcnt = p->tcf_bindcnt - bind;
 233
 234         NLA_PUT(skb, TCA_PEDIT_PARMS, s, opt);
 235         t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
 236         t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
 237         t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
 238         NLA_PUT(skb, TCA_PEDIT_TM, sizeof(t), &t);
 239         kfree(opt);
 240         return skb->len;
 241
 242 nla_put_failure:
 243         nlmsg_trim(skb, b);
 244         kfree(opt);
 245         return -1;
 246 }
 247
 248 static struct tc_action_ops act_pedit_ops = {
 249         .kind           =       "pedit",
 250         .hinfo          =       &pedit_hash_info,
 251         .type           =       TCA_ACT_PEDIT,
 252         .capab          =       TCA_CAP_NONE,
 253         .owner          =       THIS_MODULE,
 254         .act            =       tcf_pedit,
 255         .dump           =       tcf_pedit_dump,
 256         .cleanup        =       tcf_pedit_cleanup,
 257         .lookup         =       tcf_hash_search,
 258         .init           =       tcf_pedit_init,
 259         .walk           =       tcf_generic_walker
 260 };
 261
 262 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 263 MODULE_DESCRIPTION("Generic Packet Editor actions");
 264 MODULE_LICENSE("GPL");
 265
 266 static int __init pedit_init_module(void)
 267 {
 268         return tcf_register_action(&act_pedit_ops);
 269 }
 270
 271 static void __exit pedit_cleanup_module(void)
 272 {
 273         tcf_unregister_action(&act_pedit_ops);
 274 }
 275
 276 module_init(pedit_init_module);
 277 module_exit(pedit_cleanup_module);
 278