1 /* 2 * inet fragments management 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: Pavel Emelyanov <xemul@openvz.org> 10 * Started as consolidation of ipv4/ip_fragment.c, 11 * ipv6/reassembly. and ipv6 nf conntrack reassembly 12 */ 13 14 #include <linux/list.h> 15 #include <linux/spinlock.h> 16 #include <linux/module.h> 17 #include <linux/timer.h> 18 #include <linux/mm.h> 19 #include <linux/random.h> 20 #include <linux/skbuff.h> 21 #include <linux/rtnetlink.h> 22 23 #include <net/inet_frag.h> 24 25 static void inet_frag_secret_rebuild(unsigned long dummy) 26 { 27 struct inet_frags *f = (struct inet_frags *)dummy; 28 unsigned long now = jiffies; 29 int i; 30 31 write_lock(&f->lock); 32 get_random_bytes(&f->rnd, sizeof(u32)); 33 for (i = 0; i < INETFRAGS_HASHSZ; i++) { 34 struct inet_frag_queue *q; 35 struct hlist_node *p, *n; 36 37 hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) { 38 unsigned int hval = f->hashfn(q); 39 40 if (hval != i) { 41 hlist_del(&q->list); 42 43 /* Relink to new hash chain. */ 44 hlist_add_head(&q->list, &f->hash[hval]); 45 } 46 } 47 } 48 write_unlock(&f->lock); 49 50 mod_timer(&f->secret_timer, now + f->ctl->secret_interval); 51 } 52 53 void inet_frags_init(struct inet_frags *f) 54 { 55 int i; 56 57 for (i = 0; i < INETFRAGS_HASHSZ; i++) 58 INIT_HLIST_HEAD(&f->hash[i]); 59 60 INIT_LIST_HEAD(&f->lru_list); 61 rwlock_init(&f->lock); 62 63 f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ 64 (jiffies ^ (jiffies >> 6))); 65 66 f->nqueues = 0; 67 atomic_set(&f->mem, 0); 68 69 setup_timer(&f->secret_timer, inet_frag_secret_rebuild, 70 (unsigned long)f); 71 f->secret_timer.expires = jiffies + f->ctl->secret_interval; 72 add_timer(&f->secret_timer); 73 } 74 EXPORT_SYMBOL(inet_frags_init); 75 76 void inet_frags_fini(struct inet_frags *f) 77 { 78 del_timer(&f->secret_timer); 79 } 80 EXPORT_SYMBOL(inet_frags_fini); 81 82 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) 83 { 84 write_lock(&f->lock); 85 hlist_del(&fq->list); 86 list_del(&fq->lru_list); 87 f->nqueues--; 88 write_unlock(&f->lock); 89 } 90 91 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f) 92 { 93 if (del_timer(&fq->timer)) 94 atomic_dec(&fq->refcnt); 95 96 if (!(fq->last_in & COMPLETE)) { 97 fq_unlink(fq, f); 98 atomic_dec(&fq->refcnt); 99 fq->last_in |= COMPLETE; 100 } 101 } 102 103 EXPORT_SYMBOL(inet_frag_kill); 104 105 static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb, 106 int *work) 107 { 108 if (work) 109 *work -= skb->truesize; 110 111 atomic_sub(skb->truesize, &f->mem); 112 if (f->skb_free) 113 f->skb_free(skb); 114 kfree_skb(skb); 115 } 116 117 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f, 118 int *work) 119 { 120 struct sk_buff *fp; 121 122 BUG_TRAP(q->last_in & COMPLETE); 123 BUG_TRAP(del_timer(&q->timer) == 0); 124 125 /* Release all fragment data. */ 126 fp = q->fragments; 127 while (fp) { 128 struct sk_buff *xp = fp->next; 129 130 frag_kfree_skb(f, fp, work); 131 fp = xp; 132 } 133 134 if (work) 135 *work -= f->qsize; 136 atomic_sub(f->qsize, &f->mem); 137 138 if (f->destructor) 139 f->destructor(q); 140 kfree(q); 141 142 } 143 EXPORT_SYMBOL(inet_frag_destroy); 144 145 int inet_frag_evictor(struct inet_frags *f) 146 { 147 struct inet_frag_queue *q; 148 int work, evicted = 0; 149 150 work = atomic_read(&f->mem) - f->ctl->low_thresh; 151 while (work > 0) { 152 read_lock(&f->lock); 153 if (list_empty(&f->lru_list)) { 154 read_unlock(&f->lock); 155 break; 156 } 157 158 q = list_first_entry(&f->lru_list, 159 struct inet_frag_queue, lru_list); 160 atomic_inc(&q->refcnt); 161 read_unlock(&f->lock); 162 163 spin_lock(&q->lock); 164 if (!(q->last_in & COMPLETE)) 165 inet_frag_kill(q, f); 166 spin_unlock(&q->lock); 167 168 if (atomic_dec_and_test(&q->refcnt)) 169 inet_frag_destroy(q, f, &work); 170 evicted++; 171 } 172 173 return evicted; 174 } 175 EXPORT_SYMBOL(inet_frag_evictor); 176 177 static struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *qp_in, 178 struct inet_frags *f, unsigned int hash, void *arg) 179 { 180 struct inet_frag_queue *qp; 181 #ifdef CONFIG_SMP 182 struct hlist_node *n; 183 #endif 184 185 write_lock(&f->lock); 186 #ifdef CONFIG_SMP 187 /* With SMP race we have to recheck hash table, because 188 * such entry could be created on other cpu, while we 189 * promoted read lock to write lock. 190 */ 191 hlist_for_each_entry(qp, n, &f->hash[hash], list) { 192 if (f->match(qp, arg)) { 193 atomic_inc(&qp->refcnt); 194 write_unlock(&f->lock); 195 qp_in->last_in |= COMPLETE; 196 inet_frag_put(qp_in, f); 197 return qp; 198 } 199 } 200 #endif 201 qp = qp_in; 202 if (!mod_timer(&qp->timer, jiffies + f->ctl->timeout)) 203 atomic_inc(&qp->refcnt); 204 205 atomic_inc(&qp->refcnt); 206 hlist_add_head(&qp->list, &f->hash[hash]); 207 list_add_tail(&qp->lru_list, &f->lru_list); 208 f->nqueues++; 209 write_unlock(&f->lock); 210 return qp; 211 } 212 213 static struct inet_frag_queue *inet_frag_alloc(struct inet_frags *f, void *arg) 214 { 215 struct inet_frag_queue *q; 216 217 q = kzalloc(f->qsize, GFP_ATOMIC); 218 if (q == NULL) 219 return NULL; 220 221 f->constructor(q, arg); 222 atomic_add(f->qsize, &f->mem); 223 setup_timer(&q->timer, f->frag_expire, (unsigned long)q); 224 spin_lock_init(&q->lock); 225 atomic_set(&q->refcnt, 1); 226 227 return q; 228 } 229 230 static struct inet_frag_queue *inet_frag_create(struct inet_frags *f, 231 void *arg, unsigned int hash) 232 { 233 struct inet_frag_queue *q; 234 235 q = inet_frag_alloc(f, arg); 236 if (q == NULL) 237 return NULL; 238 239 return inet_frag_intern(q, f, hash, arg); 240 } 241 242 struct inet_frag_queue *inet_frag_find(struct inet_frags *f, void *key, 243 unsigned int hash) 244 { 245 struct inet_frag_queue *q; 246 struct hlist_node *n; 247 248 read_lock(&f->lock); 249 hlist_for_each_entry(q, n, &f->hash[hash], list) { 250 if (f->match(q, key)) { 251 atomic_inc(&q->refcnt); 252 read_unlock(&f->lock); 253 return q; 254 } 255 } 256 read_unlock(&f->lock); 257 258 return inet_frag_create(f, key, hash); 259 } 260 EXPORT_SYMBOL(inet_frag_find); 261