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 init_timer(&f->secret_timer); 70 f->secret_timer.function = inet_frag_secret_rebuild; 71 f->secret_timer.data = (unsigned long)f; 72 f->secret_timer.expires = jiffies + f->ctl->secret_interval; 73 add_timer(&f->secret_timer); 74 } 75 EXPORT_SYMBOL(inet_frags_init); 76 77 void inet_frags_fini(struct inet_frags *f) 78 { 79 del_timer(&f->secret_timer); 80 } 81 EXPORT_SYMBOL(inet_frags_fini); 82 83 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) 84 { 85 write_lock(&f->lock); 86 hlist_del(&fq->list); 87 list_del(&fq->lru_list); 88 f->nqueues--; 89 write_unlock(&f->lock); 90 } 91 92 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f) 93 { 94 if (del_timer(&fq->timer)) 95 atomic_dec(&fq->refcnt); 96 97 if (!(fq->last_in & COMPLETE)) { 98 fq_unlink(fq, f); 99 atomic_dec(&fq->refcnt); 100 fq->last_in |= COMPLETE; 101 } 102 } 103 104 EXPORT_SYMBOL(inet_frag_kill); 105 106 static inline void frag_kfree_skb(struct inet_frags *f, struct sk_buff *skb, 107 int *work) 108 { 109 if (work) 110 *work -= skb->truesize; 111 112 atomic_sub(skb->truesize, &f->mem); 113 if (f->skb_free) 114 f->skb_free(skb); 115 kfree_skb(skb); 116 } 117 118 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f, 119 int *work) 120 { 121 struct sk_buff *fp; 122 123 BUG_TRAP(q->last_in & COMPLETE); 124 BUG_TRAP(del_timer(&q->timer) == 0); 125 126 /* Release all fragment data. */ 127 fp = q->fragments; 128 while (fp) { 129 struct sk_buff *xp = fp->next; 130 131 frag_kfree_skb(f, fp, work); 132 fp = xp; 133 } 134 135 if (work) 136 *work -= f->qsize; 137 atomic_sub(f->qsize, &f->mem); 138 139 f->destructor(q); 140 141 } 142 EXPORT_SYMBOL(inet_frag_destroy); 143 144 int inet_frag_evictor(struct inet_frags *f) 145 { 146 struct inet_frag_queue *q; 147 int work, evicted = 0; 148 149 work = atomic_read(&f->mem) - f->ctl->low_thresh; 150 while (work > 0) { 151 read_lock(&f->lock); 152 if (list_empty(&f->lru_list)) { 153 read_unlock(&f->lock); 154 break; 155 } 156 157 q = list_first_entry(&f->lru_list, 158 struct inet_frag_queue, lru_list); 159 atomic_inc(&q->refcnt); 160 read_unlock(&f->lock); 161 162 spin_lock(&q->lock); 163 if (!(q->last_in & COMPLETE)) 164 inet_frag_kill(q, f); 165 spin_unlock(&q->lock); 166 167 if (atomic_dec_and_test(&q->refcnt)) 168 inet_frag_destroy(q, f, &work); 169 evicted++; 170 } 171 172 return evicted; 173 } 174 EXPORT_SYMBOL(inet_frag_evictor); 175 176 static struct inet_frag_queue *inet_frag_intern(struct inet_frag_queue *qp_in, 177 struct inet_frags *f, unsigned int hash, void *arg) 178 { 179 struct inet_frag_queue *qp; 180 #ifdef CONFIG_SMP 181 struct hlist_node *n; 182 #endif 183 184 write_lock(&f->lock); 185 #ifdef CONFIG_SMP 186 /* With SMP race we have to recheck hash table, because 187 * such entry could be created on other cpu, while we 188 * promoted read lock to write lock. 189 */ 190 hlist_for_each_entry(qp, n, &f->hash[hash], list) { 191 if (f->match(qp, arg)) { 192 atomic_inc(&qp->refcnt); 193 write_unlock(&f->lock); 194 qp_in->last_in |= COMPLETE; 195 inet_frag_put(qp_in, f); 196 return qp; 197 } 198 } 199 #endif 200 qp = qp_in; 201 if (!mod_timer(&qp->timer, jiffies + f->ctl->timeout)) 202 atomic_inc(&qp->refcnt); 203 204 atomic_inc(&qp->refcnt); 205 hlist_add_head(&qp->list, &f->hash[hash]); 206 list_add_tail(&qp->lru_list, &f->lru_list); 207 f->nqueues++; 208 write_unlock(&f->lock); 209 return qp; 210 } 211 212 static struct inet_frag_queue *inet_frag_alloc(struct inet_frags *f, void *arg) 213 { 214 struct inet_frag_queue *q; 215 216 q = kzalloc(f->qsize, GFP_ATOMIC); 217 if (q == NULL) 218 return NULL; 219 220 f->constructor(q, arg); 221 atomic_add(f->qsize, &f->mem); 222 setup_timer(&q->timer, f->frag_expire, (unsigned long)q); 223 spin_lock_init(&q->lock); 224 atomic_set(&q->refcnt, 1); 225 226 return q; 227 } 228 229 static struct inet_frag_queue *inet_frag_create(struct inet_frags *f, 230 void *arg, unsigned int hash) 231 { 232 struct inet_frag_queue *q; 233 234 q = inet_frag_alloc(f, arg); 235 if (q == NULL) 236 return NULL; 237 238 return inet_frag_intern(q, f, hash, arg); 239 } 240 241 struct inet_frag_queue *inet_frag_find(struct inet_frags *f, void *key, 242 unsigned int hash) 243 { 244 struct inet_frag_queue *q; 245 struct hlist_node *n; 246 247 read_lock(&f->lock); 248 hlist_for_each_entry(q, n, &f->hash[hash], list) { 249 if (f->match(q, key)) { 250 atomic_inc(&q->refcnt); 251 read_unlock(&f->lock); 252 return q; 253 } 254 } 255 read_unlock(&f->lock); 256 257 return inet_frag_create(f, key, hash); 258 } 259 EXPORT_SYMBOL(inet_frag_find); 260