include/net/inet_frag.h

   1 #ifndef __NET_FRAG_H__
   2 #define __NET_FRAG_H__
   3
   4 #include <linux/percpu_counter.h>
   5
   6 struct netns_frags {
   7         /* The percpu_counter "mem" need to be cacheline aligned.
   8          *  mem.count must not share cacheline with other writers
   9          */
  10         struct percpu_counter   mem ____cacheline_aligned_in_smp;
  11
  12         /* sysctls */
  13         int                     timeout;
  14         int                     high_thresh;
  15         int                     low_thresh;
  16         int                     max_dist;
  17 };
  18
  19 /**
  20  * fragment queue flags
  21  *
  22  * @INET_FRAG_FIRST_IN: first fragment has arrived
  23  * @INET_FRAG_LAST_IN: final fragment has arrived
  24  * @INET_FRAG_COMPLETE: frag queue has been processed and is due for destruction
  25  */
  26 enum {
  27         INET_FRAG_FIRST_IN      = BIT(0),
  28         INET_FRAG_LAST_IN       = BIT(1),
  29         INET_FRAG_COMPLETE      = BIT(2),
  30 };
  31
  32 /**
  33  * struct inet_frag_queue - fragment queue
  34  *
  35  * @lock: spinlock protecting the queue
  36  * @timer: queue expiration timer
  37  * @list: hash bucket list
  38  * @refcnt: reference count of the queue
  39  * @fragments: received fragments head
  40  * @fragments_tail: received fragments tail
  41  * @stamp: timestamp of the last received fragment
  42  * @len: total length of the original datagram
  43  * @meat: length of received fragments so far
  44  * @flags: fragment queue flags
  45  * @max_size: maximum received fragment size
  46  * @net: namespace that this frag belongs to
  47  * @list_evictor: list of queues to forcefully evict (e.g. due to low memory)
  48  */
  49 struct inet_frag_queue {
  50         spinlock_t              lock;
  51         struct timer_list       timer;
  52         struct hlist_node       list;
  53         atomic_t                refcnt;
  54         struct sk_buff          *fragments;
  55         struct sk_buff          *fragments_tail;
  56         ktime_t                 stamp;
  57         int                     len;
  58         int                     meat;
  59         __u8                    flags;
  60         u16                     max_size;
  61         struct netns_frags      *net;
  62         struct hlist_node       list_evictor;
  63 };
  64
  65 #define INETFRAGS_HASHSZ        1024
  66
  67 /* averaged:
  68  * max_depth = default ipfrag_high_thresh / INETFRAGS_HASHSZ /
  69  *             rounded up (SKB_TRUELEN(0) + sizeof(struct ipq or
  70  *             struct frag_queue))
  71  */
  72 #define INETFRAGS_MAXDEPTH      128
  73
  74 struct inet_frag_bucket {
  75         struct hlist_head       chain;
  76         spinlock_t              chain_lock;
  77 };
  78
  79 struct inet_frags {
  80         struct inet_frag_bucket hash[INETFRAGS_HASHSZ];
  81
  82         struct work_struct      frags_work;
  83         unsigned int next_bucket;
  84         unsigned long last_rebuild_jiffies;
  85         bool rebuild;
  86
  87         /* The first call to hashfn is responsible to initialize
  88          * rnd. This is best done with net_get_random_once.
  89          *
  90          * rnd_seqlock is used to let hash insertion detect
  91          * when it needs to re-lookup the hash chain to use.
  92          */
  93         u32                     rnd;
  94         seqlock_t               rnd_seqlock;
  95         int                     qsize;
  96
  97         unsigned int            (*hashfn)(const struct inet_frag_queue *);
  98         bool                    (*match)(const struct inet_frag_queue *q,
  99                                          const void *arg);
 100         void                    (*constructor)(struct inet_frag_queue *q,
 101                                                const void *arg);
 102         void                    (*destructor)(struct inet_frag_queue *);
 103         void                    (*frag_expire)(unsigned long data);
 104         struct kmem_cache       *frags_cachep;
 105         const char              *frags_cache_name;
 106 };
 107
 108 int inet_frags_init(struct inet_frags *);
 109 void inet_frags_fini(struct inet_frags *);
 110
 111 static inline int inet_frags_init_net(struct netns_frags *nf)
 112 {
 113         return percpu_counter_init(&nf->mem, 0, GFP_KERNEL);
 114 }
 115 static inline void inet_frags_uninit_net(struct netns_frags *nf)
 116 {
 117         percpu_counter_destroy(&nf->mem);
 118 }
 119
 120 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f);
 121
 122 void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
 123 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f);
 124 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 125                 struct inet_frags *f, void *key, unsigned int hash);
 126
 127 void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
 128                                    const char *prefix);
 129
 130 static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
 131 {
 132         if (atomic_dec_and_test(&q->refcnt))
 133                 inet_frag_destroy(q, f);
 134 }
 135
 136 static inline bool inet_frag_evicting(struct inet_frag_queue *q)
 137 {
 138         return !hlist_unhashed(&q->list_evictor);
 139 }
 140
 141 /* Memory Tracking Functions. */
 142
 143 /* The default percpu_counter batch size is not big enough to scale to
 144  * fragmentation mem acct sizes.
 145  * The mem size of a 64K fragment is approx:
 146  *  (44 fragments * 2944 truesize) + frag_queue struct(200) = 129736 bytes
 147  */
 148 static unsigned int frag_percpu_counter_batch = 130000;
 149
 150 static inline int frag_mem_limit(struct netns_frags *nf)
 151 {
 152         return percpu_counter_read(&nf->mem);
 153 }
 154
 155 static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
 156 {
 157         __percpu_counter_add(&nf->mem, -i, frag_percpu_counter_batch);
 158 }
 159
 160 static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
 161 {
 162         __percpu_counter_add(&nf->mem, i, frag_percpu_counter_batch);
 163 }
 164
 165 static inline unsigned int sum_frag_mem_limit(struct netns_frags *nf)
 166 {
 167         unsigned int res;
 168
 169         local_bh_disable();
 170         res = percpu_counter_sum_positive(&nf->mem);
 171         local_bh_enable();
 172
 173         return res;
 174 }
 175
 176 /* RFC 3168 support :
 177  * We want to check ECN values of all fragments, do detect invalid combinations.
 178  * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value.
 179  */
 180 #define IPFRAG_ECN_NOT_ECT      0x01 /* one frag had ECN_NOT_ECT */
 181 #define IPFRAG_ECN_ECT_1        0x02 /* one frag had ECN_ECT_1 */
 182 #define IPFRAG_ECN_ECT_0        0x04 /* one frag had ECN_ECT_0 */
 183 #define IPFRAG_ECN_CE           0x08 /* one frag had ECN_CE */
 184
 185 extern const u8 ip_frag_ecn_table[16];
 186
 187 #endif