include/net/inet_frag.h

   1 #ifndef __NET_FRAG_H__
   2 #define __NET_FRAG_H__
   3
   4 struct netns_frags {
   5         /* Keep atomic mem on separate cachelines in structs that include it */
   6         atomic_t                mem ____cacheline_aligned_in_smp;
   7         /* sysctls */
   8         int                     timeout;
   9         int                     high_thresh;
  10         int                     low_thresh;
  11         int                     max_dist;
  12 };
  13
  14 /**
  15  * fragment queue flags
  16  *
  17  * @INET_FRAG_FIRST_IN: first fragment has arrived
  18  * @INET_FRAG_LAST_IN: final fragment has arrived
  19  * @INET_FRAG_COMPLETE: frag queue has been processed and is due for destruction
  20  */
  21 enum {
  22         INET_FRAG_FIRST_IN      = BIT(0),
  23         INET_FRAG_LAST_IN       = BIT(1),
  24         INET_FRAG_COMPLETE      = BIT(2),
  25 };
  26
  27 /**
  28  * struct inet_frag_queue - fragment queue
  29  *
  30  * @lock: spinlock protecting the queue
  31  * @timer: queue expiration timer
  32  * @list: hash bucket list
  33  * @refcnt: reference count of the queue
  34  * @fragments: received fragments head
  35  * @fragments_tail: received fragments tail
  36  * @stamp: timestamp of the last received fragment
  37  * @len: total length of the original datagram
  38  * @meat: length of received fragments so far
  39  * @flags: fragment queue flags
  40  * @max_size: maximum received fragment size
  41  * @net: namespace that this frag belongs to
  42  * @list_evictor: list of queues to forcefully evict (e.g. due to low memory)
  43  */
  44 struct inet_frag_queue {
  45         spinlock_t              lock;
  46         struct timer_list       timer;
  47         struct hlist_node       list;
  48         atomic_t                refcnt;
  49         struct sk_buff          *fragments;
  50         struct sk_buff          *fragments_tail;
  51         ktime_t                 stamp;
  52         int                     len;
  53         int                     meat;
  54         __u8                    flags;
  55         u16                     max_size;
  56         struct netns_frags      *net;
  57         struct hlist_node       list_evictor;
  58 };
  59
  60 #define INETFRAGS_HASHSZ        1024
  61
  62 /* averaged:
  63  * max_depth = default ipfrag_high_thresh / INETFRAGS_HASHSZ /
  64  *             rounded up (SKB_TRUELEN(0) + sizeof(struct ipq or
  65  *             struct frag_queue))
  66  */
  67 #define INETFRAGS_MAXDEPTH      128
  68
  69 struct inet_frag_bucket {
  70         struct hlist_head       chain;
  71         spinlock_t              chain_lock;
  72 };
  73
  74 struct inet_frags {
  75         struct inet_frag_bucket hash[INETFRAGS_HASHSZ];
  76
  77         struct work_struct      frags_work;
  78         unsigned int next_bucket;
  79         unsigned long last_rebuild_jiffies;
  80         bool rebuild;
  81
  82         /* The first call to hashfn is responsible to initialize
  83          * rnd. This is best done with net_get_random_once.
  84          *
  85          * rnd_seqlock is used to let hash insertion detect
  86          * when it needs to re-lookup the hash chain to use.
  87          */
  88         u32                     rnd;
  89         seqlock_t               rnd_seqlock;
  90         int                     qsize;
  91
  92         unsigned int            (*hashfn)(const struct inet_frag_queue *);
  93         bool                    (*match)(const struct inet_frag_queue *q,
  94                                          const void *arg);
  95         void                    (*constructor)(struct inet_frag_queue *q,
  96                                                const void *arg);
  97         void                    (*destructor)(struct inet_frag_queue *);
  98         void                    (*frag_expire)(unsigned long data);
  99         struct kmem_cache       *frags_cachep;
 100         const char              *frags_cache_name;
 101 };
 102
 103 int inet_frags_init(struct inet_frags *);
 104 void inet_frags_fini(struct inet_frags *);
 105
 106 static inline void inet_frags_init_net(struct netns_frags *nf)
 107 {
 108         atomic_set(&nf->mem, 0);
 109 }
 110 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f);
 111
 112 void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
 113 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f);
 114 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 115                 struct inet_frags *f, void *key, unsigned int hash);
 116
 117 void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
 118                                    const char *prefix);
 119
 120 static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
 121 {
 122         if (atomic_dec_and_test(&q->refcnt))
 123                 inet_frag_destroy(q, f);
 124 }
 125
 126 static inline bool inet_frag_evicting(struct inet_frag_queue *q)
 127 {
 128         return !hlist_unhashed(&q->list_evictor);
 129 }
 130
 131 /* Memory Tracking Functions. */
 132
 133 static inline int frag_mem_limit(struct netns_frags *nf)
 134 {
 135         return atomic_read(&nf->mem);
 136 }
 137
 138 static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
 139 {
 140         atomic_sub(i, &nf->mem);
 141 }
 142
 143 static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
 144 {
 145         atomic_add(i, &nf->mem);
 146 }
 147
 148 static inline int sum_frag_mem_limit(struct netns_frags *nf)
 149 {
 150         return atomic_read(&nf->mem);
 151 }
 152
 153 /* RFC 3168 support :
 154  * We want to check ECN values of all fragments, do detect invalid combinations.
 155  * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value.
 156  */
 157 #define IPFRAG_ECN_NOT_ECT      0x01 /* one frag had ECN_NOT_ECT */
 158 #define IPFRAG_ECN_ECT_1        0x02 /* one frag had ECN_ECT_1 */
 159 #define IPFRAG_ECN_ECT_0        0x04 /* one frag had ECN_ECT_0 */
 160 #define IPFRAG_ECN_CE           0x08 /* one frag had ECN_CE */
 161
 162 extern const u8 ip_frag_ecn_table[16];
 163
 164 #endif