include/net/inet_frag.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __NET_FRAG_H__
   3 #define __NET_FRAG_H__
   4
   5 struct netns_frags {
   6         /* Keep atomic mem on separate cachelines in structs that include it */
   7         atomic_t                mem ____cacheline_aligned_in_smp;
   8         /* sysctls */
   9         int                     timeout;
  10         int                     high_thresh;
  11         int                     low_thresh;
  12         int                     max_dist;
  13 };
  14
  15 /**
  16  * fragment queue flags
  17  *
  18  * @INET_FRAG_FIRST_IN: first fragment has arrived
  19  * @INET_FRAG_LAST_IN: final fragment has arrived
  20  * @INET_FRAG_COMPLETE: frag queue has been processed and is due for destruction
  21  */
  22 enum {
  23         INET_FRAG_FIRST_IN      = BIT(0),
  24         INET_FRAG_LAST_IN       = BIT(1),
  25         INET_FRAG_COMPLETE      = BIT(2),
  26 };
  27
  28 /**
  29  * struct inet_frag_queue - fragment queue
  30  *
  31  * @lock: spinlock protecting the queue
  32  * @timer: queue expiration timer
  33  * @list: hash bucket list
  34  * @refcnt: reference count of the queue
  35  * @fragments: received fragments head
  36  * @fragments_tail: received fragments tail
  37  * @stamp: timestamp of the last received fragment
  38  * @len: total length of the original datagram
  39  * @meat: length of received fragments so far
  40  * @flags: fragment queue flags
  41  * @max_size: maximum received fragment size
  42  * @net: namespace that this frag belongs to
  43  * @list_evictor: list of queues to forcefully evict (e.g. due to low memory)
  44  */
  45 struct inet_frag_queue {
  46         spinlock_t              lock;
  47         struct timer_list       timer;
  48         struct hlist_node       list;
  49         refcount_t              refcnt;
  50         struct sk_buff          *fragments;
  51         struct sk_buff          *fragments_tail;
  52         ktime_t                 stamp;
  53         int                     len;
  54         int                     meat;
  55         __u8                    flags;
  56         u16                     max_size;
  57         struct netns_frags      *net;
  58         struct hlist_node       list_evictor;
  59 };
  60
  61 #define INETFRAGS_HASHSZ        1024
  62
  63 /* averaged:
  64  * max_depth = default ipfrag_high_thresh / INETFRAGS_HASHSZ /
  65  *             rounded up (SKB_TRUELEN(0) + sizeof(struct ipq or
  66  *             struct frag_queue))
  67  */
  68 #define INETFRAGS_MAXDEPTH      128
  69
  70 struct inet_frag_bucket {
  71         struct hlist_head       chain;
  72         spinlock_t              chain_lock;
  73 };
  74
  75 struct inet_frags {
  76         struct inet_frag_bucket hash[INETFRAGS_HASHSZ];
  77
  78         struct work_struct      frags_work;
  79         unsigned int next_bucket;
  80         unsigned long last_rebuild_jiffies;
  81         bool rebuild;
  82
  83         /* The first call to hashfn is responsible to initialize
  84          * rnd. This is best done with net_get_random_once.
  85          *
  86          * rnd_seqlock is used to let hash insertion detect
  87          * when it needs to re-lookup the hash chain to use.
  88          */
  89         u32                     rnd;
  90         seqlock_t               rnd_seqlock;
  91         unsigned int            qsize;
  92
  93         unsigned int            (*hashfn)(const struct inet_frag_queue *);
  94         bool                    (*match)(const struct inet_frag_queue *q,
  95                                          const void *arg);
  96         void                    (*constructor)(struct inet_frag_queue *q,
  97                                                const void *arg);
  98         void                    (*destructor)(struct inet_frag_queue *);
  99         void                    (*frag_expire)(struct timer_list *t);
 100         struct kmem_cache       *frags_cachep;
 101         const char              *frags_cache_name;
 102 };
 103
 104 int inet_frags_init(struct inet_frags *);
 105 void inet_frags_fini(struct inet_frags *);
 106
 107 static inline void inet_frags_init_net(struct netns_frags *nf)
 108 {
 109         atomic_set(&nf->mem, 0);
 110 }
 111 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f);
 112
 113 void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
 114 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f);
 115 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 116                 struct inet_frags *f, void *key, unsigned int hash);
 117
 118 void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
 119                                    const char *prefix);
 120
 121 static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
 122 {
 123         if (refcount_dec_and_test(&q->refcnt))
 124                 inet_frag_destroy(q, f);
 125 }
 126
 127 static inline bool inet_frag_evicting(struct inet_frag_queue *q)
 128 {
 129         return !hlist_unhashed(&q->list_evictor);
 130 }
 131
 132 /* Memory Tracking Functions. */
 133
 134 static inline int frag_mem_limit(struct netns_frags *nf)
 135 {
 136         return atomic_read(&nf->mem);
 137 }
 138
 139 static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
 140 {
 141         atomic_sub(i, &nf->mem);
 142 }
 143
 144 static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
 145 {
 146         atomic_add(i, &nf->mem);
 147 }
 148
 149 static inline int sum_frag_mem_limit(struct netns_frags *nf)
 150 {
 151         return atomic_read(&nf->mem);
 152 }
 153
 154 /* RFC 3168 support :
 155  * We want to check ECN values of all fragments, do detect invalid combinations.
 156  * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value.
 157  */
 158 #define IPFRAG_ECN_NOT_ECT      0x01 /* one frag had ECN_NOT_ECT */
 159 #define IPFRAG_ECN_ECT_1        0x02 /* one frag had ECN_ECT_1 */
 160 #define IPFRAG_ECN_ECT_0        0x04 /* one frag had ECN_ECT_0 */
 161 #define IPFRAG_ECN_CE           0x08 /* one frag had ECN_CE */
 162
 163 extern const u8 ip_frag_ecn_table[16];
 164
 165 #endif