include/linux/skmsg.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
   3
   4 #ifndef _LINUX_SKMSG_H
   5 #define _LINUX_SKMSG_H
   6
   7 #include <linux/bpf.h>
   8 #include <linux/filter.h>
   9 #include <linux/scatterlist.h>
  10 #include <linux/skbuff.h>
  11
  12 #include <net/sock.h>
  13 #include <net/tcp.h>
  14 #include <net/strparser.h>
  15
  16 #define MAX_MSG_FRAGS                   MAX_SKB_FRAGS
  17 #define NR_MSG_FRAG_IDS                 (MAX_MSG_FRAGS + 1)
  18
  19 enum __sk_action {
  20         __SK_DROP = 0,
  21         __SK_PASS,
  22         __SK_REDIRECT,
  23         __SK_NONE,
  24 };
  25
  26 struct sk_msg_sg {
  27         u32                             start;
  28         u32                             curr;
  29         u32                             end;
  30         u32                             size;
  31         u32                             copybreak;
  32         unsigned long                   copy;
  33         /* The extra two elements:
  34          * 1) used for chaining the front and sections when the list becomes
  35          *    partitioned (e.g. end < start). The crypto APIs require the
  36          *    chaining;
  37          * 2) to chain tailer SG entries after the message.
  38          */
  39         struct scatterlist              data[MAX_MSG_FRAGS + 2];
  40 };
  41 static_assert(BITS_PER_LONG >= NR_MSG_FRAG_IDS);
  42
  43 /* UAPI in filter.c depends on struct sk_msg_sg being first element. */
  44 struct sk_msg {
  45         struct sk_msg_sg                sg;
  46         void                            *data;
  47         void                            *data_end;
  48         u32                             apply_bytes;
  49         u32                             cork_bytes;
  50         u32                             flags;
  51         struct sk_buff                  *skb;
  52         struct sock                     *sk_redir;
  53         struct sock                     *sk;
  54         struct list_head                list;
  55 };
  56
  57 struct sk_psock_progs {
  58         struct bpf_prog                 *msg_parser;
  59         struct bpf_prog                 *skb_parser;
  60         struct bpf_prog                 *skb_verdict;
  61 };
  62
  63 enum sk_psock_state_bits {
  64         SK_PSOCK_TX_ENABLED,
  65 };
  66
  67 struct sk_psock_link {
  68         struct list_head                list;
  69         struct bpf_map                  *map;
  70         void                            *link_raw;
  71 };
  72
  73 struct sk_psock_parser {
  74         struct strparser                strp;
  75         bool                            enabled;
  76         void (*saved_data_ready)(struct sock *sk);
  77 };
  78
  79 struct sk_psock_work_state {
  80         struct sk_buff                  *skb;
  81         u32                             len;
  82         u32                             off;
  83 };
  84
  85 struct sk_psock {
  86         struct sock                     *sk;
  87         struct sock                     *sk_redir;
  88         u32                             apply_bytes;
  89         u32                             cork_bytes;
  90         u32                             eval;
  91         struct sk_msg                   *cork;
  92         struct sk_psock_progs           progs;
  93         struct sk_psock_parser          parser;
  94         struct sk_buff_head             ingress_skb;
  95         struct list_head                ingress_msg;
  96         unsigned long                   state;
  97         struct list_head                link;
  98         spinlock_t                      link_lock;
  99         refcount_t                      refcnt;
 100         void (*saved_unhash)(struct sock *sk);
 101         void (*saved_close)(struct sock *sk, long timeout);
 102         void (*saved_write_space)(struct sock *sk);
 103         struct proto                    *sk_proto;
 104         struct sk_psock_work_state      work_state;
 105         struct work_struct              work;
 106         union {
 107                 struct rcu_head         rcu;
 108                 struct work_struct      gc;
 109         };
 110 };
 111
 112 int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
 113                  int elem_first_coalesce);
 114 int sk_msg_clone(struct sock *sk, struct sk_msg *dst, struct sk_msg *src,
 115                  u32 off, u32 len);
 116 void sk_msg_trim(struct sock *sk, struct sk_msg *msg, int len);
 117 int sk_msg_free(struct sock *sk, struct sk_msg *msg);
 118 int sk_msg_free_nocharge(struct sock *sk, struct sk_msg *msg);
 119 void sk_msg_free_partial(struct sock *sk, struct sk_msg *msg, u32 bytes);
 120 void sk_msg_free_partial_nocharge(struct sock *sk, struct sk_msg *msg,
 121                                   u32 bytes);
 122
 123 void sk_msg_return(struct sock *sk, struct sk_msg *msg, int bytes);
 124 void sk_msg_return_zero(struct sock *sk, struct sk_msg *msg, int bytes);
 125
 126 int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
 127                               struct sk_msg *msg, u32 bytes);
 128 int sk_msg_memcopy_from_iter(struct sock *sk, struct iov_iter *from,
 129                              struct sk_msg *msg, u32 bytes);
 130
 131 static inline void sk_msg_check_to_free(struct sk_msg *msg, u32 i, u32 bytes)
 132 {
 133         WARN_ON(i == msg->sg.end && bytes);
 134 }
 135
 136 static inline void sk_msg_apply_bytes(struct sk_psock *psock, u32 bytes)
 137 {
 138         if (psock->apply_bytes) {
 139                 if (psock->apply_bytes < bytes)
 140                         psock->apply_bytes = 0;
 141                 else
 142                         psock->apply_bytes -= bytes;
 143         }
 144 }
 145
 146 static inline u32 sk_msg_iter_dist(u32 start, u32 end)
 147 {
 148         return end >= start ? end - start : end + (NR_MSG_FRAG_IDS - start);
 149 }
 150
 151 #define sk_msg_iter_var_prev(var)                       \
 152         do {                                            \
 153                 if (var == 0)                           \
 154                         var = NR_MSG_FRAG_IDS - 1;      \
 155                 else                                    \
 156                         var--;                          \
 157         } while (0)
 158
 159 #define sk_msg_iter_var_next(var)                       \
 160         do {                                            \
 161                 var++;                                  \
 162                 if (var == NR_MSG_FRAG_IDS)             \
 163                         var = 0;                        \
 164         } while (0)
 165
 166 #define sk_msg_iter_prev(msg, which)                    \
 167         sk_msg_iter_var_prev(msg->sg.which)
 168
 169 #define sk_msg_iter_next(msg, which)                    \
 170         sk_msg_iter_var_next(msg->sg.which)
 171
 172 static inline void sk_msg_clear_meta(struct sk_msg *msg)
 173 {
 174         memset(&msg->sg, 0, offsetofend(struct sk_msg_sg, copy));
 175 }
 176
 177 static inline void sk_msg_init(struct sk_msg *msg)
 178 {
 179         BUILD_BUG_ON(ARRAY_SIZE(msg->sg.data) - 1 != NR_MSG_FRAG_IDS);
 180         memset(msg, 0, sizeof(*msg));
 181         sg_init_marker(msg->sg.data, NR_MSG_FRAG_IDS);
 182 }
 183
 184 static inline void sk_msg_xfer(struct sk_msg *dst, struct sk_msg *src,
 185                                int which, u32 size)
 186 {
 187         dst->sg.data[which] = src->sg.data[which];
 188         dst->sg.data[which].length  = size;
 189         dst->sg.size               += size;
 190         src->sg.data[which].length -= size;
 191         src->sg.data[which].offset += size;
 192 }
 193
 194 static inline void sk_msg_xfer_full(struct sk_msg *dst, struct sk_msg *src)
 195 {
 196         memcpy(dst, src, sizeof(*src));
 197         sk_msg_init(src);
 198 }
 199
 200 static inline bool sk_msg_full(const struct sk_msg *msg)
 201 {
 202         return sk_msg_iter_dist(msg->sg.start, msg->sg.end) == MAX_MSG_FRAGS;
 203 }
 204
 205 static inline u32 sk_msg_elem_used(const struct sk_msg *msg)
 206 {
 207         return sk_msg_iter_dist(msg->sg.start, msg->sg.end);
 208 }
 209
 210 static inline struct scatterlist *sk_msg_elem(struct sk_msg *msg, int which)
 211 {
 212         return &msg->sg.data[which];
 213 }
 214
 215 static inline struct scatterlist sk_msg_elem_cpy(struct sk_msg *msg, int which)
 216 {
 217         return msg->sg.data[which];
 218 }
 219
 220 static inline struct page *sk_msg_page(struct sk_msg *msg, int which)
 221 {
 222         return sg_page(sk_msg_elem(msg, which));
 223 }
 224
 225 static inline bool sk_msg_to_ingress(const struct sk_msg *msg)
 226 {
 227         return msg->flags & BPF_F_INGRESS;
 228 }
 229
 230 static inline void sk_msg_compute_data_pointers(struct sk_msg *msg)
 231 {
 232         struct scatterlist *sge = sk_msg_elem(msg, msg->sg.start);
 233
 234         if (test_bit(msg->sg.start, &msg->sg.copy)) {
 235                 msg->data = NULL;
 236                 msg->data_end = NULL;
 237         } else {
 238                 msg->data = sg_virt(sge);
 239                 msg->data_end = msg->data + sge->length;
 240         }
 241 }
 242
 243 static inline void sk_msg_page_add(struct sk_msg *msg, struct page *page,
 244                                    u32 len, u32 offset)
 245 {
 246         struct scatterlist *sge;
 247
 248         get_page(page);
 249         sge = sk_msg_elem(msg, msg->sg.end);
 250         sg_set_page(sge, page, len, offset);
 251         sg_unmark_end(sge);
 252
 253         __set_bit(msg->sg.end, &msg->sg.copy);
 254         msg->sg.size += len;
 255         sk_msg_iter_next(msg, end);
 256 }
 257
 258 static inline void sk_msg_sg_copy(struct sk_msg *msg, u32 i, bool copy_state)
 259 {
 260         do {
 261                 if (copy_state)
 262                         __set_bit(i, &msg->sg.copy);
 263                 else
 264                         __clear_bit(i, &msg->sg.copy);
 265                 sk_msg_iter_var_next(i);
 266                 if (i == msg->sg.end)
 267                         break;
 268         } while (1);
 269 }
 270
 271 static inline void sk_msg_sg_copy_set(struct sk_msg *msg, u32 start)
 272 {
 273         sk_msg_sg_copy(msg, start, true);
 274 }
 275
 276 static inline void sk_msg_sg_copy_clear(struct sk_msg *msg, u32 start)
 277 {
 278         sk_msg_sg_copy(msg, start, false);
 279 }
 280
 281 static inline struct sk_psock *sk_psock(const struct sock *sk)
 282 {
 283         return rcu_dereference_sk_user_data(sk);
 284 }
 285
 286 static inline void sk_psock_queue_msg(struct sk_psock *psock,
 287                                       struct sk_msg *msg)
 288 {
 289         list_add_tail(&msg->list, &psock->ingress_msg);
 290 }
 291
 292 static inline bool sk_psock_queue_empty(const struct sk_psock *psock)
 293 {
 294         return psock ? list_empty(&psock->ingress_msg) : true;
 295 }
 296
 297 static inline void sk_psock_report_error(struct sk_psock *psock, int err)
 298 {
 299         struct sock *sk = psock->sk;
 300
 301         sk->sk_err = err;
 302         sk->sk_error_report(sk);
 303 }
 304
 305 struct sk_psock *sk_psock_init(struct sock *sk, int node);
 306
 307 int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock);
 308 void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock);
 309 void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock);
 310
 311 int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
 312                          struct sk_msg *msg);
 313
 314 static inline struct sk_psock_link *sk_psock_init_link(void)
 315 {
 316         return kzalloc(sizeof(struct sk_psock_link),
 317                        GFP_ATOMIC | __GFP_NOWARN);
 318 }
 319
 320 static inline void sk_psock_free_link(struct sk_psock_link *link)
 321 {
 322         kfree(link);
 323 }
 324
 325 struct sk_psock_link *sk_psock_link_pop(struct sk_psock *psock);
 326
 327 void __sk_psock_purge_ingress_msg(struct sk_psock *psock);
 328
 329 static inline void sk_psock_cork_free(struct sk_psock *psock)
 330 {
 331         if (psock->cork) {
 332                 sk_msg_free(psock->sk, psock->cork);
 333                 kfree(psock->cork);
 334                 psock->cork = NULL;
 335         }
 336 }
 337
 338 static inline void sk_psock_update_proto(struct sock *sk,
 339                                          struct sk_psock *psock,
 340                                          struct proto *ops)
 341 {
 342         /* Initialize saved callbacks and original proto only once, since this
 343          * function may be called multiple times for a psock, e.g. when
 344          * psock->progs.msg_parser is updated.
 345          *
 346          * Since we've not installed the new proto, psock is not yet in use and
 347          * we can initialize it without synchronization.
 348          */
 349         if (!psock->sk_proto) {
 350                 struct proto *orig = READ_ONCE(sk->sk_prot);
 351
 352                 psock->saved_unhash = orig->unhash;
 353                 psock->saved_close = orig->close;
 354                 psock->saved_write_space = sk->sk_write_space;
 355
 356                 psock->sk_proto = orig;
 357         }
 358
 359         /* Pairs with lockless read in sk_clone_lock() */
 360         WRITE_ONCE(sk->sk_prot, ops);
 361 }
 362
 363 static inline void sk_psock_restore_proto(struct sock *sk,
 364                                           struct sk_psock *psock)
 365 {
 366         sk->sk_prot->unhash = psock->saved_unhash;
 367         if (inet_csk_has_ulp(sk)) {
 368                 tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
 369         } else {
 370                 sk->sk_write_space = psock->saved_write_space;
 371                 /* Pairs with lockless read in sk_clone_lock() */
 372                 WRITE_ONCE(sk->sk_prot, psock->sk_proto);
 373         }
 374 }
 375
 376 static inline void sk_psock_set_state(struct sk_psock *psock,
 377                                       enum sk_psock_state_bits bit)
 378 {
 379         set_bit(bit, &psock->state);
 380 }
 381
 382 static inline void sk_psock_clear_state(struct sk_psock *psock,
 383                                         enum sk_psock_state_bits bit)
 384 {
 385         clear_bit(bit, &psock->state);
 386 }
 387
 388 static inline bool sk_psock_test_state(const struct sk_psock *psock,
 389                                        enum sk_psock_state_bits bit)
 390 {
 391         return test_bit(bit, &psock->state);
 392 }
 393
 394 static inline struct sk_psock *sk_psock_get(struct sock *sk)
 395 {
 396         struct sk_psock *psock;
 397
 398         rcu_read_lock();
 399         psock = sk_psock(sk);
 400         if (psock && !refcount_inc_not_zero(&psock->refcnt))
 401                 psock = NULL;
 402         rcu_read_unlock();
 403         return psock;
 404 }
 405
 406 void sk_psock_stop(struct sock *sk, struct sk_psock *psock);
 407 void sk_psock_destroy(struct rcu_head *rcu);
 408 void sk_psock_drop(struct sock *sk, struct sk_psock *psock);
 409
 410 static inline void sk_psock_put(struct sock *sk, struct sk_psock *psock)
 411 {
 412         if (refcount_dec_and_test(&psock->refcnt))
 413                 sk_psock_drop(sk, psock);
 414 }
 415
 416 static inline void sk_psock_data_ready(struct sock *sk, struct sk_psock *psock)
 417 {
 418         if (psock->parser.enabled)
 419                 psock->parser.saved_data_ready(sk);
 420         else
 421                 sk->sk_data_ready(sk);
 422 }
 423
 424 static inline void psock_set_prog(struct bpf_prog **pprog,
 425                                   struct bpf_prog *prog)
 426 {
 427         prog = xchg(pprog, prog);
 428         if (prog)
 429                 bpf_prog_put(prog);
 430 }
 431
 432 static inline void psock_progs_drop(struct sk_psock_progs *progs)
 433 {
 434         psock_set_prog(&progs->msg_parser, NULL);
 435         psock_set_prog(&progs->skb_parser, NULL);
 436         psock_set_prog(&progs->skb_verdict, NULL);
 437 }
 438
 439 #endif /* _LINUX_SKMSG_H */