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044fd04cb4
Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/23022)
566 lines
16 KiB
C
566 lines
16 KiB
C
/*
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* Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "internal/quic_srtm.h"
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#include "internal/common.h"
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#include <openssl/lhash.h>
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#include <openssl/core_names.h>
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#include <openssl/rand.h>
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/*
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* QUIC Stateless Reset Token Manager
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* ==================================
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*/
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typedef struct srtm_item_st SRTM_ITEM;
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#define BLINDED_SRT_LEN 16
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DEFINE_LHASH_OF_EX(SRTM_ITEM);
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/*
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* The SRTM is implemented using two LHASH instances, one matching opaque pointers to
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* an item structure, and another matching a SRT-derived value to an item
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* structure. Multiple items with different seq_num values under a given opaque,
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* and duplicate SRTs, are handled using sorted singly-linked lists.
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*
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* The O(n) insert and lookup performance is tolerated on the basis that the
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* total number of entries for a given opaque (total number of extant CIDs for a
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* connection) should be quite small, and the QUIC protocol allows us to place a
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* hard limit on this via the active_connection_id_limit TPARAM. Thus there is
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* no risk of a large number of SRTs needing to be registered under a given
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* opaque.
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*
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* It is expected one SRTM will exist per QUIC_PORT and track all SRTs across
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* all connections for that QUIC_PORT.
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*/
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struct srtm_item_st {
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SRTM_ITEM *next_by_srt_blinded; /* SORT BY opaque DESC */
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SRTM_ITEM *next_by_seq_num; /* SORT BY seq_num DESC */
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void *opaque; /* \__ unique identity for item */
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uint64_t seq_num; /* / */
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QUIC_STATELESS_RESET_TOKEN srt;
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unsigned char srt_blinded[BLINDED_SRT_LEN]; /* H(srt) */
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#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
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uint32_t debug_token;
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#endif
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};
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struct quic_srtm_st {
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/* Crypto context used to calculate blinded SRTs H(srt). */
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EVP_CIPHER_CTX *blind_ctx; /* kept with key */
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LHASH_OF(SRTM_ITEM) *items_fwd; /* (opaque) -> SRTM_ITEM */
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LHASH_OF(SRTM_ITEM) *items_rev; /* (H(srt)) -> SRTM_ITEM */
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/*
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* Monotonically transitions to 1 in event of allocation failure. The only
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* valid operation on such an object is to free it.
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*/
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unsigned int alloc_failed : 1;
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};
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static unsigned long items_fwd_hash(const SRTM_ITEM *item)
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{
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return (unsigned long)(uintptr_t)item->opaque;
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}
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static int items_fwd_cmp(const SRTM_ITEM *a, const SRTM_ITEM *b)
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{
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return a->opaque != b->opaque;
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}
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static unsigned long items_rev_hash(const SRTM_ITEM *item)
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{
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/*
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* srt_blinded has already been through a crypto-grade hash function, so we
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* can just use bits from that.
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*/
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unsigned long l;
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memcpy(&l, item->srt_blinded, sizeof(l));
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return l;
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}
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static int items_rev_cmp(const SRTM_ITEM *a, const SRTM_ITEM *b)
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{
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/*
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* We don't need to use CRYPTO_memcmp here as the relationship of
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* srt_blinded to srt is already cryptographically obfuscated.
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*/
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return memcmp(a->srt_blinded, b->srt_blinded, sizeof(a->srt_blinded));
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}
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static int srtm_check_lh(QUIC_SRTM *srtm, LHASH_OF(SRTM_ITEM) *lh)
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{
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if (lh_SRTM_ITEM_error(lh)) {
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srtm->alloc_failed = 1;
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return 0;
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}
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return 1;
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}
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QUIC_SRTM *ossl_quic_srtm_new(OSSL_LIB_CTX *libctx, const char *propq)
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{
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QUIC_SRTM *srtm = NULL;
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unsigned char key[16];
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EVP_CIPHER *ecb = NULL;
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if (RAND_priv_bytes_ex(libctx, key, sizeof(key), sizeof(key) * 8) != 1)
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goto err;
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if ((srtm = OPENSSL_zalloc(sizeof(*srtm))) == NULL)
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return NULL;
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/* Use AES-128-ECB as a permutation over 128-bit SRTs. */
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if ((ecb = EVP_CIPHER_fetch(libctx, "AES-128-ECB", propq)) == NULL)
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goto err;
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if ((srtm->blind_ctx = EVP_CIPHER_CTX_new()) == NULL)
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goto err;
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if (!EVP_EncryptInit_ex2(srtm->blind_ctx, ecb, key, NULL, NULL))
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goto err;
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EVP_CIPHER_free(ecb);
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ecb = NULL;
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/* Create mappings. */
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if ((srtm->items_fwd = lh_SRTM_ITEM_new(items_fwd_hash, items_fwd_cmp)) == NULL
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|| (srtm->items_rev = lh_SRTM_ITEM_new(items_rev_hash, items_rev_cmp)) == NULL)
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goto err;
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return srtm;
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err:
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/*
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* No cleansing of key needed as blinding exists only for side channel
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* mitigation.
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*/
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ossl_quic_srtm_free(srtm);
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EVP_CIPHER_free(ecb);
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return NULL;
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}
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static void srtm_free_each(SRTM_ITEM *ihead)
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{
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SRTM_ITEM *inext, *item = ihead;
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for (item = item->next_by_seq_num; item != NULL; item = inext) {
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inext = item->next_by_seq_num;
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OPENSSL_free(item);
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}
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OPENSSL_free(ihead);
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}
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void ossl_quic_srtm_free(QUIC_SRTM *srtm)
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{
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if (srtm == NULL)
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return;
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lh_SRTM_ITEM_free(srtm->items_rev);
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if (srtm->items_fwd != NULL) {
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lh_SRTM_ITEM_doall(srtm->items_fwd, srtm_free_each);
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lh_SRTM_ITEM_free(srtm->items_fwd);
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}
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EVP_CIPHER_CTX_free(srtm->blind_ctx);
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OPENSSL_free(srtm);
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}
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/*
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* Find a SRTM_ITEM by (opaque, seq_num). Returns NULL if no match.
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* If head is non-NULL, writes the head of the relevant opaque list to *head if
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* there is one.
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* If prev is non-NULL, writes the previous node to *prev or NULL if it is
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* the first item.
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*/
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static SRTM_ITEM *srtm_find(QUIC_SRTM *srtm, void *opaque, uint64_t seq_num,
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SRTM_ITEM **head_p, SRTM_ITEM **prev_p)
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{
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SRTM_ITEM key, *item = NULL, *prev = NULL;
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key.opaque = opaque;
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item = lh_SRTM_ITEM_retrieve(srtm->items_fwd, &key);
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if (head_p != NULL)
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*head_p = item;
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for (; item != NULL; prev = item, item = item->next_by_seq_num)
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if (item->seq_num == seq_num) {
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break;
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} else if (item->seq_num < seq_num) {
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/*
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* List is sorted in descending order so there can't be any match
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* after this.
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*/
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item = NULL;
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break;
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}
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if (prev_p != NULL)
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*prev_p = prev;
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return item;
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}
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/*
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* Inserts a SRTM_ITEM into the singly-linked by-sequence-number linked list.
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* The new head pointer is written to *new_head (which may or may not be
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* unchanged).
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*/
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static void sorted_insert_seq_num(SRTM_ITEM *head, SRTM_ITEM *item, SRTM_ITEM **new_head)
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{
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uint64_t seq_num = item->seq_num;
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SRTM_ITEM *cur = head, **fixup = new_head;
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*new_head = head;
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while (cur != NULL && cur->seq_num > seq_num) {
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fixup = &cur->next_by_seq_num;
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cur = cur->next_by_seq_num;
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}
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item->next_by_seq_num = *fixup;
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*fixup = item;
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}
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/*
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* Inserts a SRTM_ITEM into the singly-linked by-SRT list.
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* The new head pointer is written to *new_head (which may or may not be
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* unchanged).
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*/
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static void sorted_insert_srt(SRTM_ITEM *head, SRTM_ITEM *item, SRTM_ITEM **new_head)
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{
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uintptr_t opaque = (uintptr_t)item->opaque;
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SRTM_ITEM *cur = head, **fixup = new_head;
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*new_head = head;
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while (cur != NULL && (uintptr_t)cur->opaque > opaque) {
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fixup = &cur->next_by_srt_blinded;
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cur = cur->next_by_srt_blinded;
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}
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item->next_by_srt_blinded = *fixup;
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*fixup = item;
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}
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/*
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* Computes the blinded SRT value used for internal lookup for side channel
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* mitigation purposes. We compute this once as a cached value when an SRTM_ITEM
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* is formed.
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*/
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static int srtm_compute_blinded(QUIC_SRTM *srtm, SRTM_ITEM *item,
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const QUIC_STATELESS_RESET_TOKEN *token)
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{
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int outl = 0;
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/*
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* We use AES-128-ECB as a permutation using a random key to facilitate
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* blinding for side-channel purposes. Encrypt the token as a single AES
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* block.
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*/
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if (!EVP_EncryptUpdate(srtm->blind_ctx, item->srt_blinded, &outl,
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(const unsigned char *)token, sizeof(*token)))
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return 0;
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if (!ossl_assert(outl == sizeof(*token)))
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return 0;
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return 1;
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}
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int ossl_quic_srtm_add(QUIC_SRTM *srtm, void *opaque, uint64_t seq_num,
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const QUIC_STATELESS_RESET_TOKEN *token)
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{
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SRTM_ITEM *item = NULL, *head = NULL, *new_head, *r_item;
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if (srtm->alloc_failed)
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return 0;
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/* (opaque, seq_num) duplicates not allowed */
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if ((item = srtm_find(srtm, opaque, seq_num, &head, NULL)) != NULL)
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return 0;
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if ((item = OPENSSL_zalloc(sizeof(*item))) == NULL)
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return 0;
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item->opaque = opaque;
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item->seq_num = seq_num;
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item->srt = *token;
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if (!srtm_compute_blinded(srtm, item, &item->srt)) {
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OPENSSL_free(item);
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return 0;
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}
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/* Add to forward mapping. */
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if (head == NULL) {
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/* First item under this opaque */
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lh_SRTM_ITEM_insert(srtm->items_fwd, item);
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if (!srtm_check_lh(srtm, srtm->items_fwd)) {
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OPENSSL_free(item);
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return 0;
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}
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} else {
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sorted_insert_seq_num(head, item, &new_head);
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if (new_head != head) { /* head changed, update in lhash */
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lh_SRTM_ITEM_insert(srtm->items_fwd, new_head);
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if (!srtm_check_lh(srtm, srtm->items_fwd)) {
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OPENSSL_free(item);
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return 0;
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}
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}
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}
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/* Add to reverse mapping. */
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r_item = lh_SRTM_ITEM_retrieve(srtm->items_rev, item);
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if (r_item == NULL) {
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/* First item under this blinded SRT */
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lh_SRTM_ITEM_insert(srtm->items_rev, item);
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if (!srtm_check_lh(srtm, srtm->items_rev))
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/*
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* Can't free the item now as we would have to undo the insertion
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* into the forward mapping which would require an insert operation
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* to restore the previous value. which might also fail. However,
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* the item will be freed OK when we free the entire SRTM.
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*/
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return 0;
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} else {
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sorted_insert_srt(r_item, item, &new_head);
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if (new_head != r_item) { /* head changed, update in lhash */
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lh_SRTM_ITEM_insert(srtm->items_rev, new_head);
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if (!srtm_check_lh(srtm, srtm->items_rev))
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/* As above. */
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return 0;
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}
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}
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return 1;
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}
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/* Remove item from reverse mapping. */
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static int srtm_remove_from_rev(QUIC_SRTM *srtm, SRTM_ITEM *item)
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{
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SRTM_ITEM *rh_item;
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rh_item = lh_SRTM_ITEM_retrieve(srtm->items_rev, item);
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assert(rh_item != NULL);
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if (rh_item == item) {
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/*
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* Change lhash to point to item after this one, or remove the entry if
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* this is the last one.
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*/
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if (item->next_by_srt_blinded != NULL) {
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lh_SRTM_ITEM_insert(srtm->items_rev, item->next_by_srt_blinded);
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if (!srtm_check_lh(srtm, srtm->items_rev))
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return 0;
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} else {
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lh_SRTM_ITEM_delete(srtm->items_rev, item);
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}
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} else {
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/* Find our entry in the SRT list */
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for (; rh_item->next_by_srt_blinded != item;
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rh_item = rh_item->next_by_srt_blinded);
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rh_item->next_by_srt_blinded = item->next_by_srt_blinded;
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}
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return 1;
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}
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int ossl_quic_srtm_remove(QUIC_SRTM *srtm, void *opaque, uint64_t seq_num)
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{
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SRTM_ITEM *item, *prev = NULL;
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if (srtm->alloc_failed)
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return 0;
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if ((item = srtm_find(srtm, opaque, seq_num, NULL, &prev)) == NULL)
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/* No match */
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return 0;
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/* Remove from forward mapping. */
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if (prev == NULL) {
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/*
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* Change lhash to point to item after this one, or remove the entry if
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* this is the last one.
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*/
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if (item->next_by_seq_num != NULL) {
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lh_SRTM_ITEM_insert(srtm->items_fwd, item->next_by_seq_num);
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if (!srtm_check_lh(srtm, srtm->items_fwd))
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return 0;
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} else {
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lh_SRTM_ITEM_delete(srtm->items_fwd, item);
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}
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} else {
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prev->next_by_seq_num = item->next_by_seq_num;
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}
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/* Remove from reverse mapping. */
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if (!srtm_remove_from_rev(srtm, item))
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return 0;
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OPENSSL_free(item);
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return 1;
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}
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int ossl_quic_srtm_cull(QUIC_SRTM *srtm, void *opaque)
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{
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SRTM_ITEM key, *item = NULL, *inext, *ihead;
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key.opaque = opaque;
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if (srtm->alloc_failed)
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return 0;
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if ((ihead = lh_SRTM_ITEM_retrieve(srtm->items_fwd, &key)) == NULL)
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return 1; /* nothing removed is a success condition */
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for (item = ihead; item != NULL; item = inext) {
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inext = item->next_by_seq_num;
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if (item != ihead) {
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srtm_remove_from_rev(srtm, item);
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OPENSSL_free(item);
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}
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}
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lh_SRTM_ITEM_delete(srtm->items_fwd, ihead);
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srtm_remove_from_rev(srtm, ihead);
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OPENSSL_free(ihead);
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return 1;
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}
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int ossl_quic_srtm_lookup(QUIC_SRTM *srtm,
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const QUIC_STATELESS_RESET_TOKEN *token,
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size_t idx,
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void **opaque, uint64_t *seq_num)
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{
|
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SRTM_ITEM key, *item;
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|
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if (srtm->alloc_failed)
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return 0;
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if (!srtm_compute_blinded(srtm, &key, token))
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return 0;
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item = lh_SRTM_ITEM_retrieve(srtm->items_rev, &key);
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for (; idx > 0 && item != NULL; --idx, item = item->next_by_srt_blinded);
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if (item == NULL)
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return 0;
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|
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if (opaque != NULL)
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*opaque = item->opaque;
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if (seq_num != NULL)
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*seq_num = item->seq_num;
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|
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return 1;
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}
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|
|
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
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|
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static uint32_t token_next = 0x5eadbeef;
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static size_t tokens_seen;
|
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|
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struct check_args {
|
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uint32_t token;
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int mode;
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};
|
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|
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static void check_mark(SRTM_ITEM *item, void *arg)
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{
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struct check_args *arg_ = arg;
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uint32_t token = arg_->token;
|
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uint64_t prev_seq_num = 0;
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void *prev_opaque = NULL;
|
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int have_prev = 0;
|
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|
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assert(item != NULL);
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|
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while (item != NULL) {
|
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if (have_prev) {
|
|
assert(!(item->opaque == prev_opaque && item->seq_num == prev_seq_num));
|
|
if (!arg_->mode)
|
|
assert(item->opaque != prev_opaque || item->seq_num < prev_seq_num);
|
|
}
|
|
|
|
++tokens_seen;
|
|
item->debug_token = token;
|
|
prev_opaque = item->opaque;
|
|
prev_seq_num = item->seq_num;
|
|
have_prev = 1;
|
|
|
|
if (arg_->mode)
|
|
item = item->next_by_srt_blinded;
|
|
else
|
|
item = item->next_by_seq_num;
|
|
}
|
|
}
|
|
|
|
static void check_count(SRTM_ITEM *item, void *arg)
|
|
{
|
|
struct check_args *arg_ = arg;
|
|
uint32_t token = arg_->token;
|
|
|
|
assert(item != NULL);
|
|
|
|
while (item != NULL) {
|
|
++tokens_seen;
|
|
assert(item->debug_token == token);
|
|
|
|
if (arg_->mode)
|
|
item = item->next_by_seq_num;
|
|
else
|
|
item = item->next_by_srt_blinded;
|
|
}
|
|
}
|
|
|
|
#endif
|
|
|
|
void ossl_quic_srtm_check(const QUIC_SRTM *srtm)
|
|
{
|
|
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
|
|
struct check_args args = {0};
|
|
size_t tokens_expected, tokens_expected_old;
|
|
|
|
args.token = token_next;
|
|
++token_next;
|
|
|
|
assert(srtm != NULL);
|
|
assert(srtm->blind_ctx != NULL);
|
|
assert(srtm->items_fwd != NULL);
|
|
assert(srtm->items_rev != NULL);
|
|
|
|
tokens_seen = 0;
|
|
lh_SRTM_ITEM_doall_arg(srtm->items_fwd, check_mark, &args);
|
|
|
|
tokens_expected = tokens_seen;
|
|
tokens_seen = 0;
|
|
lh_SRTM_ITEM_doall_arg(srtm->items_rev, check_count, &args);
|
|
|
|
assert(tokens_seen == tokens_expected);
|
|
tokens_expected_old = tokens_expected;
|
|
|
|
args.token = token_next;
|
|
++token_next;
|
|
|
|
args.mode = 1;
|
|
tokens_seen = 0;
|
|
lh_SRTM_ITEM_doall_arg(srtm->items_rev, check_mark, &args);
|
|
|
|
tokens_expected = tokens_seen;
|
|
tokens_seen = 0;
|
|
lh_SRTM_ITEM_doall_arg(srtm->items_fwd, check_count, &args);
|
|
|
|
assert(tokens_seen == tokens_expected);
|
|
assert(tokens_seen == tokens_expected_old);
|
|
#endif
|
|
}
|