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MINOR: cache: Change hash function in default normalizer used in case of "vary"

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When building the secondary signature for cache entries when vary is
enabled, the referer part of the signature was a simple crc32 of the
first referer header.
This patch changes it to a 64bits hash based of xxhash algorithm with a
random seed built during init. This will prevent "malicious" hash
collisions between entries of the cache.
This commit is contained in:
Remi Tricot-Le Breton 2023-08-31 15:58:08 +02:00 committed by William Lallemand
parent 7a71801af6
commit e03d060aa3
2 changed files with 17 additions and 5 deletions
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2
include/haproxy/http_ana-t.h
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@ -157,7 +157,7 @@ static forceinline char *hmsg_show_flags(char *buf, size_t len, const char *deli
* request/response pairs, because they depend on the responses' optional Vary * request/response pairs, because they depend on the responses' optional Vary
* header. The different sizes can be found in the vary_information object (see * header. The different sizes can be found in the vary_information object (see
* cache.c).*/ * cache.c).*/
#define HTTP_CACHE_SEC_KEY_LEN (sizeof(uint32_t)+sizeof(int)) #define HTTP_CACHE_SEC_KEY_LEN (sizeof(uint32_t)+sizeof(uint64_t))
/* Redirect flags */ /* Redirect flags */

20
src/cache.c
View File

@ -35,11 +35,14 @@
#include <haproxy/stconn.h> #include <haproxy/stconn.h>
#include <haproxy/stream.h> #include <haproxy/stream.h>
#include <haproxy/tools.h> #include <haproxy/tools.h>
#include <haproxy/xxhash.h>
#define CACHE_FLT_F_IMPLICIT_DECL 0x00000001 /* The cache filtre was implicitly declared (ie without #define CACHE_FLT_F_IMPLICIT_DECL 0x00000001 /* The cache filtre was implicitly declared (ie without
* the filter keyword) */ * the filter keyword) */
#define CACHE_FLT_INIT 0x00000002 /* Whether the cache name was freed. */ #define CACHE_FLT_INIT 0x00000002 /* Whether the cache name was freed. */
static uint64_t cache_hash_seed = 0;
const char *cache_store_flt_id = "cache store filter"; const char *cache_store_flt_id = "cache store filter";
extern struct applet http_cache_applet; extern struct applet http_cache_applet;
@ -139,7 +142,7 @@ static int accept_encoding_bitmap_cmp(const void *ref, const void *new, unsigned
* added to this array. */ * added to this array. */
const struct vary_hashing_information vary_information[] = { const struct vary_hashing_information vary_information[] = {
{ IST("accept-encoding"), VARY_ACCEPT_ENCODING, sizeof(uint32_t), &accept_encoding_normalizer, &accept_encoding_bitmap_cmp }, { IST("accept-encoding"), VARY_ACCEPT_ENCODING, sizeof(uint32_t), &accept_encoding_normalizer, &accept_encoding_bitmap_cmp },
{ IST("referer"), VARY_REFERER, sizeof(int), &default_normalizer, NULL }, { IST("referer"), VARY_REFERER, sizeof(uint64_t), &default_normalizer, NULL },
}; };
@ -2368,7 +2371,7 @@ static int accept_encoding_normalizer(struct htx *htx, struct ist hdr_name,
/* /*
* Normalizer used by default for the Referer header. It only * Normalizer used by default for the Referer header. It only
* calculates a simple crc of the whole value. * calculates a hash of the whole value using xxhash algorithm.
* Only the first occurrence of the header will be taken into account in the * Only the first occurrence of the header will be taken into account in the
* hash. * hash.
* Returns 0 in case of success, 1 if the hash buffer should be filled with 0s * Returns 0 in case of success, 1 if the hash buffer should be filled with 0s
@ -2382,8 +2385,8 @@ static int default_normalizer(struct htx *htx, struct ist hdr_name,
if (http_find_header(htx, hdr_name, &ctx, 1)) { if (http_find_header(htx, hdr_name, &ctx, 1)) {
retval = 0; retval = 0;
write_u32(buf, hash_crc32(istptr(ctx.value), istlen(ctx.value))); write_u64(buf, XXH3(istptr(ctx.value), istlen(ctx.value), cache_hash_seed));
*buf_len = sizeof(int); *buf_len = sizeof(uint64_t);
} }
return retval; return retval;
@ -2702,6 +2705,15 @@ smp_fetch_res_cache_name(const struct arg *args, struct sample *smp,
return 0; return 0;
} }
/* early boot initialization */
static void cache_init()
{
cache_hash_seed = ha_random64();
}
INITCALL0(STG_PREPARE, cache_init);
/* Declare the filter parser for "cache" keyword */ /* Declare the filter parser for "cache" keyword */
static struct flt_kw_list filter_kws = { "CACHE", { }, { static struct flt_kw_list filter_kws = { "CACHE", { }, {
{ "cache", parse_cache_flt, NULL }, { "cache", parse_cache_flt, NULL },