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Add CHECK_FOR_INTERRUPTS() in scram_SaltedPassword() for the backend

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scram_SaltedPassword() could take a long time to compute when the number
of iterations used is large enough, and this code uses a tight loop to
compute a salted password.

Note that the same issue exists in libpq when using \password and a
large iteration number, but this cannot be interrupted.  A CFI in the
backend is useful for server-side computations, at least.

Backpatch down to 16, where the user-settable GUC scram_iterations has
been added.

Author: Bowen Shi
Reviewed-by: Aleksander Alekseev, Daniel Gustafsson
Discussion: https://postgr.es/m/CAM_vCueV6xfr08KczfaCEk5J_qeTZtgqN7+orkNLx=g+phE82Q@mail.gmail.com
Backpatch-through: 16
This commit is contained in:
Michael Paquier 2023-11-28 08:35:50 +09:00
parent 930d2b442f
commit 14f2f9eb1a
1 changed files with 11 additions and 0 deletions
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11
src/common/scram-common.c
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@ -22,6 +22,9 @@
#include "common/base64.h"
#include "common/hmac.h"
#include "common/scram-common.h"
#ifndef FRONTEND
#include "miscadmin.h"
#endif
#include "port/pg_bswap.h"
/*
@ -73,6 +76,14 @@ scram_SaltedPassword(const char *password,
/* Subsequent iterations */
for (i = 2; i <= iterations; i++)
{
#ifndef FRONTEND
/*
* Make sure that this is interruptible as scram_iterations could be
* set to a large value.
*/
CHECK_FOR_INTERRUPTS();
#endif
if (pg_hmac_init(hmac_ctx, (uint8 *) password, password_len) < 0 ||
pg_hmac_update(hmac_ctx, (uint8 *) Ui_prev, key_length) < 0 ||
pg_hmac_final(hmac_ctx, Ui, key_length) < 0)