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Make err_clear_constant_time really constant time

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[extended tests]

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8558)
This commit is contained in:
Bernd Edlinger 2019-03-20 20:01:12 +01:00
parent 94eb7d07c0
commit d284d27770
3 changed files with 25 additions and 25 deletions
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47
crypto/err/err.c
View File

@ -827,8 +827,24 @@ static unsigned long get_error_values(int inc, int top, const char **file,
return ERR_R_INTERNAL_ERROR;
}
while (es->bottom != es->top) {
if (es->err_flags[es->top] & ERR_FLAG_CLEAR) {
err_clear(es, es->top);
es->top = es->top > 0 ? es->top - 1 : ERR_NUM_ERRORS - 1;
continue;
}
i = (es->bottom + 1) % ERR_NUM_ERRORS;
if (es->err_flags[i] & ERR_FLAG_CLEAR) {
es->bottom = i;
err_clear(es, es->bottom);
continue;
}
break;
}
if (es->bottom == es->top)
return 0;
if (top)
i = es->top; /* last error */
else
@ -1158,23 +1174,6 @@ int ERR_pop_to_mark(void)
return 1;
}
#ifdef UINTPTR_T
# undef UINTPTR_T
#endif
/*
* uintptr_t is the answer, but unformtunately we can't assume that all
* compilers supported by 1.0.2 have it :-(
*/
#if defined(OPENSSL_SYS_VMS) && __INITIAL_POINTER_SIZE==64
/*
* But we can't use size_t on VMS, because it adheres to sizeof(size_t)==4
* even in 64-bit builds, which means that it won't work as mask.
*/
# define UINTPTR_T unsigned long long
#else
# define UINTPTR_T size_t
#endif
void err_clear_last_constant_time(int clear)
{
ERR_STATE *es;
@ -1186,11 +1185,11 @@ void err_clear_last_constant_time(int clear)
top = es->top;
es->err_flags[top] &= ~(0 - clear);
es->err_buffer[top] &= ~(0UL - clear);
es->err_file[top] = (const char *)((UINTPTR_T)es->err_file[top] &
~((UINTPTR_T)0 - clear));
es->err_line[top] |= 0 - clear;
es->top = (top + ERR_NUM_ERRORS - clear) % ERR_NUM_ERRORS;
/*
* Flag error as cleared but remove it elsewhere to avoid two errors
* accessing the same error stack location, revealing timing information.
*/
clear = constant_time_select_int(constant_time_eq_int(clear, 0),
0, ERR_FLAG_CLEAR);
es->err_flags[top] |= clear;
}

1
crypto/err/err.h
View File

@ -143,6 +143,7 @@ extern "C" {
# define ERR_TXT_STRING 0x02
# define ERR_FLAG_MARK 0x01
# define ERR_FLAG_CLEAR 0x02
# define ERR_NUM_ERRORS 16
typedef struct err_state_st {

2
crypto/rsa/rsa_eay.c
View File

@ -589,7 +589,7 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
goto err;
}
RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, RSA_R_PADDING_CHECK_FAILED);
err_clear_last_constant_time(r >= 0);
err_clear_last_constant_time(1 & ~constant_time_msb(r));
err:
if (ctx != NULL) {