The branch OpenSSL_1_1_1-stable has been updated
via 33726188f40fe0598849855778ce266f80d0751e (commit)
from e3568508c387681f52764514db40def3009d7a14 (commit)
- Log -----------------------------------------------------------------
commit 33726188f40fe0598849855778ce266f80d0751e
Author: Bernd Edlinger <bernd.edlin...@hotmail.de>
Date: Wed Mar 20 20:01:12 2019 +0100
Make err_clear_constant_time really constant time
[extended tests]
Reviewed-by: Paul Dale <paul.d...@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8542)
(cherry picked from commit 94dc53a3f7549040dd9e61a25485070c14b41c49)
-----------------------------------------------------------------------
Summary of changes:
crypto/err/err.c | 49 +++++++++++++++++++++++--------------------------
crypto/rsa/rsa_ossl.c | 2 +-
include/openssl/err.h | 1 +
3 files changed, 25 insertions(+), 27 deletions(-)
diff --git a/crypto/err/err.c b/crypto/err/err.c
index c737b2a..eaf6712 100644
--- a/crypto/err/err.c
+++ b/crypto/err/err.c
@@ -523,8 +523,24 @@ 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
@@ -913,25 +929,6 @@ int ERR_clear_last_mark(void)
return 1;
}
-#ifdef UINTPTR_T
-# undef UINTPTR_T
-#endif
-/*
- * uintptr_t is the answer, but unfortunately C89, current "least common
- * denominator" doesn't define it. Most legacy platforms typedef it anyway,
- * so that attempt to fill the gaps means that one would have to identify
- * that track these gaps, which would be undesirable. Macro it is...
- */
-#if defined(__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;
@@ -943,11 +940,11 @@ 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;
}
diff --git a/crypto/rsa/rsa_ossl.c b/crypto/rsa/rsa_ossl.c
index 0c93f13..adf2836 100644
--- a/crypto/rsa/rsa_ossl.c
+++ b/crypto/rsa/rsa_ossl.c
@@ -479,7 +479,7 @@ static int rsa_ossl_private_decrypt(int flen, const
unsigned char *from,
goto err;
}
RSAerr(RSA_F_RSA_OSSL_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:
BN_CTX_end(ctx);
diff --git a/include/openssl/err.h b/include/openssl/err.h
index 6cae1a3..ea304b8 100644
--- a/include/openssl/err.h
+++ b/include/openssl/err.h
@@ -37,6 +37,7 @@ 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 {
