Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Fix leakage when the cacheline is 32-bytes in CBC_MAC_ROTATE_IN_PLACE #18050

Closed
wants to merge 1 commit into from
Closed

Fix leakage when the cacheline is 32-bytes in CBC_MAC_ROTATE_IN_PLACE #18050

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
14 changes: 11 additions & 3 deletions ssl/record/ssl3_record.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1532,6 +1532,7 @@ int ssl3_cbc_copy_mac(unsigned char *out,
#if defined(CBC_MAC_ROTATE_IN_PLACE)
unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE];
unsigned char *rotated_mac;
char aux1, aux2, aux3, mask;
#else
unsigned char rotated_mac[EVP_MAX_MD_SIZE];
#endif
Expand Down Expand Up @@ -1581,9 +1582,16 @@ int ssl3_cbc_copy_mac(unsigned char *out,
#if defined(CBC_MAC_ROTATE_IN_PLACE)
j = 0;
for (i = 0; i < md_size; i++) {
/* in case cache-line is 32 bytes, touch second line */
((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32];
out[j++] = rotated_mac[rotate_offset++];
/*
* in case cache-line is 32 bytes,
* load from both lines and select appropriately
*/
aux1 = rotated_mac[rotate_offset & ~32];
aux2 = rotated_mac[rotate_offset | 32];
mask = constant_time_eq_8(rotate_offset & ~32, rotate_offset);
aux3 = constant_time_select_8(mask, aux1, aux2);
out[j++] = aux3;
rotate_offset++;
rotate_offset &= constant_time_lt_s(rotate_offset, md_size);
}
#else
Expand Down