libgcrypt: fix CVE-2019-12904

In Libgcrypt 1.8.4, the C implementation of AES is vulnerable to a
flush-and-reload side-channel attack because physical addresses are
available to other processes. (The C implementation is used on platforms
where an assembly-language implementation is unavailable.)

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2019-12904

Patches from:
https://github.com/gpg/libgcrypt/commit/1374254c2904ab5b18ba4a890856824a102d4705
https://github.com/gpg/libgcrypt/commit/daedbbb5541cd8ecda1459d3b843ea4d92788762
https://github.com/gpg/libgcrypt/commit/a4c561aab1014c3630bc88faf6f5246fee16b020

(From OE-Core rev: 757f2d50d7cd194e5f734a24e68d8f0da98b38f8)

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
(cherry picked from commit 37e390ff05b6a4509019db358ed496731d80cc51)
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 90 insertions, 0 deletions

diff --git a/meta/recipes-support/libgcrypt/files/0001-Prefetch-GCM-look-up-tables.patch b/meta/recipes-support/libgcrypt/files/0001-Prefetch-GCM-look-up-tables.patch
new file mode 100644
index 0000000000..4df96f0011
--- /dev/null
+++ b/meta/recipes-support/libgcrypt/files/0001-Prefetch-GCM-look-up-tables.patch
@@ -0,0 +1,90 @@
+From 1374254c2904ab5b18ba4a890856824a102d4705 Mon Sep 17 00:00:00 2001
+From: Jussi Kivilinna <jussi.kivilinna@iki.fi>
+Date: Sat, 27 Apr 2019 19:33:28 +0300
+Subject: [PATCH 1/3] Prefetch GCM look-up tables
+
+* cipher/cipher-gcm.c (prefetch_table, do_prefetch_tables)
+(prefetch_tables): New.
+(ghash_internal): Call prefetch_tables.
+--
+
+Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
+
+Upstream-Status: Backport
+[https://github.com/gpg/libgcrypt/commit/1374254c2904ab5b18ba4a890856824a102d4705]
+
+CVE: CVE-2019-12904
+
+Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
+---
+ cipher/cipher-gcm.c | 33 +++++++++++++++++++++++++++++++++
+ 1 file changed, 33 insertions(+)
+
+diff --git a/cipher/cipher-gcm.c b/cipher/cipher-gcm.c
+index c19f09f..11f119a 100644
+--- a/cipher/cipher-gcm.c
++++ b/cipher/cipher-gcm.c
+@@ -118,6 +118,34 @@ static const u16 gcmR[256] = {
+   0xbbf0, 0xba32, 0xb874, 0xb9b6, 0xbcf8, 0xbd3a, 0xbf7c, 0xbebe,
+ };
+ 
++static inline
++void prefetch_table(const void *tab, size_t len)
++{
++  const volatile byte *vtab = tab;
++  size_t i;
++
++  for (i = 0; i < len; i += 8 * 32)
++    {
++      (void)vtab[i + 0 * 32];
++      (void)vtab[i + 1 * 32];
++      (void)vtab[i + 2 * 32];
++      (void)vtab[i + 3 * 32];
++      (void)vtab[i + 4 * 32];
++      (void)vtab[i + 5 * 32];
++      (void)vtab[i + 6 * 32];
++      (void)vtab[i + 7 * 32];
++    }
++
++  (void)vtab[len - 1];
++}
++
++static inline void
++do_prefetch_tables (const void *gcmM, size_t gcmM_size)
++{
++  prefetch_table(gcmM, gcmM_size);
++  prefetch_table(gcmR, sizeof(gcmR));
++}
++
+ #ifdef GCM_TABLES_USE_U64
+ static void
+ bshift (u64 * b0, u64 * b1)
+@@ -365,6 +393,8 @@ do_ghash (unsigned char *result, const unsigned char *buf, const u32 *gcmM)
+ #define fillM(c) \
+   do_fillM (c->u_mode.gcm.u_ghash_key.key, c->u_mode.gcm.gcm_table)
+ #define GHASH(c, result, buf) do_ghash (result, buf, c->u_mode.gcm.gcm_table)
++#define prefetch_tables(c) \
++  do_prefetch_tables(c->u_mode.gcm.gcm_table, sizeof(c->u_mode.gcm.gcm_table))
+ 
+ #else
+ 
+@@ -430,6 +460,7 @@ do_ghash (unsigned char *hsub, unsigned char *result, const unsigned char *buf)
+ 
+ #define fillM(c) do { } while (0)
+ #define GHASH(c, result, buf) do_ghash (c->u_mode.gcm.u_ghash_key.key, result, buf)
++#define prefetch_tables(c) do {} while (0)
+ 
+ #endif /* !GCM_USE_TABLES */
+ 
+@@ -441,6 +472,8 @@ ghash_internal (gcry_cipher_hd_t c, byte *result, const byte *buf,
+   const unsigned int blocksize = GCRY_GCM_BLOCK_LEN;
+   unsigned int burn = 0;
+ 
++  prefetch_tables (c);
++
+   while (nblocks)
+     {
+       burn = GHASH (c, result, buf);
+-- 
+2.7.4
+