From bb29648102335586e9a66289a1d98a0cb392b6e5 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 18 Jun 2018 10:22:38 -0700 Subject: crypto: vmac - separate tfm and request context syzbot reported a crash in vmac_final() when multiple threads concurrently use the same "vmac(aes)" transform through AF_ALG. The bug is pretty fundamental: the VMAC template doesn't separate per-request state from per-tfm (per-key) state like the other hash algorithms do, but rather stores it all in the tfm context. That's wrong. Also, vmac_final() incorrectly zeroes most of the state including the derived keys and cached pseudorandom pad. Therefore, only the first VMAC invocation with a given key calculates the correct digest. Fix these bugs by splitting the per-tfm state from the per-request state and using the proper init/update/final sequencing for requests. Reproducer for the crash: #include #include #include int main() { int fd; struct sockaddr_alg addr = { .salg_type = "hash", .salg_name = "vmac(aes)", }; char buf[256] = { 0 }; fd = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(fd, (void *)&addr, sizeof(addr)); setsockopt(fd, SOL_ALG, ALG_SET_KEY, buf, 16); fork(); fd = accept(fd, NULL, NULL); for (;;) write(fd, buf, 256); } The immediate cause of the crash is that vmac_ctx_t.partial_size exceeds VMAC_NHBYTES, causing vmac_final() to memset() a negative length. Reported-by: syzbot+264bca3a6e8d645550d3@syzkaller.appspotmail.com Fixes: f1939f7c5645 ("crypto: vmac - New hash algorithm for intel_txt support") Cc: # v2.6.32+ Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- include/crypto/vmac.h | 63 --------------------------------------------------- 1 file changed, 63 deletions(-) delete mode 100644 include/crypto/vmac.h (limited to 'include/crypto') diff --git a/include/crypto/vmac.h b/include/crypto/vmac.h deleted file mode 100644 index 6b700c7b2fe1..000000000000 --- a/include/crypto/vmac.h +++ /dev/null @@ -1,63 +0,0 @@ -/* - * Modified to interface to the Linux kernel - * Copyright (c) 2009, Intel Corporation. - * - * This program is free software; you can redistribute it and/or modify it - * under the terms and conditions of the GNU General Public License, - * version 2, as published by the Free Software Foundation. - * - * This program is distributed in the hope it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * You should have received a copy of the GNU General Public License along with - * this program; if not, write to the Free Software Foundation, Inc., 59 Temple - * Place - Suite 330, Boston, MA 02111-1307 USA. - */ - -#ifndef __CRYPTO_VMAC_H -#define __CRYPTO_VMAC_H - -/* -------------------------------------------------------------------------- - * VMAC and VHASH Implementation by Ted Krovetz (tdk@acm.org) and Wei Dai. - * This implementation is herby placed in the public domain. - * The authors offers no warranty. Use at your own risk. - * Please send bug reports to the authors. - * Last modified: 17 APR 08, 1700 PDT - * ----------------------------------------------------------------------- */ - -/* - * User definable settings. - */ -#define VMAC_TAG_LEN 64 -#define VMAC_KEY_SIZE 128/* Must be 128, 192 or 256 */ -#define VMAC_KEY_LEN (VMAC_KEY_SIZE/8) -#define VMAC_NHBYTES 128/* Must 2^i for any 3 < i < 13 Standard = 128*/ - -/* - * This implementation uses u32 and u64 as names for unsigned 32- - * and 64-bit integer types. These are defined in C99 stdint.h. The - * following may need adaptation if you are not running a C99 or - * Microsoft C environment. - */ -struct vmac_ctx { - u64 nhkey[(VMAC_NHBYTES/8)+2*(VMAC_TAG_LEN/64-1)]; - u64 polykey[2*VMAC_TAG_LEN/64]; - u64 l3key[2*VMAC_TAG_LEN/64]; - u64 polytmp[2*VMAC_TAG_LEN/64]; - u64 cached_nonce[2]; - u64 cached_aes[2]; - int first_block_processed; -}; - -typedef u64 vmac_t; - -struct vmac_ctx_t { - struct crypto_cipher *child; - struct vmac_ctx __vmac_ctx; - u8 partial[VMAC_NHBYTES]; /* partial block */ - int partial_size; /* size of the partial block */ -}; - -#endif /* __CRYPTO_VMAC_H */ -- cgit v1.2.3-59-g8ed1b