From patchwork Mon Jan 24 19:28:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 12722846 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8955DC433F5 for ; Mon, 24 Jan 2022 19:31:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=aAIeZmgQ9Q+gHTe1mujHhNO+3tk1MVgDg3msxt9krWo=; b=QwJLVovQ+IYrdt YUp0KvFbRkQ9dOb4ddg5zy4DTYmJm4inh6r+iUHE1Mcc25xyTwQU6NdgVYov9HIOvbVyywzXGMmAV cs/6Mj6PMVhunZrT4A4EC8kAECC5upq3n6JkenGlRhvrUlIwlBENJ/3+8vN3eRsUbYqIOOIxsvJW8 PftsqTz9D/+BCIC1wbk3GKMFOYh9dOHtc2BHABx10PFFQIk0wkuB5+MprcmGHyr4VghT2FTFDcpMi u/U/99Y8mb2BT/jQpwBw+xv84P6Rx7oDB1DaaRMdoI+4K+WvDlTLHvlXHbVcMzVhFvw8HkMWzGHuD ii2FFpc8TP4FfPah2CUA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nC51t-004ufH-Og; Mon, 24 Jan 2022 19:29:29 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nC51l-004udR-8Z for linux-arm-kernel@lists.infradead.org; Mon, 24 Jan 2022 19:29:24 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3EE8BB81233; Mon, 24 Jan 2022 19:29:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC8ECC340E5; Mon, 24 Jan 2022 19:29:16 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="PPnruihN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1643052554; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YfXcMYvtLUn7d14Gnis94IiLaEOFq0Ds4XfgcosuDFQ=; b=PPnruihNHl9OeIN5HrkdQeki0Sje9B7XzWOIi+7Lux+sPDqXhAyi5IpauqszZQIyDXjM7t 2V1BDCV/8UBfpDNIdua3bl16nyWv+KpP30lNfLqUlnAk8y0X3+p6JE9cEvAsfvzkGyOVry TJUeCr8WMNCaftd8cw/0IoCCj8B6NhM= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 5b3516fc (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Mon, 24 Jan 2022 19:29:14 +0000 (UTC) From: "Jason A. Donenfeld" To: Linux ARM , Linux Crypto Mailing List , Linux Kernel Mailing List , llvm@lists.linux.dev, Nick Desaulniers , Sami Tolvanen , Nathan Chancellor , Eric Biggers , Herbert Xu , Miles Chen , Ard Biesheuvel Cc: "Jason A. Donenfeld" Subject: [PATCH v2] lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI Date: Mon, 24 Jan 2022 20:28:49 +0100 Message-Id: <20220124192849.14755-1-Jason@zx2c4.com> In-Reply-To: <20220119135450.564115-1-Jason@zx2c4.com> References: <20220119135450.564115-1-Jason@zx2c4.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220124_112921_814599_041F692A X-CRM114-Status: GOOD ( 21.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org blake2s_compress_generic is weakly aliased by blake2s_generic. The current harness for function selection uses a function pointer, which is ordinarily inlined and resolved at compile time. But when Clang's CFI is enabled, CFI still triggers when making an indirect call via a weak symbol. This seems like a bug in Clang's CFI, as though it's bucketing weak symbols and strong symbols differently. It also only seems to trigger when "full LTO" mode is used, rather than "thin LTO". [ 0.000000][ T0] Kernel panic - not syncing: CFI failure (target: blake2s_compress_generic+0x0/0x1444) [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.16.0-mainline-06981-g076c855b846e #1 [ 0.000000][ T0] Hardware name: MT6873 (DT) [ 0.000000][ T0] Call trace: [ 0.000000][ T0] dump_backtrace+0xfc/0x1dc [ 0.000000][ T0] dump_stack_lvl+0xa8/0x11c [ 0.000000][ T0] panic+0x194/0x464 [ 0.000000][ T0] __cfi_check_fail+0x54/0x58 [ 0.000000][ T0] __cfi_slowpath_diag+0x354/0x4b0 [ 0.000000][ T0] blake2s_update+0x14c/0x178 [ 0.000000][ T0] _extract_entropy+0xf4/0x29c [ 0.000000][ T0] crng_initialize_primary+0x24/0x94 [ 0.000000][ T0] rand_initialize+0x2c/0x6c [ 0.000000][ T0] start_kernel+0x2f8/0x65c [ 0.000000][ T0] __primary_switched+0xc4/0x7be4 [ 0.000000][ T0] Rebooting in 5 seconds.. Nonetheless, the function pointer method isn't so terrific anyway, so this patch replaces it with a simple boolean, which also gets inlined away. This successfully works around the Clang bug. In general, I'm not too keen on all of the indirection involved here; it clearly does more harm than good. Hopefully the whole thing can get cleaned up down the road when lib/crypto is overhauled more comprehensively. But for now, we go with a simple bandaid. Fixes: 6048fdcc5f26 ("lib/crypto: blake2s: include as built-in") Reported-by: Miles Chen Tested-by: Miles Chen Tested-by: Nathan Chancellor Link: https://github.com/ClangBuiltLinux/linux/issues/1567 Cc: Nick Desaulniers Cc: Sami Tolvanen Cc: Ard Biesheuvel Signed-off-by: Jason A. Donenfeld Acked-by: Nick Desaulniers --- Changes v1->v2: - Wrapped columns at 80 for Eric. arch/arm/crypto/blake2s-shash.c | 4 ++-- arch/x86/crypto/blake2s-shash.c | 4 ++-- crypto/blake2s_generic.c | 4 ++-- include/crypto/internal/blake2s.h | 40 +++++++++++++++++++------------ lib/crypto/blake2s.c | 4 ++-- 5 files changed, 33 insertions(+), 23 deletions(-) diff --git a/arch/arm/crypto/blake2s-shash.c b/arch/arm/crypto/blake2s-shash.c index 17c1c3bfe2f5..763c73beea2d 100644 --- a/arch/arm/crypto/blake2s-shash.c +++ b/arch/arm/crypto/blake2s-shash.c @@ -13,12 +13,12 @@ static int crypto_blake2s_update_arm(struct shash_desc *desc, const u8 *in, unsigned int inlen) { - return crypto_blake2s_update(desc, in, inlen, blake2s_compress); + return crypto_blake2s_update(desc, in, inlen, false); } static int crypto_blake2s_final_arm(struct shash_desc *desc, u8 *out) { - return crypto_blake2s_final(desc, out, blake2s_compress); + return crypto_blake2s_final(desc, out, false); } #define BLAKE2S_ALG(name, driver_name, digest_size) \ diff --git a/arch/x86/crypto/blake2s-shash.c b/arch/x86/crypto/blake2s-shash.c index f9e2fecdb761..59ae28abe35c 100644 --- a/arch/x86/crypto/blake2s-shash.c +++ b/arch/x86/crypto/blake2s-shash.c @@ -18,12 +18,12 @@ static int crypto_blake2s_update_x86(struct shash_desc *desc, const u8 *in, unsigned int inlen) { - return crypto_blake2s_update(desc, in, inlen, blake2s_compress); + return crypto_blake2s_update(desc, in, inlen, false); } static int crypto_blake2s_final_x86(struct shash_desc *desc, u8 *out) { - return crypto_blake2s_final(desc, out, blake2s_compress); + return crypto_blake2s_final(desc, out, false); } #define BLAKE2S_ALG(name, driver_name, digest_size) \ diff --git a/crypto/blake2s_generic.c b/crypto/blake2s_generic.c index 72fe480f9bd6..5f96a21f8788 100644 --- a/crypto/blake2s_generic.c +++ b/crypto/blake2s_generic.c @@ -15,12 +15,12 @@ static int crypto_blake2s_update_generic(struct shash_desc *desc, const u8 *in, unsigned int inlen) { - return crypto_blake2s_update(desc, in, inlen, blake2s_compress_generic); + return crypto_blake2s_update(desc, in, inlen, true); } static int crypto_blake2s_final_generic(struct shash_desc *desc, u8 *out) { - return crypto_blake2s_final(desc, out, blake2s_compress_generic); + return crypto_blake2s_final(desc, out, true); } #define BLAKE2S_ALG(name, driver_name, digest_size) \ diff --git a/include/crypto/internal/blake2s.h b/include/crypto/internal/blake2s.h index d39cfa0d333e..52363eee2b20 100644 --- a/include/crypto/internal/blake2s.h +++ b/include/crypto/internal/blake2s.h @@ -24,14 +24,11 @@ static inline void blake2s_set_lastblock(struct blake2s_state *state) state->f[0] = -1; } -typedef void (*blake2s_compress_t)(struct blake2s_state *state, - const u8 *block, size_t nblocks, u32 inc); - /* Helper functions for BLAKE2s shared by the library and shash APIs */ -static inline void __blake2s_update(struct blake2s_state *state, - const u8 *in, size_t inlen, - blake2s_compress_t compress) +static __always_inline void +__blake2s_update(struct blake2s_state *state, const u8 *in, size_t inlen, + bool force_generic) { const size_t fill = BLAKE2S_BLOCK_SIZE - state->buflen; @@ -39,7 +36,12 @@ static inline void __blake2s_update(struct blake2s_state *state, return; if (inlen > fill) { memcpy(state->buf + state->buflen, in, fill); - (*compress)(state, state->buf, 1, BLAKE2S_BLOCK_SIZE); + if (force_generic) + blake2s_compress_generic(state, state->buf, 1, + BLAKE2S_BLOCK_SIZE); + else + blake2s_compress(state, state->buf, 1, + BLAKE2S_BLOCK_SIZE); state->buflen = 0; in += fill; inlen -= fill; @@ -47,7 +49,12 @@ static inline void __blake2s_update(struct blake2s_state *state, if (inlen > BLAKE2S_BLOCK_SIZE) { const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_SIZE); /* Hash one less (full) block than strictly possible */ - (*compress)(state, in, nblocks - 1, BLAKE2S_BLOCK_SIZE); + if (force_generic) + blake2s_compress_generic(state, in, nblocks - 1, + BLAKE2S_BLOCK_SIZE); + else + blake2s_compress(state, in, nblocks - 1, + BLAKE2S_BLOCK_SIZE); in += BLAKE2S_BLOCK_SIZE * (nblocks - 1); inlen -= BLAKE2S_BLOCK_SIZE * (nblocks - 1); } @@ -55,13 +62,16 @@ static inline void __blake2s_update(struct blake2s_state *state, state->buflen += inlen; } -static inline void __blake2s_final(struct blake2s_state *state, u8 *out, - blake2s_compress_t compress) +static __always_inline void +__blake2s_final(struct blake2s_state *state, u8 *out, bool force_generic) { blake2s_set_lastblock(state); memset(state->buf + state->buflen, 0, BLAKE2S_BLOCK_SIZE - state->buflen); /* Padding */ - (*compress)(state, state->buf, 1, state->buflen); + if (force_generic) + blake2s_compress_generic(state, state->buf, 1, state->buflen); + else + blake2s_compress(state, state->buf, 1, state->buflen); cpu_to_le32_array(state->h, ARRAY_SIZE(state->h)); memcpy(out, state->h, state->outlen); } @@ -99,20 +109,20 @@ static inline int crypto_blake2s_init(struct shash_desc *desc) static inline int crypto_blake2s_update(struct shash_desc *desc, const u8 *in, unsigned int inlen, - blake2s_compress_t compress) + bool force_generic) { struct blake2s_state *state = shash_desc_ctx(desc); - __blake2s_update(state, in, inlen, compress); + __blake2s_update(state, in, inlen, force_generic); return 0; } static inline int crypto_blake2s_final(struct shash_desc *desc, u8 *out, - blake2s_compress_t compress) + bool force_generic) { struct blake2s_state *state = shash_desc_ctx(desc); - __blake2s_final(state, out, compress); + __blake2s_final(state, out, force_generic); return 0; } diff --git a/lib/crypto/blake2s.c b/lib/crypto/blake2s.c index 9364f79937b8..c71c09621c09 100644 --- a/lib/crypto/blake2s.c +++ b/lib/crypto/blake2s.c @@ -18,14 +18,14 @@ void blake2s_update(struct blake2s_state *state, const u8 *in, size_t inlen) { - __blake2s_update(state, in, inlen, blake2s_compress); + __blake2s_update(state, in, inlen, false); } EXPORT_SYMBOL(blake2s_update); void blake2s_final(struct blake2s_state *state, u8 *out) { WARN_ON(IS_ENABLED(DEBUG) && !out); - __blake2s_final(state, out, blake2s_compress); + __blake2s_final(state, out, false); memzero_explicit(state, sizeof(*state)); } EXPORT_SYMBOL(blake2s_final);