From patchwork Tue Nov 29 20:15:59 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: 629241 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 215AFC433FE for ; Tue, 29 Nov 2022 20:17:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236182AbiK2URP (ORCPT ); Tue, 29 Nov 2022 15:17:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236517AbiK2UQ2 (ORCPT ); Tue, 29 Nov 2022 15:16:28 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 619892EF0E; Tue, 29 Nov 2022 12:16:22 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id E5D7B618E5; Tue, 29 Nov 2022 20:16:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3550C433D6; Tue, 29 Nov 2022 20:16:19 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="pP5+mvia" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1669752978; 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=scBTgu25qR/Po4qPvR9EF2OY+/Gag445QTtqtv4xyfU=; b=pP5+mvias3uTiLQ5JAQxtIfJVsbLUm8vG9SV109Ns3ID+UvW1DrTT+Az/bGjX6YZa71iii o6z/3dh5v6FRwD7lzEiCE3TSr2ZSKMty5kTZX5lNpUdFu3TjOKfz00SwQKEhVfrG9IEbbA Usm4al0whY6AzEollG4QbfLfHIKtqz8= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id c8e3333f (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 29 Nov 2022 20:16:18 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, patches@lists.linux.dev, tglx@linutronix.de Cc: "Jason A. Donenfeld" , linux-crypto@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, Greg Kroah-Hartman , Adhemerval Zanella Netto , Carlos O'Donell , Florian Weimer , Arnd Bergmann , Christian Brauner , Samuel Neves Subject: [PATCH v9 3/3] x86: vdso: Wire up getrandom() vDSO implementation Date: Tue, 29 Nov 2022 21:15:59 +0100 Message-Id: <20221129201559.39449-4-Jason@zx2c4.com> In-Reply-To: <20221129201559.39449-1-Jason@zx2c4.com> References: <20221129201559.39449-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Hook up the generic vDSO implementation to the x86 vDSO data page. Since the existing vDSO infrastructure is heavily based on the timekeeping functionality, which works over arrays of bases, a new macro is introduced for vvars that are not arrays. The vDSO function requires a ChaCha20 implementation that does not write to the stack, yet can still do an entire ChaCha20 permutation, so provide this using SSE2, since this is userland code that must work on all x86-64 processors. Reviewed-by: Samuel Neves # for vgetrandom-chacha.S Signed-off-by: Jason A. Donenfeld --- arch/x86/Kconfig | 1 + arch/x86/entry/vdso/Makefile | 3 +- arch/x86/entry/vdso/vdso.lds.S | 2 + arch/x86/entry/vdso/vgetrandom-chacha.S | 177 ++++++++++++++++++++++++ arch/x86/entry/vdso/vgetrandom.c | 17 +++ arch/x86/include/asm/vdso/getrandom.h | 55 ++++++++ arch/x86/include/asm/vdso/vsyscall.h | 2 + arch/x86/include/asm/vvar.h | 16 +++ 8 files changed, 272 insertions(+), 1 deletion(-) create mode 100644 arch/x86/entry/vdso/vgetrandom-chacha.S create mode 100644 arch/x86/entry/vdso/vgetrandom.c create mode 100644 arch/x86/include/asm/vdso/getrandom.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 67745ceab0db..357148c4a3a4 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -269,6 +269,7 @@ config X86 select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_USER_RETURN_NOTIFIER select HAVE_GENERIC_VDSO + select VDSO_GETRANDOM if X86_64 select HOTPLUG_SMT if SMP select IRQ_FORCED_THREADING select NEED_PER_CPU_EMBED_FIRST_CHUNK diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 3e88b9df8c8f..2de64e52236a 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -27,7 +27,7 @@ VDSO32-$(CONFIG_X86_32) := y VDSO32-$(CONFIG_IA32_EMULATION) := y # files to link into the vdso -vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o +vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vgetrandom.o vgetrandom-chacha.o vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o vobjs32-y += vdso32/vclock_gettime.o vobjs-$(CONFIG_X86_SGX) += vsgx.o @@ -104,6 +104,7 @@ CFLAGS_REMOVE_vclock_gettime.o = -pg CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg CFLAGS_REMOVE_vgetcpu.o = -pg CFLAGS_REMOVE_vsgx.o = -pg +CFLAGS_REMOVE_vgetrandom.o = -pg # # X32 processes use x32 vDSO to access 64bit kernel data. diff --git a/arch/x86/entry/vdso/vdso.lds.S b/arch/x86/entry/vdso/vdso.lds.S index 4bf48462fca7..1919cc39277e 100644 --- a/arch/x86/entry/vdso/vdso.lds.S +++ b/arch/x86/entry/vdso/vdso.lds.S @@ -28,6 +28,8 @@ VERSION { clock_getres; __vdso_clock_getres; __vdso_sgx_enter_enclave; + getrandom; + __vdso_getrandom; local: *; }; } diff --git a/arch/x86/entry/vdso/vgetrandom-chacha.S b/arch/x86/entry/vdso/vgetrandom-chacha.S new file mode 100644 index 000000000000..91fbb7ac7af4 --- /dev/null +++ b/arch/x86/entry/vdso/vgetrandom-chacha.S @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022 Jason A. Donenfeld . All Rights Reserved. + */ + +#include +#include + +.section .rodata.cst16.CONSTANTS, "aM", @progbits, 16 +.align 16 +CONSTANTS: .octa 0x6b20657479622d323320646e61707865 +.text + +/* + * Very basic SSE2 implementation of ChaCha20. Produces a given positive number + * of blocks of output with a nonce of 0, taking an input key and 8-byte + * counter. Importantly does not spill to the stack. Its arguments are: + * + * rdi: output bytes + * rsi: 32-byte key input + * rdx: 8-byte counter input/output + * rcx: number of 64-byte blocks to write to output + */ +SYM_FUNC_START(__arch_chacha20_blocks_nostack) + +#define output %rdi +#define key %rsi +#define counter %rdx +#define nblocks %rcx +#define i %al +#define state0 %xmm0 +#define state1 %xmm1 +#define state2 %xmm2 +#define state3 %xmm3 +#define copy0 %xmm4 +#define copy1 %xmm5 +#define copy2 %xmm6 +#define copy3 %xmm7 +#define temp %xmm8 +#define one %xmm9 + + /* copy0 = "expand 32-byte k" */ + movaps CONSTANTS(%rip),copy0 + /* copy1,copy2 = key */ + movups 0x00(key),copy1 + movups 0x10(key),copy2 + /* copy3 = counter || zero nonce */ + movq 0x00(counter),copy3 + /* one = 1 || 0 */ + movq $1,%rax + movq %rax,one + +.Lblock: + /* state0,state1,state2,state3 = copy0,copy1,copy2,copy3 */ + movdqa copy0,state0 + movdqa copy1,state1 + movdqa copy2,state2 + movdqa copy3,state3 + + movb $10,i +.Lpermute: + /* state0 += state1, state3 = rotl32(state3 ^ state0, 16) */ + paddd state1,state0 + pxor state0,state3 + movdqa state3,temp + pslld $16,temp + psrld $16,state3 + por temp,state3 + + /* state2 += state3, state1 = rotl32(state1 ^ state2, 12) */ + paddd state3,state2 + pxor state2,state1 + movdqa state1,temp + pslld $12,temp + psrld $20,state1 + por temp,state1 + + /* state0 += state1, state3 = rotl32(state3 ^ state0, 8) */ + paddd state1,state0 + pxor state0,state3 + movdqa state3,temp + pslld $8,temp + psrld $24,state3 + por temp,state3 + + /* state2 += state3, state1 = rotl32(state1 ^ state2, 7) */ + paddd state3,state2 + pxor state2,state1 + movdqa state1,temp + pslld $7,temp + psrld $25,state1 + por temp,state1 + + /* state1[0,1,2,3] = state1[0,3,2,1] */ + pshufd $0x39,state1,state1 + /* state2[0,1,2,3] = state2[1,0,3,2] */ + pshufd $0x4e,state2,state2 + /* state3[0,1,2,3] = state3[2,1,0,3] */ + pshufd $0x93,state3,state3 + + /* state0 += state1, state3 = rotl32(state3 ^ state0, 16) */ + paddd state1,state0 + pxor state0,state3 + movdqa state3,temp + pslld $16,temp + psrld $16,state3 + por temp,state3 + + /* state2 += state3, state1 = rotl32(state1 ^ state2, 12) */ + paddd state3,state2 + pxor state2,state1 + movdqa state1,temp + pslld $12,temp + psrld $20,state1 + por temp,state1 + + /* state0 += state1, state3 = rotl32(state3 ^ state0, 8) */ + paddd state1,state0 + pxor state0,state3 + movdqa state3,temp + pslld $8,temp + psrld $24,state3 + por temp,state3 + + /* state2 += state3, state1 = rotl32(state1 ^ state2, 7) */ + paddd state3,state2 + pxor state2,state1 + movdqa state1,temp + pslld $7,temp + psrld $25,state1 + por temp,state1 + + /* state1[0,1,2,3] = state1[2,1,0,3] */ + pshufd $0x93,state1,state1 + /* state2[0,1,2,3] = state2[1,0,3,2] */ + pshufd $0x4e,state2,state2 + /* state3[0,1,2,3] = state3[0,3,2,1] */ + pshufd $0x39,state3,state3 + + decb i + jnz .Lpermute + + /* output0 = state0 + copy0 */ + paddd copy0,state0 + movups state0,0x00(output) + /* output1 = state1 + copy1 */ + paddd copy1,state1 + movups state1,0x10(output) + /* output2 = state2 + copy2 */ + paddd copy2,state2 + movups state2,0x20(output) + /* output3 = state3 + copy3 */ + paddd copy3,state3 + movups state3,0x30(output) + + /* ++copy3.counter */ + paddq one,copy3 + + /* output += 64, --nblocks */ + addq $64,output + decq nblocks + jnz .Lblock + + /* counter = copy3.counter */ + movq copy3,0x00(counter) + + /* Zero out the potentially sensitive regs, in case nothing uses these again. */ + pxor state0,state0 + pxor state1,state1 + pxor state2,state2 + pxor state3,state3 + pxor copy1,copy1 + pxor copy2,copy2 + pxor temp,temp + + ret +SYM_FUNC_END(__arch_chacha20_blocks_nostack) diff --git a/arch/x86/entry/vdso/vgetrandom.c b/arch/x86/entry/vdso/vgetrandom.c new file mode 100644 index 000000000000..6045ded5da90 --- /dev/null +++ b/arch/x86/entry/vdso/vgetrandom.c @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2022 Jason A. Donenfeld . All Rights Reserved. + */ +#include + +#include "../../../../lib/vdso/getrandom.c" + +ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *state); + +ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *state) +{ + return __cvdso_getrandom(buffer, len, flags, state); +} + +ssize_t getrandom(void *, size_t, unsigned int, void *) + __attribute__((weak, alias("__vdso_getrandom"))); diff --git a/arch/x86/include/asm/vdso/getrandom.h b/arch/x86/include/asm/vdso/getrandom.h new file mode 100644 index 000000000000..a2bb2dc4443e --- /dev/null +++ b/arch/x86/include/asm/vdso/getrandom.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2022 Jason A. Donenfeld . All Rights Reserved. + */ +#ifndef __ASM_VDSO_GETRANDOM_H +#define __ASM_VDSO_GETRANDOM_H + +#ifndef __ASSEMBLY__ + +#include +#include + +/** + * getrandom_syscall - invoke the getrandom() syscall + * @buffer: destination buffer to fill with random bytes + * @len: size of @buffer in bytes + * @flags: zero or more GRND_* flags + * Returns the number of random bytes written to @buffer, or a negative value indicating an error. + */ +static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags) +{ + long ret; + + asm ("syscall" : "=a" (ret) : + "0" (__NR_getrandom), "D" (buffer), "S" (len), "d" (flags) : + "rcx", "r11", "memory"); + + return ret; +} + +#define __vdso_rng_data (VVAR(_vdso_rng_data)) + +static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void) +{ + if (__vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS) + return (void *)&__vdso_rng_data + ((void *)&__timens_vdso_data - (void *)&__vdso_data); + return &__vdso_rng_data; +} + +/** + * __arch_chacha20_blocks_nostack - generate ChaCha20 stream without using the stack + * @dst_bytes: a destination buffer to hold @nblocks * 64 bytes of output + * @key: 32-byte input key + * @counter: 8-byte counter, read on input and updated on return + * @nblocks: the number of blocks to generate + * + * Generates a given positive number of block of ChaCha20 output with nonce=0, and does not write to + * any stack or memory outside of the parameters passed to it. This way, there's no concern about + * stack data leaking into forked child processes. + */ +extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, u32 *counter, size_t nblocks); + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETRANDOM_H */ diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h index be199a9b2676..71c56586a22f 100644 --- a/arch/x86/include/asm/vdso/vsyscall.h +++ b/arch/x86/include/asm/vdso/vsyscall.h @@ -11,6 +11,8 @@ #include DEFINE_VVAR(struct vdso_data, _vdso_data); +DEFINE_VVAR_SINGLE(struct vdso_rng_data, _vdso_rng_data); + /* * Update the vDSO data page to keep in sync with kernel timekeeping. */ diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h index 183e98e49ab9..9d9af37f7cab 100644 --- a/arch/x86/include/asm/vvar.h +++ b/arch/x86/include/asm/vvar.h @@ -26,6 +26,8 @@ */ #define DECLARE_VVAR(offset, type, name) \ EMIT_VVAR(name, offset) +#define DECLARE_VVAR_SINGLE(offset, type, name) \ + EMIT_VVAR(name, offset) #else @@ -37,6 +39,10 @@ extern char __vvar_page; extern type timens_ ## name[CS_BASES] \ __attribute__((visibility("hidden"))); \ +#define DECLARE_VVAR_SINGLE(offset, type, name) \ + extern type vvar_ ## name \ + __attribute__((visibility("hidden"))); \ + #define VVAR(name) (vvar_ ## name) #define TIMENS(name) (timens_ ## name) @@ -44,12 +50,22 @@ extern char __vvar_page; type name[CS_BASES] \ __attribute__((section(".vvar_" #name), aligned(16))) __visible +#define DEFINE_VVAR_SINGLE(type, name) \ + type name \ + __attribute__((section(".vvar_" #name), aligned(16))) __visible + #endif /* DECLARE_VVAR(offset, type, name) */ DECLARE_VVAR(128, struct vdso_data, _vdso_data) +#if !defined(_SINGLE_DATA) +#define _SINGLE_DATA +DECLARE_VVAR_SINGLE(640, struct vdso_rng_data, _vdso_rng_data) +#endif + #undef DECLARE_VVAR +#undef DECLARE_VVAR_SINGLE #endif