From patchwork Tue Sep 22 21:53:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Madhavan T. Venkataraman" X-Patchwork-Id: 11793323 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CF06359D for ; Tue, 22 Sep 2020 21:53:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFF18207C3 for ; Tue, 22 Sep 2020 21:53:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="R8hQixnw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726615AbgIVVxs (ORCPT ); Tue, 22 Sep 2020 17:53:48 -0400 Received: from linux.microsoft.com ([13.77.154.182]:55318 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726779AbgIVVxn (ORCPT ); Tue, 22 Sep 2020 17:53:43 -0400 Received: from localhost.localdomain (unknown [47.187.206.220]) by linux.microsoft.com (Postfix) with ESMTPSA id DA8CD20C27C2; Tue, 22 Sep 2020 14:53:39 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com DA8CD20C27C2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600811621; bh=7zXFDd5e9gQDRl70elYDzZIUqUSxDlwg1R6LYZvjU+I=; h=From:To:Subject:Date:In-Reply-To:References:From; b=R8hQixnwCw7jKlbVUp2WcLjT2B1eBsMGQhRGCHNCB47lVsvQkkqkE3GV8ZKHy6wm3 vjRjNeec0yvuNQGVTYgEsDBiFlWgGUdbCIl0J/1RtyjlTOyS71ozka1LIzRDkzafYK 4hr5haytbkwGkefRtLhPALrM+xuyoPG5a6DtkxXU= From: madvenka@linux.microsoft.com To: kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, oleg@redhat.com, x86@kernel.org, luto@kernel.org, David.Laight@ACULAB.COM, fweimer@redhat.com, mark.rutland@arm.com, mic@digikod.net, pavel@ucw.cz, madvenka@linux.microsoft.com Subject: [PATCH v2 3/4] [RFC] arm64/trampfd: Provide support for the trampoline file descriptor Date: Tue, 22 Sep 2020 16:53:25 -0500 Message-Id: <20200922215326.4603-4-madvenka@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200922215326.4603-1-madvenka@linux.microsoft.com> References: <210d7cd762d5307c2aa1676705b392bd445f1baa> <20200922215326.4603-1-madvenka@linux.microsoft.com> Precedence: bulk List-ID: From: "Madhavan T. Venkataraman" - Define architecture specific register names - Architecture specific functions for: - system call init - code descriptor check - data descriptor check - Fill a page with a trampoline table for: - 32-bit user process - 64-bit user process Signed-off-by: Madhavan T. Venkataraman --- arch/arm64/include/asm/unistd.h | 2 +- arch/arm64/include/asm/unistd32.h | 2 + arch/arm64/include/uapi/asm/ptrace.h | 59 +++++++ arch/arm64/kernel/Makefile | 2 + arch/arm64/kernel/trampfd.c | 244 +++++++++++++++++++++++++++ 5 files changed, 308 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/trampfd.c diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index 3b859596840d..b3b2019f8d16 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -38,7 +38,7 @@ #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5) #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800) -#define __NR_compat_syscalls 440 +#define __NR_compat_syscalls 441 #endif #define __ARCH_WANT_SYS_CLONE diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h index 6d95d0c8bf2f..c0493c5322d9 100644 --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -885,6 +885,8 @@ __SYSCALL(__NR_openat2, sys_openat2) __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd) #define __NR_faccessat2 439 __SYSCALL(__NR_faccessat2, sys_faccessat2) +#define __NR_trampfd 440 +__SYSCALL(__NR_trampfd, sys_trampfd) /* * Please add new compat syscalls above this comment and update diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h index 42cbe34d95ce..2778789c1cbe 100644 --- a/arch/arm64/include/uapi/asm/ptrace.h +++ b/arch/arm64/include/uapi/asm/ptrace.h @@ -88,6 +88,65 @@ struct user_pt_regs { __u64 pstate; }; +/* + * These register names are to be used by 32-bit applications. + */ +enum reg_32_name { + arm_min, + arm_r0 = arm_min, + arm_r1, + arm_r2, + arm_r3, + arm_r4, + arm_r5, + arm_r6, + arm_r7, + arm_r8, + arm_r9, + arm_r10, + arm_r11, + arm_r12, + arm_max, +}; + +/* + * These register names are to be used by 64-bit applications. + */ +enum reg_64_name { + arm64_min = arm_max, + arm64_r0 = arm64_min, + arm64_r1, + arm64_r2, + arm64_r3, + arm64_r4, + arm64_r5, + arm64_r6, + arm64_r7, + arm64_r8, + arm64_r9, + arm64_r10, + arm64_r11, + arm64_r12, + arm64_r13, + arm64_r14, + arm64_r15, + arm64_r16, + arm64_r17, + arm64_r18, + arm64_r19, + arm64_r20, + arm64_r21, + arm64_r22, + arm64_r23, + arm64_r24, + arm64_r25, + arm64_r26, + arm64_r27, + arm64_r28, + arm64_r29, + arm64_max, +}; + struct user_fpsimd_state { __uint128_t vregs[32]; __u32 fpsr; diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index a561cbb91d4d..18d373fb1208 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -71,3 +71,5 @@ extra-y += $(head-y) vmlinux.lds ifeq ($(CONFIG_DEBUG_EFI),y) AFLAGS_head.o += -DVMLINUX_PATH="\"$(realpath $(objtree)/vmlinux)\"" endif + +obj-$(CONFIG_TRAMPFD) += trampfd.o diff --git a/arch/arm64/kernel/trampfd.c b/arch/arm64/kernel/trampfd.c new file mode 100644 index 000000000000..3b40ebb12907 --- /dev/null +++ b/arch/arm64/kernel/trampfd.c @@ -0,0 +1,244 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Trampoline FD - ARM64 support. + * + * Author: Madhavan T. Venkataraman (madvenka@linux.microsoft.com) + * + * Copyright (c) 2020, Microsoft Corporation. + */ + +#include +#include +#include + +#define TRAMPFD_CODE_32_SIZE 28 +#define TRAMPFD_CODE_64_SIZE 48 + +static inline bool is_compat(void) +{ + return is_compat_thread(task_thread_info(current)); +} + +/* + * trampfd syscall. + */ +void trampfd_arch(struct trampfd_info *info) +{ + if (is_compat()) + info->code_size = TRAMPFD_CODE_32_SIZE; + else + info->code_size = TRAMPFD_CODE_64_SIZE; + info->ntrampolines = PAGE_SIZE / info->code_size; + info->code_offset = TRAMPFD_CODE_PGOFF << PAGE_SHIFT; + info->reserved = 0; +} + +/* + * trampfd code descriptor check. + */ +int trampfd_code_arch(struct trampfd_code *code) +{ + int ntrampolines; + int min, max; + + if (is_compat()) { + min = arm_min; + max = arm_max; + ntrampolines = PAGE_SIZE / TRAMPFD_CODE_32_SIZE; + } else { + min = arm64_min; + max = arm64_max; + ntrampolines = PAGE_SIZE / TRAMPFD_CODE_64_SIZE; + } + + if (code->reg < min || code->reg >= max) + return -EINVAL; + + if (!code->ntrampolines || code->ntrampolines > ntrampolines) + return -EINVAL; + return 0; +} + +/* + * trampfd data descriptor check. + */ +int trampfd_data_arch(struct trampfd_data *data) +{ + int min, max; + + if (is_compat()) { + min = arm_min; + max = arm_max; + } else { + min = arm64_min; + max = arm64_max; + } + + if (data->reg < min || data->reg >= max) + return -EINVAL; + return 0; +} + +#define MOVARM(ins, reg, imm32) \ +{ \ + u16 *_imm16 = (u16 *) &(imm32); /* little endian */ \ + int _hw, _opcode; \ + \ + for (_hw = 0; _hw < 2; _hw++) { \ + /* movw or movt */ \ + _opcode = _hw ? 0xe3400000 : 0xe3000000; \ + *ins++ = _opcode | (_imm16[_hw] >> 12) << 16 | \ + (reg) << 12 | (_imm16[_hw] & 0xFFF); \ + } \ +} + +#define LDRARM(ins, reg) \ +{ \ + *ins++ = 0xe5900000 | (reg) << 16 | (reg) << 12; \ +} + +#define BXARM(ins, reg) \ +{ \ + *ins++ = 0xe12fff10 | (reg); \ +} + +static void trampfd_code_fill_32(struct trampfd *trampfd, char *addr) +{ + char *eaddr = addr + PAGE_SIZE; + int creg = trampfd->code_reg - arm_min; + int dreg = trampfd->data_reg - arm_min; + u32 *code = trampfd->code; + u32 *data = trampfd->data; + u32 *instruction = (u32 *) addr; + int i; + + for (i = 0; i < trampfd->ntrampolines; i++, code++, data++) { + /* + * movw creg, code & 0xFFFF + * movt creg, code >> 16 + */ + MOVARM(instruction, creg, code); + + /* + * ldr creg, [creg] + */ + LDRARM(instruction, creg); + + /* + * movw dreg, data & 0xFFFF + * movt dreg, data >> 16 + */ + MOVARM(instruction, dreg, data); + + /* + * ldr dreg, [dreg] + */ + LDRARM(instruction, dreg); + + /* + * bx creg + */ + BXARM(instruction, creg); + } + addr = (char *) instruction; + memset(addr, 0, eaddr - addr); +} + +#define MOVQ(ins, reg, imm64) \ +{ \ + u16 *_imm16 = (u16 *) &(imm64); /* little endian */ \ + int _hw, _opcode; \ + \ + for (_hw = 0; _hw < 4; _hw++) { \ + /* movz or movk */ \ + _opcode = _hw ? 0xf2800000 : 0xd2800000; \ + *ins++ = _opcode | _hw << 21 | _imm16[_hw] << 5 | (reg);\ + } \ +} + +#define LDR(ins, reg) \ +{ \ + *ins++ = 0xf9400000 | (reg) << 5 | (reg); \ +} + +#define BR(ins, reg) \ +{ \ + *ins++ = 0xd61f0000 | (reg) << 5; \ +} + +#define PAD(ins) \ +{ \ + while ((uintptr_t) ins & 7) \ + *ins++ = 0; \ +} + +static void trampfd_code_fill_64(struct trampfd *trampfd, char *addr) +{ + char *eaddr = addr + PAGE_SIZE; + int creg = trampfd->code_reg - arm64_min; + int dreg = trampfd->data_reg - arm64_min; + u64 *code = trampfd->code; + u64 *data = trampfd->data; + u32 *instruction = (u32 *) addr; + int i; + + for (i = 0; i < trampfd->ntrampolines; i++, code++, data++) { + /* + * Pseudo instruction: + * + * movq creg, code + * + * Actual instructions: + * + * movz creg, code & 0xFFFF + * movk creg, (code >> 16) & 0xFFFF, lsl 16 + * movk creg, (code >> 32) & 0xFFFF, lsl 32 + * movk creg, (code >> 48) & 0xFFFF, lsl 48 + */ + MOVQ(instruction, creg, code); + + /* + * ldr creg, [creg] + */ + LDR(instruction, creg); + + /* + * Pseudo instruction: + * + * movq dreg, data + * + * Actual instructions: + * + * movz dreg, data & 0xFFFF + * movk dreg, (data >> 16) & 0xFFFF, lsl 16 + * movk dreg, (data >> 32) & 0xFFFF, lsl 32 + * movk dreg, (data >> 48) & 0xFFFF, lsl 48 + */ + MOVQ(instruction, dreg, data); + + /* + * ldr dreg, [dreg] + */ + LDR(instruction, dreg); + + /* + * br creg + */ + BR(instruction, creg); + + /* + * Pad to 8-byte boundary + */ + PAD(instruction); + } + addr = (char *) instruction; + memset(addr, 0, eaddr - addr); +} + +void trampfd_code_fill(struct trampfd *trampfd, char *addr) +{ + if (is_compat()) + trampfd_code_fill_32(trampfd, addr); + else + trampfd_code_fill_64(trampfd, addr); +}