From patchwork Fri Oct 28 17:27:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Catalin Marinas X-Patchwork-Id: 9402465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CA6016022E for ; Fri, 28 Oct 2016 17:27:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BBE762A8A4 for ; Fri, 28 Oct 2016 17:27:54 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AF74B2A8B4; Fri, 28 Oct 2016 17:27:54 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 1A2CD2A8A4 for ; Fri, 28 Oct 2016 17:27:52 +0000 (UTC) Received: (qmail 7646 invoked by uid 550); 28 Oct 2016 17:27:44 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 7260 invoked from network); 28 Oct 2016 17:27:40 -0000 From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Cc: Will Deacon , James Morse , Kees Cook , Mark Rutland , Ard Biesheuvel , AKASHI Takahiro , Sami Tolvanen , kernel-hardening@lists.openwall.com Date: Fri, 28 Oct 2016 18:27:10 +0100 Message-Id: <1477675636-3957-3-git-send-email-catalin.marinas@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1477675636-3957-1-git-send-email-catalin.marinas@arm.com> References: <1477675636-3957-1-git-send-email-catalin.marinas@arm.com> Subject: [kernel-hardening] [PATCH v4 2/8] arm64: Factor out PAN enabling/disabling into separate uaccess_* macros X-Virus-Scanned: ClamAV using ClamSMTP This patch moves the directly coded alternatives for turning PAN on/off into separate uaccess_{enable,disable} macros or functions. The asm macros take a few arguments which will be used in subsequent patches. Note that any (unlikely) access that the compiler might generate between uaccess_enable() and uaccess_disable(), other than those explicitly specified by the user access code, will not be protected by PAN. Cc: Will Deacon Cc: James Morse Cc: Kees Cook Reviewed-by: Mark Rutland Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/futex.h | 17 ++++---- arch/arm64/include/asm/uaccess.h | 79 +++++++++++++++++++++++++++++++----- arch/arm64/kernel/armv8_deprecated.c | 11 +++-- arch/arm64/lib/clear_user.S | 11 ++--- arch/arm64/lib/copy_from_user.S | 11 ++--- arch/arm64/lib/copy_in_user.S | 11 ++--- arch/arm64/lib/copy_to_user.S | 11 ++--- 7 files changed, 93 insertions(+), 58 deletions(-) diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index f2585cdd32c2..85c4a8981d47 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -21,15 +21,12 @@ #include #include -#include -#include #include -#include #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \ +do { \ + uaccess_enable(); \ asm volatile( \ - ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ " prfm pstl1strm, %2\n" \ "1: ldxr %w1, %2\n" \ insn "\n" \ @@ -44,11 +41,11 @@ " .popsection\n" \ _ASM_EXTABLE(1b, 4b) \ _ASM_EXTABLE(2b, 4b) \ - ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \ : "r" (oparg), "Ir" (-EFAULT) \ - : "memory") + : "memory"); \ + uaccess_disable(); \ +} while (0) static inline int futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) @@ -118,8 +115,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; + uaccess_enable(); asm volatile("// futex_atomic_cmpxchg_inatomic\n" -ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN) " prfm pstl1strm, %2\n" "1: ldxr %w1, %2\n" " sub %w3, %w1, %w4\n" @@ -134,10 +131,10 @@ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN) " .popsection\n" _ASM_EXTABLE(1b, 4b) _ASM_EXTABLE(2b, 4b) -ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN) : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp) : "r" (oldval), "r" (newval), "Ir" (-EFAULT) : "memory"); + uaccess_disable(); *uval = val; return ret; diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 55d0adbf6509..154659509afb 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -18,6 +18,11 @@ #ifndef __ASM_UACCESS_H #define __ASM_UACCESS_H +#include +#include + +#ifndef __ASSEMBLY__ + /* * User space memory access functions */ @@ -26,10 +31,8 @@ #include #include -#include #include #include -#include #include #include #include @@ -120,6 +123,44 @@ static inline void set_fs(mm_segment_t fs) " .popsection\n" /* + * User access enabling/disabling. + */ +#define __uaccess_disable(alt) \ +do { \ + asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ + CONFIG_ARM64_PAN)); \ +} while (0) + +#define __uaccess_enable(alt) \ +do { \ + asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ + CONFIG_ARM64_PAN)); \ +} while (0) + +static inline void uaccess_disable(void) +{ + __uaccess_disable(ARM64_HAS_PAN); +} + +static inline void uaccess_enable(void) +{ + __uaccess_enable(ARM64_HAS_PAN); +} + +/* + * These functions are no-ops when UAO is present. + */ +static inline void uaccess_disable_not_uao(void) +{ + __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); +} + +static inline void uaccess_enable_not_uao(void) +{ + __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); +} + +/* * The "__xxx" versions of the user access functions do not verify the address * space - it must have been done previously with a separate "access_ok()" * call. @@ -146,8 +187,7 @@ static inline void set_fs(mm_segment_t fs) do { \ unsigned long __gu_val; \ __chk_user_ptr(ptr); \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ - CONFIG_ARM64_PAN)); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ @@ -168,9 +208,8 @@ do { \ default: \ BUILD_BUG(); \ } \ + uaccess_disable_not_uao(); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ - CONFIG_ARM64_PAN)); \ } while (0) #define __get_user(x, ptr) \ @@ -215,8 +254,7 @@ do { \ do { \ __typeof__(*(ptr)) __pu_val = (x); \ __chk_user_ptr(ptr); \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ - CONFIG_ARM64_PAN)); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ @@ -237,8 +275,7 @@ do { \ default: \ BUILD_BUG(); \ } \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ - CONFIG_ARM64_PAN)); \ + uaccess_disable_not_uao(); \ } while (0) #define __put_user(x, ptr) \ @@ -331,4 +368,26 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *str, long n); +#else /* __ASSEMBLY__ */ + +#include + +/* + * User access enabling/disabling macros. These are no-ops when UAO is + * present. + */ + .macro uaccess_disable_not_uao, tmp1 +alternative_if ARM64_ALT_PAN_NOT_UAO + SET_PSTATE_PAN(1) +alternative_else_nop_endif + .endm + + .macro uaccess_enable_not_uao, tmp1, tmp2 +alternative_if ARM64_ALT_PAN_NOT_UAO + SET_PSTATE_PAN(0) +alternative_else_nop_endif + .endm + +#endif /* __ASSEMBLY__ */ + #endif /* __ASM_UACCESS_H */ diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index b0988bb1bf64..bdb35b92003e 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -14,7 +14,6 @@ #include #include -#include #include #include #include @@ -285,10 +284,10 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) #define __SWP_LL_SC_LOOPS 4 #define __user_swpX_asm(data, addr, res, temp, temp2, B) \ +do { \ + uaccess_enable(); \ __asm__ __volatile__( \ " mov %w3, %w7\n" \ - ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ "0: ldxr"B" %w2, [%4]\n" \ "1: stxr"B" %w0, %w1, [%4]\n" \ " cbz %w0, 2f\n" \ @@ -306,12 +305,12 @@ static void __init register_insn_emulation_sysctl(struct ctl_table *table) " .popsection" \ _ASM_EXTABLE(0b, 4b) \ _ASM_EXTABLE(1b, 4b) \ - ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN) \ : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \ : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \ "i" (__SWP_LL_SC_LOOPS) \ - : "memory") + : "memory"); \ + uaccess_disable(); \ +} while (0) #define __user_swp_asm(data, addr, res, temp, temp2) \ __user_swpX_asm(data, addr, res, temp, temp2, "") diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S index 5d1cad3ce6d6..d7150e30438a 100644 --- a/arch/arm64/lib/clear_user.S +++ b/arch/arm64/lib/clear_user.S @@ -17,10 +17,7 @@ */ #include -#include -#include -#include -#include +#include .text @@ -33,8 +30,7 @@ * Alignment fixed up by hardware. */ ENTRY(__clear_user) -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_enable_not_uao x2, x3 mov x2, x1 // save the size for fixup return subs x1, x1, #8 b.mi 2f @@ -54,8 +50,7 @@ uao_user_alternative 9f, strh, sttrh, wzr, x0, 2 b.mi 5f uao_user_alternative 9f, strb, sttrb, wzr, x0, 0 5: mov x0, #0 -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_disable_not_uao x2 ret ENDPROC(__clear_user) diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S index 4fd67ea03bb0..cfe13396085b 100644 --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S @@ -16,11 +16,8 @@ #include -#include -#include #include -#include -#include +#include /* * Copy from user space to a kernel buffer (alignment handled by the hardware) @@ -67,12 +64,10 @@ end .req x5 ENTRY(__arch_copy_from_user) -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_enable_not_uao x3, x4 add end, x0, x2 #include "copy_template.S" -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_disable_not_uao x3 mov x0, #0 // Nothing to copy ret ENDPROC(__arch_copy_from_user) diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S index f7292dd08c84..718b1c4e2f85 100644 --- a/arch/arm64/lib/copy_in_user.S +++ b/arch/arm64/lib/copy_in_user.S @@ -18,11 +18,8 @@ #include -#include -#include #include -#include -#include +#include /* * Copy from user space to user space (alignment handled by the hardware) @@ -68,12 +65,10 @@ end .req x5 ENTRY(__copy_in_user) -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_enable_not_uao x3, x4 add end, x0, x2 #include "copy_template.S" -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_disable_not_uao x3 mov x0, #0 ret ENDPROC(__copy_in_user) diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S index 7a7efe255034..e99e31c9acac 100644 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S @@ -16,11 +16,8 @@ #include -#include -#include #include -#include -#include +#include /* * Copy to user space from a kernel buffer (alignment handled by the hardware) @@ -66,12 +63,10 @@ end .req x5 ENTRY(__arch_copy_to_user) -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_enable_not_uao x3, x4 add end, x0, x2 #include "copy_template.S" -ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_ALT_PAN_NOT_UAO, \ - CONFIG_ARM64_PAN) + uaccess_disable_not_uao x3 mov x0, #0 ret ENDPROC(__arch_copy_to_user)