From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8103C432C3 for ; Mon, 25 Nov 2019 08:19:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9111E20830 for ; Mon, 25 Nov 2019 08:19:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727315AbfKYITu (ORCPT ); Mon, 25 Nov 2019 03:19:50 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:38700 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbfKYIT0 (ORCPT ); Mon, 25 Nov 2019 03:19:26 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iZ9aR-0001QS-LA; Mon, 25 Nov 2019 09:19:11 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 576301C1AF3; Mon, 25 Nov 2019 09:19:11 +0100 (CET) Date: Mon, 25 Nov 2019 08:19:11 -0000 From: "tip-bot2 for Will Deacon" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/refcount: Consolidate implementations of refcount_t Cc: Will Deacon , Ard Biesheuvel , Kees Cook , Hanjun Guo , Ard Biesheuvel , Elena Reshetova , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , x86 , LKML In-Reply-To: <20191121115902.2551-9-will@kernel.org> References: <20191121115902.2551-9-will@kernel.org> MIME-Version: 1.0 Message-ID: <157466995127.21853.8023988577315790855.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: fb041bb7c0a918b95c6889fc965cdc4a75b4c0ca Gitweb: https://git.kernel.org/tip/fb041bb7c0a918b95c6889fc965cdc4a75b4c0ca Author: Will Deacon AuthorDate: Thu, 21 Nov 2019 11:59:00 Committer: Ingo Molnar CommitterDate: Mon, 25 Nov 2019 09:15:32 +01:00 locking/refcount: Consolidate implementations of refcount_t The generic implementation of refcount_t should be good enough for everybody, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. Signed-off-by: Will Deacon Reviewed-by: Ard Biesheuvel Acked-by: Kees Cook Tested-by: Hanjun Guo Cc: Ard Biesheuvel Cc: Elena Reshetova Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191121115902.2551-9-will@kernel.org Signed-off-by: Ingo Molnar --- arch/Kconfig | 21 +---- arch/arm/Kconfig | 1 +- arch/arm64/Kconfig | 1 +- arch/s390/configs/debug_defconfig | 1 +- arch/x86/Kconfig | 1 +- arch/x86/include/asm/asm.h | 6 +- arch/x86/include/asm/refcount.h | 126 +---------------------- arch/x86/mm/extable.c | 49 +--------- drivers/gpu/drm/i915/Kconfig.debug | 1 +- include/linux/refcount.h | 158 ++++++++++------------------ lib/refcount.c | 2 +- 11 files changed, 59 insertions(+), 308 deletions(-) delete mode 100644 arch/x86/include/asm/refcount.h diff --git a/arch/Kconfig b/arch/Kconfig index 5f8a5d8..8bcc1c7 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -892,27 +892,6 @@ config STRICT_MODULE_RWX config ARCH_HAS_PHYS_TO_DMA bool -config ARCH_HAS_REFCOUNT - bool - help - An architecture selects this when it has implemented refcount_t - using open coded assembly primitives that provide an optimized - refcount_t implementation, possibly at the expense of some full - refcount state checks of CONFIG_REFCOUNT_FULL=y. - - The refcount overflow check behavior, however, must be retained. - Catching overflows is the primary security concern for protecting - against bugs in reference counts. - -config REFCOUNT_FULL - bool "Perform full reference count validation at the expense of speed" - help - Enabling this switches the refcounting infrastructure from a fast - unchecked atomic_t implementation to a fully state checked - implementation, which can be (slightly) slower but provides protections - against various use-after-free conditions that can be used in - security flaw exploits. - config HAVE_ARCH_COMPILER_H bool help diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8a50efb..0d3c5d7 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -117,7 +117,6 @@ config ARM select OLD_SIGSUSPEND3 select PCI_SYSCALL if PCI select PERF_USE_VMALLOC - select REFCOUNT_FULL select RTC_LIB select SYS_SUPPORTS_APM_EMULATION # Above selects are sorted alphabetically; please add new ones diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 41a9b42..bc990d3 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -181,7 +181,6 @@ config ARM64 select PCI_SYSCALL if PCI select POWER_RESET select POWER_SUPPLY - select REFCOUNT_FULL select SPARSE_IRQ select SWIOTLB select SYSCTL_EXCEPTION_TRACE diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig index 38d6403..2e60c80 100644 --- a/arch/s390/configs/debug_defconfig +++ b/arch/s390/configs/debug_defconfig @@ -62,7 +62,6 @@ CONFIG_OPROFILE=m CONFIG_KPROBES=y CONFIG_JUMP_LABEL=y CONFIG_STATIC_KEYS_SELFTEST=y -CONFIG_REFCOUNT_FULL=y CONFIG_LOCK_EVENT_COUNTS=y CONFIG_MODULES=y CONFIG_MODULE_FORCE_LOAD=y diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d6e1faa..fa6274f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -73,7 +73,6 @@ config X86 select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_PTE_DEVMAP if X86_64 select ARCH_HAS_PTE_SPECIAL - select ARCH_HAS_REFCOUNT select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE select ARCH_HAS_SET_MEMORY diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h index 3ff577c..5a0c14e 100644 --- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -139,9 +139,6 @@ # define _ASM_EXTABLE_EX(from, to) \ _ASM_EXTABLE_HANDLE(from, to, ex_handler_ext) -# define _ASM_EXTABLE_REFCOUNT(from, to) \ - _ASM_EXTABLE_HANDLE(from, to, ex_handler_refcount) - # define _ASM_NOKPROBE(entry) \ .pushsection "_kprobe_blacklist","aw" ; \ _ASM_ALIGN ; \ @@ -170,9 +167,6 @@ # define _ASM_EXTABLE_EX(from, to) \ _ASM_EXTABLE_HANDLE(from, to, ex_handler_ext) -# define _ASM_EXTABLE_REFCOUNT(from, to) \ - _ASM_EXTABLE_HANDLE(from, to, ex_handler_refcount) - /* For C file, we already have NOKPROBE_SYMBOL macro */ #endif diff --git a/arch/x86/include/asm/refcount.h b/arch/x86/include/asm/refcount.h deleted file mode 100644 index 232f856..0000000 --- a/arch/x86/include/asm/refcount.h +++ /dev/null @@ -1,126 +0,0 @@ -#ifndef __ASM_X86_REFCOUNT_H -#define __ASM_X86_REFCOUNT_H -/* - * x86-specific implementation of refcount_t. Based on PAX_REFCOUNT from - * PaX/grsecurity. - */ -#include -#include - -/* - * This is the first portion of the refcount error handling, which lives in - * .text.unlikely, and is jumped to from the CPU flag check (in the - * following macros). This saves the refcount value location into CX for - * the exception handler to use (in mm/extable.c), and then triggers the - * central refcount exception. The fixup address for the exception points - * back to the regular execution flow in .text. - */ -#define _REFCOUNT_EXCEPTION \ - ".pushsection .text..refcount\n" \ - "111:\tlea %[var], %%" _ASM_CX "\n" \ - "112:\t" ASM_UD2 "\n" \ - ASM_UNREACHABLE \ - ".popsection\n" \ - "113:\n" \ - _ASM_EXTABLE_REFCOUNT(112b, 113b) - -/* Trigger refcount exception if refcount result is negative. */ -#define REFCOUNT_CHECK_LT_ZERO \ - "js 111f\n\t" \ - _REFCOUNT_EXCEPTION - -/* Trigger refcount exception if refcount result is zero or negative. */ -#define REFCOUNT_CHECK_LE_ZERO \ - "jz 111f\n\t" \ - REFCOUNT_CHECK_LT_ZERO - -/* Trigger refcount exception unconditionally. */ -#define REFCOUNT_ERROR \ - "jmp 111f\n\t" \ - _REFCOUNT_EXCEPTION - -static __always_inline void refcount_add(unsigned int i, refcount_t *r) -{ - asm volatile(LOCK_PREFIX "addl %1,%0\n\t" - REFCOUNT_CHECK_LT_ZERO - : [var] "+m" (r->refs.counter) - : "ir" (i) - : "cc", "cx"); -} - -static __always_inline void refcount_inc(refcount_t *r) -{ - asm volatile(LOCK_PREFIX "incl %0\n\t" - REFCOUNT_CHECK_LT_ZERO - : [var] "+m" (r->refs.counter) - : : "cc", "cx"); -} - -static __always_inline void refcount_dec(refcount_t *r) -{ - asm volatile(LOCK_PREFIX "decl %0\n\t" - REFCOUNT_CHECK_LE_ZERO - : [var] "+m" (r->refs.counter) - : : "cc", "cx"); -} - -static __always_inline __must_check -bool refcount_sub_and_test(unsigned int i, refcount_t *r) -{ - bool ret = GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", - REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, e, "er", i, "cx"); - - if (ret) { - smp_acquire__after_ctrl_dep(); - return true; - } - - return false; -} - -static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r) -{ - bool ret = GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", - REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, e, "cx"); - - if (ret) { - smp_acquire__after_ctrl_dep(); - return true; - } - - return false; -} - -static __always_inline __must_check -bool refcount_add_not_zero(unsigned int i, refcount_t *r) -{ - int c, result; - - c = atomic_read(&(r->refs)); - do { - if (unlikely(c == 0)) - return false; - - result = c + i; - - /* Did we try to increment from/to an undesirable state? */ - if (unlikely(c < 0 || c == INT_MAX || result < c)) { - asm volatile(REFCOUNT_ERROR - : : [var] "m" (r->refs.counter) - : "cc", "cx"); - break; - } - - } while (!atomic_try_cmpxchg(&(r->refs), &c, result)); - - return c != 0; -} - -static __always_inline __must_check bool refcount_inc_not_zero(refcount_t *r) -{ - return refcount_add_not_zero(1, r); -} - -#endif diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 4d75bc6..30bb0bd 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -45,55 +45,6 @@ __visible bool ex_handler_fault(const struct exception_table_entry *fixup, EXPORT_SYMBOL_GPL(ex_handler_fault); /* - * Handler for UD0 exception following a failed test against the - * result of a refcount inc/dec/add/sub. - */ -__visible bool ex_handler_refcount(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) -{ - /* First unconditionally saturate the refcount. */ - *(int *)regs->cx = INT_MIN / 2; - - /* - * Strictly speaking, this reports the fixup destination, not - * the fault location, and not the actually overflowing - * instruction, which is the instruction before the "js", but - * since that instruction could be a variety of lengths, just - * report the location after the overflow, which should be close - * enough for finding the overflow, as it's at least back in - * the function, having returned from .text.unlikely. - */ - regs->ip = ex_fixup_addr(fixup); - - /* - * This function has been called because either a negative refcount - * value was seen by any of the refcount functions, or a zero - * refcount value was seen by refcount_dec(). - * - * If we crossed from INT_MAX to INT_MIN, OF (Overflow Flag: result - * wrapped around) will be set. Additionally, seeing the refcount - * reach 0 will set ZF (Zero Flag: result was zero). In each of - * these cases we want a report, since it's a boundary condition. - * The SF case is not reported since it indicates post-boundary - * manipulations below zero or above INT_MAX. And if none of the - * flags are set, something has gone very wrong, so report it. - */ - if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) { - bool zero = regs->flags & X86_EFLAGS_ZF; - - refcount_error_report(regs, zero ? "hit zero" : "overflow"); - } else if ((regs->flags & X86_EFLAGS_SF) == 0) { - /* Report if none of OF, ZF, nor SF are set. */ - refcount_error_report(regs, "unexpected saturation"); - } - - return true; -} -EXPORT_SYMBOL(ex_handler_refcount); - -/* * Handler for when we fail to restore a task's FPU state. We should never get * here because the FPU state of a task using the FPU (task->thread.fpu.state) * should always be valid. However, past bugs have allowed userspace to set diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug index 00786a1..1400fce 100644 --- a/drivers/gpu/drm/i915/Kconfig.debug +++ b/drivers/gpu/drm/i915/Kconfig.debug @@ -22,7 +22,6 @@ config DRM_I915_DEBUG depends on DRM_I915 select DEBUG_FS select PREEMPT_COUNT - select REFCOUNT_FULL select I2C_CHARDEV select STACKDEPOT select DRM_DP_AUX_CHARDEV diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 757d463..0ac50cf 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -1,64 +1,4 @@ /* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _LINUX_REFCOUNT_H -#define _LINUX_REFCOUNT_H - -#include -#include -#include -#include - -struct mutex; - -/** - * struct refcount_t - variant of atomic_t specialized for reference counts - * @refs: atomic_t counter field - * - * The counter saturates at REFCOUNT_SATURATED and will not move once - * there. This avoids wrapping the counter and causing 'spurious' - * use-after-free bugs. - */ -typedef struct refcount_struct { - atomic_t refs; -} refcount_t; - -#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), } -#define REFCOUNT_MAX INT_MAX -#define REFCOUNT_SATURATED (INT_MIN / 2) - -enum refcount_saturation_type { - REFCOUNT_ADD_NOT_ZERO_OVF, - REFCOUNT_ADD_OVF, - REFCOUNT_ADD_UAF, - REFCOUNT_SUB_UAF, - REFCOUNT_DEC_LEAK, -}; - -void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t); - -/** - * refcount_set - set a refcount's value - * @r: the refcount - * @n: value to which the refcount will be set - */ -static inline void refcount_set(refcount_t *r, int n) -{ - atomic_set(&r->refs, n); -} - -/** - * refcount_read - get a refcount's value - * @r: the refcount - * - * Return: the refcount's value - */ -static inline unsigned int refcount_read(const refcount_t *r) -{ - return atomic_read(&r->refs); -} - -#ifdef CONFIG_REFCOUNT_FULL -#include - /* * Variant of atomic_t specialized for reference counts. * @@ -136,6 +76,64 @@ static inline unsigned int refcount_read(const refcount_t *r) * */ +#ifndef _LINUX_REFCOUNT_H +#define _LINUX_REFCOUNT_H + +#include +#include +#include +#include +#include + +struct mutex; + +/** + * struct refcount_t - variant of atomic_t specialized for reference counts + * @refs: atomic_t counter field + * + * The counter saturates at REFCOUNT_SATURATED and will not move once + * there. This avoids wrapping the counter and causing 'spurious' + * use-after-free bugs. + */ +typedef struct refcount_struct { + atomic_t refs; +} refcount_t; + +#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), } +#define REFCOUNT_MAX INT_MAX +#define REFCOUNT_SATURATED (INT_MIN / 2) + +enum refcount_saturation_type { + REFCOUNT_ADD_NOT_ZERO_OVF, + REFCOUNT_ADD_OVF, + REFCOUNT_ADD_UAF, + REFCOUNT_SUB_UAF, + REFCOUNT_DEC_LEAK, +}; + +void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t); + +/** + * refcount_set - set a refcount's value + * @r: the refcount + * @n: value to which the refcount will be set + */ +static inline void refcount_set(refcount_t *r, int n) +{ + atomic_set(&r->refs, n); +} + +/** + * refcount_read - get a refcount's value + * @r: the refcount + * + * Return: the refcount's value + */ +static inline unsigned int refcount_read(const refcount_t *r) +{ + return atomic_read(&r->refs); +} + /** * refcount_add_not_zero - add a value to a refcount unless it is 0 * @i: the value to add to the refcount @@ -298,46 +296,6 @@ static inline void refcount_dec(refcount_t *r) if (unlikely(atomic_fetch_sub_release(1, &r->refs) <= 1)) refcount_warn_saturate(r, REFCOUNT_DEC_LEAK); } -#else /* CONFIG_REFCOUNT_FULL */ -# ifdef CONFIG_ARCH_HAS_REFCOUNT -# include -# else -static inline __must_check bool refcount_add_not_zero(int i, refcount_t *r) -{ - return atomic_add_unless(&r->refs, i, 0); -} - -static inline void refcount_add(int i, refcount_t *r) -{ - atomic_add(i, &r->refs); -} - -static inline __must_check bool refcount_inc_not_zero(refcount_t *r) -{ - return atomic_add_unless(&r->refs, 1, 0); -} - -static inline void refcount_inc(refcount_t *r) -{ - atomic_inc(&r->refs); -} - -static inline __must_check bool refcount_sub_and_test(int i, refcount_t *r) -{ - return atomic_sub_and_test(i, &r->refs); -} - -static inline __must_check bool refcount_dec_and_test(refcount_t *r) -{ - return atomic_dec_and_test(&r->refs); -} - -static inline void refcount_dec(refcount_t *r) -{ - atomic_dec(&r->refs); -} -# endif /* !CONFIG_ARCH_HAS_REFCOUNT */ -#endif /* !CONFIG_REFCOUNT_FULL */ extern __must_check bool refcount_dec_if_one(refcount_t *r); extern __must_check bool refcount_dec_not_one(refcount_t *r); diff --git a/lib/refcount.c b/lib/refcount.c index 8b7e249..ebac8b7 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Out-of-line refcount functions common to all refcount implementations. + * Out-of-line refcount functions. */ #include