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s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=mEM9r2TrIcyS5QiUJ5WsI/WGUVLPWWhwkAU6Ibh3jIs=; b=an3gHxKb9aqFy6SnMUWFTHZHgshiUqblht88uf2+VslioNsdk6fSse0n+5T3utr1p1 uEXk/EQ9KZXlij5UoqVFiaRsitCyHFa6QuffeGTTwV09frKI5S3uu0azJMAxW0ibw/5X AQ4kxt5KgR7pBufFSE4t0xqzlvL+4edFxVlHKhG4uqgRB/lJixKC+Big3aLzfViBIIkC VbQab31qHB1njI8vAcfeNL+5O+OAMSiX9VivQrjHXvmzLLAV7Amc8SX86pTuMVbhUAiX ciFUiqDCoHkWf78VGHku++m7N0puAzOcmqGHvAFCEPaaxFsgy64Pg84C8aOlKUWOLvBY vsXQ== X-Gm-Message-State: APjAAAVU+DAB8jtAJaBhp0lFAWJ3/wHF9dYR/cJd1ZvXk+osC54Qumx+ JU+cV7gqMzbDOttNIkIrxZ2EbKW/8pJ1uWnLogxRGPExsscDePlkCaQ/PEBTxMpSf2MaMlrc4yN 0IReiUsPktZMr6NexYDw5OzZHE2+m+zd4OhnZZqpf+JzpbBgxQ1C3M8ADILDQDpUNXysM5wqRh1 bsBityC7gV0rVZYX8= X-Google-Smtp-Source: APXvYqzAUxNwopC91TOnVL5OWCCwX02ZC910lFa3yrWgPSH4oaNT26Uf7JNL1bImHscifmXrtCV+ZCB9Y2uf5vV7 X-Received: by 2002:a0c:8705:: with SMTP id 5mr54401806qvh.32.1563904752366; Tue, 23 Jul 2019 10:59:12 -0700 (PDT) Date: Tue, 23 Jul 2019 19:58:39 +0200 In-Reply-To: Message-Id: <1c05651c53f90d07e98ee4973c2786ccf315db12.1563904656.git.andreyknvl@google.com> Mime-Version: 1.0 References: X-Mailer: git-send-email 2.22.0.709.g102302147b-goog Subject: [PATCH v19 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI From: Andrey Konovalov To: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190723_105915_399939_6A96BF27 X-CRM114-Status: GOOD ( 22.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Szabolcs Nagy , Catalin Marinas , Will Deacon , Kostya Serebryany , Khalid Aziz , Felix Kuehling , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , Christoph Hellwig , Jason Gunthorpe , Dave Martin , Evgeniy Stepanov , Kevin Brodsky , Kees Cook , Ruben Ayrapetyan , Andrey Konovalov , Ramana Radhakrishnan , Alex Williamson , Mauro Carvalho Chehab , Dmitry Vyukov , Greg Kroah-Hartman , Yishai Hadas , Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Catalin Marinas It is not desirable to relax the ABI to allow tagged user addresses into the kernel indiscriminately. This patch introduces a prctl() interface for enabling or disabling the tagged ABI with a global sysctl control for preventing applications from enabling the relaxed ABI (meant for testing user-space prctl() return error checking without reconfiguring the kernel). The ABI properties are inherited by threads of the same application and fork()'ed children but cleared on execve(). A Kconfig option allows the overall disabling of the relaxed ABI. The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle MTE-specific settings like imprecise vs precise exceptions. Reviewed-by: Kees Cook Signed-off-by: Catalin Marinas Signed-off-by: Andrey Konovalov Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig | 9 ++++ arch/arm64/include/asm/processor.h | 8 +++ arch/arm64/include/asm/thread_info.h | 1 + arch/arm64/include/asm/uaccess.h | 4 +- arch/arm64/kernel/process.c | 73 ++++++++++++++++++++++++++++ include/uapi/linux/prctl.h | 5 ++ kernel/sys.c | 12 +++++ 7 files changed, 111 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3adcec05b1f6..5d254178b9ca 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1110,6 +1110,15 @@ config ARM64_SW_TTBR0_PAN zeroed area and reserved ASID. The user access routines restore the valid TTBR0_EL1 temporarily. +config ARM64_TAGGED_ADDR_ABI + bool "Enable the tagged user addresses syscall ABI" + default y + help + When this option is enabled, user applications can opt in to a + relaxed ABI via prctl() allowing tagged addresses to be passed + to system calls as pointer arguments. For details, see + Documentation/arm64/tagged-address-abi.txt. + menuconfig COMPAT bool "Kernel support for 32-bit EL0" depends on ARM64_4K_PAGES || EXPERT diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index fd5b1a4efc70..ee86070a28d4 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -296,6 +296,14 @@ extern void __init minsigstksz_setup(void); /* PR_PAC_RESET_KEYS prctl */ #define PAC_RESET_KEYS(tsk, arg) ptrauth_prctl_reset_keys(tsk, arg) +#ifdef CONFIG_ARM64_TAGGED_ADDR_ABI +/* PR_{SET,GET}_TAGGED_ADDR_CTRL prctl */ +long set_tagged_addr_ctrl(unsigned long arg); +long get_tagged_addr_ctrl(void); +#define SET_TAGGED_ADDR_CTRL(arg) set_tagged_addr_ctrl(arg) +#define GET_TAGGED_ADDR_CTRL() get_tagged_addr_ctrl() +#endif + /* * For CONFIG_GCC_PLUGIN_STACKLEAK * diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 180b34ec5965..012238d8e58d 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -90,6 +90,7 @@ void arch_release_task_struct(struct task_struct *tsk); #define TIF_SVE 23 /* Scalable Vector Extension in use */ #define TIF_SVE_VL_INHERIT 24 /* Inherit sve_vl_onexec across exec */ #define TIF_SSBD 25 /* Wants SSB mitigation */ +#define TIF_TAGGED_ADDR 26 /* Allow tagged user addresses */ #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index a138e3b4f717..097d6bfac0b7 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -62,7 +62,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si { unsigned long ret, limit = current_thread_info()->addr_limit; - addr = untagged_addr(addr); + if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI) && + test_thread_flag(TIF_TAGGED_ADDR)) + addr = untagged_addr(addr); __chk_user_ptr(addr); asm volatile( diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 6a869d9f304f..ef06a303bda0 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -38,6 +39,7 @@ #include #include #include +#include #include #include @@ -307,11 +309,18 @@ static void tls_thread_flush(void) } } +static void flush_tagged_addr_state(void) +{ + if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI)) + clear_thread_flag(TIF_TAGGED_ADDR); +} + void flush_thread(void) { fpsimd_flush_thread(); tls_thread_flush(); flush_ptrace_hw_breakpoint(current); + flush_tagged_addr_state(); } void release_thread(struct task_struct *dead_task) @@ -541,3 +550,67 @@ void arch_setup_new_exec(void) ptrauth_thread_init_user(current); } + +#ifdef CONFIG_ARM64_TAGGED_ADDR_ABI +/* + * Control the relaxed ABI allowing tagged user addresses into the kernel. + */ +static unsigned int tagged_addr_prctl_allowed = 1; + +long set_tagged_addr_ctrl(unsigned long arg) +{ + if (!tagged_addr_prctl_allowed) + return -EINVAL; + if (is_compat_task()) + return -EINVAL; + if (arg & ~PR_TAGGED_ADDR_ENABLE) + return -EINVAL; + + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); + + return 0; +} + +long get_tagged_addr_ctrl(void) +{ + if (!tagged_addr_prctl_allowed) + return -EINVAL; + if (is_compat_task()) + return -EINVAL; + + if (test_thread_flag(TIF_TAGGED_ADDR)) + return PR_TAGGED_ADDR_ENABLE; + + return 0; +} + +/* + * Global sysctl to disable the tagged user addresses support. This control + * only prevents the tagged address ABI enabling via prctl() and does not + * disable it for tasks that already opted in to the relaxed ABI. + */ +static int zero; +static int one = 1; + +static struct ctl_table tagged_addr_sysctl_table[] = { + { + .procname = "tagged_addr", + .mode = 0644, + .data = &tagged_addr_prctl_allowed, + .maxlen = sizeof(int), + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, + { } +}; + +static int __init tagged_addr_init(void) +{ + if (!register_sysctl("abi", tagged_addr_sysctl_table)) + return -EINVAL; + return 0; +} + +core_initcall(tagged_addr_init); +#endif /* CONFIG_ARM64_TAGGED_ADDR_ABI */ diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 094bb03b9cc2..2e927b3e9d6c 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -229,4 +229,9 @@ struct prctl_mm_map { # define PR_PAC_APDBKEY (1UL << 3) # define PR_PAC_APGAKEY (1UL << 4) +/* Tagged user address controls for arm64 */ +#define PR_SET_TAGGED_ADDR_CTRL 55 +#define PR_GET_TAGGED_ADDR_CTRL 56 +# define PR_TAGGED_ADDR_ENABLE (1UL << 0) + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index 2969304c29fe..c6c4d5358bd3 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -124,6 +124,12 @@ #ifndef PAC_RESET_KEYS # define PAC_RESET_KEYS(a, b) (-EINVAL) #endif +#ifndef SET_TAGGED_ADDR_CTRL +# define SET_TAGGED_ADDR_CTRL(a) (-EINVAL) +#endif +#ifndef GET_TAGGED_ADDR_CTRL +# define GET_TAGGED_ADDR_CTRL() (-EINVAL) +#endif /* * this is where the system-wide overflow UID and GID are defined, for @@ -2492,6 +2498,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, return -EINVAL; error = PAC_RESET_KEYS(me, arg2); break; + case PR_SET_TAGGED_ADDR_CTRL: + error = SET_TAGGED_ADDR_CTRL(arg2); + break; + case PR_GET_TAGGED_ADDR_CTRL: + error = GET_TAGGED_ADDR_CTRL(); + break; default: error = -EINVAL; break;