From: Kees Cook <keescook@chromium.org>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: 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,
Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will.deacon@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Yishai Hadas <yishaih@mellanox.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Alexander Deucher <Alexander.Deucher@amd.com>,
Christian Koenig <Christian.Koenig@amd.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Jens Wiklander <jens.wiklander@linaro.org>,
Alex Williamson <alex.williamson@redhat.com>,
Leon Romanovsky <leon@kernel.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Dave Martin <Dave.Martin@arm.com>,
Khalid Aziz <khalid.aziz@oracle.com>, enh <enh@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Christoph Hellwig <hch@infradead.org>,
Dmitry Vyukov <dvyukov@google.com>,
Kostya Serebryany <kcc@google.com>,
Evgeniy Stepanov <eugenis@google.com>,
Lee Smith <Lee.Smith@arm.com>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
Jacob Bramley <Jacob.Bramley@arm.com>,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Subject: Re: [PATCH v18 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI
Date: Mon, 24 Jun 2019 08:04:10 -0700 [thread overview]
Message-ID: <201906240804.899CE7BE3@keescook> (raw)
In-Reply-To: <653598b3cfcd80f0cc69f72a214e156bb1afde68.1561386715.git.andreyknvl@google.com>
On Mon, Jun 24, 2019 at 04:32:47PM +0200, Andrey Konovalov wrote:
> From: Catalin Marinas <catalin.marinas@arm.com>
>
> 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.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> 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 | 72 ++++++++++++++++++++++++++++
> include/uapi/linux/prctl.h | 5 ++
> kernel/sys.c | 12 +++++
> 7 files changed, 110 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 697ea0510729..55fbaf20af2d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1107,6 +1107,15 @@ 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 2372e97db29c..4f81c4f15404 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -88,6 +88,7 @@ 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 9856395ccdb7..60e70158a4a1 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -19,6 +19,7 @@
> #include <linux/kernel.h>
> #include <linux/mm.h>
> #include <linux/stddef.h>
> +#include <linux/sysctl.h>
> #include <linux/unistd.h>
> #include <linux/user.h>
> #include <linux/delay.h>
> @@ -307,11 +308,18 @@ 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 +549,67 @@ 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;
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
--
Kees Cook
next prev parent reply other threads:[~2019-06-24 15:04 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 14:32 [PATCH v18 00/15] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 01/15] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Andrey Konovalov
2019-06-24 15:04 ` Kees Cook [this message]
2019-06-24 14:32 ` [PATCH v18 03/15] lib: untag user pointers in strn*_user Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 04/15] mm: untag user pointers passed to memory syscalls Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 05/15] mm: untag user pointers in mm/gup.c Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 06/15] mm: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 07/15] fs/namespace: untag user pointers in copy_mount_options Andrey Konovalov
2019-06-24 17:50 ` Catalin Marinas
2019-07-15 16:00 ` Andrey Konovalov
2019-07-22 16:46 ` Kees Cook
2019-06-24 14:32 ` [PATCH v18 08/15] userfaultfd: untag user pointers Andrey Konovalov
2019-06-24 17:51 ` Catalin Marinas
2019-07-15 16:00 ` Andrey Konovalov
2019-07-17 11:09 ` Mike Rapoport
2019-07-17 11:46 ` Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 09/15] drm/amdgpu: " Andrey Konovalov
2019-06-24 15:00 ` Kees Cook
2019-06-24 14:32 ` [PATCH v18 10/15] drm/radeon: untag user pointers in radeon_gem_userptr_ioctl Andrey Konovalov
2019-06-24 15:01 ` Kees Cook
2019-06-24 15:02 ` Kees Cook
2019-06-26 17:50 ` Khalid Aziz
2019-06-24 14:32 ` [PATCH v18 11/15] IB/mlx4: untag user pointers in mlx4_get_umem_mr Andrey Konovalov
2019-06-24 15:01 ` Kees Cook
2019-06-24 17:40 ` Catalin Marinas
2019-07-15 16:01 ` Andrey Konovalov
2019-07-15 18:05 ` Jason Gunthorpe
2019-07-16 10:42 ` Andrey Konovalov
2019-07-16 12:06 ` Jason Gunthorpe
2019-07-17 11:42 ` Andrey Konovalov
2019-07-17 11:44 ` Andrey Konovalov
2019-07-17 11:58 ` Jason Gunthorpe
2019-07-17 13:36 ` Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 12/15] media/v4l2-core: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 13/15] tee/shm: untag user pointers in tee_shm_register Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 14/15] vfio/type1: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-06-24 14:33 ` [PATCH v18 15/15] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2019-06-24 15:02 ` Kees Cook
2019-06-24 17:38 ` Catalin Marinas
2019-08-23 13:56 ` Cristian Marussi
2019-08-23 17:16 ` Andrey Konovalov
2019-08-23 17:49 ` Cristian Marussi
2019-09-04 14:52 ` Andrey Konovalov
2019-09-04 16:22 ` Cristian Marussi
2019-09-04 16:42 ` Andrey Konovalov
2019-06-26 17:18 ` [PATCH v18 00/15] arm64: untag user pointers passed to the kernel Catalin Marinas
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