KVM Archive on lore.kernel.org
 help / color / Atom feed
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
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

  reply index

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

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=201906240804.899CE7BE3@keescook \
    --to=keescook@chromium.org \
    --cc=Alexander.Deucher@amd.com \
    --cc=Christian.Koenig@amd.com \
    --cc=Dave.Martin@arm.com \
    --cc=Felix.Kuehling@amd.com \
    --cc=Jacob.Bramley@arm.com \
    --cc=Lee.Smith@arm.com \
    --cc=Ramana.Radhakrishnan@arm.com \
    --cc=Ruben.Ayrapetyan@arm.com \
    --cc=Szabolcs.Nagy@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=alex.williamson@redhat.com \
    --cc=amd-gfx@lists.freedesktop.org \
    --cc=andreyknvl@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=dvyukov@google.com \
    --cc=enh@google.com \
    --cc=eugenis@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@infradead.org \
    --cc=jens.wiklander@linaro.org \
    --cc=jgg@ziepe.ca \
    --cc=kcc@google.com \
    --cc=kevin.brodsky@arm.com \
    --cc=khalid.aziz@oracle.com \
    --cc=kvm@vger.kernel.org \
    --cc=leon@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=luc.vanoostenryck@gmail.com \
    --cc=mark.rutland@arm.com \
    --cc=mchehab@kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=vincenzo.frascino@arm.com \
    --cc=will.deacon@arm.com \
    --cc=yishaih@mellanox.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git