From: Kevin Brodsky <kevin.brodsky@arm.com>
To: "Andrey Konovalov" <andreyknvl@google.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will.deacon@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Kees Cook" <keescook@chromium.org>,
"Kate Stewart" <kstewart@linuxfoundation.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Ingo Molnar" <mingo@kernel.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Shuah Khan" <shuah@kernel.org>,
"Vincenzo Frascino" <vincenzo.frascino@arm.com>,
"Eric Dumazet" <edumazet@google.com>,
"David S. Miller" <davem@davemloft.net>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Arnaldo Carvalho de Melo" <acme@kernel.org>,
"Alex Deucher" <alexander.deucher@amd.com>,
"Christian König" <christian.koenig@amd.com>,
"David (ChunMing) Zhou" <David1.Zhou@amd.com>,
"Yishai Hadas" <yishaih@mellanox.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Jens Wiklander" <jens.wiklander@linaro.org>,
"Alex Williamson" <alex.williamson@redhat.com>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, netdev@vger.kernel.org,
bpf@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, linux-kernel@vger.kernel.org
Cc: 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>,
Chintan Pandya <cpandya@codeaurora.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Dave Martin <Dave.Martin@arm.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Subject: Re: [PATCH v13 10/20] kernel, arm64: untag user pointers in prctl_set_mm*
Date: Thu, 21 Mar 2019 17:52:37 +0000 [thread overview]
Message-ID: <c5b9f421-0dd8-d56f-c591-0c841cbdfe3b@arm.com> (raw)
In-Reply-To: <76f96eb9162b3a7fa5949d71af38bf8fdf6924c4.1553093421.git.andreyknvl@google.com>
On 20/03/2019 14:51, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> prctl_set_mm() and prctl_set_mm_map() use provided user pointers for vma
> lookups and do some pointer comparisons to perform validation, which can
> only by done with untagged pointers.
>
> Untag user pointers in these functions for vma lookup and validity checks.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> kernel/sys.c | 44 ++++++++++++++++++++++++++++++--------------
> 1 file changed, 30 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 12df0e5434b8..fe26ccf3c9e6 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1885,11 +1885,12 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
> * WARNING: we don't require any capability here so be very careful
> * in what is allowed for modification from userspace.
> */
> -static int validate_prctl_map(struct prctl_mm_map *prctl_map)
> +static int validate_prctl_map(struct prctl_mm_map *tagged_prctl_map)
> {
> unsigned long mmap_max_addr = TASK_SIZE;
> struct mm_struct *mm = current->mm;
> int error = -EINVAL, i;
> + struct prctl_mm_map prctl_map;
>
> static const unsigned char offsets[] = {
> offsetof(struct prctl_mm_map, start_code),
> @@ -1905,12 +1906,25 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map)
> offsetof(struct prctl_mm_map, env_end),
> };
>
> + memcpy(&prctl_map, tagged_prctl_map, sizeof(prctl_map));
> + prctl_map.start_code = untagged_addr(prctl_map.start_code);
> + prctl_map.end_code = untagged_addr(prctl_map.end_code);
> + prctl_map.start_data = untagged_addr(prctl_map.start_data);
> + prctl_map.end_data = untagged_addr(prctl_map.end_data);
> + prctl_map.start_brk = untagged_addr(prctl_map.start_brk);
> + prctl_map.brk = untagged_addr(prctl_map.brk);
> + prctl_map.start_stack = untagged_addr(prctl_map.start_stack);
> + prctl_map.arg_start = untagged_addr(prctl_map.arg_start);
> + prctl_map.arg_end = untagged_addr(prctl_map.arg_end);
> + prctl_map.env_start = untagged_addr(prctl_map.env_start);
> + prctl_map.env_end = untagged_addr(prctl_map.env_end);
> +
> /*
> * Make sure the members are not somewhere outside
> * of allowed address space.
> */
> for (i = 0; i < ARRAY_SIZE(offsets); i++) {
> - u64 val = *(u64 *)((char *)prctl_map + offsets[i]);
> + u64 val = *(u64 *)((char *)&prctl_map + offsets[i]);
>
> if ((unsigned long)val >= mmap_max_addr ||
> (unsigned long)val < mmap_min_addr)
> @@ -1921,8 +1935,8 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map)
> * Make sure the pairs are ordered.
> */
> #define __prctl_check_order(__m1, __op, __m2) \
> - ((unsigned long)prctl_map->__m1 __op \
> - (unsigned long)prctl_map->__m2) ? 0 : -EINVAL
> + ((unsigned long)prctl_map.__m1 __op \
> + (unsigned long)prctl_map.__m2) ? 0 : -EINVAL
> error = __prctl_check_order(start_code, <, end_code);
> error |= __prctl_check_order(start_data, <, end_data);
> error |= __prctl_check_order(start_brk, <=, brk);
> @@ -1937,23 +1951,24 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map)
> /*
> * @brk should be after @end_data in traditional maps.
> */
> - if (prctl_map->start_brk <= prctl_map->end_data ||
> - prctl_map->brk <= prctl_map->end_data)
> + if (prctl_map.start_brk <= prctl_map.end_data ||
> + prctl_map.brk <= prctl_map.end_data)
> goto out;
>
> /*
> * Neither we should allow to override limits if they set.
> */
> - if (check_data_rlimit(rlimit(RLIMIT_DATA), prctl_map->brk,
> - prctl_map->start_brk, prctl_map->end_data,
> - prctl_map->start_data))
> + if (check_data_rlimit(rlimit(RLIMIT_DATA), prctl_map.brk,
> + prctl_map.start_brk, prctl_map.end_data,
> + prctl_map.start_data))
> goto out;
>
> /*
> * Someone is trying to cheat the auxv vector.
> */
> - if (prctl_map->auxv_size) {
> - if (!prctl_map->auxv || prctl_map->auxv_size > sizeof(mm->saved_auxv))
> + if (prctl_map.auxv_size) {
> + if (!prctl_map.auxv || prctl_map.auxv_size >
> + sizeof(mm->saved_auxv))
> goto out;
> }
>
> @@ -1962,7 +1977,7 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map)
> * change /proc/pid/exe link: only local sys admin should
> * be allowed to.
> */
> - if (prctl_map->exe_fd != (u32)-1) {
> + if (prctl_map.exe_fd != (u32)-1) {
> if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
> goto out;
> }
> @@ -2120,13 +2135,14 @@ static int prctl_set_mm(int opt, unsigned long addr,
> if (opt == PR_SET_MM_AUXV)
> return prctl_set_auxv(mm, addr, arg4);
>
> - if (addr >= TASK_SIZE || addr < mmap_min_addr)
> + if (untagged_addr(addr) >= TASK_SIZE ||
> + untagged_addr(addr) < mmap_min_addr)
> return -EINVAL;
>
> error = -EINVAL;
>
> down_write(&mm->mmap_sem);
> - vma = find_vma(mm, addr);
> + vma = find_vma(mm, untagged_addr(addr));
>
> prctl_map.start_code = mm->start_code;
> prctl_map.end_code = mm->end_code;
I think this new version is consistent w.r.t. tagged/untagged pointer usage. However,
I also note that a significant change has been introduced: it is now possible to set
MM fields to tagged addresses (tags are ignored by validate_prctl_map()). I am not
opposed to this as such, but have you considered the implications? Does it make sense
to have a tagged value for e.g. prctl_map.arg_start? Is the kernel able to handle
tagged values in those fields? I have the feeling that it's safer to discard tags for
now, and if necessary allow them to be preserved later on.
Kevin
next prev parent reply other threads:[~2019-03-21 17:52 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 14:51 [PATCH v13 00/20] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 01/20] uaccess: add untagged_addr definition for other arches Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 02/20] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 03/20] lib, arm64: untag user pointers in strn*_user Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 04/20] mm, arm64: untag user pointers passed to memory syscalls Andrey Konovalov
2019-03-22 11:43 ` Catalin Marinas
2019-03-28 18:10 ` Andrey Konovalov
2019-03-28 18:19 ` Steven Rostedt
2019-03-29 10:30 ` Catalin Marinas
2019-04-02 12:47 ` Andrey Konovalov
2019-04-11 16:40 ` Andrey Konovalov
2019-04-26 14:17 ` Catalin Marinas
2019-04-29 14:22 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 05/20] mm, arm64: untag user pointers in mm/gup.c Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 06/20] mm, arm64: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 07/20] fs, arm64: untag user pointers in copy_mount_options Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 08/20] fs, arm64: untag user pointers in fs/userfaultfd.c Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 09/20] net, arm64: untag user pointers in tcp_zerocopy_receive Andrey Konovalov
2019-03-22 12:04 ` Catalin Marinas
2019-03-25 13:54 ` Kevin Brodsky
2019-04-01 16:04 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 10/20] kernel, arm64: untag user pointers in prctl_set_mm* Andrey Konovalov
2019-03-21 17:52 ` Kevin Brodsky [this message]
2019-03-22 15:41 ` Catalin Marinas
2019-04-01 16:44 ` Andrey Konovalov
2019-04-11 16:40 ` Andrey Konovalov
2019-04-26 14:50 ` Catalin Marinas
2019-04-29 14:23 ` Andrey Konovalov
2019-05-01 14:43 ` Vincenzo Frascino
2019-03-20 14:51 ` [PATCH v13 11/20] tracing, arm64: untag user pointers in seq_print_user_ip Andrey Konovalov
2019-03-22 15:45 ` Catalin Marinas
2019-04-01 15:38 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 12/20] uprobes, arm64: untag user pointers in find_active_uprobe Andrey Konovalov
2019-03-22 15:46 ` Catalin Marinas
2019-03-20 14:51 ` [PATCH v13 13/20] bpf, arm64: untag user pointers in stack_map_get_build_id_offset Andrey Konovalov
2019-03-22 15:52 ` Catalin Marinas
2019-04-01 16:00 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 14/20] drm/amdgpu, arm64: untag user pointers in amdgpu_ttm_tt_get_user_pages Andrey Konovalov
2019-03-22 15:59 ` Catalin Marinas
2019-03-25 14:02 ` Kevin Brodsky
2019-03-25 22:21 ` Kuehling, Felix
2019-04-02 14:37 ` Andrey Konovalov
2019-04-02 17:52 ` Kuehling, Felix
2019-03-20 14:51 ` [PATCH v13 15/20] drm/radeon, arm64: untag user pointers in radeon_ttm_tt_pin_userptr Andrey Konovalov
2019-03-22 16:00 ` Catalin Marinas
2019-04-02 14:17 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 16/20] IB/mlx4, arm64: untag user pointers in mlx4_get_umem_mr Andrey Konovalov
2019-04-29 18:09 ` Leon Romanovsky
2019-04-30 11:16 ` Catalin Marinas
2019-04-30 12:03 ` Leon Romanovsky
2019-05-02 18:44 ` Jason Gunthorpe
2019-05-03 16:28 ` Catalin Marinas
2019-05-03 23:52 ` Jason Gunthorpe
2019-03-20 14:51 ` [PATCH v13 17/20] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-03-22 16:07 ` Catalin Marinas
2019-03-25 14:08 ` Kevin Brodsky
2019-04-01 16:13 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 18/20] tee/optee, arm64: untag user pointers in check_mem_type Andrey Konovalov
2019-03-22 16:22 ` Catalin Marinas
2019-04-01 16:31 ` Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 19/20] vfio/type1, arm64: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-03-20 14:51 ` [PATCH v13 20/20] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
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