From: Dave Hansen <dave.hansen@intel.com>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
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linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
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Balbir Singh <bsingharora@gmail.com>,
Borislav Petkov <bp@alien8.de>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
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Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
Haitao Huang <haitao.huang@intel.com>,
Rick P Edgecombe <rick.p.edgecombe@intel.com>
Subject: Re: [PATCH v28 25/32] x86/cet/shstk: Handle thread shadow stack
Date: Thu, 22 Jul 2021 14:05:29 -0700 [thread overview]
Message-ID: <9b5eb1a8-fc75-d1e4-36c4-e83ab0ce682b@intel.com> (raw)
In-Reply-To: <20210722205219.7934-26-yu-cheng.yu@intel.com>
On 7/22/21 1:52 PM, Yu-cheng Yu wrote:
> + if (!stack_size)
> + stack_size = min_t(unsigned long long, rlimit(RLIMIT_STACK), SZ_4G);
> +
> + if (!shstk->size)
> + return 0;
> +
> + /*
> + * For CLONE_VM, except vfork, the child needs a separate shadow
> + * stack.
> + */
> + if ((clone_flags & (CLONE_VFORK | CLONE_VM)) != CLONE_VM)
> + return 0;
> +
> + /*
> + * This is in clone() syscall and fpu__copy() already copies xstates
> + * from the parent. If get_xsave_addr() returns null, then XFEATURE_
> + * CET_USER is still in init state, which certainly is an error.
> + */
> + state = get_xsave_addr(&tsk->thread.fpu.state.xsave, XFEATURE_CET_USER);
> + if (!state)
> + return -EINVAL;
I don't care much for that comment.
This code is meant to copy shadow stack config information into children
when it is already enabled. We *just* checked for that above in the
"shstk->size" check. The fact that this is called from clone() is
irrelevant. The shadow stack enabling status *is*.
I think I'd rather this be more along the lines of:
/*
* 'tsk' is configured with a shadow stack and the fpu.state is
* up to date since it was just copied from the parent. There
* must be a valid non-init CET state location in the buffer.
*/
There is also a strong enough assumption violation that I'd probably
WARN() in addition to returning -EINVAL.
next prev parent reply other threads:[~2021-07-22 21:05 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 20:51 [PATCH v28 00/32] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 01/32] Documentation/x86: Add CET description Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 02/32] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 03/32] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 04/32] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-08-09 16:06 ` Borislav Petkov
2021-08-10 15:39 ` Yu, Yu-cheng
2021-08-10 16:51 ` Borislav Petkov
2021-07-22 20:51 ` [PATCH v28 05/32] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-08-09 16:46 ` Borislav Petkov
2021-08-10 15:50 ` Yu, Yu-cheng
2021-07-22 20:51 ` [PATCH v28 06/32] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-08-09 17:51 ` Borislav Petkov
2021-08-10 16:06 ` Yu, Yu-cheng
2021-07-22 20:51 ` [PATCH v28 07/32] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 08/32] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-08-09 18:02 ` Borislav Petkov
2021-07-22 20:51 ` [PATCH v28 09/32] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-08-16 10:43 ` Borislav Petkov
2021-08-17 18:24 ` Yu, Yu-cheng
2021-08-17 19:54 ` Borislav Petkov
2021-08-17 20:13 ` Andy Lutomirski
2021-08-17 20:24 ` Borislav Petkov
2021-08-17 20:51 ` Andy Lutomirski
2021-08-17 21:01 ` Borislav Petkov
2021-08-18 16:38 ` Yu, Yu-cheng
2021-08-21 16:27 ` Borislav Petkov
2021-07-22 20:51 ` [PATCH v28 10/32] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 11/32] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-07-22 20:51 ` [PATCH v28 12/32] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-08-16 16:01 ` Borislav Petkov
2021-08-17 18:33 ` Yu, Yu-cheng
2021-07-22 20:52 ` [PATCH v28 13/32] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 14/32] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-08-16 16:35 ` Borislav Petkov
2021-08-17 18:35 ` Yu, Yu-cheng
2021-07-22 20:52 ` [PATCH v28 15/32] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 16/32] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-08-16 17:03 ` Borislav Petkov
2021-08-17 18:36 ` Yu, Yu-cheng
2021-07-22 20:52 ` [PATCH v28 17/32] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 18/32] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 19/32] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 20/32] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 21/32] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 22/32] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 23/32] x86/cet/shstk: Add user-mode shadow stack support Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 24/32] x86/process: Change copy_thread() argument 'arg' to 'stack_size' Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 25/32] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-07-22 21:05 ` Dave Hansen [this message]
2021-07-23 17:30 ` Yu, Yu-cheng
2021-07-22 20:52 ` [PATCH v28 26/32] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-07-22 21:15 ` Dave Hansen
2021-07-23 18:01 ` Yu, Yu-cheng
2021-07-22 20:52 ` [PATCH v28 27/32] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 28/32] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 29/32] x86/cet/shstk: Add arch_prctl functions for shadow stack Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 30/32] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 31/32] mm: Update arch_validate_flags() to test vma anonymous Yu-cheng Yu
2021-07-22 20:52 ` [PATCH v28 32/32] mm: Introduce PROT_SHADOW_STACK for shadow stack Yu-cheng Yu
2021-07-22 21:08 ` [PATCH v28 00/32] Control-flow Enforcement: Shadow Stack Dave Hansen
2021-07-23 17:28 ` Yu, Yu-cheng
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