From: Florian Weimer <fweimer@redhat.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>,
linux-arch <linux-arch@vger.kernel.org>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
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>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
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Nadav Amit <nadav.amit@gmail.com>,
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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>
Subject: Re: extending ucontext (Re: [PATCH v26 25/30] x86/cet/shstk: Handle signals for shadow stack)
Date: Fri, 30 Apr 2021 08:45:40 +0200 [thread overview]
Message-ID: <87a6pgb78r.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <CALCETrVTeYfzO-XWh+VwTuKCyPyp-oOMGH=QR_msG9tPQ4xPmA@mail.gmail.com> (Andy Lutomirski's message of "Wed, 28 Apr 2021 16:03:55 -0700")
* Andy Lutomirski:
> The kernel has:
>
> struct rt_sigframe {
> char __user *pretcode;
> struct ucontext uc;
> struct siginfo info;
> /* fp state follows here */
> };
>
> This is roughly the actual signal frame. But userspace does not have
> this struct declared, and user code does not know the sizes of the
> fields. So it's accessed in a nonsensical way. The signal handler
> function is passed a pointer to the whole sigframe implicitly in RSP,
> a pointer to &frame->info in RSI, anda pointer to &frame->uc in RDX.
> User code can *find* the fp state by following a pointer from
> mcontext, which is, in turn, found via uc:
>
> struct ucontext {
> unsigned long uc_flags;
> struct ucontext *uc_link;
> stack_t uc_stack;
> struct sigcontext uc_mcontext; <-- fp pointer is in here
> sigset_t uc_sigmask; /* mask last for extensibility */
> };
I must say that I haven't reviewed this in detail, but for historic
reasons, glibc userspace has a differently-sized sigset_t. So the
kernel ucontext (used in signals) and user ucontext (used for
swapcontext et al.) are already fully decoupled?
Thanks,
Florian
next prev parent reply other threads:[~2021-04-30 6:45 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 20:42 [PATCH v26 00/30] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 01/30] Documentation/x86: Add CET description Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 02/30] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 03/30] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 04/30] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 05/30] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 06/30] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 07/30] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 08/30] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 09/30] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 10/30] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 11/30] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 12/30] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 13/30] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-04-27 20:42 ` [PATCH v26 14/30] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 15/30] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 16/30] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 17/30] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 18/30] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 19/30] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 20/30] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 21/30] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 22/30] x86/cet/shstk: Add user-mode shadow stack support Yu-cheng Yu
2021-04-28 17:52 ` Borislav Petkov
2021-04-28 18:39 ` Yu, Yu-cheng
2021-04-29 9:12 ` Borislav Petkov
2021-04-29 16:17 ` Yu, Yu-cheng
2021-04-29 16:45 ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 23/30] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-05-10 14:15 ` Borislav Petkov
2021-05-10 22:57 ` Yu, Yu-cheng
2021-05-11 17:09 ` Borislav Petkov
2021-05-12 8:12 ` David Laight
2021-05-11 18:35 ` Yu, Yu-cheng
2021-05-12 15:56 ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 24/30] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-05-17 7:45 ` Borislav Petkov
2021-05-17 20:55 ` Yu, Yu-cheng
2021-05-18 0:14 ` Eugene Syromiatnikov
2021-05-18 17:58 ` Borislav Petkov
2021-05-18 19:45 ` Yu, Yu-cheng
2021-05-18 18:05 ` Yu, Yu-cheng
2021-05-18 5:56 ` Borislav Petkov
2021-05-21 16:17 ` Yu, Yu-cheng
2021-05-21 18:40 ` Borislav Petkov
2021-04-27 20:43 ` [PATCH v26 25/30] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-04-28 23:03 ` extending ucontext (Re: [PATCH v26 25/30] x86/cet/shstk: Handle signals for shadow stack) Andy Lutomirski
2021-04-28 23:20 ` Yu, Yu-cheng
2021-04-29 7:28 ` Cyrill Gorcunov
2021-04-29 14:44 ` Andy Lutomirski
2021-04-29 15:35 ` Cyrill Gorcunov
2021-04-30 6:45 ` Florian Weimer [this message]
2021-04-30 17:00 ` Yu, Yu-cheng
2021-04-30 17:47 ` Andy Lutomirski
2021-04-30 18:32 ` Yu, Yu-cheng
2021-05-04 20:49 ` Yu, Yu-cheng
2021-05-06 22:05 ` Yu, Yu-cheng
2021-05-06 23:31 ` Andy Lutomirski
2021-05-02 23:23 ` Andy Lutomirski
2021-05-03 6:03 ` H. Peter Anvin
2021-05-03 15:13 ` Yu, Yu-cheng
2021-05-03 15:29 ` Andy Lutomirski
2021-05-03 20:25 ` Yu, Yu-cheng
2021-04-27 20:43 ` [PATCH v26 26/30] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-05-19 18:10 ` Borislav Petkov
2021-05-19 22:14 ` Yu, Yu-cheng
2021-05-20 9:26 ` Borislav Petkov
2021-05-20 17:18 ` Yu, Yu-cheng
2021-05-20 17:35 ` Borislav Petkov
2021-05-20 17:51 ` Yu, Yu-cheng
2021-05-20 17:38 ` Matthew Wilcox
2021-05-20 17:52 ` Yu, Yu-cheng
2021-05-20 21:06 ` Yu, Yu-cheng
2021-04-27 20:43 ` [PATCH v26 27/30] x86/cet/shstk: Add arch_prctl functions for shadow stack Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 28/30] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-04-27 20:43 ` [PATCH v26 29/30] mm: Update arch_validate_flags() to test vma anonymous Yu-cheng Yu
2021-05-11 11:35 ` Kirill A. Shutemov
2021-04-27 20:43 ` [PATCH v26 30/30] mm: Introduce PROT_SHADOW_STACK for shadow stack Yu-cheng Yu
2021-05-11 11:48 ` Kirill A. Shutemov
2021-05-11 14:44 ` Yu, Yu-cheng
2021-04-29 17:13 ` [PATCH v26 00/30] Control-flow Enforcement: Shadow Stack Borislav Petkov
2021-04-29 17:32 ` Yu, Yu-cheng
2021-04-29 17:49 ` Borislav Petkov
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