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bh=8M3tlnbS9Pz471dSvOzN4aKK6qk+Uej9KAtfSfq3hVM=; b=AoiltTMvFbe/f/ypMXgOnhHwt+phRCl8mXS5lx3DkxlOxvdf31/yUuFf6amM69Bov1xqnP 44Md0Q+v9X6VCHe229Cfao5EsmCUhy/O+5uqW3SelHzpFRnaj/yN+ErabZpQAMGomc7Rfb noGKmIIfKLYOoiyBdkJwLQWaY5b+Os8= Date: Tue, 28 Feb 2023 11:58:25 +0100 From: Borislav Petkov To: "Edgecombe, Rick P" Cc: "david@redhat.com" , "bsingharora@gmail.com" , "hpa@zytor.com" , "Syromiatnikov, Eugene" , "peterz@infradead.org" , "rdunlap@infradead.org" , "keescook@chromium.org" , "dave.hansen@linux.intel.com" , "kirill.shutemov@linux.intel.com" , "Eranian, Stephane" , "linux-mm@kvack.org" , "fweimer@redhat.com" , "nadav.amit@gmail.com" , "jannh@google.com" , "dethoma@microsoft.com" , "kcc@google.com" , "linux-arch@vger.kernel.org" , "pavel@ucw.cz" , "oleg@redhat.com" , "hjl.tools@gmail.com" , "Yang, Weijiang" , "Lutomirski, Andy" , "linux-doc@vger.kernel.org" , "arnd@arndb.de" , "tglx@linutronix.de" , "Schimpe, Christina" , "mike.kravetz@oracle.com" , "x86@kernel.org" , "akpm@linux-foundation.org" , "debug@rivosinc.com" , "jamorris@linux.microsoft.com" , "john.allen@amd.com" , "rppt@kernel.org" , "andrew.cooper3@citrix.com" , "mingo@redhat.com" , "corbet@lwn.net" , "linux-kernel@vger.kernel.org" , "linux-api@vger.kernel.org" , "gorcunov@gmail.com" Subject: Re: [PATCH v6 28/41] x86: Introduce userspace API for shadow stack Message-ID: References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-29-rick.p.edgecombe@intel.com> <9c67abd16cce9251bfdb87bcc7e47bbf32e4a9f2.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <9c67abd16cce9251bfdb87bcc7e47bbf32e4a9f2.camel@intel.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C29E818001D X-Stat-Signature: pjo7f9e5iys94q7mqgkbh5r7tiiepzzm X-HE-Tag: 1677582394-407737 X-HE-Meta: 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 1omXzlOo c2hxeAV6j2BBm2U4DOxc8iJGCHdj+Bzi8HeEHcYvhQQ8vEXGnIXF+1ZALv5r1rHveF15HLM4Eimh39RzM5oyMPRfxveFMQQWWI3LzVhpi1LfnDKioqrw972NL6FOaOqYmY0e4sYrUnCCZ2NlG6YczYCgufNuxNxqG85UqmbEcMu0jozSeviqs9gZi/hwdbzSTUODPjafYLpexRszQ1236jVgw39eP8oWmhD/8DbK47s/ZJbMIy3usR17bt2Aewu6qr50SovYKAqT8l+3L8ZlRCvi79Z9S/A24JHMkVEuP18EB5xxqRgd1LIu9DTdy1FAOoC3QydqtztLw4dGno5TvsVrCiQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Feb 24, 2023 at 06:37:57PM +0000, Edgecombe, Rick P wrote: > In the first patch: > > https://lore.kernel.org/lkml/20230218211433.26859-2-rick.p.edgecombe@intel.com/ > > Then some more documentation is added about ARCH_SHSTK_UNLOCK and > ARCH_SHSTK_STATUS (which are for CRIU) in those patches. Right, I was thinking more about ARCH_PRCTL(2), the man page. But you can send that to the manpages folks later. I.e., it should be nearly impossible to be missed. :) > There are glibc patches prepared by HJ to use the new interface and > it's my understanding that he has discussed the changes with the other > glibc folks. Those glibc patches are used for testing these kernel > patches, but will not get upstream until the kernel patches to avoid > repeating the past problems. So I think it's as prepared as it can be. Good. > One future thing that might come up... Glibc has this mode called > "permissive mode". When glibc is configured this way (compile time or > env var), it is supposed to disable shadow stack when dlopen()ing any > DSO that doesn't have the shadow stack elf header bit. Maybe I don't understand all the possible use cases but if I were interested in using shadow stack, then I'd enable it for all objects. And if I want permissive, I'd disable it for all. A mixed thing sounds like a mixed can of worms waiting to be opened. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette