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Edgecombe" , Ard Biesheuvel , Szabolcs Nagy , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v7 02/39] prctl: arch-agnostic prctl for shadow stack Message-ID: References: <20231122-arm64-gcs-v7-0-201c483bd775@kernel.org> <20231122-arm64-gcs-v7-2-201c483bd775@kernel.org> <0d0d8802-09e3-4ea5-a0b4-b3a08c8a282e@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="PqL9xaSuINxjZ0qj" Content-Disposition: inline In-Reply-To: X-Cookie: One size fits all. X-Rspamd-Queue-Id: 98A5810001B X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 5nqbt7mkmiccry9uyd7jnqutjcu9tmyo X-HE-Tag: 1702496923-103976 X-HE-Meta: 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 mT4PJm6l ODP5TG2qXbN7rTaw8ZP1my3T0kGPX59MyAhoW/WRhpY+04Sohl+7acKCHRrIiIvW3Rd/AyZY16nHFynfaKjO5bHUEYoPi7imhk2bGdiz0ZdewffQZzxsbz1OERVAFQSH6ZHEUYpGDjjYwPD7pFUWBlq0Tnt1xwKNfAhiLWXrYz7dUCwa0Imnx/1QhMwRMi7FDlJZi70p6hySFBTMB6eQZnbckLTwV4C0fZQ1sGz3etJUrr5lvwhOjJ7fzhomA6T5Ket4yYyUE4UYHxtGji61c/OC0lg93TMnjkmrWiHwkYXCei4oIbmJ/d4j51wP6KtuAHHklek3KujMNzgDjiFgfMNwMUIVx7DiqcN3A6yw7iyPACq0RbFXwtl1Co246ghzz9rq+ 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: List-Subscribe: List-Unsubscribe: --PqL9xaSuINxjZ0qj Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Dec 13, 2023 at 11:43:49AM -0800, Deepak Gupta wrote: > On Wed, Dec 13, 2023 at 5:37=E2=80=AFAM Mark Brown w= rote: > > On Tue, Dec 12, 2023 at 04:50:38PM -0800, Deepak Gupta wrote: > > > How will it do that (currently _ENABLE is married to _WRITE and _PUSH= ) ? > > That's feeling moderately firmly into "don't do that" territory to be > > honest, the problems of trying to modify the stack of another running > > thread while it's active just don't seem worth it - if you're > > coordinating enough to do the modifications it's probably possible to > > just ask the thread who's stack is being modified to do the modification > > itself and having an unprotected thread writing into shadow stack memory > > doesn't feel great. > Yeah no leanings on my side. Just wanted to articulate this scenario. > Since this is new ground, > we can define what's appropriate. Let's keep it this way where a > thread can write to shadow > stack mappings only when it itself has shadow stack enabled. Sounds good to me - it's much easier to relax permissions later than to tighten them up. --PqL9xaSuINxjZ0qj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmV6CosACgkQJNaLcl1U h9ALhgf/X0uXQk/jQmE5Jq0LTM5Dq11ls+1yrW1dnXA7KxS0COIsEEUbdISRGMla V+YwOPaYph3UvrmaWSwwvJoYLBnF5otV9j195V9CyQ0+ffNtfzadl8v/tCaf9Kj8 w3gJY/USQR8ILQtuKGWengTYUOgoygMfNi5bjUokSG8R06ZNY9d51H/aOjGUgnUQ 8EaJ6bxBsbsqd4FlcP8EcxYfwdpfhEf9EKrHF+ZIlHTZdP4abSGD5mb7B1w4Tqpj iVf/C2FzA5H8OSh7cMg/9WfDUCs74i+AUc2sIVVpFNYvfcxyCqQIfdwk5Okiyc8t LBjtoBgkATaNC4M22Ino8jfc5Dasew== =qiqv -----END PGP SIGNATURE----- --PqL9xaSuINxjZ0qj--