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X-IronPort-AV: E=McAfee;i="6600,9927,10712"; a="415019734" X-IronPort-AV: E=Sophos;i="5.99,280,1677571200"; d="scan'208";a="415019734" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 May 2023 16:14:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10712"; a="679039950" X-IronPort-AV: E=Sophos;i="5.99,280,1677571200"; d="scan'208";a="679039950" Received: from mtpanu-mobl1.amr.corp.intel.com (HELO [10.212.203.6]) ([10.212.203.6]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 May 2023 16:14:47 -0700 Message-ID: <6cb7df56-0479-30be-5389-b4b819572deb@intel.com> Date: Tue, 16 May 2023 16:14:47 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH 1/6] PKEY: Introduce PKEY_ENFORCE_API flag Content-Language: en-US To: jeffxu@chromium.org, luto@kernel.org, jorgelo@chromium.org, keescook@chromium.org, groeck@chromium.org, jannh@google.com, sroettger@google.com Cc: akpm@linux-foundation.org, jeffxu@google.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org References: <20230515130553.2311248-1-jeffxu@chromium.org> <20230515130553.2311248-2-jeffxu@chromium.org> From: Dave Hansen In-Reply-To: <20230515130553.2311248-2-jeffxu@chromium.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: A6A9A1C0007 X-Stat-Signature: dsa4xqzxho94b541egd48doq1pbt37km X-HE-Tag: 1684278889-136916 X-HE-Meta: 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 AzKF1+Ae yB/2MbcN1LrHO92KwJ4A2FZjQ5jhsF3kXIuUiGua9iA6KNZHIouOgOVKcUfIbd/EdE/gok0gxn7Ptt0kn0GmI0LgaETd/VGMJwxcnq/nU9G9ce5jUFX2otvNKyJVdAAreYczPU0LTGY00hd3TBmpnTo6U6ygxOiqOYA8XUuUIFyWI+2gVMXO47YXG0K8EFcvF/hr2FsDK7RAhieZXE+cFvQ0O2ERR9dIrNQtoH/mN2uvFeKslJYHHHCYNMfGNxjBC916i 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 5/15/23 06:05, jeffxu@chromium.org wrote: > --- a/arch/x86/mm/pkeys.c > +++ b/arch/x86/mm/pkeys.c > @@ -20,7 +20,7 @@ int __execute_only_pkey(struct mm_struct *mm) > /* Do we need to assign a pkey for mm's execute-only maps? */ > if (execute_only_pkey == -1) { > /* Go allocate one to use, which might fail */ > - execute_only_pkey = mm_pkey_alloc(mm); > + execute_only_pkey = mm_pkey_alloc(mm, 0); > if (execute_only_pkey < 0) > return -1; > need_to_set_mm_pkey = true; In your threat model, what mechanism prevents the attacker from modifying executable mappings? I was trying to figure out if the implicit execute-only pkey should have the PKEY_ENFORCE_API bit set. I think that in particular would probably cause some kind of ABI breakage, but it still reminded me that I have an incomplete picture of the threat model.