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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id d2sm18527244pgp.17.2020.08.03.13.11.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Aug 2020 13:11:28 -0700 (PDT) Date: Mon, 3 Aug 2020 13:11:27 -0700 From: Kees Cook To: "Frank Ch. Eigler" Cc: Joe Lawrence , Evgenii Shatokhin , Kristen Carlson Accardi , Miroslav Benes , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arjan@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, live-patching@vger.kernel.org, Josh Poimboeuf , Jessica Yu Subject: Re: [PATCH v4 00/10] Function Granular KASLR Message-ID: <202008031310.4F8DAA20@keescook> References: <20200717170008.5949-1-kristen@linux.intel.com> <202008031043.FE182E9@keescook> <20200803193837.GB30810@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200803193837.GB30810@redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 03, 2020 at 03:38:37PM -0400, Frank Ch. Eigler wrote: > Hi - > > > > While this does seem to be the right solution for the extant problem, I > > > do want to take a moment and ask if the function sections need to be > > > exposed at all? What tools use this information, and do they just want > > > to see the bounds of the code region? (i.e. the start/end of all the > > > .text* sections) Perhaps .text.* could be excluded from the sysfs > > > section list? > > > [[cc += FChE, see [0] for Evgenii's full mail ]] > > Thanks! > > > It looks like debugging tools like systemtap [1], gdb [2] and its > > add-symbol-file cmd, etc. peek at the /sys/module//section/ info. > > But yeah, it would be preferable if we didn't export a long sysfs > > representation if nobody actually needs it. > > Systemtap needs to know base addresses of loaded text & data sections, > in order to perform relocation of probe point PCs and context data > addresses. It uses /sys/module/...., kind of under protest, because > there seems to exist no MODULE_EXPORT'd API to get at that information > some other way. Wouldn't /proc/kallsysms entries cover this? I must be missing something... -- Kees Cook