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From: Florian Weimer <fweimer@redhat.com>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: libc-alpha@sourceware.org,  Jeremy Linton <jeremy.linton@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Mark Rutland <mark.rutland@arm.com>,
	 Will Deacon <will.deacon@arm.com>,
	 Mark Brown <broonie@kernel.org>,
	 Kees Cook <keescook@chromium.org>,
	 Salvatore Mesoraca <s.mesoraca16@gmail.com>,
	 Lennart Poettering <mzxreary@0pointer.de>,
	 Topi Miettinen <toiwoton@gmail.com>,
	linux-kernel@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org,
	kernel-hardening@lists.openwall.com,
	 linux-hardening@vger.kernel.org
Subject: Re: [PATCH 3/4] aarch64: Use mmap to add PROT_BTI instead of mprotect [BZ #26831]
Date: Tue, 03 Nov 2020 11:34:22 +0100	[thread overview]
Message-ID: <87v9embufl.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <f5eaa74cb7538382b2fd2439755386ac68f7c8db.1604393169.git.szabolcs.nagy@arm.com> (Szabolcs Nagy's message of "Tue, 3 Nov 2020 10:26:29 +0000")

* Szabolcs Nagy:

> Re-mmap executable segments if possible instead of using mprotect
> to add PROT_BTI. This allows using BTI protection with security
> policies that prevent mprotect with PROT_EXEC.
>
> If the fd of the ELF module is not available because it was kernel
> mapped then mprotect is used and failures are ignored.  It is
> expected that linux kernel will add PROT_BTI when mapping a module
> (current linux as of version 5.9 does not do this).
>
> Computing the mapping parameters follows the logic of
> _dl_map_object_from_fd more closely now.

What's the performance of this on execve-heavy workloads, such as kernel
or glibc builds?  Hopefully it's cheap because these mappings have not
been faulted in yet.

Thanks,
Florian
-- 
Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn,
Commercial register: Amtsgericht Muenchen, HRB 153243,
Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill


WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fweimer@redhat.com>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Salvatore Mesoraca <s.mesoraca16@gmail.com>,
	libc-alpha@sourceware.org, Kees Cook <keescook@chromium.org>,
	kernel-hardening@lists.openwall.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-kernel@vger.kernel.org,
	Jeremy Linton <jeremy.linton@arm.com>,
	Mark Brown <broonie@kernel.org>,
	Lennart Poettering <mzxreary@0pointer.de>,
	linux-hardening@vger.kernel.org,
	Topi Miettinen <toiwoton@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/4] aarch64: Use mmap to add PROT_BTI instead of mprotect [BZ #26831]
Date: Tue, 03 Nov 2020 11:34:22 +0100	[thread overview]
Message-ID: <87v9embufl.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <f5eaa74cb7538382b2fd2439755386ac68f7c8db.1604393169.git.szabolcs.nagy@arm.com> (Szabolcs Nagy's message of "Tue, 3 Nov 2020 10:26:29 +0000")

* Szabolcs Nagy:

> Re-mmap executable segments if possible instead of using mprotect
> to add PROT_BTI. This allows using BTI protection with security
> policies that prevent mprotect with PROT_EXEC.
>
> If the fd of the ELF module is not available because it was kernel
> mapped then mprotect is used and failures are ignored.  It is
> expected that linux kernel will add PROT_BTI when mapping a module
> (current linux as of version 5.9 does not do this).
>
> Computing the mapping parameters follows the logic of
> _dl_map_object_from_fd more closely now.

What's the performance of this on execve-heavy workloads, such as kernel
or glibc builds?  Hopefully it's cheap because these mappings have not
been faulted in yet.

Thanks,
Florian
-- 
Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn,
Commercial register: Amtsgericht Muenchen, HRB 153243,
Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill


_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-11-03 10:34 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-03 10:25 [PATCH 0/4] aarch64: avoid mprotect(PROT_BTI|PROT_EXEC) [BZ #26831] Szabolcs Nagy
2020-11-03 10:25 ` Szabolcs Nagy
2020-11-03 10:25 ` [PATCH 1/4] elf: Pass the fd to note processing " Szabolcs Nagy
2020-11-03 10:25   ` Szabolcs Nagy
2020-11-03 10:26 ` [PATCH 2/4] elf: Move note processing after l_phdr is updated " Szabolcs Nagy
2020-11-03 10:26   ` Szabolcs Nagy
2020-11-03 10:38   ` Florian Weimer
2020-11-03 10:38     ` Florian Weimer
2020-11-03 12:36     ` H.J. Lu
2020-11-03 12:36       ` H.J. Lu
2020-11-03 15:04       ` Szabolcs Nagy
2020-11-03 15:04         ` Szabolcs Nagy
2020-11-03 15:27         ` H.J. Lu
2020-11-03 15:27           ` H.J. Lu
2020-11-03 10:26 ` [PATCH 3/4] aarch64: Use mmap to add PROT_BTI instead of mprotect " Szabolcs Nagy
2020-11-03 10:26   ` Szabolcs Nagy
2020-11-03 10:34   ` Florian Weimer [this message]
2020-11-03 10:34     ` Florian Weimer
2020-11-03 10:26 ` [PATCH 4/4] aarch64: Remove the bti link_map field " Szabolcs Nagy
2020-11-03 10:26   ` Szabolcs Nagy
2020-11-03 17:34 ` [PATCH 0/4] aarch64: avoid mprotect(PROT_BTI|PROT_EXEC) " Mark Brown
2020-11-03 17:34   ` Mark Brown
2020-11-04  5:41   ` Jeremy Linton
2020-11-04  5:41     ` Jeremy Linton
2020-11-04  8:57     ` Szabolcs Nagy
2020-11-04  8:57       ` Szabolcs Nagy
2020-11-04 14:41       ` Catalin Marinas
2020-11-04 14:41         ` Catalin Marinas
2020-11-04 14:45         ` Florian Weimer
2020-11-04 14:45           ` Florian Weimer
2020-11-04 10:50     ` Mark Brown
2020-11-04 10:50       ` Mark Brown
2020-11-04 18:47       ` Jeremy Linton
2020-11-04 18:47         ` Jeremy Linton
2020-11-04 18:53         ` Mark Brown
2020-11-04 18:53           ` Mark Brown
2020-11-04  9:02   ` Topi Miettinen
2020-11-04  9:02     ` Topi Miettinen
2020-11-04  9:20   ` Will Deacon
2020-11-04  9:20     ` Will Deacon
2020-11-04  9:29     ` Florian Weimer
2020-11-04  9:29       ` Florian Weimer
2020-11-04  9:55       ` Topi Miettinen
2020-11-04  9:55         ` Topi Miettinen
2020-11-04 14:35         ` Catalin Marinas
2020-11-04 14:35           ` Catalin Marinas
2020-11-04 15:19           ` Topi Miettinen
2020-11-04 15:19             ` Topi Miettinen
2020-11-04 16:08             ` Szabolcs Nagy
2020-11-04 16:08               ` Szabolcs Nagy
2020-11-04 15:20         ` Mark Rutland
2020-11-04 15:20           ` Mark Rutland
2020-11-04 18:59           ` Jeremy Linton
2020-11-04 18:59             ` Jeremy Linton
2020-11-05 11:31     ` Szabolcs Nagy
2020-11-05 11:31       ` Szabolcs Nagy

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