From: Florian Weimer <fw@deneb.enyo.de> To: madvenka@linux.microsoft.com Cc: kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, oleg@redhat.com, x86@kernel.org, libffi-discuss@sourceware.org Subject: Re: [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Date: Thu, 17 Sep 2020 03:04:10 +0200 [thread overview] Message-ID: <87v9gdz01h.fsf@mid.deneb.enyo.de> (raw) In-Reply-To: <20200916150826.5990-1-madvenka@linux.microsoft.com> (madvenka's message of "Wed, 16 Sep 2020 10:08:22 -0500") * madvenka: > Examples of trampolines > ======================= > > libffi (A Portable Foreign Function Interface Library): > > libffi allows a user to define functions with an arbitrary list of > arguments and return value through a feature called "Closures". > Closures use trampolines to jump to ABI handlers that handle calling > conventions and call a target function. libffi is used by a lot > of different applications. To name a few: > > - Python > - Java > - Javascript > - Ruby FFI > - Lisp > - Objective C libffi does not actually need this. It currently collocates trampolines and the data they need on the same page, but that's actually unecessary. It's possible to avoid doing this just by changing libffi, without any kernel changes. I think this has already been done for the iOS port. > The code for trampoline X in the trampoline table is: > > load &code_table[X], code_reg > load (code_reg), code_reg > load &data_table[X], data_reg > load (data_reg), data_reg > jump code_reg > > The addresses &code_table[X] and &data_table[X] are baked into the > trampoline code. So, PC-relative data references are not needed. The user > can modify code_table[X] and data_table[X] dynamically. You can put this code into the libffi shared object and map it from there, just like the rest of the libffi code. To get more trampolines, you can map the page containing the trampolines multiple times, each instance preceded by a separate data page with the control information. I think the previous patch submission has also resulted in several comments along those lines, so I'm not sure why you are reposting this. > libffi > ====== > > I have implemented my solution for libffi and provided the changes for > X86 and ARM, 32-bit and 64-bit. Here is the reference patch: > > http://linux.microsoft.com/~madvenka/libffi/libffi.v2.txt The URL does not appear to work, I get a 403 error. > If the trampfd patchset gets accepted, I will send the libffi changes > to the maintainers for a review. BTW, I have also successfully executed > the libffi self tests. I have not seen your libffi changes, but I expect that the complexity is about the same as a userspace-only solution. Cc:ing libffi upstream for awareness. The start of the thread is here: <https://lore.kernel.org/linux-api/20200916150826.5990-1-madvenka@linux.microsoft.com/>
WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fw@deneb.enyo.de> To: madvenka@linux.microsoft.com Cc: kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, oleg@redhat.com, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, libffi-discuss@sourceware.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Date: Thu, 17 Sep 2020 03:04:10 +0200 [thread overview] Message-ID: <87v9gdz01h.fsf@mid.deneb.enyo.de> (raw) In-Reply-To: <20200916150826.5990-1-madvenka@linux.microsoft.com> (madvenka's message of "Wed, 16 Sep 2020 10:08:22 -0500") * madvenka: > Examples of trampolines > ======================= > > libffi (A Portable Foreign Function Interface Library): > > libffi allows a user to define functions with an arbitrary list of > arguments and return value through a feature called "Closures". > Closures use trampolines to jump to ABI handlers that handle calling > conventions and call a target function. libffi is used by a lot > of different applications. To name a few: > > - Python > - Java > - Javascript > - Ruby FFI > - Lisp > - Objective C libffi does not actually need this. It currently collocates trampolines and the data they need on the same page, but that's actually unecessary. It's possible to avoid doing this just by changing libffi, without any kernel changes. I think this has already been done for the iOS port. > The code for trampoline X in the trampoline table is: > > load &code_table[X], code_reg > load (code_reg), code_reg > load &data_table[X], data_reg > load (data_reg), data_reg > jump code_reg > > The addresses &code_table[X] and &data_table[X] are baked into the > trampoline code. So, PC-relative data references are not needed. The user > can modify code_table[X] and data_table[X] dynamically. You can put this code into the libffi shared object and map it from there, just like the rest of the libffi code. To get more trampolines, you can map the page containing the trampolines multiple times, each instance preceded by a separate data page with the control information. I think the previous patch submission has also resulted in several comments along those lines, so I'm not sure why you are reposting this. > libffi > ====== > > I have implemented my solution for libffi and provided the changes for > X86 and ARM, 32-bit and 64-bit. Here is the reference patch: > > http://linux.microsoft.com/~madvenka/libffi/libffi.v2.txt The URL does not appear to work, I get a 403 error. > If the trampfd patchset gets accepted, I will send the libffi changes > to the maintainers for a review. BTW, I have also successfully executed > the libffi self tests. I have not seen your libffi changes, but I expect that the complexity is about the same as a userspace-only solution. Cc:ing libffi upstream for awareness. The start of the thread is here: <https://lore.kernel.org/linux-api/20200916150826.5990-1-madvenka@linux.microsoft.com/> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-09-17 1:11 UTC|newest] Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <210d7cd762d5307c2aa1676705b392bd445f1baa> 2020-09-16 15:08 ` [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor madvenka 2020-09-16 15:08 ` madvenka 2020-09-16 15:08 ` [PATCH v2 1/4] [RFC] fs/trampfd: Implement the trampoline file descriptor API madvenka 2020-09-16 15:08 ` madvenka 2020-09-16 15:08 ` [PATCH v2 2/4] [RFC] x86/trampfd: Provide support for the trampoline file descriptor madvenka 2020-09-16 15:08 ` madvenka 2020-09-17 1:10 ` kernel test robot 2020-09-17 3:04 ` kernel test robot 2020-09-16 15:08 ` [PATCH v2 3/4] [RFC] arm64/trampfd: " madvenka 2020-09-16 15:08 ` madvenka 2020-09-16 15:08 ` [PATCH v2 4/4] [RFC] arm/trampfd: " madvenka 2020-09-16 15:08 ` madvenka 2020-09-17 1:04 ` Florian Weimer [this message] 2020-09-17 1:04 ` [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Florian Weimer 2020-09-17 1:04 ` Florian Weimer 2020-09-17 15:36 ` Madhavan T. Venkataraman 2020-09-17 15:36 ` Madhavan T. Venkataraman 2020-09-17 15:57 ` Madhavan T. Venkataraman 2020-09-17 15:57 ` Madhavan T. Venkataraman 2020-09-17 16:01 ` Florian Weimer 2020-09-17 16:01 ` Florian Weimer 2020-09-17 16:01 ` Florian Weimer 2020-09-23 1:46 ` Arvind Sankar 2020-09-23 1:46 ` Arvind Sankar 2020-09-23 9:11 ` Arvind Sankar 2020-09-23 9:11 ` Arvind Sankar 2020-09-23 19:17 ` Madhavan T. Venkataraman 2020-09-23 19:17 ` Madhavan T. Venkataraman 2020-09-23 19:51 ` Arvind Sankar 2020-09-23 19:51 ` Arvind Sankar 2020-09-23 23:51 ` Madhavan T. Venkataraman 2020-09-23 23:51 ` Madhavan T. Venkataraman 2020-09-24 20:23 ` Madhavan T. Venkataraman 2020-09-24 20:23 ` Madhavan T. Venkataraman 2020-09-24 20:52 ` Florian Weimer 2020-09-24 20:52 ` Florian Weimer 2020-09-24 20:52 ` Florian Weimer 2020-09-25 22:22 ` Madhavan T. Venkataraman 2020-09-25 22:22 ` Madhavan T. Venkataraman 2020-09-27 18:25 ` Madhavan T. Venkataraman 2020-09-27 18:25 ` Madhavan T. Venkataraman 2020-10-03 9:43 ` Jay K 2020-10-03 9:43 ` Jay K 2020-09-24 22:13 ` Pavel Machek 2020-09-24 22:13 ` Pavel Machek 2020-09-24 23:43 ` Arvind Sankar 2020-09-24 23:43 ` Arvind Sankar 2020-09-25 22:44 ` Madhavan T. Venkataraman 2020-09-25 22:44 ` Madhavan T. Venkataraman 2020-09-26 15:55 ` Arvind Sankar 2020-09-26 15:55 ` Arvind Sankar 2020-09-27 17:59 ` Madhavan T. Venkataraman 2020-09-27 17:59 ` Madhavan T. Venkataraman 2020-09-23 2:50 ` Jay K 2020-09-23 2:50 ` Jay K 2020-09-22 21:53 ` madvenka 2020-09-22 21:53 ` madvenka 2020-09-22 21:53 ` [PATCH v2 1/4] [RFC] fs/trampfd: Implement the trampoline file descriptor API madvenka 2020-09-22 21:53 ` madvenka 2020-09-22 21:53 ` [PATCH v2 2/4] [RFC] x86/trampfd: Provide support for the trampoline file descriptor madvenka 2020-09-22 21:53 ` madvenka 2020-09-23 13:40 ` kernel test robot 2020-09-22 21:53 ` [PATCH v2 3/4] [RFC] arm64/trampfd: " madvenka 2020-09-22 21:53 ` madvenka 2020-09-22 21:53 ` [PATCH v2 4/4] [RFC] arm/trampfd: " madvenka 2020-09-22 21:53 ` madvenka 2020-09-22 21:54 ` [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Madhavan T. Venkataraman 2020-09-22 21:54 ` Madhavan T. Venkataraman 2020-09-23 8:14 ` Pavel Machek 2020-09-23 8:14 ` Pavel Machek 2020-09-23 9:14 ` Solar Designer 2020-09-23 9:14 ` Solar Designer 2020-09-23 14:11 ` Solar Designer 2020-09-23 14:11 ` Solar Designer 2020-09-23 15:18 ` Pavel Machek 2020-09-23 15:18 ` Pavel Machek 2020-09-23 18:00 ` Solar Designer 2020-09-23 18:00 ` Solar Designer 2020-09-23 18:21 ` Solar Designer 2020-09-23 18:21 ` Solar Designer 2020-09-23 14:39 ` Florian Weimer 2020-09-23 14:39 ` Florian Weimer 2020-09-23 14:39 ` Florian Weimer 2020-09-23 18:09 ` Andy Lutomirski 2020-09-23 18:09 ` Andy Lutomirski 2020-09-23 18:11 ` Solar Designer 2020-09-23 18:11 ` Solar Designer 2020-09-23 18:49 ` Arvind Sankar 2020-09-23 18:49 ` Arvind Sankar 2020-09-23 23:53 ` Madhavan T. Venkataraman 2020-09-23 23:53 ` Madhavan T. Venkataraman 2020-09-23 19:41 ` Madhavan T. Venkataraman 2020-09-23 19:41 ` Madhavan T. Venkataraman 2020-09-23 18:10 ` James Morris 2020-09-23 18:10 ` James Morris 2020-09-23 18:32 ` Madhavan T. Venkataraman 2020-09-23 18:32 ` Madhavan T. Venkataraman 2020-09-23 8:42 ` Pavel Machek 2020-09-23 8:42 ` Pavel Machek 2020-09-23 18:56 ` Madhavan T. Venkataraman 2020-09-23 18:56 ` Madhavan T. Venkataraman 2020-09-23 20:51 ` Pavel Machek 2020-09-23 20:51 ` Pavel Machek 2020-09-23 23:04 ` Madhavan T. Venkataraman 2020-09-23 23:04 ` Madhavan T. Venkataraman 2020-09-24 16:44 ` Mickaël Salaün 2020-09-24 16:44 ` Mickaël Salaün 2020-09-24 22:05 ` Pavel Machek 2020-09-24 22:05 ` Pavel Machek 2020-09-25 10:12 ` Mickaël Salaün 2020-09-25 10:12 ` Mickaël Salaün
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