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2fab02b2 |
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12-Jun-2023 |
Rick Edgecombe <rick.p.edgecombe@intel.com> |
x86: Add PTRACE interface for shadow stack Some applications (like GDB) would like to tweak shadow stack state via ptrace. This allows for existing functionality to continue to work for seized shadow stack applications. Provide a regset interface for manipulating the shadow stack pointer (SSP). There is already ptrace functionality for accessing xstate, but this does not include supervisor xfeatures. So there is not a completely clear place for where to put the shadow stack state. Adding it to the user xfeatures regset would complicate that code, as it currently shares logic with signals which should not have supervisor features. Don't add a general supervisor xfeature regset like the user one, because it is better to maintain flexibility for other supervisor xfeatures to define their own interface. For example, an xfeature may decide not to expose all of it's state to userspace, as is actually the case for shadow stack ptrace functionality. A lot of enum values remain to be used, so just put it in dedicated shadow stack regset. The only downside to not having a generic supervisor xfeature regset, is that apps need to be enlightened of any new supervisor xfeature exposed this way (i.e. they can't try to have generic save/restore logic). But maybe that is a good thing, because they have to think through each new xfeature instead of encountering issues when a new supervisor xfeature was added. By adding a shadow stack regset, it also has the effect of including the shadow stack state in a core dump, which could be useful for debugging. The shadow stack specific xstate includes the SSP, and the shadow stack and WRSS enablement status. Enabling shadow stack or WRSS in the kernel involves more than just flipping the bit. The kernel is made aware that it has to do extra things when cloning or handling signals. That logic is triggered off of separate feature enablement state kept in the task struct. So the flipping on HW shadow stack enforcement without notifying the kernel to change its behavior would severely limit what an application could do without crashing, and the results would depend on kernel internal implementation details. There is also no known use for controlling this state via ptrace today. So only expose the SSP, which is something that userspace already has indirect control over. Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Tested-by: Pengfei Xu <pengfei.xu@intel.com> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/all/20230613001108.3040476-41-rick.p.edgecombe%40intel.com
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b2441318 |
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01-Nov-2017 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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