linux/kernel/livepatch/core.h

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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>
2017-11-01 14:07:57 +00:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LIVEPATCH_CORE_H
#define _LIVEPATCH_CORE_H
#include <linux/livepatch.h>
extern struct mutex klp_mutex;
extern struct list_head klp_patches;
#define klp_for_each_patch_safe(patch, tmp_patch) \
list_for_each_entry_safe(patch, tmp_patch, &klp_patches, list)
#define klp_for_each_patch(patch) \
list_for_each_entry(patch, &klp_patches, list)
void klp_free_patch_async(struct klp_patch *patch);
void klp_free_replaced_patches_async(struct klp_patch *new_patch);
void klp_unpatch_replaced_patches(struct klp_patch *new_patch);
livepatch: Remove Nop structures when unused Replaced patches are removed from the stack when the transition is finished. It means that Nop structures will never be needed again and can be removed. Why should we care? + Nop structures give the impression that the function is patched even though the ftrace handler has no effect. + Ftrace handlers do not come for free. They cause slowdown that might be visible in some workloads. The ftrace-related slowdown might actually be the reason why the function is no longer patched in the new cumulative patch. One would expect that cumulative patch would help solve these problems as well. + Cumulative patches are supposed to replace any earlier version of the patch. The amount of NOPs depends on which version was replaced. This multiplies the amount of scenarios that might happen. One might say that NOPs are innocent. But there are even optimized NOP instructions for different processors, for example, see arch/x86/kernel/alternative.c. And klp_ftrace_handler() is much more complicated. + It sounds natural to clean up a mess that is no longer needed. It could only be worse if we do not do it. This patch allows to unpatch and free the dynamic structures independently when the transition finishes. The free part is a bit tricky because kobject free callbacks are called asynchronously. We could not wait for them easily. Fortunately, we do not have to. Any further access can be avoided by removing them from the dynamic lists. Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2019-01-09 12:43:26 +00:00
void klp_discard_nops(struct klp_patch *new_patch);
livepatch: Simplify API by removing registration step The possibility to re-enable a registered patch was useful for immediate patches where the livepatch module had to stay until the system reboot. The improved consistency model allows to achieve the same result by unloading and loading the livepatch module again. Also we are going to add a feature called atomic replace. It will allow to create a patch that would replace all already registered patches. The aim is to handle dependent patches more securely. It will obsolete the stack of patches that helped to handle the dependencies so far. Then it might be unclear when a cumulative patch re-enabling is safe. It would be complicated to support the many modes. Instead we could actually make the API and code easier to understand. Therefore, remove the two step public API. All the checks and init calls are moved from klp_register_patch() to klp_enabled_patch(). Also the patch is automatically freed, including the sysfs interface when the transition to the disabled state is completed. As a result, there is never a disabled patch on the top of the stack. Therefore we do not need to check the stack in __klp_enable_patch(). And we could simplify the check in __klp_disable_patch(). Also the API and logic is much easier. It is enough to call klp_enable_patch() in module_init() call. The patch can be disabled by writing '0' into /sys/kernel/livepatch/<patch>/enabled. Then the module can be removed once the transition finishes and sysfs interface is freed. The only problem is how to free the structures and kobjects safely. The operation is triggered from the sysfs interface. We could not put the related kobject from there because it would cause lock inversion between klp_mutex and kernfs locks, see kn->count lockdep map. Therefore, offload the free task to a workqueue. It is perfectly fine: + The patch can no longer be used in the livepatch operations. + The module could not be removed until the free operation finishes and module_put() is called. + The operation is asynchronous already when the first klp_try_complete_transition() fails and another call is queued with a delay. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2019-01-09 12:43:23 +00:00
static inline bool klp_is_object_loaded(struct klp_object *obj)
{
return !obj->name || obj->mod;
}
static inline int klp_pre_patch_callback(struct klp_object *obj)
{
livepatch: Correctly call klp_post_unpatch_callback() in error paths The post_unpatch_enabled flag in struct klp_callbacks is set when a pre-patch callback successfully executes, indicating that we need to call a corresponding post-unpatch callback when the patch is reverted. This is true for ordinary patch disable as well as the error paths of klp_patch_object() callers. As currently coded, we inadvertently execute the post-patch callback twice in klp_module_coming() when klp_patch_object() fails: - We explicitly call klp_post_unpatch_callback() for the failed object - We call it again for the same object (and all the others) via klp_cleanup_module_patches_limited() We should clear the flag in klp_post_unpatch_callback() to make sure that the callback is not called twice. It makes the API more safe. (We could have removed the callback from the former error path as it would be covered by the latter call, but I think that is is cleaner to clear the post_unpatch_enabled after its invoked. For example, someone might later decide to call the callback only when obj->patched flag is set.) There is another mistake in the error path of klp_coming_module() in which it skips the post-unpatch callback for the klp_transition_patch. However, the pre-patch callback was called even for this patch, so be sure to make the corresponding callbacks for all patches. Finally, I used this opportunity to make klp_pre_patch_callback() more readable. [jkosina@suse.cz: incorporate changelog wording changes proposed by Joe Lawrence] Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-10-20 14:56:50 +00:00
int ret = 0;
livepatch: Correctly call klp_post_unpatch_callback() in error paths The post_unpatch_enabled flag in struct klp_callbacks is set when a pre-patch callback successfully executes, indicating that we need to call a corresponding post-unpatch callback when the patch is reverted. This is true for ordinary patch disable as well as the error paths of klp_patch_object() callers. As currently coded, we inadvertently execute the post-patch callback twice in klp_module_coming() when klp_patch_object() fails: - We explicitly call klp_post_unpatch_callback() for the failed object - We call it again for the same object (and all the others) via klp_cleanup_module_patches_limited() We should clear the flag in klp_post_unpatch_callback() to make sure that the callback is not called twice. It makes the API more safe. (We could have removed the callback from the former error path as it would be covered by the latter call, but I think that is is cleaner to clear the post_unpatch_enabled after its invoked. For example, someone might later decide to call the callback only when obj->patched flag is set.) There is another mistake in the error path of klp_coming_module() in which it skips the post-unpatch callback for the klp_transition_patch. However, the pre-patch callback was called even for this patch, so be sure to make the corresponding callbacks for all patches. Finally, I used this opportunity to make klp_pre_patch_callback() more readable. [jkosina@suse.cz: incorporate changelog wording changes proposed by Joe Lawrence] Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-10-20 14:56:50 +00:00
if (obj->callbacks.pre_patch)
ret = (*obj->callbacks.pre_patch)(obj);
obj->callbacks.post_unpatch_enabled = !ret;
return ret;
}
static inline void klp_post_patch_callback(struct klp_object *obj)
{
if (obj->callbacks.post_patch)
(*obj->callbacks.post_patch)(obj);
}
static inline void klp_pre_unpatch_callback(struct klp_object *obj)
{
if (obj->callbacks.pre_unpatch)
(*obj->callbacks.pre_unpatch)(obj);
}
static inline void klp_post_unpatch_callback(struct klp_object *obj)
{
if (obj->callbacks.post_unpatch_enabled &&
obj->callbacks.post_unpatch)
(*obj->callbacks.post_unpatch)(obj);
livepatch: Correctly call klp_post_unpatch_callback() in error paths The post_unpatch_enabled flag in struct klp_callbacks is set when a pre-patch callback successfully executes, indicating that we need to call a corresponding post-unpatch callback when the patch is reverted. This is true for ordinary patch disable as well as the error paths of klp_patch_object() callers. As currently coded, we inadvertently execute the post-patch callback twice in klp_module_coming() when klp_patch_object() fails: - We explicitly call klp_post_unpatch_callback() for the failed object - We call it again for the same object (and all the others) via klp_cleanup_module_patches_limited() We should clear the flag in klp_post_unpatch_callback() to make sure that the callback is not called twice. It makes the API more safe. (We could have removed the callback from the former error path as it would be covered by the latter call, but I think that is is cleaner to clear the post_unpatch_enabled after its invoked. For example, someone might later decide to call the callback only when obj->patched flag is set.) There is another mistake in the error path of klp_coming_module() in which it skips the post-unpatch callback for the klp_transition_patch. However, the pre-patch callback was called even for this patch, so be sure to make the corresponding callbacks for all patches. Finally, I used this opportunity to make klp_pre_patch_callback() more readable. [jkosina@suse.cz: incorporate changelog wording changes proposed by Joe Lawrence] Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-10-20 14:56:50 +00:00
obj->callbacks.post_unpatch_enabled = false;
}
#endif /* _LIVEPATCH_CORE_H */