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linux/samples/livepatch/livepatch-shadow-fix1.c

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details [based] [from] [clk] [highbank] [c] you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 355 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-19 15:51:43 +02:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch: Initialize shadow variables safely by a custom callback The existing API allows to pass a sample data to initialize the shadow data. It works well when the data are position independent. But it fails miserably when we need to set a pointer to the shadow structure itself. Unfortunately, we might need to initialize the pointer surprisingly often because of struct list_head. It is even worse because the list might be hidden in other common structures, for example, struct mutex, struct wait_queue_head. For example, this was needed to fix races in ALSA sequencer. It required to add mutex into struct snd_seq_client. See commit b3defb791b26ea06 ("ALSA: seq: Make ioctls race-free") and commit d15d662e89fc667b9 ("ALSA: seq: Fix racy pool initializations") This patch makes the API more safe. A custom constructor function and data are passed to klp_shadow_*alloc() functions instead of the sample data. Note that ctor_data are no longer a template for shadow->data. It might point to any data that might be necessary when the constructor is called. Also note that the constructor is called under klp_shadow_lock. It is an internal spin_lock that synchronizes alloc() vs. get() operations, see klp_shadow_get_or_alloc(). On one hand, this adds a risk of ABBA deadlocks. On the other hand, it allows to do some operations safely. For example, we could add the new structure into an existing list. This must be done only once when the structure is allocated. Reported-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:46 +02:00
livepatch/sample: Use the right type for the leaking data pointer The "leak" pointer, in the sample of shadow variable API, is allocated as sizeof(int). Let's help developers and static analyzers with understanding the code by using the appropriate pointer type. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:42 +01:00
livepatch/samples/selftest: Use klp_shadow_alloc() API correctly The commit e91c2518a5d22a ("livepatch: Initialize shadow variables safely by a custom callback") leads to the following static checker warning: samples/livepatch/livepatch-shadow-fix1.c:86 livepatch_fix1_dummy_alloc() error: 'klp_shadow_alloc()' 'leak' too small (4 vs 8) It is because klp_shadow_alloc() is used a wrong way: int *leak; shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL, shadow_leak_ctor, leak); The code is supposed to store the "leak" pointer into the shadow variable. 3rd parameter correctly passes size of the data (size of pointer). But the 5th parameter is wrong. It should pass pointer to the data (pointer to the pointer) but it passes the pointer directly. It works because shadow_leak_ctor() handle "ctor_data" as the data instead of pointer to the data. But it is semantically wrong and confusing. The same problem is also in the module used by selftests. In this case, "pvX" variables are introduced. They represent the data stored in the shadow variables. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:44 +01:00
livepatch: Initialize shadow variables safely by a custom callback The existing API allows to pass a sample data to initialize the shadow data. It works well when the data are position independent. But it fails miserably when we need to set a pointer to the shadow structure itself. Unfortunately, we might need to initialize the pointer surprisingly often because of struct list_head. It is even worse because the list might be hidden in other common structures, for example, struct mutex, struct wait_queue_head. For example, this was needed to fix races in ALSA sequencer. It required to add mutex into struct snd_seq_client. See commit b3defb791b26ea06 ("ALSA: seq: Make ioctls race-free") and commit d15d662e89fc667b9 ("ALSA: seq: Fix racy pool initializations") This patch makes the API more safe. A custom constructor function and data are passed to klp_shadow_*alloc() functions instead of the sample data. Note that ctor_data are no longer a template for shadow->data. It might point to any data that might be necessary when the constructor is called. Also note that the constructor is called under klp_shadow_lock. It is an internal spin_lock that synchronizes alloc() vs. get() operations, see klp_shadow_get_or_alloc(). On one hand, this adds a risk of ABBA deadlocks. On the other hand, it allows to do some operations safely. For example, we could add the new structure into an existing list. This must be done only once when the structure is allocated. Reported-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:46 +02:00
livepatch/samples/selftest: Use klp_shadow_alloc() API correctly The commit e91c2518a5d22a ("livepatch: Initialize shadow variables safely by a custom callback") leads to the following static checker warning: samples/livepatch/livepatch-shadow-fix1.c:86 livepatch_fix1_dummy_alloc() error: 'klp_shadow_alloc()' 'leak' too small (4 vs 8) It is because klp_shadow_alloc() is used a wrong way: int *leak; shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL, shadow_leak_ctor, leak); The code is supposed to store the "leak" pointer into the shadow variable. 3rd parameter correctly passes size of the data (size of pointer). But the 5th parameter is wrong. It should pass pointer to the data (pointer to the pointer) but it passes the pointer directly. It works because shadow_leak_ctor() handle "ctor_data" as the data instead of pointer to the data. But it is semantically wrong and confusing. The same problem is also in the module used by selftests. In this case, "pvX" variables are introduced. They represent the data stored in the shadow variables. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:44 +01:00
livepatch: Initialize shadow variables safely by a custom callback The existing API allows to pass a sample data to initialize the shadow data. It works well when the data are position independent. But it fails miserably when we need to set a pointer to the shadow structure itself. Unfortunately, we might need to initialize the pointer surprisingly often because of struct list_head. It is even worse because the list might be hidden in other common structures, for example, struct mutex, struct wait_queue_head. For example, this was needed to fix races in ALSA sequencer. It required to add mutex into struct snd_seq_client. See commit b3defb791b26ea06 ("ALSA: seq: Make ioctls race-free") and commit d15d662e89fc667b9 ("ALSA: seq: Fix racy pool initializations") This patch makes the API more safe. A custom constructor function and data are passed to klp_shadow_*alloc() functions instead of the sample data. Note that ctor_data are no longer a template for shadow->data. It might point to any data that might be necessary when the constructor is called. Also note that the constructor is called under klp_shadow_lock. It is an internal spin_lock that synchronizes alloc() vs. get() operations, see klp_shadow_get_or_alloc(). On one hand, this adds a risk of ABBA deadlocks. On the other hand, it allows to do some operations safely. For example, we could add the new structure into an existing list. This must be done only once when the structure is allocated. Reported-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:46 +02:00
livepatch: samples: non static warnings fix Sparse reported warnings about non-static symbols. For the variables a simple static attribute is fine - for the functions referenced by livepatch via klp_func the symbol-names must be unmodified in the symbol table and the patchable code has to be emitted. The resolution is to attach __used attribute to the shared statically declared functions. Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@osadl.org/ Suggested-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2019-01-24 02:48:16 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch/sample: Use the right type for the leaking data pointer The "leak" pointer, in the sample of shadow variable API, is allocated as sizeof(int). Let's help developers and static analyzers with understanding the code by using the appropriate pointer type. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:42 +01:00
livepatch: Handle allocation failure in the sample of shadow variable API klp_shadow_alloc() is not handled in the sample of shadow variable API. It is not strictly necessary because livepatch_fix1_dummy_free() is able to handle the potential failure. But it is an example and it should use the API a clean way. Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:45 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch/sample: Use the right type for the leaking data pointer The "leak" pointer, in the sample of shadow variable API, is allocated as sizeof(int). Let's help developers and static analyzers with understanding the code by using the appropriate pointer type. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:42 +01:00
livepatch: Handle allocation failure in the sample of shadow variable API klp_shadow_alloc() is not handled in the sample of shadow variable API. It is not strictly necessary because livepatch_fix1_dummy_free() is able to handle the potential failure. But it is an example and it should use the API a clean way. Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:45 +01:00
livepatch: check kzalloc return values kzalloc() return should always be checked - notably in example code where this may be seen as reference. On failure of allocation in livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous allocation is freed (thanks to Petr Mladek <pmladek@suse.com> for catching this) and NULL returned. Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API") Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-12-14 17:56:10 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch: Handle allocation failure in the sample of shadow variable API klp_shadow_alloc() is not handled in the sample of shadow variable API. It is not strictly necessary because livepatch_fix1_dummy_free() is able to handle the potential failure. But it is an example and it should use the API a clean way. Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:45 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch: Allow to call a custom callback when freeing shadow variables We might need to do some actions before the shadow variable is freed. For example, we might need to remove it from a list or free some data that it points to. This is already possible now. The user can get the shadow variable by klp_shadow_get(), do the necessary actions, and then call klp_shadow_free(). This patch allows to do it a more elegant way. The user could implement the needed actions in a callback that is passed to klp_shadow_free() as a parameter. The callback usually does reverse operations to the constructor callback that can be called by klp_shadow_*alloc(). It is especially useful for klp_shadow_free_all(). There we need to do these extra actions for each found shadow variable with the given ID. Note that the memory used by the shadow variable itself is still released later by rcu callback. It is needed to protect internal structures that keep all shadow variables. But the destructor is called immediately. The shadow variable must not be access anyway after klp_shadow_free() is called. The user is responsible to protect this any suitable way. Be aware that the destructor is called under klp_shadow_lock. It is the same as for the contructor in klp_shadow_alloc(). Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:47 +02:00
livepatch/sample: Use the right type for the leaking data pointer The "leak" pointer, in the sample of shadow variable API, is allocated as sizeof(int). Let's help developers and static analyzers with understanding the code by using the appropriate pointer type. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:42 +01:00
livepatch: Allow to call a custom callback when freeing shadow variables We might need to do some actions before the shadow variable is freed. For example, we might need to remove it from a list or free some data that it points to. This is already possible now. The user can get the shadow variable by klp_shadow_get(), do the necessary actions, and then call klp_shadow_free(). This patch allows to do it a more elegant way. The user could implement the needed actions in a callback that is passed to klp_shadow_free() as a parameter. The callback usually does reverse operations to the constructor callback that can be called by klp_shadow_*alloc(). It is especially useful for klp_shadow_free_all(). There we need to do these extra actions for each found shadow variable with the given ID. Note that the memory used by the shadow variable itself is still released later by rcu callback. It is needed to protect internal structures that keep all shadow variables. But the destructor is called immediately. The shadow variable must not be access anyway after klp_shadow_free() is called. The user is responsible to protect this any suitable way. Be aware that the destructor is called under klp_shadow_lock. It is the same as for the contructor in klp_shadow_alloc(). Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:47 +02:00
livepatch: Reorder to use before freeing a pointer Clang static analysis reports this issue livepatch-shadow-fix1.c:113:2: warning: Use of memory after it is freed pr_info("%s: dummy @ %p, prevented leak @ %p\n", ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The pointer is freed in the previous statement. Reorder the pr_info to report before the free. Similar issue in livepatch-shadow-fix2.c Note that it is a false positive. pr_info() just prints the address. The freed memory is not accessed. Well, the static analyzer could not know this easily. Signed-off-by: Tom Rix <trix@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: David Vernet <void@manifault.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> [pmladek@suse.com: Note about that it was false positive.] Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20220320015143.2208591-1-trix@redhat.com
2022-03-19 18:51:43 -07:00
livepatch: Allow to call a custom callback when freeing shadow variables We might need to do some actions before the shadow variable is freed. For example, we might need to remove it from a list or free some data that it points to. This is already possible now. The user can get the shadow variable by klp_shadow_get(), do the necessary actions, and then call klp_shadow_free(). This patch allows to do it a more elegant way. The user could implement the needed actions in a callback that is passed to klp_shadow_free() as a parameter. The callback usually does reverse operations to the constructor callback that can be called by klp_shadow_*alloc(). It is especially useful for klp_shadow_free_all(). There we need to do these extra actions for each found shadow variable with the given ID. Note that the memory used by the shadow variable itself is still released later by rcu callback. It is needed to protect internal structures that keep all shadow variables. But the destructor is called immediately. The shadow variable must not be access anyway after klp_shadow_free() is called. The user is responsible to protect this any suitable way. Be aware that the destructor is called under klp_shadow_lock. It is the same as for the contructor in klp_shadow_alloc(). Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:47 +02:00
livepatch: samples: non static warnings fix Sparse reported warnings about non-static symbols. For the variables a simple static attribute is fine - for the functions referenced by livepatch via klp_func the symbol-names must be unmodified in the symbol table and the patchable code has to be emitted. The resolution is to attach __used attribute to the shared statically declared functions. Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@osadl.org/ Suggested-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2019-01-24 02:48:16 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch/sample: Use the right type for the leaking data pointer The "leak" pointer, in the sample of shadow variable API, is allocated as sizeof(int). Let's help developers and static analyzers with understanding the code by using the appropriate pointer type. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2020-01-16 16:31:42 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch: Allow to call a custom callback when freeing shadow variables We might need to do some actions before the shadow variable is freed. For example, we might need to remove it from a list or free some data that it points to. This is already possible now. The user can get the shadow variable by klp_shadow_get(), do the necessary actions, and then call klp_shadow_free(). This patch allows to do it a more elegant way. The user could implement the needed actions in a callback that is passed to klp_shadow_free() as a parameter. The callback usually does reverse operations to the constructor callback that can be called by klp_shadow_*alloc(). It is especially useful for klp_shadow_free_all(). There we need to do these extra actions for each found shadow variable with the given ID. Note that the memory used by the shadow variable itself is still released later by rcu callback. It is needed to protect internal structures that keep all shadow variables. But the destructor is called immediately. The shadow variable must not be access anyway after klp_shadow_free() is called. The user is responsible to protect this any suitable way. Be aware that the destructor is called under klp_shadow_lock. It is the same as for the contructor in klp_shadow_alloc(). Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:47 +02:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
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 13:43:23 +01:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00
livepatch: Allow to call a custom callback when freeing shadow variables We might need to do some actions before the shadow variable is freed. For example, we might need to remove it from a list or free some data that it points to. This is already possible now. The user can get the shadow variable by klp_shadow_get(), do the necessary actions, and then call klp_shadow_free(). This patch allows to do it a more elegant way. The user could implement the needed actions in a callback that is passed to klp_shadow_free() as a parameter. The callback usually does reverse operations to the constructor callback that can be called by klp_shadow_*alloc(). It is especially useful for klp_shadow_free_all(). There we need to do these extra actions for each found shadow variable with the given ID. Note that the memory used by the shadow variable itself is still released later by rcu callback. It is needed to protect internal structures that keep all shadow variables. But the destructor is called immediately. The shadow variable must not be access anyway after klp_shadow_free() is called. The user is responsible to protect this any suitable way. Be aware that the destructor is called under klp_shadow_lock. It is the same as for the contructor in klp_shadow_alloc(). Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-16 13:36:47 +02:00
livepatch: introduce shadow variable API Add exported API for livepatch modules: klp_shadow_get() klp_shadow_alloc() klp_shadow_get_or_alloc() klp_shadow_free() klp_shadow_free_all() that implement "shadow" variables, which allow callers to associate new shadow fields to existing data structures. This is intended to be used by livepatch modules seeking to emulate additions to data structure definitions. See Documentation/livepatch/shadow-vars.txt for a summary of the new shadow variable API, including a few common use cases. See samples/livepatch/livepatch-shadow-* for example modules that demonstrate shadow variables. [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by Josh] Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-08-31 16:37:41 -04:00