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* kernel/: fix repeated words in commentsRandy Dunlap2020-10-161-1/+1
| | | | | | | | | | | | | Fix multiple occurrences of duplicated words in kernel/. Fix one typo/spello on the same line as a duplicate word. Change one instance of "the the" to "that the". Otherwise just drop one of the repeated words. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/98202fa6-8919-ef63-9efe-c0fad5ca7af1@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* livepatch: Make klp_apply_object_relocs staticSamuel Zou2020-05-111-1/+2
| | | | | | | | | | | | | | | | Fix the following sparse warning: kernel/livepatch/core.c:748:5: warning: symbol 'klp_apply_object_relocs' was not declared. The klp_apply_object_relocs() has only one call site within core.c; it should be static Fixes: 7c8e2bdd5f0d ("livepatch: Apply vmlinux-specific KLP relocations early") Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Samuel Zou <zou_wei@huawei.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* x86/module: Use text_mutex in apply_relocate_add()Josh Poimboeuf2020-05-081-6/+0
| | | | | | | | | | | | | | Now that the livepatch code no longer needs the text_mutex for changing module permissions, move its usage down to apply_relocate_add(). Note the s390 version of apply_relocate_add() doesn't need to use the text_mutex because it already uses s390_kernel_write_lock, which accomplishes the same task. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Remove module_disable_ro() usageJosh Poimboeuf2020-05-081-2/+0
| | | | | | | | | | | With arch_klp_init_object_loaded() gone, and apply_relocate_add() now using text_poke(), livepatch no longer needs to use module_disable_ro(). Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Prevent module-specific KLP rela sections from referencing ↵Josh Poimboeuf2020-05-081-11/+27
| | | | | | | | | | | | | | | | vmlinux symbols Prevent module-specific KLP rela sections from referencing vmlinux symbols. This helps prevent ordering issues with module special section initializations. Presumably such symbols are exported and normal relas can be used instead. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Remove .klp.archPeter Zijlstra2020-05-081-18/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After the previous patch, vmlinux-specific KLP relocations are now applied early during KLP module load. This means that .klp.arch sections are no longer needed for *vmlinux-specific* KLP relocations. One might think they're still needed for *module-specific* KLP relocations. If a to-be-patched module is loaded *after* its corresponding KLP module is loaded, any corresponding KLP relocations will be delayed until the to-be-patched module is loaded. If any special sections (.parainstructions, for example) rely on those relocations, their initializations (apply_paravirt) need to be done afterwards. Thus the apparent need for arch_klp_init_object_loaded() and its corresponding .klp.arch sections -- it allows some of the special section initializations to be done at a later time. But... if you look closer, that dependency between the special sections and the module-specific KLP relocations doesn't actually exist in reality. Looking at the contents of the .altinstructions and .parainstructions sections, there's not a realistic scenario in which a KLP module's .altinstructions or .parainstructions section needs to access a symbol in a to-be-patched module. It might need to access a local symbol or even a vmlinux symbol; but not another module's symbol. When a special section needs to reference a local or vmlinux symbol, a normal rela can be used instead of a KLP rela. Since the special section initializations don't actually have any real dependency on module-specific KLP relocations, .klp.arch and arch_klp_init_object_loaded() no longer have a reason to exist. So remove them. As Peter said much more succinctly: So the reason for .klp.arch was that .klp.rela.* stuff would overwrite paravirt instructions. If that happens you're doing it wrong. Those RELAs are core kernel, not module, and thus should've happened in .rela.* sections at patch-module loading time. Reverting this removes the two apply_{paravirt,alternatives}() calls from the late patching path, and means we don't have to worry about them when removing module_disable_ro(). [ jpoimboe: Rewrote patch description. Tweaked klp_init_object_loaded() error path. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Apply vmlinux-specific KLP relocations earlyJosh Poimboeuf2020-05-081-51/+86
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KLP relocations are livepatch-specific relocations which are applied to a KLP module's text or data. They exist for two reasons: 1) Unexported symbols: replacement functions often need to access unexported symbols (e.g. static functions), which "normal" relocations don't allow. 2) Late module patching: this is the ability for a KLP module to bypass normal module dependencies, such that the KLP module can be loaded *before* a to-be-patched module. This means that relocations which need to access symbols in the to-be-patched module might need to be applied to the KLP module well after it has been loaded. Non-late-patched KLP relocations are applied from the KLP module's init function. That usually works fine, unless the patched code wants to use alternatives, paravirt patching, jump tables, or some other special section which needs relocations. Then we run into ordering issues and crashes. In order for those special sections to work properly, the KLP relocations should be applied *before* the special section init code runs, such as apply_paravirt(), apply_alternatives(), or jump_label_apply_nops(). You might think the obvious solution would be to move the KLP relocation initialization earlier, but it's not necessarily that simple. The problem is the above-mentioned late module patching, for which KLP relocations can get applied well after the KLP module is loaded. To "fix" this issue in the past, we created .klp.arch sections: .klp.arch.{module}..altinstructions .klp.arch.{module}..parainstructions Those sections allow KLP late module patching code to call apply_paravirt() and apply_alternatives() after the module-specific KLP relocations (.klp.rela.{module}.{section}) have been applied. But that has a lot of drawbacks, including code complexity, the need for arch-specific code, and the (per-arch) danger that we missed some special section -- for example the __jump_table section which is used for jump labels. It turns out there's a simpler and more functional approach. There are two kinds of KLP relocation sections: 1) vmlinux-specific KLP relocation sections .klp.rela.vmlinux.{sec} These are relocations (applied to the KLP module) which reference unexported vmlinux symbols. 2) module-specific KLP relocation sections .klp.rela.{module}.{sec}: These are relocations (applied to the KLP module) which reference unexported or exported module symbols. Up until now, these have been treated the same. However, they're inherently different. Because of late module patching, module-specific KLP relocations can be applied very late, thus they can create the ordering headaches described above. But vmlinux-specific KLP relocations don't have that problem. There's nothing to prevent them from being applied earlier. So apply them at the same time as normal relocations, when the KLP module is being loaded. This means that for vmlinux-specific KLP relocations, we no longer have any ordering issues. vmlinux-referencing jump labels, alternatives, and paravirt patching will work automatically, without the need for the .klp.arch hacks. All that said, for module-specific KLP relocations, the ordering problems still exist and we *do* still need .klp.arch. Or do we? Stay tuned. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Jessica Yu <jeyu@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Disallow vmlinux.koJosh Poimboeuf2020-05-081-0/+5
| | | | | | | | | | | | | | | This is purely a theoretical issue, but if there were a module named vmlinux.ko, the livepatch relocation code wouldn't be able to distinguish between vmlinux-specific and vmlinux.o-specific KLP relocations. If CONFIG_LIVEPATCH is enabled, don't allow a module named vmlinux.ko. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* Merge tag 'trace-v5.5' of ↵Linus Torvalds2019-11-271-1/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "New tracing features: - New PERMANENT flag to ftrace_ops when attaching a callback to a function. As /proc/sys/kernel/ftrace_enabled when set to zero will disable all attached callbacks in ftrace, this has a detrimental impact on live kernel tracing, as it disables all that it patched. If a ftrace_ops is registered to ftrace with the PERMANENT flag set, it will prevent ftrace_enabled from being disabled, and if ftrace_enabled is already disabled, it will prevent a ftrace_ops with PREMANENT flag set from being registered. - New register_ftrace_direct(). As eBPF would like to register its own trampolines to be called by the ftrace nop locations directly, without going through the ftrace trampoline, this function has been added. This allows for eBPF trampolines to live along side of ftrace, perf, kprobe and live patching. It also utilizes the ftrace enabled_functions file that keeps track of functions that have been modified in the kernel, to allow for security auditing. - Allow for kernel internal use of ftrace instances. Subsystems in the kernel can now create and destroy their own tracing instances which allows them to have their own tracing buffer, and be able to record events without worrying about other users from writing over their data. - New seq_buf_hex_dump() that lets users use the hex_dump() in their seq_buf usage. - Notifications now added to tracing_max_latency to allow user space to know when a new max latency is hit by one of the latency tracers. - Wider spread use of generic compare operations for use of bsearch and friends. - More synthetic event fields may be defined (32 up from 16) - Use of xarray for architectures with sparse system calls, for the system call trace events. This along with small clean ups and fixes" * tag 'trace-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (51 commits) tracing: Enable syscall optimization for MIPS tracing: Use xarray for syscall trace events tracing: Sample module to demonstrate kernel access to Ftrace instances. tracing: Adding new functions for kernel access to Ftrace instances tracing: Fix Kconfig indentation ring-buffer: Fix typos in function ring_buffer_producer ftrace: Use BIT() macro ftrace: Return ENOTSUPP when DYNAMIC_FTRACE_WITH_DIRECT_CALLS is not configured ftrace: Rename ftrace_graph_stub to ftrace_stub_graph ftrace: Add a helper function to modify_ftrace_direct() to allow arch optimization ftrace: Add helper find_direct_entry() to consolidate code ftrace: Add another check for match in register_ftrace_direct() ftrace: Fix accounting bug with direct->count in register_ftrace_direct() ftrace/selftests: Fix spelling mistake "wakeing" -> "waking" tracing: Increase SYNTH_FIELDS_MAX for synthetic_events ftrace/samples: Add a sample module that implements modify_ftrace_direct() ftrace: Add modify_ftrace_direct() tracing: Add missing "inline" in stub function of latency_fsnotify() tracing: Remove stray tab in TRACE_EVAL_MAP_FILE's help text tracing: Use seq_buf_hex_dump() to dump buffers ...
| * ftrace: Introduce PERMANENT ftrace_ops flagMiroslav Benes2019-11-041-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Livepatch uses ftrace for redirection to new patched functions. It means that if ftrace is disabled, all live patched functions are disabled as well. Toggling global 'ftrace_enabled' sysctl thus affect it directly. It is not a problem per se, because only administrator can set sysctl values, but it still may be surprising. Introduce PERMANENT ftrace_ops flag to amend this. If the FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be disabled by disabling ftrace_enabled. Equally, a callback with the flag set cannot be registered if ftrace_enabled is disabled. Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
* | livepatch: Allow to distinguish different version of system state changesPetr Mladek2019-11-013-0/+53
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The atomic replace runs pre/post (un)install callbacks only from the new livepatch. There are several reasons for this: + Simplicity: clear ordering of operations, no interactions between old and new callbacks. + Reliability: only new livepatch knows what changes can already be made by older livepatches and how to take over the state. + Testing: the atomic replace can be properly tested only when a newer livepatch is available. It might be too late to fix unwanted effect of callbacks from older livepatches. It might happen that an older change is not enough and the same system state has to be modified another way. Different changes need to get distinguished by a version number added to struct klp_state. The version can also be used to prevent loading incompatible livepatches. The check is done when the livepatch is enabled. The rules are: + Any completely new system state modification is allowed. + System state modifications with the same or higher version are allowed for already modified system states. + Cumulative livepatches must handle all system state modifications from already installed livepatches. + Non-cumulative livepatches are allowed to touch already modified system states. Link: http://lkml.kernel.org/r/20191030154313.13263-4-pmladek@suse.com To: Jiri Kosina <jikos@kernel.org> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Cc: Nicolai Stange <nstange@suse.de> Cc: live-patching@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* | livepatch: Basic API to track system state changesPetr Mladek2019-11-012-1/+84
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is another step how to help maintaining more livepatches. One big help was the atomic replace and cumulative livepatches. These livepatches replace the already installed ones. Therefore it should be enough when each cumulative livepatch is consistent. The problems might come with shadow variables and callbacks. They might change the system behavior or state so that it is no longer safe to go back and use an older livepatch or the original kernel code. Also, a new livepatch must be able to detect changes which were made by the already installed livepatches. This is where the livepatch system state tracking gets useful. It allows to: - find whether a system state has already been modified by previous livepatches - store data needed to manipulate and restore the system state The information about the manipulated system states is stored in an array of struct klp_state. It can be searched by two new functions klp_get_state() and klp_get_prev_state(). The dependencies are going to be solved by a version field added later. The only important information is that it will be allowed to modify the same state by more non-cumulative livepatches. It is similar to allowing to modify the same function several times. The livepatch author is responsible for preventing incompatible changes. Link: http://lkml.kernel.org/r/20191030154313.13263-3-pmladek@suse.com To: Jiri Kosina <jikos@kernel.org> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Cc: Nicolai Stange <nstange@suse.de> Cc: live-patching@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* | livepatch: Keep replaced patches until post_patch callback is calledPetr Mladek2019-11-013-18/+35
|/ | | | | | | | | | | | | | | | | | | | | | | Pre/post (un)patch callbacks might manipulate the system state. Cumulative livepatches might need to take over the changes made by the replaced ones. For this they might need to access some data stored or referenced by the old livepatches. Therefore the replaced livepatches have to stay around until post_patch() callback is called. It is achieved by calling the free functions later. It is the same location where disabled livepatches have already been freed. Link: http://lkml.kernel.org/r/20191030154313.13263-2-pmladek@suse.com To: Jiri Kosina <jikos@kernel.org> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Cc: Nicolai Stange <nstange@suse.de> Cc: live-patching@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* livepatch: Nullify obj->mod in klp_module_coming()'s error pathMiroslav Benes2019-08-191-0/+1
| | | | | | | | | | | | | | | klp_module_coming() is called for every module appearing in the system. It sets obj->mod to a patched module for klp_object obj. Unfortunately it leaves it set even if an error happens later in the function and the patched module is not allowed to be loaded. klp_is_object_loaded() uses obj->mod variable and could currently give a wrong return value. The bug is probably harmless as of now. Signed-off-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2019-07-121-3/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching Pull livepatching updates from Jiri Kosina: - stacktrace handling improvements from Miroslav benes - debug output improvements from Petr Mladek * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: livepatch: Remove duplicate warning about missing reliable stacktrace support Revert "livepatch: Remove reliable stacktrace check in klp_try_switch_task()" stacktrace: Remove weak version of save_stack_trace_tsk_reliable() livepatch: Use static buffer for debugging messages under rq lock livepatch: Remove stale kobj_added entries from kernel-doc descriptions
| * livepatch: Remove duplicate warning about missing reliable stacktrace supportPetr Mladek2019-06-201-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | WARN_ON_ONCE() could not be called safely under rq lock because of console deadlock issues. Moreover WARN_ON_ONCE() is superfluous in klp_check_stack(), because stack_trace_save_tsk_reliable() cannot return -ENOSYS thanks to klp_have_reliable_stack() check in klp_try_switch_task(). [ mbenes: changelog edited ] Signed-off-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
| * Revert "livepatch: Remove reliable stacktrace check in klp_try_switch_task()"Miroslav Benes2019-06-201-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 1d98a69e5cef3aeb68bcefab0e67e342d6bb4dad. Commit 31adf2308f33 ("livepatch: Convert error about unsupported reliable stacktrace into a warning") weakened the enforcement for architectures to have reliable stack traces support. The system only warns now about it. It only makes sense to reintroduce the compile time checking in klp_try_switch_task() again and bail out early. Signed-off-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
| * livepatch: Use static buffer for debugging messages under rq lockPetr Mladek2019-06-051-2/+1
| | | | | | | | | | | | | | | | | | | | | | The err_buf array uses 128 bytes of stack space. Move it off the stack by making it static. It's safe to use a shared buffer because klp_try_switch_task() is called under klp_mutex. Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* | Merge tag 'trace-v5.2-rc4' of ↵Linus Torvalds2019-06-151-0/+6
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: - Out of range read of stack trace output - Fix for NULL pointer dereference in trace_uprobe_create() - Fix to a livepatching / ftrace permission race in the module code - Fix for NULL pointer dereference in free_ftrace_func_mapper() - A couple of build warning clean ups * tag 'trace-v5.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Fix NULL pointer dereference in free_ftrace_func_mapper() module: Fix livepatch/ftrace module text permissions race tracing/uprobe: Fix obsolete comment on trace_uprobe_create() tracing/uprobe: Fix NULL pointer dereference in trace_uprobe_create() tracing: Make two symbols static tracing: avoid build warning with HAVE_NOP_MCOUNT tracing: Fix out-of-range read in trace_stack_print()
| * | module: Fix livepatch/ftrace module text permissions raceJosh Poimboeuf2019-06-141-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's possible for livepatch and ftrace to be toggling a module's text permissions at the same time, resulting in the following panic: BUG: unable to handle page fault for address: ffffffffc005b1d9 #PF: supervisor write access in kernel mode #PF: error_code(0x0003) - permissions violation PGD 3ea0c067 P4D 3ea0c067 PUD 3ea0e067 PMD 3cc13067 PTE 3b8a1061 Oops: 0003 [#1] PREEMPT SMP PTI CPU: 1 PID: 453 Comm: insmod Tainted: G O K 5.2.0-rc1-a188339ca5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014 RIP: 0010:apply_relocate_add+0xbe/0x14c Code: fa 0b 74 21 48 83 fa 18 74 38 48 83 fa 0a 75 40 eb 08 48 83 38 00 74 33 eb 53 83 38 00 75 4e 89 08 89 c8 eb 0a 83 38 00 75 43 <89> 08 48 63 c1 48 39 c8 74 2e eb 48 83 38 00 75 32 48 29 c1 89 08 RSP: 0018:ffffb223c00dbb10 EFLAGS: 00010246 RAX: ffffffffc005b1d9 RBX: 0000000000000000 RCX: ffffffff8b200060 RDX: 000000000000000b RSI: 0000004b0000000b RDI: ffff96bdfcd33000 RBP: ffffb223c00dbb38 R08: ffffffffc005d040 R09: ffffffffc005c1f0 R10: ffff96bdfcd33c40 R11: ffff96bdfcd33b80 R12: 0000000000000018 R13: ffffffffc005c1f0 R14: ffffffffc005e708 R15: ffffffff8b2fbc74 FS: 00007f5f447beba8(0000) GS:ffff96bdff900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc005b1d9 CR3: 000000003cedc002 CR4: 0000000000360ea0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: klp_init_object_loaded+0x10f/0x219 ? preempt_latency_start+0x21/0x57 klp_enable_patch+0x662/0x809 ? virt_to_head_page+0x3a/0x3c ? kfree+0x8c/0x126 patch_init+0x2ed/0x1000 [livepatch_test02] ? 0xffffffffc0060000 do_one_initcall+0x9f/0x1c5 ? kmem_cache_alloc_trace+0xc4/0xd4 ? do_init_module+0x27/0x210 do_init_module+0x5f/0x210 load_module+0x1c41/0x2290 ? fsnotify_path+0x3b/0x42 ? strstarts+0x2b/0x2b ? kernel_read+0x58/0x65 __do_sys_finit_module+0x9f/0xc3 ? __do_sys_finit_module+0x9f/0xc3 __x64_sys_finit_module+0x1a/0x1c do_syscall_64+0x52/0x61 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The above panic occurs when loading two modules at the same time with ftrace enabled, where at least one of the modules is a livepatch module: CPU0 CPU1 klp_enable_patch() klp_init_object_loaded() module_disable_ro() ftrace_module_enable() ftrace_arch_code_modify_post_process() set_all_modules_text_ro() klp_write_object_relocations() apply_relocate_add() *patches read-only code* - BOOM A similar race exists when toggling ftrace while loading a livepatch module. Fix it by ensuring that the livepatch and ftrace code patching operations -- and their respective permissions changes -- are protected by the text_mutex. Link: http://lkml.kernel.org/r/ab43d56ab909469ac5d2520c5d944ad6d4abd476.1560474114.git.jpoimboe@redhat.com Reported-by: Johannes Erdfelt <johannes@erdfelt.com> Fixes: 444d13ff10fb ("modules: add ro_after_init support") Acked-by: Jessica Yu <jeyu@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
* | | treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13Thomas Gleixner2019-05-214-52/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner2019-05-212-0/+2
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge tag 'trace-v5.2' of ↵Linus Torvalds2019-05-161-8/+0
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "The major changes in this tracing update includes: - Removal of non-DYNAMIC_FTRACE from 32bit x86 - Removal of mcount support from x86 - Emulating a call from int3 on x86_64, fixes live kernel patching - Consolidated Tracing Error logs file Minor updates: - Removal of klp_check_compiler_support() - kdb ftrace dumping output changes - Accessing and creating ftrace instances from inside the kernel - Clean up of #define if macro - Introduction of TRACE_EVENT_NOP() to disable trace events based on config options And other minor fixes and clean ups" * tag 'trace-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits) x86: Hide the int3_emulate_call/jmp functions from UML livepatch: Remove klp_check_compiler_support() ftrace/x86: Remove mcount support ftrace/x86_32: Remove support for non DYNAMIC_FTRACE tracing: Simplify "if" macro code tracing: Fix documentation about disabling options using trace_options tracing: Replace kzalloc with kcalloc tracing: Fix partial reading of trace event's id file tracing: Allow RCU to run between postponed startup tests tracing: Fix white space issues in parse_pred() function tracing: Eliminate const char[] auto variables ring-buffer: Fix mispelling of Calculate tracing: probeevent: Fix to make the type of $comm string tracing: probeevent: Do not accumulate on ret variable tracing: uprobes: Re-enable $comm support for uprobe events ftrace/x86_64: Emulate call function while updating in breakpoint handler x86_64: Allow breakpoints to emulate call instructions x86_64: Add gap to int3 to allow for call emulation tracing: kdb: Allow ftdump to skip all but the last few entries tracing: Add trace_total_entries() / trace_total_entries_cpu() ...
| * | livepatch: Remove klp_check_compiler_support()Jiri Kosina2019-05-101-8/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The only purpose of klp_check_compiler_support() is to make sure that we are not using ftrace on x86 via mcount (because that's executed only after prologue has already happened, and that's too late for livepatching purposes). Now that mcount is not supported by ftrace any more, there is no need for klp_check_compiler_support() either. Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1905102346100.17054@cbobk.fhfr.pm Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
* | | Merge tag 'driver-core-5.2-rc1' of ↵Linus Torvalds2019-05-071-1/+2
|\ \ \ | |_|/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core/kobject updates from Greg KH: "Here is the "big" set of driver core patches for 5.2-rc1 There are a number of ACPI patches in here as well, as Rafael said they should go through this tree due to the driver core changes they required. They have all been acked by the ACPI developers. There are also a number of small subsystem-specific changes in here, due to some changes to the kobject core code. Those too have all been acked by the various subsystem maintainers. As for content, it's pretty boring outside of the ACPI changes: - spdx cleanups - kobject documentation updates - default attribute groups for kobjects - other minor kobject/driver core fixes All have been in linux-next for a while with no reported issues" * tag 'driver-core-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (47 commits) kobject: clean up the kobject add documentation a bit more kobject: Fix kernel-doc comment first line kobject: Remove docstring reference to kset firmware_loader: Fix a typo ("syfs" -> "sysfs") kobject: fix dereference before null check on kobj Revert "driver core: platform: Fix the usage of platform device name(pdev->name)" init/config: Do not select BUILD_BIN2C for IKCONFIG Provide in-kernel headers to make extending kernel easier kobject: Improve doc clarity kobject_init_and_add() kobject: Improve docs for kobject_add/del driver core: platform: Fix the usage of platform device name(pdev->name) livepatch: Replace klp_ktype_patch's default_attrs with groups cpufreq: schedutil: Replace default_attrs field with groups padata: Replace padata_attr_type default_attrs field with groups irqdesc: Replace irq_kobj_type's default_attrs field with groups net-sysfs: Replace ktype default_attrs field with groups block: Replace all ktype default_attrs with groups samples/kobject: Replace foo_ktype's default_attrs field with groups kobject: Add support for default attribute groups to kobj_type driver core: Postpone DMA tear-down until after devres release for probe failure ...
| * | livepatch: Replace klp_ktype_patch's default_attrs with groupsKimberly Brown2019-04-251-1/+2
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kobj_type default_attrs field is being replaced by the default_groups field. Replace klp_ktype_patch's default_attrs field with default_groups and use the ATTRIBUTE_GROUPS macro to create klp_patch_groups. This patch was tested by loading the livepatch-sample module and verifying that the sysfs files for the attributes in the default groups were created. Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com> Acked-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge branch 'for-linus' of ↵Linus Torvalds2019-05-071-52/+39
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching Pull livepatching updates from Jiri Kosina: - livepatching kselftests improvements from Joe Lawrence and Miroslav Benes - making use of gcc's -flive-patching option when available, from Miroslav Benes - kobject handling cleanups, from Petr Mladek * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: livepatch: Remove duplicated code for early initialization livepatch: Remove custom kobject state handling livepatch: Convert error about unsupported reliable stacktrace into a warning selftests/livepatch: Add functions.sh to TEST_PROGS_EXTENDED kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled selftests/livepatch: use TEST_PROGS for test scripts
| * | livepatch: Remove duplicated code for early initializationPetr Mladek2019-05-031-16/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kobject_init() call added one more operation that has to be done when doing the early initialization of both static and dynamic livepatch structures. It would have been easier when the early initialization code was not duplicated. Let's deduplicate it for future generations of livepatching hackers. The patch does not change the existing behavior. Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
| * | livepatch: Remove custom kobject state handlingPetr Mladek2019-05-031-39/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kobject_init() always succeeds and sets the reference count to 1. It allows to always free the structures via kobject_put() and the related release callback. Note that the custom kobject state handling was used only because we did not know that kobject_put() can and actually should get called even when kobject_init_and_add() fails. The patch should not change the existing behavior. Suggested-by: "Tobin C. Harding" <tobin@kernel.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
| * | livepatch: Convert error about unsupported reliable stacktrace into a warningPetr Mladek2019-04-291-3/+2
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused that any livepatch was refused when reliable stacktraces were not supported on the given architecture. The limitation is too strong. User space processes are safely migrated even when entering or leaving the kernel. Kthreads transition would need to get forced. But it is safe when: + The livepatch does not change the semantic of the code. + Callbacks do not depend on a safely finished transition. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* / livepatch: Simplify stack trace retrievalThomas Gleixner2019-04-291-13/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace the indirection through struct stack_trace by using the storage array based interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Cc: Andy Lutomirski <luto@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alexander Potapenko <glider@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: linux-mm@kvack.org Cc: David Rientjes <rientjes@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy <robin.murphy@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: David Sterba <dsterba@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: linux-btrfs@vger.kernel.org Cc: dm-devel@redhat.com Cc: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: dri-devel@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094803.437950229@linutronix.de
* Merge branch 'for-5.1/atomic-replace' into for-linusJiri Kosina2019-03-053-26/+18
|\ | | | | | | | | | | | | | | | | | | The atomic replace allows to create cumulative patches. They are useful when you maintain many livepatches and want to remove one that is lower on the stack. In addition it is very useful when more patches touch the same function and there are dependencies between them. It's also a feature some of the distros are using already to distribute their patches.
| * livepatch: Module coming and going callbacks can proceed with all listed patchesPetr Mladek2019-02-061-20/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Livepatches can no longer get enabled and disabled repeatedly. The list klp_patches contains only enabled patches and eventually the patch in transition. The module coming and going callbacks do no longer need to check for these state. They have to proceed with all listed patches. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
| * livepatch: Introduce klp_for_each_patch macroPetr Mladek2019-02-063-5/+11
| | | | | | | | | | | | | | | | | | | | | | | | There are already macros to iterate over struct klp_func and klp_object. Add also klp_for_each_patch(). But make it internal because also klp_patches list is internal. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
| * livepatch: core: Return EOPNOTSUPP instead of ENOSYSAlice Ferrazzi2019-02-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | As a result of an unsupported operation is better to use EOPNOTSUPP as error code. ENOSYS is only used for 'invalid syscall nr' and nothing else. Signed-off-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
* | livepatch: Remove signal sysfs attributeMiroslav Benes2019-01-163-74/+41
| | | | | | | | | | | | | | | | The fake signal is send automatically now. We can rely on it completely and remove the sysfs attribute. Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* | livepatch: Send a fake signal periodicallyMiroslav Benes2019-01-161-3/+13
|/ | | | | | | | | | | | | | | | | | | | | An administrator may send a fake signal to all remaining blocking tasks of a running transition by writing to /sys/kernel/livepatch/<patch>/signal attribute. Let's do it automatically after 15 seconds. The timeout is chosen deliberately. It gives the tasks enough time to transition themselves. Theoretically, sending it once should be more than enough. However, every task must get outside of a patched function to be successfully transitioned. It could prove not to be simple and resending could be helpful in that case. A new workqueue job could be a cleaner solution to achieve it, but it could also introduce deadlocks and cause more headaches with synchronization and cancelling. [jkosina@suse.cz: removed added newline] Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Remove ordering (stacking) of the livepatchesPetr Mladek2019-01-111-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The atomic replace and cumulative patches were introduced as a more secure way to handle dependent patches. They simplify the logic: + Any new cumulative patch is supposed to take over shadow variables and changes made by callbacks from previous livepatches. + All replaced patches are discarded and the modules can be unloaded. As a result, there is only one scenario when a cumulative livepatch gets disabled. The different handling of "normal" and cumulative patches might cause confusion. It would make sense to keep only one mode. On the other hand, it would be rude to enforce using the cumulative livepatches even for trivial and independent (hot) fixes. However, the stack of patches is not really necessary any longer. The patch ordering was never clearly visible via the sysfs interface. Also the "normal" patches need a lot of caution anyway. Note that the list of enabled patches is still necessary but the ordering is not longer enforced. Otherwise, the code is ready to disable livepatches in an random order. Namely, klp_check_stack_func() always looks for the function from the livepatch that is being disabled. klp_func structures are just removed from the related func_stack. Finally, the ftrace handlers is removed only when the func_stack becomes empty. 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>
* livepatch: Remove Nop structures when unusedPetr Mladek2019-01-115-9/+76
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* livepatch: Add atomic replaceJason Baron2019-01-114-8/+236
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sometimes we would like to revert a particular fix. Currently, this is not easy because we want to keep all other fixes active and we could revert only the last applied patch. One solution would be to apply new patch that implemented all the reverted functions like in the original code. It would work as expected but there will be unnecessary redirections. In addition, it would also require knowing which functions need to be reverted at build time. Another problem is when there are many patches that touch the same functions. There might be dependencies between patches that are not enforced on the kernel side. Also it might be pretty hard to actually prepare the patch and ensure compatibility with the other patches. Atomic replace && cumulative patches: A better solution would be to create cumulative patch and say that it replaces all older ones. This patch adds a new "replace" flag to struct klp_patch. When it is enabled, a set of 'nop' klp_func will be dynamically created for all functions that are already being patched but that will no longer be modified by the new patch. They are used as a new target during the patch transition. The idea is to handle Nops' structures like the static ones. When the dynamic structures are allocated, we initialize all values that are normally statically defined. The only exception is "new_func" in struct klp_func. It has to point to the original function and the address is known only when the object (module) is loaded. Note that we really need to set it. The address is used, for example, in klp_check_stack_func(). Nevertheless we still need to distinguish the dynamically allocated structures in some operations. For this, we add "nop" flag into struct klp_func and "dynamic" flag into struct klp_object. They need special handling in the following situations: + The structures are added into the lists of objects and functions immediately. In fact, the lists were created for this purpose. + The address of the original function is known only when the patched object (module) is loaded. Therefore it is copied later in klp_init_object_loaded(). + The ftrace handler must not set PC to func->new_func. It would cause infinite loop because the address points back to the beginning of the original function. + The various free() functions must free the structure itself. Note that other ways to detect the dynamic structures are not considered safe. For example, even the statically defined struct klp_object might include empty funcs array. It might be there just to run some callbacks. Also note that the safe iterator must be used in the free() functions. Otherwise already freed structures might get accessed. Special callbacks handling: The callbacks from the replaced patches are _not_ called by intention. It would be pretty hard to define a reasonable semantic and implement it. It might even be counter-productive. The new patch is cumulative. It is supposed to include most of the changes from older patches. In most cases, it will not want to call pre_unpatch() post_unpatch() callbacks from the replaced patches. It would disable/break things for no good reasons. Also it should be easier to handle various scenarios in a single script in the new patch than think about interactions caused by running many scripts from older patches. Not to say that the old scripts even would not expect to be called in this situation. Removing replaced patches: One nice effect of the cumulative patches is that the code from the older patches is no longer used. Therefore the replaced patches can be removed. It has several advantages: + Nops' structs will no longer be necessary and might be removed. This would save memory, restore performance (no ftrace handler), allow clear view on what is really patched. + Disabling the patch will cause using the original code everywhere. Therefore the livepatch callbacks could handle only one scenario. Note that the complication is already complex enough when the patch gets enabled. It is currently solved by calling callbacks only from the new cumulative patch. + The state is clean in both the sysfs interface and lsmod. The modules with the replaced livepatches might even get removed from the system. Some people actually expected this behavior from the beginning. After all a cumulative patch is supposed to "completely" replace an existing one. It is like when a new version of an application replaces an older one. This patch does the first step. It removes the replaced patches from the list of patches. It is safe. The consistency model ensures that they are no longer used. By other words, each process works only with the structures from klp_transition_patch. The removal is done by a special function. It combines actions done by __disable_patch() and klp_complete_transition(). But it is a fast track without all the transaction-related stuff. Signed-off-by: Jason Baron <jbaron@akamai.com> [pmladek@suse.com: Split, reuse existing code, simplified] Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Jiri Kosina <jikos@kernel.org> Cc: Miroslav Benes <mbenes@suse.cz> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Use lists to manage patches, objects and functionsJason Baron2019-01-111-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently klp_patch contains a pointer to a statically allocated array of struct klp_object and struct klp_objects contains a pointer to a statically allocated array of klp_func. In order to allow for the dynamic allocation of objects and functions, link klp_patch, klp_object, and klp_func together via linked lists. This allows us to more easily allocate new objects and functions, while having the iterator be a simple linked list walk. The static structures are added to the lists early. It allows to add the dynamically allocated objects before klp_init_object() and klp_init_func() calls. Therefore it reduces the further changes to the code. This patch does not change the existing behavior. Signed-off-by: Jason Baron <jbaron@akamai.com> [pmladek@suse.com: Initialize lists before init calls] Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Simplify API by removing registration stepPetr Mladek2019-01-113-193/+108
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* livepatch: Don't block the removal of patches loaded after a forced transitionPetr Mladek2019-01-113-6/+9
| | | | | | | | | | | | | | | | | | | | | | | | | module_put() is currently never called in klp_complete_transition() when klp_force is set. As a result, we might keep the reference count even when klp_enable_patch() fails and klp_cancel_transition() is called. This might give the impression that a module might get blocked in some strange init state. Fortunately, it is not the case. The reference count is ignored when mod->init fails and erroneous modules are always removed. Anyway, this might be confusing. Instead, this patch moves the global klp_forced flag into struct klp_patch. As a result, we block only modules that might still be in use after a forced transition. Newly loaded livepatches might be eventually completely removed later. It is not a big deal. But the code is at least consistent with the reality. Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Consolidate klp_free functionsPetr Mladek2019-01-111-45/+92
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code for freeing livepatch structures is a bit scattered and tricky: + direct calls to klp_free_*_limited() and kobject_put() are used to release partially initialized objects + klp_free_patch() removes the patch from the public list and releases all objects except for patch->kobj + object_put(&patch->kobj) and the related wait_for_completion() are called directly outside klp_mutex; this code is duplicated; Now, we are going to remove the registration stage to simplify the API and the code. This would require handling more situations in klp_enable_patch() error paths. More importantly, we are going to add a feature called atomic replace. It will need to dynamically create func and object structures. We will want to reuse the existing init() and free() functions. This would create even more error path scenarios. This patch implements more straightforward free functions: + checks kobj_added flag instead of @limit[*] + initializes patch->list early so that the check for empty list always works + The action(s) that has to be done outside klp_mutex are done in separate klp_free_patch_finish() function. It waits only when patch->kobj was really released via the _start() part. The patch does not change the existing behavior. [*] We need our own flag to track that the kobject was successfully added to the hierarchy. Note that kobj.state_initialized only indicates that kobject has been initialized, not whether is has been added (and needs to be removed on cleanup). Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Jessica Yu <jeyu@kernel.org> Cc: Jiri Kosina <jikos@kernel.org> Cc: Jason Baron <jbaron@akamai.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Shuffle klp_enable_patch()/klp_disable_patch() codePetr Mladek2019-01-111-164/+166
| | | | | | | | | | | | | | | | We are going to simplify the API and code by removing the registration step. This would require calling init/free functions from enable/disable ones. This patch just moves the code to prevent more forward declarations. This patch does not change the code except for two forward declarations. Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Change unsigned long old_addr -> void *old_func in struct klp_funcPetr Mladek2019-01-114-15/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The address of the to be patched function and new function is stored in struct klp_func as: void *new_func; unsigned long old_addr; The different naming scheme and type are derived from the way the addresses are set. @old_addr is assigned at runtime using kallsyms-based search. @new_func is statically initialized, for example: static struct klp_func funcs[] = { { .old_name = "cmdline_proc_show", .new_func = livepatch_cmdline_proc_show, }, { } }; This patch changes unsigned long old_addr -> void *old_func. It removes some confusion when these address are later used in the code. It is motivated by a followup patch that adds special NOP struct klp_func where we want to assign func->new_func = func->old_addr respectively func->new_func = func->old_func. This patch does not modify the existing behavior. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Alice Ferrazzi <alice.ferrazzi@gmail.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* livepatch: Replace synchronize_sched() with synchronize_rcu()Paul E. McKenney2018-12-012-4/+4
| | | | | | | | | Now that synchronize_rcu() waits for preempt-disable regions of code as well as RCU read-side critical sections, synchronize_sched() can be replaced by synchronize_rcu(). This commit therefore makes this change, even though it is but a comment. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* Merge branch 'for-4.19/upstream' into for-linusJiri Kosina2018-08-201-7/+0
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| * livepatch: Remove reliable stacktrace check in klp_try_switch_task()Kamalesh Babulal2018-07-161-7/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Support for immediate flag was removed by commit d0807da78e11 ("livepatch: Remove immediate feature"). We bail out during patch registration for architectures, those don't support reliable stack trace. Remove the check in klp_try_switch_task(), as its not required. Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Reviewed-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>
* | livepatch: Validate module/old func name lengthKamalesh Babulal2018-07-231-0/+6
|/ | | | | | | | | | | | | | | | | | | | | | livepatch module author can pass module name/old function name with more than the defined character limit. With obj->name length greater than MODULE_NAME_LEN, the livepatch module gets loaded but waits forever on the module specified by obj->name to be loaded. It also populates a /sys directory with an untruncated object name. In the case of funcs->old_name length greater then KSYM_NAME_LEN, it would not match against any of the symbol table entries. Instead loop through the symbol table comparing them against a nonexisting function, which can be avoided. The same issues apply, to misspelled/incorrect names. At least gatekeep the modules with over the limit string length, by checking for their length during livepatch module registration. Cc: stable@vger.kernel.org Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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