Lines Matching +full:target +full:- +full:module

5 Livepatch (un)patch-callbacks provide a mechanism for livepatch modules
10   - Safe updates to global data
12   - "Patches" to init and probe functions
14   - Patching otherwise unpatchable code (i.e. assembly)
22   - Module init/exit code doesn't run when disabling and re-enabling a
25   - A module notifier can't stop a to-be-patched module from loading.
29 be patched, irrespective of the target klp_object's current state.
33   * Pre-patch    - before a klp_object is patched
35   * Post-patch   - after a klp_object has been patched and is active
38   * Pre-unpatch  - before a klp_object is unpatched (ie, patched code is
39                    active), used to clean up post-patch callback
42   * Post-unpatch - after a klp_object has been patched, all code has
44                    used to cleanup pre-patch callback resources
48 symmetry: pre-patch callbacks have a post-unpatch counterpart and
49 post-patch callbacks have a pre-unpatch counterpart.  An unpatch
56 in-kernel vmlinux targets, this means that callbacks will always execute
57 when a livepatch is enabled/disabled.  For patch target kernel modules,
58 callbacks will only execute if the target module is loaded.  When a
59 module target is (un)loaded, its callbacks will execute only if the
60 livepatch module is enabled.
62 The pre-patch callback, if specified, is expected to return a status
63 code (0 for success, -ERRNO on error).  An error status code indicates
65 safe and to stop the current patching request.  (When no pre-patch
67 pre-patch callback returns failure, the kernel's module loader will:
69   - Refuse to load a livepatch, if the livepatch is loaded after
74   - Refuse to load a module, if the livepatch was already successfully
77 No post-patch, pre-unpatch, or post-unpatch callbacks will be executed
81 If a patch transition is reversed, no pre-unpatch handlers will be run
82 (this follows the previously mentioned symmetry -- pre-unpatch callbacks
83 will only occur if their corresponding post-patch callback executed).
87 only the post-unpatch callback will be called.
90 Example Use-cases
94 ------------------
96 A pre-patch callback can be useful to update a global variable.  For
102 patch the data *after* patching is complete with a post-patch callback,
108 -----------------------------------------
110 Although __init and probe functions are not directly livepatch-able, it
111 may be possible to implement similar updates via pre/post-patch
114 48900cb6af42 ("virtio-net: drop NETIF_F_FRAGLIST") change the way that
116 pre/post-patch callback could iterate over all such devices, making a
125 pre/post-(un)patch combination, but a selection that demonstrates a few
132 ------
134 Test a combination of loading a kernel module and a livepatch that
135 patches a function in the first module.  (Un)load the target module
136 before the livepatch module:
138 - load target module
139 - load livepatch
140 - disable livepatch
141 - unload target module
142 - unload livepatch
144 First load a target module:
146   % insmod samples/livepatch/livepatch-callbacks-mod.ko
149 On livepatch enable, before the livepatch transition starts, pre-patch
152 to the klp_patch, their post-patch callbacks run and the transition
155   % insmod samples/livepatch/livepatch-callbacks-demo.ko
159 …[   36.504721] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
163 …[   37.727860] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_S…
166 Similarly, on livepatch disable, pre-patch callbacks run before the
167 unpatching transition starts.  klp_objects are reverted, post-patch
173 …[   38.510982] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_…
177 …[   39.711779] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
180   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
181   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
186 ------
189 module before the target kernel module.  This tests the livepatch core's
192 - load livepatch
193 - load target module
194 - disable livepatch
195 - unload livepatch
196 - unload target module
199 On livepatch enable, only pre/post-patch callbacks are executed for
202   % insmod samples/livepatch/livepatch-callbacks-demo.ko
211 When a targeted module is subsequently loaded, only its pre/post-patch
214   % insmod samples/livepatch/livepatch-callbacks-mod.ko
215 …[   46.560845] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_c…
216 …[   46.561988] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
217 …[   46.563452] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_S…
221 livepatch_callbacks_mod) pre/post-unpatch callbacks are executed:
226 …[   48.569441] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_…
230 …[   49.759742] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
233   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
234   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
239 ------
241 Test loading the livepatch after a targeted kernel module, then unload
242 the kernel module before disabling the livepatch.  This tests the
245 - load target module
246 - load livepatch
247 - unload target module
248 - disable livepatch
249 - unload livepatch
251 First load a target module, then the livepatch:
253   % insmod samples/livepatch/livepatch-callbacks-mod.ko
256   % insmod samples/livepatch/livepatch-callbacks-demo.ko
260 …[   56.614818] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
264 …[   57.759621] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_S…
267 When a target module is unloaded, the livepatch is only reverted from
269 post-unpatch callbacks are executed when this occurs:
271   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
273 …[   58.623903] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_…
274 …[   58.624658] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatc…
275 …[   58.625305] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
277 When the livepatch is disabled, pre and post-unpatch callbacks are run
288   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
292 ------
298 - load livepatch
299 - load target module
300 - unload target module
301 - disable livepatch
302 - unload livepatch
306   % insmod samples/livepatch/livepatch-callbacks-demo.ko
315 When a targeted kernel module is subsequently loaded, only its
316 pre/post-patch callbacks are executed:
318   % insmod samples/livepatch/livepatch-callbacks-mod.ko
319 …[   66.669196] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_c…
320 …[   66.669882] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
321 …[   66.670744] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_S…
324 When the target module is unloaded, the livepatch is only reverted from
326 post-unpatch callbacks are executed when this occurs:
328   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
330 …[   68.680688] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_…
331 …[   68.681452] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatc…
332 …[   68.682094] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
342   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
346 ------
348 A simple test of loading a livepatch without one of its patch target
351 - load livepatch
352 - disable livepatch
353 - unload livepatch
357   % insmod samples/livepatch/livepatch-callbacks-demo.ko
366 As expected, only pre/post-(un)patch handlers are executed for vmlinux:
376   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
380 ------
382 Test a scenario where a vmlinux pre-patch callback returns a non-zero
385 - load target module
386 - load livepatch -ENODEV
387 - unload target module
389 First load a target module:
391   % insmod samples/livepatch/livepatch-callbacks-mod.ko
394 Load the livepatch module, setting its 'pre_patch_ret' value to -19
395 (-ENODEV).  When its vmlinux pre-patch callback executed, this status
396 code will propagate back to the module-loading subsystem.  The result is
397 that the insmod command refuses to load the livepatch module:
399   % insmod samples/livepatch/livepatch-callbacks-demo.ko pre_patch_ret=-19
403   [   82.748237] livepatch: pre-patch callback failed for object 'vmlinux'
408 …[   82.765809] insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-demo.k…
410   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
415 ------
418 pre-patch callback returns success.  However, when a targeted kernel
419 module is later loaded, have the livepatch return a failing status code:
421 - load livepatch
422 - setup -ENODEV
423 - load target module
424 - disable livepatch
425 - unload livepatch
427 Load the livepatch, notice vmlinux pre-patch callback succeeds:
429   % insmod samples/livepatch/livepatch-callbacks-demo.ko
438 Set a trap so subsequent pre-patch callbacks to this livepatch will
439 return -ENODEV:
441   % echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
443 The livepatch pre-patch callback for subsequently loaded target modules
444 will return failure, so the module loader refuses to load the kernel
445 module.  Notice that no post-patch or pre/post-unpatch callbacks are
448   % insmod samples/livepatch/livepatch-callbacks-mod.ko
449 …[   90.796976] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_c…
450 …[   90.797834] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
451   [   90.798900] livepatch: pre-patch callback failed for object 'livepatch_callbacks_mod'
452 …ch: patch 'livepatch_callbacks_demo' failed for module 'livepatch_callbacks_mod', refusing to load…
453 …[   90.819737] insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko…
455 However, pre/post-unpatch callbacks run for the vmlinux klp_object:
465   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
469 ------
471 Test loading multiple targeted kernel modules.  This test-case is
472 mainly for comparing with the next test-case.
474 - load busy target module (0s sleep),
475 - load livepatch
476 - load target module
477 - unload target module
478 - disable livepatch
479 - unload livepatch
480 - unload busy target module
483 Load a target "busy" kernel module which kicks off a worker function
486   % insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=0
491 Proceed with loading the livepatch and another ordinary target module,
492 notice that the post-patch callbacks are executed and the transition
495   % insmod samples/livepatch/livepatch-callbacks-demo.ko
499 …[   98.918955] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_busymod -> [MODUL…
503 …[   99.743679] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_busymod -> [MODU…
506   % insmod samples/livepatch/livepatch-callbacks-mod.ko
507 …[  100.930955] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_c…
508 …[  100.931668] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
509 …[  100.932645] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_S…
512   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
514 …[  102.943640] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_…
515 …[  102.944585] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatc…
516 …[  102.945455] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
521 …[  104.954431] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_busymod -> [MOD…
525 …[  106.723282] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_busymod -> [MO…
528   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
529   % rmmod samples/livepatch/livepatch-callbacks-busymod.ko
534 ------
536 A similar test as the previous one, but force the "busy" kernel module
540 executing a to-be-patched function -- the consistency model stalls the
541 current patch transition until this safety-check is met.  Test a
542 scenario where one of a livepatch's target klp_objects sits on such a
543 function for a long time.  Meanwhile, load and unload other target
546 - load busy target module (30s sleep)
547 - load livepatch
548 - load target module
549 - unload target module
550 - disable livepatch
551 - unload livepatch
552 - unload busy target module
555 Load the "busy" kernel module, this time make it do 30 seconds worth of
558   % insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
563 does not complete as the targeted "busy" module is sitting on a
564 to-be-patched function:
566   % insmod samples/livepatch/livepatch-callbacks-demo.ko
570 …[  113.001289] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_busymod -> [MODUL…
573 Load a second target module (this one is an ordinary idle kernel
574 module).  Note that *no* post-patch callbacks will be executed while the
577   % insmod samples/livepatch/livepatch-callbacks-mod.ko
578 …[  115.012740] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_c…
579 …[  115.013406] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_ST…
582 Request an unload of the simple kernel module.  The patch is still
583 transitioning, so its pre-unpatch callbacks are skipped:
585   % rmmod samples/livepatch/livepatch-callbacks-mod.ko
587 …[  117.023376] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatc…
588 …[  117.024533] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE…
591 klp_object's post-patch callbacks executed, the remaining klp_object's
592 pre-unpatch callbacks are skipped:
599 …[  119.714653] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_busymod -> [MO…
602   % rmmod samples/livepatch/livepatch-callbacks-demo.ko
603   % rmmod samples/livepatch/livepatch-callbacks-busymod.ko