Currently kpatch rely on systemd to load all kmods on startup.
This patch aims to enable kpatch to be used on upstart systems.
Limitations:
With systemd, it would be possible to unload all modules by issuing:
systemctl stop kpatch
It was not possible to make a reasonable upstart's equivalent of it, so
to unload the modules it will be necessary to call kpatch explicitly:
kpatch unload --all
I believe this it an non-issue, as it is still possible to unload
the modules by calling kpatch explicitly.
The file /etc/init/kpatch.conf will be installed unconditionally, and
removed on uninstall.
On my tests I have verified that all newly added files by this commit
are also deleted on uninstall.
It was also verified that applied patches are loaded again on startup.
rpmlint does not complain about anything new.
Signed-off-by: Bruno Loreto <loretob@amazon.com>
Fixes sparse warnings:
kmod/core/core.c:142:20: warning: symbol 'trace' was not declared. Should it be static?
livepatch-patch-hook.c:73:18: warning: symbol 'lpatch' was not declared. Should it be static?
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Cleanup some of the new bash script code to appease 'make check':
- kpatch: Use integer comparison for $MAX_LOAD_ATTEMPTS
- kpatch-build: Quote ${TEMPDIR} variable
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
kpatch_include_symbol() is confusing. Refactor it:
- Remove the "inclusion tree" debug messages. I never use them, and
they just help make the code more confusing and the debug output more
cluttered.
- Split it up into two functions: kpatch_include_symbol() and
kpatch_include_section(), so that kpatch_include_section() can be used
elsewhere.
- Call kpatch_include_section() from kpatch_include_standard_elements().
This covertly fixes#702, by also including the .rela.rodata section.
- Add a bunch of comments to clarify some of the trickier points.
Fixes#702.
Fixes#807.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
It was observed by Evgenii Shatokhin in PR#755, that when the RCU
callback was called on the patched function, from unloaded livepatch
module triggered a kernel crash.
This patch implements the approach on PowerPC outlined in PR#755.
With -mcmodel=large, like any other data, function pointers are also
loaded relative to the current TOC base and are populated as
relocation entries in .toc section. Every function passing a function
pointer as the argument need to load the function address through
.toc section + offset. Convert such .toc + offset relocation into
a dynamic rela, which resolves to original function address, during
module load.
Also move the comment related to nested function check, into
may_need_dynrela().
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
Cc: Joe Lawrence <jdl1291@gmail.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
A kernel crash happened in __do_softirq() in very rare cases when the
binary patch created from mainline commit be82485fbcbb
("netlink: fix an use-after-free issue for nlk groups") was unloaded.
Investigation has shown that the kernel tried to execute an RCU
callback, deferred_put_nlk_sk(), defined in the patch module after the
module had been unloaded.
The callback was set by the patched variant of netlink_release() and
the address of the patched deferred_put_nlk_sk() was used, rather than
the address of the original function.
Similar problems occur with workqueue functions as well.
As suggested in
https://github.com/dynup/kpatch/pull/755#issuecomment-344135224,
create-diff-object was modified so that the addresses of the original
functions were used in such situations, at least for x86 systems. A
similar fix for PowerPC was added as well.
Changes in v4:
* '#ifdef __x86_64__' was removed. It is not actually needed right now
because the constants for relocation types are different on different
architectures.
Changes in v3:
* Minor refactoring and a comment explaining what this all is about.
Quite lengthy, but the dynrela-related code is really far from obvious.
Changes in v2:
* Handle the nested functions the same way as before, because they are
unlikely to be used as asynchronous callbacks. Example: cmp() in
bch_cache_show() from drivers/md/bcache/sysfs.c in the kernel 4.4.
As the nested functions are local to the functions they are defined in,
the compiler names them in a similar way to static locals: <name>.<number>.
Currently, we filter out all functions with '.' in their names. If there
are any asynchronous callbacks in the kernel that have a dot in their
names too, they could be handled in the future patches. It is unclear
though, if the callbacks with such names can appear in the kernel.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
Don't die outright when encountering an 'undefined reference' error,
instead write those down and check if needed symbols are provided by the
resulting module or core kpatch module.
Fixes#783.
v2:
- make undefined_references and new_symbols unique before comparing
- remove leftover $KMOD_PATH from new_symbols readelf
Signed-off-by: Artem Savkov <asavkov@redhat.com>
for-next branch of kbuild repo contains a "kbuild: rename built-in.o to
built-in.a" which renames all built-in.o instances. Filter on both .o
and .a in kpatch-gcc/kpatch-build to be prepared for this change.
Fixes#800.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Effective Kernel v4.16, the immediate flag is removed by upstream
kernel commit d0807da78e11 ("livepatch: Remove immediate feature").
Add an upper bound kernel version check for inclusion of the
immediate flag.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
With kernel commit b1fca27d384 ("kernel debug: support resetting
WARN*_ONCE") the *_ONCE warnings are placed .data.once section.
Including .data.once section is valid, so add an check in
kpatch_verify_patchability() while checking for included invalid
sections.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Symbols with R_PPC64_REL24 relocation type are functions and it's
currently assumed that all functions are replaced with their respective
section symbols.
There are function whose reference are not straight forward section
symbol but section + offset. These function replacement should be
handled more like bundled sections. Remove the check, which imposes
the inital assumption.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
.toc section entries are mostly place holder for relocation entries,
specified in .rela.toc section. Sometimes, .toc section may have
constants as entries. These constants are not reference to any symbols,
but plain instructions mostly due to some arthimetics in the functions
referring them.
They are referred by the functions like normal .toc entries, these
entries can not be resolved to any symbols. This patch creates a list
of constants if available for .toc sections and compares them in
rela_equal() to ensure their is no mismatch in the generated constants
for original and patched .o files.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
GCC 7.2.1 complains about the usage of the PPC64_LOCAL_ENTRY_OFFSET
macro:
create-diff-object.c: In function ‘is_gcc6_localentry_bundled_sym’:
create-diff-object.c:119:83: error: ‘<<’ in boolean context, did you mean ‘<’ ? [-Werror=int-in-bool-context]
(((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
create-diff-object.c:140:10: note: in expansion of macro ‘PPC64_LOCAL_ENTRY_OFFSET’
return (PPC64_LOCAL_ENTRY_OFFSET(sym->sym.st_other) &&
^~~~~~~~~~~~~~~~~~~~~~~~
Fix it by explicitly treating the macro as an integer instead of a bool.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
On ppc64le, building drivers/media/i2c/cx25840/cx25840.ko with GCC 4.85,
the plugin triggers the following errors:
{standard input}: Assembler messages:
{standard input}:1078: Error: operand out of range (0x0000000000008fd4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:1288: Error: operand out of range (0x000000000000874c is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:3844: Error: operand out of range (0x00000000000080e8 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:4028: Error: operand out of range (0x00000000000082b4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:4031: Error: operand out of range (0x00000000000080b4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6661: Error: operand out of range (0x000000000000841c is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6664: Error: operand out of range (0x0000000000008214 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6845: Error: operand out of range (0x00000000000089dc is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6848: Error: operand out of range (0x00000000000087d4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:7587: Error: operand out of range (0x0000000000008930 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:7590: Error: operand out of range (0x0000000000008728 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:14592: Error: operand out of range (0xffffffffffff79b8 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
make[1]: *** [drivers/media/i2c/cx25840/cx25840-core.o] Error 1
The problem is that the plugin nops were inserted too late. GCC laid
out the code with knowledge about the distance between branches, but
then the plugin came along after that and increased the branch distances
by inserting the nops.
Fix it by inserting the nops as early as possible. The 'vregs' pass is
where the insn codes get initialized, so run the plugin immediately
afterwards.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Sometimes git doesn't see that the patches have been reverted, if that
happens during ./scripts/setlocalversion call the resulting patch module
is built with a wrong vermagic because the tree is still considered
dirty.
Fix by moving git update-index call into remove_patches function so that
it is called every time the patches are reverted, not only on cleanup.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
This is similar to how loading of the patches works now. Needed mostly
for the "old" kpatch, i.e. for the kernels that do not support livepatch.
If the patched functions are currently used, loading of the patch fails
with "Device or resource busy" error. kpatch script then retries the
operation several times.
In some cases, it could be convenient to do the same thing when
unloading or simply disabling the patches. One of the use cases is when
it is needed to replace a loaded cumulative patch with its previous
version, esp. if the patches have patch/unpatch hooks. It is often more
reliable to disable the loaded patches first and then load the new
patch. Disable operation may fail due to activeness safety check - so
let us retry it a few times.
v2:
As suggested in PR #790, disable_patch() no longer returns a value but
rather calls die() at the point of error.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
Found in the scope of https://github.com/dynup/kpatch/pull/755 but not
related to the main problem discussed there.
kpatch_create_patches_sections() and kpatch_create_intermediate_sections()
used 'hint' in error messages.
However, the string 'hint' refers to is owned by 'kelf_base' and is
freed before kpatch_create_*_sections() are called. As a result, if
these functions try to output errors and print 'hint',
create-diff-object will crash.
As suggested in the mentioned PR, 'hint' is actually no longer needed at
that stage, so I have removed it from kpatch_create_*_sections().
Kpatch no longer uses initrd to make sure the patch modules are loaded
at boot. The users could either install the provided systemd service
for that or come up with some other solution.
The messages mentioning initrd could confuse the users.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
A cosmetic fix.
If KPATCH_BUILD ending with 'build/' is passed to 'make', KERNELRELEASE
will become 'build' and the error message will look like:
"<...> doesn't exist. Try installing the kernel-devel-build RPM or
linux-headers-build DEB."
Let us fix that.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
... and the interval between the retries.
If activeness safety check fails and the patch fails to load, kpatch waits
for 2 seconds and then retries loading of that patch.
It may be needed to change the number of retries and the interval
between them in some cases, e.g. during stress testing of patches, etc.
Make it a bit easier by keeping these values in the variables close to
the beginning of the script.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
kpatch checks the messages output by insmod to decide if loading failed
with -EBUSY (i.e. activeness safety check failed). It looks for
"Device or resource busy" message, but one cannot guarantee it is not
output in some other language.
Let us use LC_ALL=C to be sure.
Signed-off-by: Evgenii Shatokhin <eshatokhin@virtuozzo.com>
