Fix the version checks for when we enable CONFIG_LIVEPATCH on RHEL. It
will be based on the latest upstream code.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Use kpatch-<modname>.ko or livepatch-<modname>.ko depending on the type
of module we're building.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
This patch adds support for livepatch hook based module
creation for PPC64le. It introduces PPC64le architecture
bits:
- Add relocation type of R_PPC64_ADDR64 while parsing powerpc ELF.
- Introduce .toc sections mainpulation.
- Skip kpatch specific details for livepatch hook.
Also remove the definition of rela_insn() for powerpc. The only
call site is been guarded by #ifdef x86.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Restructure kpatch's sysfs interface and mirror the sysfs tree after
livepatch's sysfs layout. With the current sysfs layout, we cannot
distinguish which object a function belongs to, and we cannot tell which
modules/objects are patched. Therefore, restructure the kpatch sysfs tree
such that module/object information is available. With the new layout, each
patched object has its own directory, with each function being a
subdirectory of its object.
Implement this by embedding a kobject struct within the kpatch_module,
kpatch_func, and kpatch_object structs and supplying their ktypes and
kobject release methods.
Before:
/sys/kernel/kpatch
└── patches
└── <patch_module>
├── checksum
├── enabled
└── functions
├── <function> # from <object1>
│ ├── new_addr
│ └── old_addr
├── <function> # from <object2>
│ ├── new_addr
│ └── old_addr
└─── <function> # from <object3>
├── new_addr
└── old_addr
After:
/sys/kernel/kpatch
└── <patch_module>
├── <object1>
│ └── <function,sympos>
│ ├── new_addr
│ └── old_addr
├── <object2>
│ └── <function,sympos>
│ ├── new_addr
│ └── old_addr
├── checksum
├── enabled
└── <object3>
└── <function,sympos>
├── new_addr
└── old_addr
Previous commit "kmod: let kernel apply TAINT_LIVEPATCH" modified the
kpatch patch module to set the "livepatch" module info. This breaks
module loading for kernel config CONFIG_LIVEPATCH=n
kpatch_kmalloc: module is marked as livepatch module, but livepatch support is disabled
kpatch modules can still use TAINT_LIVEPATCH as a per-module taint flag,
but only if it is set after the module loads.
Fixes: 660.
Introduce a second phase in the kpatch-build process that creates kpatch
modules or livepatch modules that use the new klp rela sections depending on
the kernel version being worked on. This change uses the two new programs to
either create a patch module that uses dynrelas (create-kpatch-module) or a
patch module that uses klp rela and arch sections + klp symbols marked with the
correct Elf flags (create-klp-module).
For klp patch modules, the --unique flag for ld is needed to prevent
.parainstructions and .altinstructions sections from different objects
from being merged, as arch_klp_init_object_loaded() applies these sections
per-object.
Upstream commit 2992ef29ae01 ("livepatch/module: make TAINT_LIVEPATCH
module-specific") v4.9+ modified the kernel to add the TAINT_LIVEPATCH
flag on module load. To support this feature, add the "livepatch"
module info in the {k,live}patch modules and drop the add_taint() in the
core module.
Some features were backported into the 4.4 kernel which change the fields
of the livepatch structures. Ensure we can work with either v4.5 or greater,
or Ubuntu 4.4.0-7 or greater.
Backport the symbol lookup and checking code from upstream livepatch
code that relies on a symbol position enumeration rather than a fixed
memory address.
Fixes#617.
Support patching objects that have duplicated function names. This feature was
introduced upstream in Linux v4.5.
This patch appends the symbol position to the symbol structure when
lookup_local_symbol is called. This pos variable is then used when creating the
funcs and dynrelas sections. Finally, incorporate sympos into the livepatch
patch hook only if the kernel version is greater than v4.5. In other cases the
older format is used.
Fixes: #493
Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Fixes issue #494. A null pointer dereference can result with patch
modules for multiple objects since the "vmlinux" patch object's "name"
field is null. strcmp therefore crashes trying to compare object->name
if the current object is vmlinux and the supplied "name" argument is
not. Check that object->name is not null before invoking strcmp.
Adds a new patch module scaffold for use when building against a kernel
with CONFIG_LIVE_PATCHING=y.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
When patching a kernel module, if we can't find a needed dynrela symbol,
we currently assume it's exported. However, it's also possible that
it's provided by another .o in the patch module. Add support for that.
Fixes#445.
Make the kpatch-patch-hook.c function and variable names consistent by
prefixing them all with 'patch_'. This makes it easier to distinguish
the patch hook sections from the patched sections when looking at the
ELF section data.
In order to safely re-enable patch modules, add a special
.kpatch.checksum section containing an md5sum of a patch module's
contents. The contents of this section are exported to sysfs via
patch_init and double checked when kpatch load finds that a module of
the same name is already loaded.
To reduce redundancy, remove/change the old_offset fields in the
kpatch_func and kpatch_patch_func structs to just old_addr. Since
old_offset is being used as a placeholder for old_addr, might as well
consolidate it to just one variable.
Fix incorrect old_offsets for loadable modules during sysfs
initialization in patch_init.
sysfs will be initialized on patch module init regardless of whether
or not the module is loaded. func_old_addr_show() will read from func->old_addr,
which is initially set to 0; it'll be eventually filled in by the core module.
Use this instead of calling printk to avoid unwanted compiler
optimizations which cause kpatch-build errors.
The printk function is annotated with the __cold attribute, which tells
gcc that the function is unlikely to be called. A side effect of this
is that code paths containing calls to printk might also be marked cold,
leading to other functions called in those code paths getting moved into
.text.unlikely or being uninlined.
This macro places printk in its own code path so as not to make the
surrounding code path cold.
I have a related integration test to add, but right now it's broken
because we don't yet properly support the __verbose special section.
That'll be another PR.
Fixes#296.
This macro is for ignoring sections that may change as a side effect of
another change or might be a non-bundlable section; that is one that
does not honor -ffunction-section and create a one-to-one relation from
function symbol to section.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This commit adds the KPATCH_IGNORE_FUNC() macro for ignoring functions
that may change as a side effect of a change in another function. The
WARN class of macros, for example, embed the line number in an
instruction, which will cause the function to be detected as changed
when, in fact, there has been no functional change.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
WARN macros are problematic because they embed the line number in an
instruction. As a result, when a function is changed higher in a file,
the line numbers for any WARN calls below that function in the file can
result in unnecessarily changed functions.
These macros allow a patch author to hard code the line numbers in WARN
macros to prevent functions from otherwise changing and getting pulled
into a patch module unnecessarily.
Some functions in the kernel are always on the stack of some thread
in the system. Attempts to patch these function will currently always
fail the activeness safety check.
However, through human inspection, it can be determined that, for a
particular function, consistency is maintained even if the old and new
versions of the function run concurrently.
This commit introduces a KPATCH_FORCE_UNSAFE() macro to define patched
functions that such be exempted from the activeness safety check.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This commit enables the ability to create user-defined hooks as part of
the normal code patch that can do preparatory work for the application
of the patch. This work could include, but is not limited to, changing
data structure semantics.
The user may define a new function as part of the patch and mark it as a
load-time or unload-time hook with the kpatch_load_hook() and
kpatch_unload_hook() macros. These macros are in an include file that
gets copied into the source tree at include/linux/kpatch-hooks.h at
patch build time. The signature for both hooks is "int kpatch_unload_hook(void)".
For now, the return code is ignored. The hooks may not fail. They also
run in stop_machine() context and may not sleep. These hooks, more or
less, must follow all the rules of interrupt context code.
Right now, if there is a failure in patch_make_dynrelas_list(),
patch_free_objects() is called twice; once in the error section of
patch_make_dynrelas_list() and again in the err_objects section of
patch_init().
This fixes this and cleans up the error handling a bit.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
When patching module A, if one of the new function's relas reference a
symbol in module B, we currently just leave it as a normal rela. But if
module B hasn't been loaded yet, the patch module will fail to load due
to the rela's reference to an undefined symbol.
The fix is to convert these relas to dynrelas, which can be resolved
later in the module notifier when A is loaded.
Also added support for the R_X86_64_NONE relocation type, needed for
dynrelas which reference __fentry__.
The recent module patching code has exposed some problems with our data
structures. We currently patch the funcs and dynrelas individually,
which is kind of scary now that different objects can be patched at
different times. Instead it's cleaner and safer to group them by
patched object.
This patch implements per-object patching and relocations by refactoring
the interfaces:
- Completely separate the create-diff-object <-> patch module interface
from the patch module <-> core module interface. create-diff-object
will include "kpatch-patch.h" but not "kpatch.h". Thus,
create-diff-object has no knowledge about the core module's
interfaces, and the core module has no knowledge about the patch
module's special sections.
- Newly added kpatch-patch.h defines the format of the patch module
special sections. It's used by create-diff-object to create the
special sections and used by the patch module to read them.
- kpatch.h still defines the core module interfaces. Each kpatch_module
has a list of kpatch_objects for each module object to be patched.
Each kpatch_object has a list of kpatch_funcs and a list of
kpatch_dynrelas. The patch module creates these lists when populating
kpatch_module.
This way of structuring the data allows us to patch funcs and dynrelas
on a per patched object basis, which will allow us to catch more error
scenarios and make the code easier to manage going forward. It also
allows the use of much more common code between kpatch_register() and
kpatch_module_notify().
Make old addresses relative to the start address of the relocatable
kernel or module.
This commit has no functional effect; it just prepares the code for
future acceptance of the module patching support.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
This feature is implemented as:
```
[root@localhost kpatch]# insmod ./kpatch-meminfo.ko
[root@localhost kpatch]# ls /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/
new_addr old_addr
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/new_addr
0xffffffffa05211e0
[root@localhost kpatch]# cat /sys/kernel/kpatch/patches/kpatch_meminfo/functions/meminfo_proc_show/old_addr
0xffffffff8125d0e0
```
The patch module init function will allocate and init kpatch_func_obj with
customized kobj_type func_ktype. The attribute new_addr and old_addr of
kpatch_func_obj is attached to this func_ktype, so that these files could
be created by kobject_add automatically.
Signed-off-by: Jincheng Miao <jincheng.miao@gmail.com>
This adds dynamic linking support for the patch modules. It is the
first step toward supporting patching module code and relocatable
kernels.
Rela entries that reference non-included local and non-exported global
symbols are converted to "dynrelas". These dynrelas are relocations
that are done by the core module, not the kernel module linker. This
allows the core module to apply offsets to the base addresses found
in the base vmlinux or module.
Signed-off-by: Seth Jennings <sjenning@redhat.com>
Conflicts:
kpatch-build/kpatch-build
We merged PR #186 a little too hastily. It seg faults with the new
parainstructions-section.patch in the integration test suite. Reverting
it for now until we get it figured out.
This reverts commit e1177e3a03.
This reverts commit 880e271841.
This reverts commit 2de5f6cbfb.
This reverts commit 38b7ac74ad.
This reverts commit 108cd9f95e.
