linux-toradex.git/kernel/livepatch/core.c, branch v4.6-rc6

livepatch/module: remove livepatch module notifier

2016-03-17T08:45:10+00:00

Remove the livepatch module notifier in favor of directly enabling and
disabling patches to modules in the module loader. Hard-coding the
function calls ensures that ftrace_module_enable() is run before
klp_module_coming() during module load, and that klp_module_going() is
run before ftrace_release_mod() during module unload. This way, ftrace
and livepatch code is run in the correct order during the module
load/unload sequence without dependence on the module notifier call chain.

Signed-off-by: Jessica Yu 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Acked-by: Rusty Russell 
Signed-off-by: Jiri Kosina

livepatch: Fix the error message about unresolvable ambiguity

2016-03-09T20:58:41+00:00

klp_find_callback() stops the search when sympos is not defined and
a second symbol of the same name is found. It means that the current
error message about the unresolvable ambiguity always prints "(2 matches)".

Let's remove this information. The total number of occurrences is
not much helpful. The author of the patch still must put a non-trivial
effort into searching the right position in the object file.

[jkosina@suse.cz: fixed grammar as suggested by Josh]
Signed-off-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Acked-by: Chris J Arges 
Signed-off-by: Jiri Kosina

livepatch: Cleanup module page permission changes

2015-12-04T21:51:07+00:00

Calling set_memory_rw() and set_memory_ro() for every iteration of the
loop in klp_write_object_relocations() is messy, inefficient, and
error-prone.

Change all the read-only pages to read-write before the loop and convert
them back to read-only again afterwards.

Suggested-by: Miroslav Benes 
Signed-off-by: Josh Poimboeuf 
Reviewed-by: Petr Mladek 
Signed-off-by: Jiri Kosina

livepatch: function,sympos scheme in livepatch sysfs directory

2015-12-03T22:01:27+00:00

The following directory structure will allow for cases when the same
function name exists in a single object.
	/sys/kernel/livepatch///

The sympos number corresponds to the nth occurrence of the symbol name in
kallsyms for the patched object.

An example of patching multiple symbols can be found here:
	https://github.com/dynup/kpatch/issues/493

Signed-off-by: Chris J Arges 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: add sympos as disambiguator field to klp_reloc

2015-12-03T22:01:27+00:00

In cases of duplicate symbols, sympos will be used to disambiguate instead
of val. By default sympos will be 0, and patching will only succeed if
the symbol is unique. Specifying a positive value will ensure that
occurrence of the symbol in kallsyms for the patched object will be used
for patching if it is valid. For external relocations sympos is not
supported.

Remove klp_verify_callback, klp_verify_args and klp_verify_vmlinux_symbol
as they are no longer used.

From the klp_reloc structure remove val, as it can be refactored as a
local variable in klp_write_object_relocations.

Signed-off-by: Chris J Arges 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: add old_sympos as disambiguator field to klp_func

2015-12-03T22:01:26+00:00

Currently, patching objects with duplicate symbol names fail because the
creation of the sysfs function directory collides with the previous
attempt. Appending old_addr to the function name is problematic as it
reveals the address of the function being patch to a normal user. Using
the symbol's occurrence in kallsyms to postfix the function name in the
sysfs directory solves the issue of having consistent unique names and
ensuring that the address is not exposed to a normal user.

In addition, using the symbol position as the user's method to disambiguate
symbols instead of addr allows for disambiguating symbols in modules as
well for both function addresses and for relocs. This also simplifies much
of the code. Special handling for kASLR is no longer needed and can be
removed. The klp_find_verify_func_addr function can be replaced by
klp_find_object_symbol, and klp_verify_vmlinux_symbol and its callback can
be removed completely.

In cases of duplicate symbols, old_sympos will be used to disambiguate
instead of old_addr. By default old_sympos will be 0, and patching will
only succeed if the symbol is unique. Specifying a positive value will
ensure that occurrence of the symbol in kallsyms for the patched object
will be used for patching if it is valid.

In addition, make old_addr an internal structure field not to be specified
by the user. Finally, remove klp_find_verify_func_addr as it can be
replaced by klp_find_object_symbol directly.

Support for symbol position disambiguation for relocations is added in the
next patch in this series.

Signed-off-by: Chris J Arges 
Reviewed-by: Petr Mladek 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: x86: fix relocation computation with kASLR

2015-11-11T16:36:04+00:00

With kASLR enabled, old_addr provided by patch module is being shifted
accrodingly so that the symbol lookups work. To have module relocations
handled properly as well, the same transformation needs to be perfomed
on relocation address information.

[jkosina@suse.cz: extended / reworded changelog a bit]
Reported-by: Cyril B. 
Signed-off-by: Zhou Chengming 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

livepatch: Improve error handling in klp_disable_func()

2015-07-14T20:48:06+00:00

In case of func->state or func->old_addr not having expected values,
we'd rather bail out immediately from klp_disable_func().

This can't really happen with the current codebase, but fix this
anyway in the sake of robustness.

[jkosina@suse.com: reworded the changelog a bit]
Signed-off-by: Minfei Huang 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina

Merge branches 'for-4.1/upstream-fixes', 'for-4.2/kaslr' and 'for-4.2/upstream' into for-linus

2015-06-22T14:26:56+00:00

livepatch: add module locking around kallsyms calls

2015-06-02T20:54:38+00:00

The list of loaded modules is walked through in
module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The
module_mutex lock should be acquired to prevent potential corruptions
in the list.

This was uncovered with new lockdep asserts in module code introduced by
the commit 0be964be0d45 ("module: Sanitize RCU usage and locking") in
recent next- trees.

Signed-off-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina