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 <chris.j.arges@canonical.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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 <chris.j.arges@canonical.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
klp_for_each_object and klp_for_each_func are now used all over the
code. One need not think what is the proper condition to check in the
for loop now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Make kobj variable (of type struct kobject) statically allocated in
klp_object structure. It will allow us to move in the func-object-patch
hierarchy through kobject links.
The only reason to have it dynamic was to not have empty release
callback in the code. However we have empty callbacks for function and
patch in the code now, so it is no longer valid and the advantage of
static allocation is clear.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Storage-class specifier 'extern' is redundant in front of the function
declaration. According to the C specification it has the same meaning as
if not present at all. So remove it.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Rename CONFIG_LIVE_PATCHING to CONFIG_LIVEPATCH to make the naming of
the config and the code more consistent.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Add support for patching a function multiple times. If multiple patches
affect a function, the function in the most recently enabled patch
"wins". This enables a cumulative patch upgrade path, where each patch
is a superset of previous patches.
This requires restructuring the data a little bit. With the current
design, where each klp_func struct has its own ftrace_ops, we'd have to
unregister the old ops and then register the new ops, because
FTRACE_OPS_FL_IPMODIFY prevents us from having two ops registered for
the same function at the same time. That would leave a regression
window where the function isn't patched at all (not good for a patch
upgrade path).
This patch replaces the per-klp_func ftrace_ops with a global klp_ops
list, with one ftrace_ops per original function. A single ftrace_ops is
shared between all klp_funcs which have the same old_addr. This allows
the switch between function versions to happen instantaneously by
updating the klp_ops struct's func_stack list. The winner is the
klp_func at the top of the func_stack (front of the list).
[ jkosina@suse.cz: turn WARN_ON() into WARN_ON_ONCE() in ftrace handler to
avoid storm in pathological cases ]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit introduces code for the live patching core. It implements
an ftrace-based mechanism and kernel interface for doing live patching
of kernel and kernel module functions.
It represents the greatest common functionality set between kpatch and
kgraft and can accept patches built using either method.
This first version does not implement any consistency mechanism that
ensures that old and new code do not run together. In practice, ~90% of
CVEs are safe to apply in this way, since they simply add a conditional
check. However, any function change that can not execute safely with
the old version of the function can _not_ be safely applied in this
version.
[ jkosina@suse.cz: due to the number of contributions that got folded into
this original patch from Seth Jennings, add SUSE's copyright as well, as
discussed via e-mail ]
Signed-off-by: Seth Jennings <sjenning@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Chris J Arges