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livepatch: enforce patch stacking semantics

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Only allow the topmost patch on the stack to be enabled or disabled, so
that patches can't be removed or added in an arbitrary order.

Suggested-by: Jiri Kosina <jkosina@suse.cz>
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 is contained in:
Josh Poimboeuf 2015-01-20 09:26:18 -06:00 committed by Jiri Kosina
parent 32b7eb8771
commit 83a90bb134
1 changed files with 10 additions and 0 deletions
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10
kernel/livepatch/core.c
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@ -379,6 +379,11 @@ static int __klp_disable_patch(struct klp_patch *patch)
struct klp_object *obj; struct klp_object *obj;
int ret; int ret;
/* enforce stacking: only the last enabled patch can be disabled */
if (!list_is_last(&patch->list, &klp_patches) &&
list_next_entry(patch, list)->state == KLP_ENABLED)
return -EBUSY;
pr_notice("disabling patch '%s'\n", patch->mod->name); pr_notice("disabling patch '%s'\n", patch->mod->name);
for (obj = patch->objs; obj->funcs; obj++) { for (obj = patch->objs; obj->funcs; obj++) {
@ -435,6 +440,11 @@ static int __klp_enable_patch(struct klp_patch *patch)
if (WARN_ON(patch->state != KLP_DISABLED)) if (WARN_ON(patch->state != KLP_DISABLED))
return -EINVAL; return -EINVAL;
/* enforce stacking: only the first disabled patch can be enabled */
if (patch->list.prev != &klp_patches &&
list_prev_entry(patch, list)->state == KLP_DISABLED)
return -EBUSY;
pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n"); pr_notice_once("tainting kernel with TAINT_LIVEPATCH\n");
add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK); add_taint(TAINT_LIVEPATCH, LOCKDEP_STILL_OK);