Commit b1f6f161 authored by Pavel Tatashin's avatar Pavel Tatashin Committed by Kees Cook

printk: honor the max_reason field in kmsg_dumper

kmsg_dump() allows to dump kmesg buffer for various system events: oops,
panic, reboot, etc. It provides an interface to register a callback
call for clients, and in that callback interface there is a field
"max_reason", but it was getting ignored when set to any "reason"
higher than KMSG_DUMP_OOPS unless "always_kmsg_dump" was passed as
kernel parameter.

Allow clients to actually control their "max_reason", and keep the
current behavior when "max_reason" is not set.
Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/lkml/20200515184434.8470-3-keescook@chromium.org/Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 6d3cf962
...@@ -26,6 +26,7 @@ enum kmsg_dump_reason { ...@@ -26,6 +26,7 @@ enum kmsg_dump_reason {
KMSG_DUMP_OOPS, KMSG_DUMP_OOPS,
KMSG_DUMP_EMERG, KMSG_DUMP_EMERG,
KMSG_DUMP_SHUTDOWN, KMSG_DUMP_SHUTDOWN,
KMSG_DUMP_MAX
}; };
/** /**
......
...@@ -3157,12 +3157,19 @@ void kmsg_dump(enum kmsg_dump_reason reason) ...@@ -3157,12 +3157,19 @@ void kmsg_dump(enum kmsg_dump_reason reason)
struct kmsg_dumper *dumper; struct kmsg_dumper *dumper;
unsigned long flags; unsigned long flags;
if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
return;
rcu_read_lock(); rcu_read_lock();
list_for_each_entry_rcu(dumper, &dump_list, list) { list_for_each_entry_rcu(dumper, &dump_list, list) {
if (dumper->max_reason && reason > dumper->max_reason) enum kmsg_dump_reason max_reason = dumper->max_reason;
/*
* If client has not provided a specific max_reason, default
* to KMSG_DUMP_OOPS, unless always_kmsg_dump was set.
*/
if (max_reason == KMSG_DUMP_UNDEF) {
max_reason = always_kmsg_dump ? KMSG_DUMP_MAX :
KMSG_DUMP_OOPS;
}
if (reason > max_reason)
continue; continue;
/* initialize iterator with data about the stored records */ /* initialize iterator with data about the stored records */
......
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