среда, 7 декабря 2022 г.

timers in linux kernel

timers are very important artifact for forensics, for example Volatility even has plugin to dump timers from windows kernel. Unfortunately Volatility cannot dump timers from linux kernel so I made such dump in my lkcd (with -T option)

kernel timers are just structures timer_list and the most important field is

void (*function)(unsigned long); 

bcs if your machine rootkited - probably one of timers will contains address from some unknown module. timers are chained in linked list via entry field and lots of this lists stored in array vectors into per-cpu variable timer_base. As you can see there can be 2 instances of this structure - this depends from undocumented config option CONFIG_NO_HZ_COMMON

Some timers are part of so called workqueue - structure delayed_work. In such case timer_list.function contains address of exported function delayed_work_timer_fn

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