How su binary works?

Question

I was browsing su binary code by Chainsdd when I was browsing it i saw it using setuid(0) setgid(0) to give root permissions

so my question is : Can this method used in my own c library ?

if not then how does the su does it? is it because it is placed in /system partition with some chmod or other operations like that have been perfomed on it?

this does not belong to android.stackexchange.com because im asking a programmatical question on my own c library — DevUt, Jul 12 '15 at 14:07

score 1 · Accepted Answer · answered Jul 12 '15 at 14:28

1

su executable file should have suid flag set. This allows it to start with uid and gid of its owner which should both be root. From a normal application on Android it's impossible to call setuid(0) or setgid(0) because they're all started with arbitrary non-root uid and gid.

answered Jul 12 '15 at 14:28

Ilya Polenov

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@llya why is my question downvoted? – DevUt Jul 12 '15 at 14:29
I don't know. I'm not the one who downvoted it. – Ilya Polenov Jul 12 '15 at 14:34
Maybe because it's a duplicate question: http://stackoverflow.com/questions/10028032/how-does-su-work-on-android-and-what-are-the-pre-requisites-for-it-to-work-wha – Ilya Polenov Jul 12 '15 at 14:39
but my question is diffreent and it is according to your answer – DevUt Jul 12 '15 at 14:41

How su binary works?

1 Answers1