linux-kernel - Re: [RFC] kreplace: Rebootless kernel updates

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <492AC522.4020202@redhat.com>
Date:	Mon, 24 Nov 2008 10:15:46 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Nikanth Karthikesan <knikanth@...e.de>
CC:	linux-kernel@...r.kernel.org, ananth@...ibm.com,
	davem@...emloft.net, contact@...lice.com, jbarnold@...lice.com,
	tabbott@...lice.com, wdaher@...lice.com, andersk@...lice.com
Subject: Re: [RFC] kreplace: Rebootless kernel updates

Nikanth Karthikesan wrote:
> On Friday 21 November 2008 20:09:52 Masami Hiramatsu wrote:
>> Hi Nikanth,
>>
>> Nikanth Karthikesan wrote:
> 
>> Hmm,
>> Would you like to replace a function to another function?
>> If so, AFAIK, you can do that with kprobe and below pre_handler.
>> (see booster enabled path in setup_singlestep())
>>
>> pre_handler(...)
>> {
>> 	reset_current_kprobe();	/* this kprobe doesn't need any more */
>> 	regs->ip = new_function;	/* change IP to new function */
>> 	preempt_enable_no_resched();	/* recover preempt count */
>> 	return 1;	/* No need to setup singlestep */
>> }
>>
>>
> 
> So, am I seeing worries to enable something, which is already possible, but 
> just not documented?

Actually, you can do this with kprobes, but not documented,
because the regs->ip setup depends on arch. (above code is only for
x86/x86-64).

I think it's easier to just provide above pre_handler for each arch than
jprobe-based kreplace approach.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/