LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
	akpm@linux-foundation.org,
	"K . Prasad" <prasad@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	Quentin Perret <qperret@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	rostedt@goodmis.org
Subject: Re: [PATCH 0/3] Unexport kallsyms_lookup_name() and kallsyms_on_each_symbol()
Date: Mon, 2 Mar 2020 14:28:11 -0500
Message-ID: <20200302192811.n6o5645rsib44vco@localhost> (raw)
In-Reply-To: <20200221114404.14641-1-will@kernel.org>

On 21-Feb-2020 11:44:01 AM, Will Deacon wrote:
> Hi folks,
> 
> Despite having just a single modular in-tree user that I could spot,
> kallsyms_lookup_name() is exported to modules and provides a mechanism
> for out-of-tree modules to access and invoke arbitrary, non-exported
> kernel symbols when kallsyms is enabled.
> 
> This patch series fixes up that one user and unexports the symbol along
> with kallsyms_on_each_symbol(), since that could also be abused in a
> similar manner.

Hi,

I maintain a GPL kernel tracer (LTTng) since 2005 which happens to be
out-of-tree, even though we have made unsuccessful attempts to upstream
it in the past. It uses kallsyms_lookup_name() to fetch a few symbols. I
would be very glad to have them GPL-exported upstream rather than
relying on this work-around. Here is the list of symbols we would need
to GPL-export:

stack_trace_save
stack_trace_save_user
vmalloc_sync_all (CONFIG_X86)
get_pfnblock_flags_mask
disk_name
block_class
disk_type
global_wb_domain
task_prio

In order to provide address-to-symbol mapping at trace post-processing
(for which we have a prototype branch), we would also need the "_text"
symbol to be GPL-exported, as well as the list of currently loaded
modules (LIST_HEAD(modules) or a getter function).

The tricky part is justifying having those exported for a project
which is not upstream.

I welcome advice on this matter,

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-21 11:44 Will Deacon
2020-02-21 11:44 ` [PATCH 1/3] samples/hw_breakpoint: Drop HW_BREAKPOINT_R when reporting writes Will Deacon
2020-02-21 14:12   ` Christoph Hellwig
2020-02-21 11:44 ` [PATCH 2/3] samples/hw_breakpoint: Drop use of kallsyms_lookup_name() Will Deacon
2020-02-21 14:13   ` Christoph Hellwig
2020-02-21 14:20     ` Will Deacon
2020-02-21 11:44 ` [PATCH 3/3] kallsyms: Unexport kallsyms_lookup_name() and kallsyms_on_each_symbol() Will Deacon
2020-02-21 11:53   ` Greg Kroah-Hartman
2020-02-21 14:14   ` Christoph Hellwig
2020-02-21 15:11   ` Alexei Starovoitov
2020-02-21 14:27 ` [PATCH 0/3] " Masami Hiramatsu
2020-02-21 14:48   ` Will Deacon
2020-02-21 23:44     ` Masami Hiramatsu
2020-02-21 15:41 ` David Laight
2020-02-21 16:25   ` Quentin Perret
2020-02-25 10:05 ` Miroslav Benes
2020-02-25 12:11   ` Petr Mladek
2020-02-25 15:00     ` Joe Lawrence
2020-02-25 18:01       ` Miroslav Benes
2020-02-26 14:16         ` Joe Lawrence
2020-03-02 19:28 ` Mathieu Desnoyers [this message]
2020-03-02 19:36   ` Greg Kroah-Hartman
2020-03-02 19:39     ` Greg Kroah-Hartman
2020-03-02 20:17       ` Mathieu Desnoyers
2020-03-03  6:57         ` Greg Kroah-Hartman
2020-03-03 16:58           ` Mathieu Desnoyers

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200302192811.n6o5645rsib44vco@localhost \
    --to=mathieu.desnoyers@efficios.com \
    --cc=akpm@linux-foundation.org \
    --cc=ast@kernel.org \
    --cc=frederic@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@lst.de \
    --cc=kernel-team@android.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=prasad@linux.vnet.ibm.com \
    --cc=qperret@google.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git