Home » Mailing list archives » linux-kernel » 2008 » February » 10

kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit

Previous thread: [PATCH] Silent compiler warning introduced by commit 801c135ce73d5df1caf3eca35b66a10824ae0707 (UBI: Unsorted Block Images) by S.Çağlar on Saturday, February 9, 2008 - 11:37 pm. (4 messages)

Next thread: /bin/sh: -c: line 0: syntax error near unexpected token `;' by Mr. James W. Laferriere on Sunday, February 10, 2008 - 2:08 am. (1 message)
[view original message]
From: Niki Denev <ndenev@...>
To: <linux-kernel@...>
Subject: kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 2:04 am

Hi,


As the subject says the 2.6.24.1 is still vulnerable to the vmsplice

local root exploit.


[opa@test tmp]$ uname -a

Linux tester 2.6.24.1 #1 Sun Feb 10 00:06:49 EST 2008 i686 unknown

[opa@test tmp]$ ./vms


-----------------------------------

 Linux vmsplice Local Root Exploit

 By qaaz

-----------------------------------

[+] mmap: 0x0 .. 0x1000

[+] page: 0x0

[+] page: 0x20

[+] mmap: 0x4000 .. 0x5000

[+] page: 0x4000

[+] page: 0x4020

[+] mmap: 0x1000 .. 0x2000

[+] page: 0x1000

[+] mmap: 0xb7f56000 .. 0xb7f88000

[+] root

[root@test tmp]#

[root@test tmp]# id

uid=0(root) gid=0(root) groups=2033(opa)

[root@test tmp]# uname -a

Linux test 2.6.24.1 #1 Sun Feb 10 00:06:49 EST 2008 i686 unknown


Is there any known fix/patch for this?

--
[view original message]
From: Willy Tarreau <w@...>
To: Niki Denev <ndenev@...>
Cc: <linux-kernel@...>, <jens.axboe@...>
Subject: Re: kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 2:32 am

Yes indeed, that's quite bad. 2.6.24-git is still vulnerable too, and

also contains the fix :-(


CC'd Jens as he worked on the fix.


Willy


--
[view original message]
From: Niki Denev <ndenev@...>
To: Willy Tarreau <w@...>
Cc: <linux-kernel@...>, <jens.axboe@...>
Subject: Re: kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 2:38 am

I was unable to gain root on 2.6.24-git20

but after several segfaults when executing the exploit continously

the machine crashes.


--Niki

--
[view original message]
From: Niki Denev <ndenev@...>
To: Willy Tarreau <w@...>
Cc: <linux-kernel@...>, <jens.axboe@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 5:40 am

this fixed the problem for me (kernel 2.6.24.1) :

It appears that the initial patch checked the input to vmsplice_to_user,

but the exploit used vmsplice_to_pipe which remained open to the attack.


--- fs/splice.c.orig	2008-02-08 21:55:30.000000000 +0200

+++ fs/splice.c	2008-02-10 11:32:50.000000000 +0200

@@ -1443,6 +1443,10 @@

 	struct pipe_inode_info *pipe;

 	struct page *pages[PIPE_BUFFERS];

 	struct partial_page partial[PIPE_BUFFERS];

+	int error;

+	long ret;

+	void __user *base;

+	size_t len;

 	struct splice_pipe_desc spd = {

 		.pages = pages,

 		.partial = partial,

@@ -1450,6 +1454,31 @@

 		.ops = &user_page_pipe_buf_ops,

 	};


+	error = ret = 0;

+

+	/*

+	 * Get user address base and length for this iovec.

+	 */

+	error = get_user(base, &iov->iov_base);

+	if (unlikely(error))

+		return error;

+	error = get_user(len, &iov->iov_len);

+	if (unlikely(error))

+		return error;

+

+	/*

+	 * Sanity check this iovec. 0 read succeeds.

+	 */

+	if (unlikely(!len))

+		return 0;

+	if (unlikely(!base)) {

+		return -EFAULT;

+	}

+

+	if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {

+		return -EFAULT;

+	}

+

 	pipe = pipe_info(file->f_path.dentry->d_inode);

 	if (!pipe)

 		return -EBADF;

--
[view original message]
From: Bastian Blank <bastian@...>
To: Niki Denev <ndenev@...>, Willy Tarreau <w@...>
Cc: <linux-kernel@...>, <jens.axboe@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 8:22 am

Use VERIFY_READ and this only checks the first entry.


I checked the following patch and it at least fixes the known exploit.


diff --git a/fs/splice.c b/fs/splice.c

index 14e2262..80beb2b 100644

--- a/fs/splice.c

+++ b/fs/splice.c

@@ -1237,6 +1237,11 @@ static int get_iovec_page_array(const struct iovec __user *iov,

 		if (unlikely(!base))

 			break;


+		if (!access_ok(VERIFY_READ, base, len)) {

+			error = -EFAULT;

+			break;

+		}

+

 		/*

 		 * Get this base offset and number of pages, then map

 		 * in the user pages.

--

Even historians fail to learn from history -- they repeat the same mistakes.

		-- John Gill, "Patterns of Force", stardate 2534.7

--
[view original message]
From: Niki Denev <ndenev@...>
To: Bastian Blank <bastian@...>, <linux-kernel@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 9:48 am

As far as i can see, at least on x86 and x86_64 the first argument to

access_ok : (VERIFY_READ|VERIFY_WRITE) is ignored.

Also even if it is used on different arch, using WRITE instead of READ

should be safe because WRITE is a superset of READ.


You are right that it only catches the first entry.


--Niki

--
[view original message]
From: Niki Denev <ndenev@...>
To: Bastian Blank <bastian@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 8:39 am

This patch is against 2.6.24.1 which has already the fix to vmsplice_to_user

With it i can't exploit the hole, and it is returns "invalid address"

--
[view original message]
From: Bastian Blank <bastian@...>
To: Niki Denev <ndenev@...>
Cc: Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 8:47 am

This is the vmsplice_to_pipe path and I have many reports that it is not

fixed.


Bastian


--

If there are self-made purgatories, then we all have to live in them.

		-- Spock, "This Side of Paradise", stardate 3417.7

--
[view original message]
From: Oliver Pinter <oliver.pntr@...>
To: Bastian Blank <bastian@...>, Niki Denev <ndenev@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>
Cc: <stable@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 9:02 am

commit f6e993b835393543bab2d917f9dea75218473edd

Author: Oliver Pinter <oliver.pntr@gmail.com>

Date:   Sun Feb 10 14:03:46 2008 +0100


    [PATCH] vm: splice local root exploit fix for 2.6.22.y


    Based on Bastian Blank's patch


    Fix for CVE_2008_0009 and CVE_2008-0010


    ----->8-----


    oliver@pancs:/tmp$ ./2617_26241_root_exploit

    -----------------------------------

     Linux vmsplice Local Root Exploit

      By qaaz

      -----------------------------------

      [+] mmap: 0x0 .. 0x1000

      [+] page: 0x0

      [+] page: 0x20

      [+] mmap: 0x4000 .. 0x5000

      [+] page: 0x4000

      [+] page: 0x4020

      [+] mmap: 0x1000 .. 0x2000

      [+] page: 0x1000

      [+] mmap: 0xb7f1a000 .. 0xb7f4c000

      [-] vmsplice: Bad address


    -----8<-----


    Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>


diff --git a/fs/splice.c b/fs/splice.c

index e263d3b..d8b106e 100644

--- a/fs/splice.c

+++ b/fs/splice.c

@@ -1182,6 +1182,12 @@ static int get_iovec_page_array(const struct

iovec __user *iov,

 		if (unlikely(!base))

 			break;


+		/* CVE-2008-0009, CVE-2008-0010 fix */

+		if(!access_ok(VERIFY_READ, base, len)) {

+			error = -EFAULT;

+			break;

+		}

+

 		/*

 		 * Get this base offset and number of pages, then map

 		 * in the user pages.


<<<<<<<


oliver@pancs:/tmp$ ./2617_26241_root_exploit

-----------------------------------

 Linux vmsplice Local Root Exploit

 By qaaz

-----------------------------------

[+] mmap: 0x0 .. 0x1000

[+] page: 0x0

[+] page: 0x20

[+] mmap: 0x4000 .. 0x5000

[+] page: 0x4000

[+] page: 0x4020

[+] mmap: 0x1000 .. 0x2000

[+] page: 0x1000

[+] mmap: 0xb7f1a000 .. 0xb7f4c000

[-] vmsplice: Bad addres


--

Thanks,

Oliver

--
[view original message]
From: Greg KH <greg@...>
To: Oliver Pinter <oliver.pntr@...>
Cc: Bastian Blank <bastian@...>, Niki Denev <ndenev@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>, <stable@...>
Subject: Re: [stable] [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 1:05 pm

No, this is a different CVE, as it is a different problem from the

original 09 and 10 report.


It has been given CVE-2008-0600 to address this issue (09 and 10 only


Hm, perhaps we should just properly check the len field instead?  That's

what is being overflowed here...


thanks,


greg k-h

--
[view original message]
From: Oliver Pinter <oliver.pntr@...>
To: Greg KH <greg@...>
Cc: Bastian Blank <bastian@...>, Niki Denev <ndenev@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>, <stable@...>
Subject: Re: [stable] [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 1:48 pm

thanks the info


--

Thanks,

Oliver

--
[view original message]
From: Oliver Pinter <oliver.pntr@...>
To: Greg KH <greg@...>
Cc: Bastian Blank <bastian@...>, Niki Denev <ndenev@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>, <stable@...>
Subject: Re: [stable] [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 1:44 pm

simple len and base check is already in kernel:


2.6.22.17 @ 1176,2-16 - fs/splice.c


                /*

                 * Sanity check this iovec. 0 read succeeds.

                 */

                if (unlikely(!len))

                        break;

                error = -EFAULT;

                if (unlikely(!base))

                        break;


--

Thanks,

Oliver

--
[view original message]
From: Pekka Enberg <penberg@...>
To: Greg KH <greg@...>
Cc: Oliver Pinter <oliver.pntr@...>, Bastian Blank <bastian@...>, Niki Denev <ndenev@...>, Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>, <stable@...>
Subject: Re: [stable] [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 1:11 pm

Sorry, I forgot to cc you on this one:


http://lkml.org/lkml/2008/2/10/153


I don't see where the current code is checking that base is

accessible. We just check that we can copy the struct iovecs, right?


                        Pekka

--
[view original message]
From: Niki Denev <ndenev@...>
To: Bastian Blank <bastian@...>, <linux-kernel@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 8:54 am

Exactly, my patch is for the the vmsplice_to_pipe path.

I don't guarantee correctness, but it stops the exploit in my environment.


Niki

--
[view original message]
From: Oliver Pinter <oliver.pntr@...>
To: Niki Denev <ndenev@...>
Cc: Willy Tarreau <w@...>, <linux-kernel@...>, <jens.axboe@...>, Andrew Morton <akpm@...>, Greg KH <gregkh@...>, Greg KH <greg@...>, Linus Torvalds <torvalds@...>, <stable@...>
Subject: Re: [PATCH] kernel 2.6.24.1 still vulnerable to the vmsplice local root exploit
Date: Sunday, February 10, 2008 - 8:04 am

hmmm, with 2.6.22.y serie is too affected


Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent

permitted by applicable law.

Last login: Sat Feb  9 15:34:35 2008

oliver@home:~$ ./2617_26241_root_exploit

-----------------------------------

 Linux vmsplice Local Root Exploit

 By qaaz

-----------------------------------

[+] mmap: 0x0 .. 0x1000

[+] page: 0x0

[+] page: 0x20

[+] mmap: 0x4000 .. 0x5000

[+] page: 0x4000

[+] page: 0x4020

[+] mmap: 0x1000 .. 0x2000

[+] page: 0x1000

[+] mmap: 0xb7f79000 .. 0xb7fab000

[+] root

root@home:~# uname -a

Linux home 2.6.22.17 #3 SMP PREEMPT Mon Feb 4 17:38:33 CET 2008 i686 GNU/Linux

root@home:~#


--

Thanks,

Oliver

--
Previous thread: [PATCH] Silent compiler warning introduced by commit 801c135ce73d5df1caf3eca35b66a10824ae0707 (UBI: Unsorted Block Images) by S.Çağlar on Saturday, February 9, 2008 - 11:37 pm. (4 messages)

Next thread: /bin/sh: -c: line 0: syntax error near unexpected token `;' by Mr. James W. Laferriere on Sunday, February 10, 2008 - 2:08 am. (1 message)