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Re: [PATCH 5/6] userns strict: hook ext2 [message #13784 is a reply to message #13757]

Tue, 05 June 2007 10:16

xemul
Messages: 248
Registered: November 2005

Senior Member

Serge E. Hallyn wrote:
>>From nobody Mon Sep 17 00:00:00 2001
> From: Serge Hallyn <serue@us.ibm.com>
> Date: Wed, 28 Mar 2007 15:06:47 -0500
> Subject: [PATCH 5/6] userns strict: hook ext2
>
> Add a user namespace pointer to the ext2 superblock and inode.
>
> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
>
> ---
>
> fs/ext2/acl.c | 4 +++-
> fs/ext2/balloc.c | 13 ++++++++++---
> fs/ext2/ialloc.c | 5 +++++
> fs/ext2/inode.c | 2 ++
> fs/ext2/ioctl.c | 12 ++++++++----
> fs/ext2/super.c | 4 ++++
> fs/ext2/xattr_trusted.c | 3 ++-
> include/linux/ext2_fs_sb.h | 1 +
> include/linux/user_namespace.h | 16 ++++++++++++++++
> 9 files changed, 51 insertions(+), 9 deletions(-)
>

[snip]

> diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
> index 86a2f3b..34f16ab 100644
> --- a/fs/ext2/ialloc.c
> +++ b/fs/ext2/ialloc.c
> @@ -17,6 +17,7 @@ #include <linux/sched.h>
> #include <linux/backing-dev.h>
> #include <linux/buffer_head.h>
> #include <linux/random.h>
> +#include <linux/user_namespace.h>
> #include "ext2.h"
> #include "xattr.h"
> #include "acl.h"
> @@ -133,6 +134,9 @@ void ext2_free_inode (struct inode * ino
> /* Do this BEFORE marking the inode not in use or returning an error */
> clear_inode (inode);
>
> + put_user_ns(inode->i_userns);
> + inode->i_userns = NULL;
> +
> if (ino < EXT2_FIRST_INO(sb) ||
> ino > le32_to_cpu(es->s_inodes_count)) {
> ext2_error (sb, "ext2_free_inode",
> @@ -563,6 +567,7 @@ got:
> sb->s_dirt = 1;
> mark_buffer_dirty(bh2);
> inode->i_uid = current->fsuid;
> + inode->i_userns = get_task_user_ns(current);

We have all the ext2 (and in the next patch - the ext3) inodes
attached to a particular user and prohibit access to the inodes
belonging to other tasks' namespaces, don't we?

If so how can we allow the admin of the node to configure the
root of a virtual server on the fly?

[snip]

> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 932579b..75ce9e8 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -29,6 +29,7 @@ #include <linux/smp_lock.h>
> #include <linux/vfs.h>
> #include <linux/seq_file.h>
> #include <linux/mount.h>
> +#include <linux/user_namespace.h>
> #include <asm/uaccess.h>
> #include "ext2.h"
> #include "xattr.h"
> @@ -125,6 +126,7 @@ static void ext2_put_super (struct super
> brelse (sbi->s_group_desc[i]);
> kfree(sbi->s_group_desc);
> kfree(sbi->s_debts);
> + put_user_ns(sbi->s_resuidns);
> percpu_counter_destroy(&sbi->s_freeblocks_counter);
> percpu_counter_destroy(&sbi->s_freeinodes_counter);
> percpu_counter_destroy(&sbi->s_dirs_counter);
> @@ -742,6 +744,7 @@ #endif
>
> sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
> sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
> + sbi->s_resuidns = get_task_user_ns(current);
>
> set_opt(sbi->s_mount_opt, RESERVATION);
>
> @@ -990,6 +993,7 @@ failed_mount_group_desc:
> kfree(sbi->s_group_desc);
> kfree(sbi->s_debts);
> failed_mount:
> + put_user_ns(sbi->s_resuidns);
> brelse(bh);
> failed_sbi:
> sb->s_fs_info = NULL;

If we have a super block attached to a namespace, why not attach
the inodes to the same namespace, not to the task opening the inode?

Thanks,
Pavel

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[Message index]

		user namespace - introduction By: serue on Mon, 04 June 2007 19:39
		[PATCH 1/6] user namespace : add the framework By: serue on Mon, 04 June 2007 19:40
		Re: [PATCH 1/6] user namespace : add the framework By: Pavel Emelianov on Fri, 08 June 2007 08:35
		Re: [PATCH 1/6] user namespace : add the framework By: akpm on Mon, 16 July 2007 01:31
		Re: [PATCH 1/6] user namespace : add the framework By: serue on Mon, 16 July 2007 14:34
		Re: [PATCH 1/6] user namespace : add the framework By: serue on Mon, 16 July 2007 14:38
		Re: [PATCH 1/6] user namespace : add the framework By: dev on Mon, 16 July 2007 14:54
		Re: [PATCH 1/6] user namespace : add the framework By: serue on Mon, 16 July 2007 15:08
		Re: [PATCH 1/6] user namespace : add the framework By: Herbert Poetzl on Wed, 18 July 2007 00:11
		Re: [PATCH 1/6] user namespace : add the framework By: serue on Wed, 18 July 2007 14:21
		Re: [PATCH 1/6] user namespace : add the framework By: serue on Mon, 16 July 2007 15:27
		[PATCH 5/6] userns strict: hook ext2 By: serue on Mon, 04 June 2007 19:42
		Re: [PATCH 5/6] userns strict: hook ext2 By: xemul on Tue, 05 June 2007 10:16
		Re: [PATCH 5/6] userns strict: hook ext2 By: serue on Tue, 05 June 2007 12:37

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