[PATCH 02/10] vfs: syscall: Add move_mount(2) to move mounts around

[Tetsuo Handa]

Al, will you send this patch to 5.3-rcX via vfs.git tree?

On 2019/07/23 13:16, John Johansen wrote:
> On 7/22/19 3:12 AM, Tetsuo Handa wrote:
>> I did not see AppArmor patch for this problem in 5.3-rc1. 
>> John, are you OK with this patch for 5.2-stable and 5.3 ?
>>
> yes, I have some larger mount rework and clean-up to do and an apparmor
> patch for this is waiting on that. Looking at the thread I am wondering
> where my previous reply is, probably lost in a mail client crash, I have
> had a few of those lately.
> 
> Acked-by: John Johansen <john.johansen at canonical.com>
> 
> 
>> On 2019/07/09 19:51, Tetsuo Handa wrote:
>>> For now, can we apply this patch for 5.2-stable ?
>>>
>>>
>>> >From dd62fab0592e02580fd5a34222a2d11bfc179f61 Mon Sep 17 00:00:00 2001
>>> From: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
>>> Date: Tue, 9 Jul 2019 19:05:49 +0900
>>> Subject: [PATCH] LSM: Disable move_mount() syscall when TOMOYO or AppArmor is enabled.
>>>
>>> Commit 2db154b3ea8e14b0 ("vfs: syscall: Add move_mount(2) to move mounts
>>> around") introduced security_move_mount() LSM hook, but we missed that
>>> TOMOYO and AppArmor did not implement hooks for checking move_mount(2).
>>> For pathname based access controls like TOMOYO and AppArmor, unchecked
>>> mount manipulation is not acceptable. Therefore, until TOMOYO and AppArmor
>>> implement hooks, in order to avoid unchecked mount manipulation, pretend
>>> as if move_mount(2) is unavailable when either TOMOYO or AppArmor is
>>> enabled.
>>>
>>> Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
>>> Fixes: 2db154b3ea8e14b0 ("vfs: syscall: Add move_mount(2) to move mounts around")
>>> Cc: stable at vger.kernel.org # 5.2
>>> ---
>>>  include/linux/lsm_hooks.h | 6 ++++++
>>>  security/apparmor/lsm.c   | 1 +
>>>  security/tomoyo/tomoyo.c  | 1 +
>>>  3 files changed, 8 insertions(+)
>>>
>>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>>> index 47f58cf..cd411b7 100644
>>> --- a/include/linux/lsm_hooks.h
>>> +++ b/include/linux/lsm_hooks.h
>>> @@ -2142,4 +2142,10 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
>>>  
>>>  extern int lsm_inode_alloc(struct inode *inode);
>>>  
>>> +static inline int no_move_mount(const struct path *from_path,
>>> +				const struct path *to_path)
>>> +{
>>> +	return -ENOSYS;
>>> +}
>>> +
>>>  #endif /* ! __LINUX_LSM_HOOKS_H */
>>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
>>> index ec3a928..5cdf63b 100644
>>> --- a/security/apparmor/lsm.c
>>> +++ b/security/apparmor/lsm.c
>>> @@ -1158,6 +1158,7 @@ struct lsm_blob_sizes apparmor_blob_sizes __lsm_ro_after_init = {
>>>  	LSM_HOOK_INIT(capable, apparmor_capable),
>>>  
>>>  	LSM_HOOK_INIT(sb_mount, apparmor_sb_mount),
>>> +	LSM_HOOK_INIT(move_mount, no_move_mount),
>>>  	LSM_HOOK_INIT(sb_umount, apparmor_sb_umount),
>>>  	LSM_HOOK_INIT(sb_pivotroot, apparmor_sb_pivotroot),
>>>  
>>> diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
>>> index 716c92e..be1b1a1 100644
>>> --- a/security/tomoyo/tomoyo.c
>>> +++ b/security/tomoyo/tomoyo.c
>>> @@ -558,6 +558,7 @@ static void tomoyo_task_free(struct task_struct *task)
>>>  	LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
>>>  	LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
>>>  	LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
>>> +	LSM_HOOK_INIT(move_mount, no_move_mount),
>>>  	LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
>>>  	LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
>>>  	LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
>>>
>>
> 
>