[01/11] ext4: Don't clear SGID when inheriting ACLs
diff mbox

Message ID 20170622133115.16968-2-jack@suse.cz
State New
Headers show

Commit Message

Jan Kara June 22, 2017, 1:31 p.m. UTC
When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
set, DIR1 is expected to have SGID bit set (and owning group equal to
the owning group of 'DIR0'). However when 'DIR0' also has some default
ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
'DIR1' to get cleared if user is not member of the owning group.

Fix the problem by moving posix_acl_update_mode() out of
__ext4_set_acl() into ext4_set_acl(). That way the function will not be
called when inheriting ACLs which is what we want as it prevents SGID
bit clearing and the mode has been properly set by posix_acl_create()
anyway.

Fixes: 073931017b49d9458aa351605b43a7e34598caef
CC: stable@vger.kernel.org
CC: linux-ext4@vger.kernel.org
CC: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/acl.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

Comments

Andreas Gruenbacher June 22, 2017, 3:32 p.m. UTC | #1
On Thu, Jun 22, 2017 at 3:31 PM, Jan Kara <jack@suse.cz> wrote:
> When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
> set, DIR1 is expected to have SGID bit set (and owning group equal to
> the owning group of 'DIR0'). However when 'DIR0' also has some default
> ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
> 'DIR1' to get cleared if user is not member of the owning group.
>
> Fix the problem by moving posix_acl_update_mode() out of
> __ext4_set_acl() into ext4_set_acl(). That way the function will not be
> called when inheriting ACLs which is what we want as it prevents SGID
> bit clearing and the mode has been properly set by posix_acl_create()
> anyway.
>
> Fixes: 073931017b49d9458aa351605b43a7e34598caef
> CC: stable@vger.kernel.org
> CC: linux-ext4@vger.kernel.org
> CC: "Theodore Ts'o" <tytso@mit.edu>
> Signed-off-by: Jan Kara <jack@suse.cz>

This is looking good, thanks.

Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>

> ---
>  fs/ext4/acl.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
> index 3ec0e46de95f..37242af33ff2 100644
> --- a/fs/ext4/acl.c
> +++ b/fs/ext4/acl.c
> @@ -193,13 +193,6 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
>         switch (type) {
>         case ACL_TYPE_ACCESS:
>                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
> -               if (acl) {
> -                       error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
> -                       if (error)
> -                               return error;
> -                       inode->i_ctime = current_time(inode);
> -                       ext4_mark_inode_dirty(handle, inode);
> -               }
>                 break;
>
>         case ACL_TYPE_DEFAULT:
> @@ -242,7 +235,16 @@ ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>         if (IS_ERR(handle))
>                 return PTR_ERR(handle);
>
> +       if (type == ACL_TYPE_ACCESS && acl) {
> +               error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
> +               if (error)
> +                       goto out_stop;
> +               inode->i_ctime = current_time(inode);
> +               ext4_mark_inode_dirty(handle, inode);
> +       }
> +
>         error = __ext4_set_acl(handle, inode, type, acl);
> +out_stop:
>         ext4_journal_stop(handle);
>         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
>                 goto retry;
> --
> 2.12.3
>
Jan Kara July 18, 2017, 4:16 p.m. UTC | #2
On Thu 22-06-17 15:31:05, Jan Kara wrote:
> When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
> set, DIR1 is expected to have SGID bit set (and owning group equal to
> the owning group of 'DIR0'). However when 'DIR0' also has some default
> ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
> 'DIR1' to get cleared if user is not member of the owning group.
> 
> Fix the problem by moving posix_acl_update_mode() out of
> __ext4_set_acl() into ext4_set_acl(). That way the function will not be
> called when inheriting ACLs which is what we want as it prevents SGID
> bit clearing and the mode has been properly set by posix_acl_create()
> anyway.
> 
> Fixes: 073931017b49d9458aa351605b43a7e34598caef
> CC: stable@vger.kernel.org
> CC: linux-ext4@vger.kernel.org
> CC: "Theodore Ts'o" <tytso@mit.edu>
> Signed-off-by: Jan Kara <jack@suse.cz>

Ted, can you please pick up this fix? Thanks!

								Honza
> ---
>  fs/ext4/acl.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
> index 3ec0e46de95f..37242af33ff2 100644
> --- a/fs/ext4/acl.c
> +++ b/fs/ext4/acl.c
> @@ -193,13 +193,6 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
>  	switch (type) {
>  	case ACL_TYPE_ACCESS:
>  		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
> -		if (acl) {
> -			error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
> -			if (error)
> -				return error;
> -			inode->i_ctime = current_time(inode);
> -			ext4_mark_inode_dirty(handle, inode);
> -		}
>  		break;
>  
>  	case ACL_TYPE_DEFAULT:
> @@ -242,7 +235,16 @@ ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>  	if (IS_ERR(handle))
>  		return PTR_ERR(handle);
>  
> +	if (type == ACL_TYPE_ACCESS && acl) {
> +		error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
> +		if (error)
> +			goto out_stop;
> +		inode->i_ctime = current_time(inode);
> +		ext4_mark_inode_dirty(handle, inode);
> +	}
> +
>  	error = __ext4_set_acl(handle, inode, type, acl);
> +out_stop:
>  	ext4_journal_stop(handle);
>  	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
>  		goto retry;
> -- 
> 2.12.3
>
Theodore Y. Ts'o July 31, 2017, 3:34 a.m. UTC | #3
On Tue, Jul 18, 2017 at 06:16:31PM +0200, Jan Kara wrote:
> On Thu 22-06-17 15:31:05, Jan Kara wrote:
> > When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
> > set, DIR1 is expected to have SGID bit set (and owning group equal to
> > the owning group of 'DIR0'). However when 'DIR0' also has some default
> > ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
> > 'DIR1' to get cleared if user is not member of the owning group.
> > 
> > Fix the problem by moving posix_acl_update_mode() out of
> > __ext4_set_acl() into ext4_set_acl(). That way the function will not be
> > called when inheriting ACLs which is what we want as it prevents SGID
> > bit clearing and the mode has been properly set by posix_acl_create()
> > anyway.
> > 
> > Fixes: 073931017b49d9458aa351605b43a7e34598caef
> > CC: stable@vger.kernel.org
> > CC: linux-ext4@vger.kernel.org
> > CC: "Theodore Ts'o" <tytso@mit.edu>
> > Signed-off-by: Jan Kara <jack@suse.cz>
> 
> Ted, can you please pick up this fix? Thanks!

Thanks, applied.

						- Ted

Patch
diff mbox

diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
index 3ec0e46de95f..37242af33ff2 100644
--- a/fs/ext4/acl.c
+++ b/fs/ext4/acl.c
@@ -193,13 +193,6 @@  __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 	switch (type) {
 	case ACL_TYPE_ACCESS:
 		name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
-		if (acl) {
-			error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
-			if (error)
-				return error;
-			inode->i_ctime = current_time(inode);
-			ext4_mark_inode_dirty(handle, inode);
-		}
 		break;
 
 	case ACL_TYPE_DEFAULT:
@@ -242,7 +235,16 @@  ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	if (IS_ERR(handle))
 		return PTR_ERR(handle);
 
+	if (type == ACL_TYPE_ACCESS && acl) {
+		error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+		if (error)
+			goto out_stop;
+		inode->i_ctime = current_time(inode);
+		ext4_mark_inode_dirty(handle, inode);
+	}
+
 	error = __ext4_set_acl(handle, inode, type, acl);
+out_stop:
 	ext4_journal_stop(handle);
 	if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 		goto retry;