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From: Andreas Gruenbacher <agruenba@redhat.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Jeff Layton <jlayton@poochiereds.net>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Dave Chinner <david@fromorbit.com>,
	linux-ext4@vger.kernel.org, xfs@oss.sgi.com,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
	linux-api@vger.kernel.org
Subject: [PATCH v21 03/22] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags
Date: Tue, 10 May 2016 00:02:36 +0200	[thread overview]
Message-ID: <1462831375-23017-4-git-send-email-agruenba@redhat.com> (raw)
In-Reply-To: <1462831375-23017-1-git-send-email-agruenba@redhat.com>

Normally, deleting a file requires MAY_WRITE access to the parent
directory.  With richacls, a file may be deleted with MAY_DELETE_CHILD access
to the parent directory or with MAY_DELETE_SELF access to the file.

To support that, pass the MAY_DELETE_CHILD mask flag to inode_permission()
when checking for delete access inside a directory, and MAY_DELETE_SELF
when checking for delete access to a file itelf.

The MAY_DELETE_SELF permission overrides the sticky directory check.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Steve French <steve.french@primarydata.com>
---
 fs/namei.c         | 20 ++++++++++++--------
 include/linux/fs.h |  2 ++
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index b013950..858ed96 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -453,9 +453,9 @@ static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
  * this, letting us set arbitrary permissions for filesystem access without
  * changing the "normal" UIDs which are used for other things.
  *
- * MAY_WRITE must be set in @mask whenever MAY_APPEND, MAY_CREATE_FILE, or
- * MAY_CREATE_DIR are set.  That way, file systems that don't support these
- * permissions will check for MAY_WRITE instead.
+ * MAY_WRITE must be set in @mask whenever MAY_APPEND, MAY_CREATE_FILE,
+ * MAY_CREATE_DIR, or MAY_DELETE_CHILD are set.  That way, file systems that
+ * don't support these permissions will check for MAY_WRITE instead.
  */
 int inode_permission(struct inode *inode, int mask)
 {
@@ -2603,14 +2603,18 @@ static int may_delete_or_replace(struct inode *dir, struct dentry *victim,
 	BUG_ON(victim->d_parent->d_inode != dir);
 	audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
 
-	error = inode_permission(dir, mask);
+	error = inode_permission(dir, mask | MAY_WRITE | MAY_DELETE_CHILD);
+	if (!error && check_sticky(dir, inode))
+		error = -EPERM;
+	if (error && IS_RICHACL(inode) &&
+	    inode_permission(inode, MAY_DELETE_SELF) == 0 &&
+	    inode_permission(dir, mask) == 0)
+		error = 0;
 	if (error)
 		return error;
 	if (IS_APPEND(dir))
 		return -EPERM;
-
-	if (check_sticky(dir, inode) || IS_APPEND(inode) ||
-	    IS_IMMUTABLE(inode) || IS_SWAPFILE(inode))
+	if (IS_APPEND(inode) || IS_IMMUTABLE(inode) || IS_SWAPFILE(inode))
 		return -EPERM;
 	if (isdir) {
 		if (!d_is_dir(victim))
@@ -2628,7 +2632,7 @@ static int may_delete_or_replace(struct inode *dir, struct dentry *victim,
 
 static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
 {
-	return may_delete_or_replace(dir, victim, isdir, MAY_WRITE | MAY_EXEC);
+	return may_delete_or_replace(dir, victim, isdir, MAY_EXEC);
 }
 
 static int may_replace(struct inode *dir, struct dentry *victim, bool isdir)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0b6d5ff..0807a9c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -87,6 +87,8 @@ typedef void (dax_iodone_t)(struct buffer_head *bh_map, int uptodate);
 #define MAY_NOT_BLOCK		0x00000080
 #define MAY_CREATE_FILE		0x00000100
 #define MAY_CREATE_DIR		0x00000200
+#define MAY_DELETE_CHILD	0x00000400
+#define MAY_DELETE_SELF		0x00000800
 
 /*
  * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
-- 
2.5.5

  parent reply	other threads:[~2016-05-09 22:03 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-09 22:02 [PATCH v21 00/22] Richacls Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 01/22] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 02/22] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher
2016-05-09 22:02 ` Andreas Gruenbacher [this message]
2016-05-09 22:02 ` [PATCH v21 04/22] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 05/22] vfs: Add permission flags for setting file attributes Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 06/22] richacl: In-memory representation and helper functions Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 07/22] richacl: Permission mapping functions Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 08/22] richacl: Compute maximum file masks from an acl Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 09/22] richacl: Permission check algorithm Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 10/22] posix_acl: Improve xattr fixup code Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 11/22] vfs: Cache base_acl objects in inodes Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 12/22] vfs: Add get_richacl and set_richacl inode operations Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 13/22] vfs: Cache richacl in struct inode Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 14/22] richacl: Update the file masks in chmod() Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 15/22] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 16/22] richacl: Create-time inheritance Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 17/22] richacl: Automatic Inheritance Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 18/22] richacl: xattr mapping functions Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 19/22] richacl: Add richacl xattr handler Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 20/22] vfs: Add richacl permission checking Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 21/22] ext4: Add richacl support Andreas Gruenbacher
2016-05-09 22:02 ` [PATCH v21 22/22] ext4: Add richacl feature flag Andreas Gruenbacher
2016-05-10  4:18 ` [PATCH v21 00/22] Richacls Volker Lendecke
2016-05-10  8:11   ` Jeremy Allison
2016-05-10  8:20     ` Volker Lendecke
2016-05-10 15:55     ` Frank Filz

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