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Groups > linux.kernel > #1493045

[PATCH v26 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags

From Andreas Gruenbacher <agruenba@redhat.com>
Newsgroups linux.kernel
Subject [PATCH v26 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags
Date 2016-09-29 01:40 +0200
Message-ID <smwCe-4SR-29@gated-at.bofh.it> (permalink)
References <smwsx-4PC-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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 itself.

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>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
---
 fs/namei.c         | 20 +++++++++++++-------
 include/linux/fs.h |  2 ++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 7290dea..c8bc9fd 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -463,9 +463,9 @@ 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)
 {
@@ -2780,14 +2780,20 @@ 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) || HAS_UNMAPPED_ID(inode))
+	if (IS_APPEND(inode) || IS_IMMUTABLE(inode) ||
+	    IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode))
 		return -EPERM;
 	if (isdir) {
 		if (!d_is_dir(victim))
@@ -2805,7 +2811,7 @@ 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 54b2a07..f3e21b0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -86,6 +86,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #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
-- 
2.7.4

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Thread

[PATCH v25 00/21] Richacls (Core and Ext4) Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:30 +0200
  [PATCH v26 17/21] richacl: Add richacl xattr handler Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 08/21] richacl: Compute maximum file masks from an acl Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 20/21] ext4: Add richacl support Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 05/21] richacl: In-memory representation and helper functions Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 06/21] richacl: Permission mapping functions Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 15/21] richacl: Automatic Inheritance Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 21/21] ext4: Add richacl feature flag Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 09/21] vfs: Cache base_acl objects in inodes Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 01/21] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 12/21] richacl: Update the file masks in chmod() Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 14/21] richacl: Create-time inheritance Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 18/21] vfs: Add richacl permission checking Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 02/21] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 19/21] vfs: Move check_posix_acl and check_richacl out of fs/namei.c Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 10/21] vfs: Add get_richacl and set_richacl inode operations Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 13/21] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 11/21] vfs: Cache richacl in struct inode Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 07/21] richacl: Permission check algorithm Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 04/21] vfs: Add permission flags for setting file attributes Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  [PATCH v26 16/21] richacl: xattr mapping functions Andreas Gruenbacher <agruenba@redhat.com> - 2016-09-29 01:40 +0200
  Re: [PATCH v25 00/21] Richacls (Core and Ext4) "J. Bruce Fields" <bfields@fieldses.org> - 2016-09-30 18:20 +0200

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