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Groups > linux.kernel > #1254901

[PATCH v12 13/49] richacl: Update the file masks in chmod()

From Andreas Gruenbacher <agruenba@redhat.com>
Newsgroups linux.kernel
Subject [PATCH v12 13/49] richacl: Update the file masks in chmod()
Date 2015-10-23 20:50 +0200
Message-ID <qmPzB-1ob-25@gated-at.bofh.it> (permalink)
References <qmPzA-1ob-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Doing a chmod() sets the file mode, which includes the file permission
bits.  When a file has a richacl, the permissions that the richacl
grants need to be limited to what the new file permission bits allow.

This is done by setting the file masks in the richacl to what the file
permission bits map to.  The richacl access check algorithm takes the
file masks into account, which ensures that the richacl cannot grant too
many permissions.

It is possible to explicitly add permissions to the file masks which go
beyond what the file permission bits can grant (like the
RICHACE_WRITE_ACL permission).  The POSIX.1 standard calls this an
alternate file access control mechanism.  A subsequent chmod() would
ensure that those permissions are disabled again.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/richacl_base.c       | 42 ++++++++++++++++++++++++++++++++++++++++++
 fs/richacl_inode.c      | 30 ++++++++++++++++++++++++++++++
 include/linux/richacl.h |  2 ++
 3 files changed, 74 insertions(+)

diff --git a/fs/richacl_base.c b/fs/richacl_base.c
index d0ab5e9..00e87be 100644
--- a/fs/richacl_base.c
+++ b/fs/richacl_base.c
@@ -340,3 +340,45 @@ restart:
 	acl->a_flags &= ~(RICHACL_WRITE_THROUGH | RICHACL_MASKED);
 }
 EXPORT_SYMBOL_GPL(richacl_compute_max_masks);
+
+/**
+ * __richacl_chmod  -  update the file masks to reflect the new mode
+ * @acl:	access control list
+ * @mode:	new file permission bits including the file type
+ *
+ * Return a copy of @acl where the file masks have been replaced by the file
+ * masks corresponding to the file permission bits in @mode, or returns @acl
+ * itself if the file masks are already up to date.  Takes over a reference
+ * to @acl.
+ */
+struct richacl *
+__richacl_chmod(struct richacl *acl, umode_t mode)
+{
+	unsigned int x = S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD;
+	unsigned int owner_mask, group_mask, other_mask;
+	struct richacl *clone;
+
+	owner_mask = richacl_mode_to_mask(mode >> 6) & ~x;
+	group_mask = richacl_mode_to_mask(mode >> 3) & ~x;
+	other_mask = richacl_mode_to_mask(mode)      & ~x;
+
+	if (acl->a_owner_mask == owner_mask &&
+	    acl->a_group_mask == group_mask &&
+	    acl->a_other_mask == other_mask &&
+	    (acl->a_flags & RICHACL_MASKED) &&
+	    (acl->a_flags & RICHACL_WRITE_THROUGH))
+		return acl;
+
+	clone = richacl_clone(acl, GFP_KERNEL);
+	richacl_put(acl);
+	if (!clone)
+		return ERR_PTR(-ENOMEM);
+
+	clone->a_flags |= (RICHACL_WRITE_THROUGH | RICHACL_MASKED);
+	clone->a_owner_mask = owner_mask;
+	clone->a_group_mask = group_mask;
+	clone->a_other_mask = other_mask;
+
+	return clone;
+}
+EXPORT_SYMBOL_GPL(__richacl_chmod);
diff --git a/fs/richacl_inode.c b/fs/richacl_inode.c
index c41a6c4..301f246 100644
--- a/fs/richacl_inode.c
+++ b/fs/richacl_inode.c
@@ -222,3 +222,33 @@ out:
 	return denied ? -EACCES : 0;
 }
 EXPORT_SYMBOL_GPL(richacl_permission);
+
+/**
+ * richacl_chmod  -  filesystem chmod helper
+ * @inode:	inode whose file permission bits to change
+ * @mode:	new file permission bits including the file type
+ *
+ * Helper for filesystems to use to perform a chmod on the richacl of an inode.
+ */
+int
+richacl_chmod(struct inode *inode, umode_t mode)
+{
+	struct richacl *acl;
+	int retval;
+
+	if (S_ISLNK(mode))
+		return -EOPNOTSUPP;
+	if (!inode->i_op->set_richacl)
+		return -EOPNOTSUPP;
+	acl = get_richacl(inode);
+	if (IS_ERR_OR_NULL(acl))
+		return PTR_ERR(acl);
+	acl = __richacl_chmod(acl, mode);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	retval = inode->i_op->set_richacl(inode, acl);
+	richacl_put(acl);
+
+	return retval;
+}
+EXPORT_SYMBOL(richacl_chmod);
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index de7d0d9..3626314 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -184,8 +184,10 @@ extern int richacl_masks_to_mode(const struct richacl *);
 extern unsigned int richacl_mode_to_mask(umode_t);
 extern unsigned int richacl_want_to_mask(unsigned int);
 extern void richacl_compute_max_masks(struct richacl *);
+extern struct richacl *__richacl_chmod(struct richacl *, umode_t);
 
 /* richacl_inode.c */
 extern int richacl_permission(struct inode *, const struct richacl *, int);
+extern int richacl_chmod(struct inode *, umode_t);
 
 #endif /* __RICHACL_H */
-- 
2.5.0

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Thread

[PATCH v12 00/49] Richacls Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 04/49] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 01/49] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 08/49] richacl: Compute maximum file masks from an acl Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 38/49] nfsd: Add support for the MAY_CREATE_{FILE,DIR} permissions Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 25/49] xfs: Add richacl support Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 09/49] richacl: Permission check algorithm Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 34/49] nfsd: Keep list of acls to dispose of in compoundargs Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 42/49] xfs: Don't allow unmapped identifiers in richacls Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 13/49] richacl: Update the file masks in chmod() Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 32/49] richacl: Apply the file masks to a richacl Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 28/49] richacl: Propagate everyone@ permissions to other aces Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 49/49] nfs: Add support for the v4.1 dacl attribute Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 41/49] ext4: Don't allow unmapped identifiers in richacls Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 33/49] richacl: Create richacl from mode values Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 03/49] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 12/49] vfs: Cache richacl in struct inode Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 44/49] sunrpc: Add xdr_init_encode_pages Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 16/49] richacl: Automatic Inheritance Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 29/49] richacl: Set the owner permissions to the owner mask Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 17/49] richacl: xattr mapping functions Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 20/49] ext4: Add richacl support Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 06/49] richacl: In-memory representation and helper functions Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 45/49] nfs: Fix GETATTR bitmap verification Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 15/49] richacl: Create-time inheritance Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 48/49] nfs: Add richacl support Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 35/49] nfsd: Use richacls as internal acl representation Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 21/49] ext4: Add richacl feature flag Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
    Re: [PATCH v12 21/49] ext4: Add richacl feature flag Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-10-23 21:40 +0200
  [PATCH v12 47/49] nfs: Distinguish missing users and groups from nobody Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 24/49] xfs: Change how listxattr generates synthetic attributes Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 31/49] richacl: Isolate the owner and group classes Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 26/49] richacl: acl editing helper functions Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 02/49] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 05/49] vfs: Add permission flags for setting file attributes Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 19/49] vfs: Add richacl permission checking Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 14/49] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 07/49] richacl: Permission mapping functions Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 40/49] nfsd: Add support for unmapped richace identifiers Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 11/49] vfs: Add get_richacl and set_richacl inode operations Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 39/49] richacl: Add support for unmapped identifiers Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 43/49] sunrpc: Allow to demand-allocate pages to encode into Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 37/49] nfsd: Add support for the v4.1 dacl attribute Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 20:50 +0200
  [PATCH v12 36/49] nfsd: Add richacl support Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:00 +0200
  [PATCH v12 27/49] richacl: Move everyone@ aces down the acl Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:10 +0200
  [PATCH v12 30/49] richacl: Set the other permissions to the other mask Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:10 +0200
  [PATCH v12 23/49] xfs: Make xfs_set_mode non-static Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:20 +0200
  [PATCH v12 18/49] richacl: Add richacl xattr handler Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:20 +0200
  [PATCH v12 22/49] xfs: Fix error path in xfs_get_acl Andreas Gruenbacher <agruenba@redhat.com> - 2015-10-23 21:20 +0200
  RE: [PATCH v12 00/49] Richacls "Frank Filz" <ffilzlnx@mindspring.com> - 2015-10-23 22:20 +0200

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