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[PATCH v12 27/49] richacl: Move everyone@ aces down the acl

From Andreas Gruenbacher <agruenba@redhat.com>
Newsgroups linux.kernel
Subject [PATCH v12 27/49] richacl: Move everyone@ aces down the acl
Date 2015-10-23 21:10 +0200
Message-ID <qmPSX-20c-39@gated-at.bofh.it> (permalink)
References <qmPzA-1ob-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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The POSIX standard puts processes which are not the owner or a member in
the owning group or which match any ace other then everyone@ on the
other file class.  We only know if a process is in the other class after
processing the entire acl.

Move all everyone@ aces in the acl down in the acl so that at most a
single everyone@ allow ace remains at the end.  Permissions which are
not explicitly allowed are implicitly denied, so an everyone@ deny ace
is unneeded.

The everyone@ aces can be moved down the acl without changing the
permissions that the acl grants.  This transformation simplifies the
following algorithms, and eventually allows us to turn the final
everyone@ allow ace into an entry for the other class.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/richacl_compat.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c
index 5c59999..962d314 100644
--- a/fs/richacl_compat.c
+++ b/fs/richacl_compat.c
@@ -153,3 +153,68 @@ richace_change_mask(struct richacl_alloc *alloc, struct richace **ace,
 	}
 	return 0;
 }
+
+/**
+ * richacl_move_everyone_aces_down  -  move everyone@ aces to the end of the acl
+ * @alloc:	acl and number of allocated entries
+ *
+ * Move all everyone aces to the end of the acl so that only a single everyone@
+ * allow ace remains at the end, and update the mask fields of all aces on the
+ * way.  The last ace of the resulting acl will be an everyone@ allow ace only
+ * if @acl grants any permissions to @everyone.  No @everyone deny aces will
+ * remain.
+ *
+ * This transformation does not alter the permissions that the acl grants.
+ * Having at most one everyone@ allow ace at the end of the acl helps us in the
+ * following algorithms.
+ */
+static int
+richacl_move_everyone_aces_down(struct richacl_alloc *alloc)
+{
+	struct richace *ace;
+	unsigned int allowed = 0, denied = 0;
+
+	richacl_for_each_entry(ace, alloc->acl) {
+		if (richace_is_inherit_only(ace))
+			continue;
+		if (richace_is_everyone(ace)) {
+			if (richace_is_allow(ace))
+				allowed |= (ace->e_mask & ~denied);
+			else if (richace_is_deny(ace))
+				denied |= (ace->e_mask & ~allowed);
+			else
+				continue;
+			if (richace_change_mask(alloc, &ace, 0))
+				return -1;
+		} else {
+			if (richace_is_allow(ace)) {
+				if (richace_change_mask(alloc, &ace, allowed |
+						(ace->e_mask & ~denied)))
+					return -1;
+			} else if (richace_is_deny(ace)) {
+				if (richace_change_mask(alloc, &ace, denied |
+						(ace->e_mask & ~allowed)))
+					return -1;
+			}
+		}
+	}
+	if (allowed & ~RICHACE_POSIX_ALWAYS_ALLOWED) {
+		struct richace *last_ace = ace - 1;
+
+		if (alloc->acl->a_entries &&
+		    richace_is_everyone(last_ace) &&
+		    richace_is_allow(last_ace) &&
+		    richace_is_inherit_only(last_ace) &&
+		    last_ace->e_mask == allowed)
+			last_ace->e_flags &= ~RICHACE_INHERIT_ONLY_ACE;
+		else {
+			if (richacl_insert_entry(alloc, &ace))
+				return -1;
+			ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE;
+			ace->e_flags = RICHACE_SPECIAL_WHO;
+			ace->e_mask = allowed;
+			ace->e_id.special = RICHACE_EVERYONE_SPECIAL_ID;
+		}
+	}
+	return 0;
+}
-- 
2.5.0

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[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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