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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 15/22] richacl: Check if an acl is equivalent to a file mode
Date: Tue, 10 May 2016 00:02:48 +0200	[thread overview]
Message-ID: <1462831375-23017-16-git-send-email-agruenba@redhat.com> (raw)
In-Reply-To: <1462831375-23017-1-git-send-email-agruenba@redhat.com>

ACLs are considered equivalent to file modes if they only consist of
owner@, group@, and everyone@ entries, the owner@ permissions do not
depend on whether the owner is a member in the owning group, and no
inheritance flags are set.  This test is used to avoid storing richacls
if the acl can be computed from the file permission bits.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/richacl.c            | 104 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/richacl.h |   1 +
 2 files changed, 105 insertions(+)

diff --git a/fs/richacl.c b/fs/richacl.c
index ba110a6..e8a383b 100644
--- a/fs/richacl.c
+++ b/fs/richacl.c
@@ -618,3 +618,107 @@ richacl_chmod(struct inode *inode, umode_t mode)
 	return retval;
 }
 EXPORT_SYMBOL(richacl_chmod);
+
+/**
+ * richacl_equiv_mode  -  compute the mode equivalent of @acl
+ *
+ * An acl is considered equivalent to a file mode if it only consists of
+ * owner@, group@, and everyone@ entries and the owner@ permissions do not
+ * depend on whether the owner is a member in the owning group.
+ */
+int
+richacl_equiv_mode(const struct richacl *acl, umode_t *mode_p)
+{
+	umode_t mode = *mode_p;
+
+	/*
+	 * The RICHACE_DELETE_CHILD flag is meaningless for non-directories, so
+	 * we ignore it.
+	 */
+	unsigned int x = S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD;
+	struct {
+		unsigned int allowed;
+		unsigned int defined;  /* allowed or denied */
+	} owner = {
+		.defined = RICHACE_POSIX_ALWAYS_ALLOWED |
+			   RICHACE_POSIX_OWNER_ALLOWED  | x,
+	}, group = {
+		.defined = RICHACE_POSIX_ALWAYS_ALLOWED | x,
+	}, everyone = {
+		.defined = RICHACE_POSIX_ALWAYS_ALLOWED | x,
+	};
+	const struct richace *ace;
+
+	if (acl->a_flags & ~(RICHACL_WRITE_THROUGH | RICHACL_MASKED))
+		return -1;
+
+	richacl_for_each_entry(ace, acl) {
+		if (ace->e_flags & ~RICHACE_SPECIAL_WHO)
+			return -1;
+
+		if (richace_is_owner(ace) || richace_is_everyone(ace)) {
+			x = ace->e_mask & ~owner.defined;
+			if (richace_is_allow(ace)) {
+				unsigned int group_denied =
+					group.defined & ~group.allowed;
+
+				if (x & group_denied)
+					return -1;
+				owner.allowed |= x;
+			} else /* if (richace_is_deny(ace)) */ {
+				if (x & group.allowed)
+					return -1;
+			}
+			owner.defined |= x;
+
+			if (richace_is_everyone(ace)) {
+				x = ace->e_mask;
+				if (richace_is_allow(ace)) {
+					group.allowed |=
+						x & ~group.defined;
+					everyone.allowed |=
+						x & ~everyone.defined;
+				}
+				group.defined |= x;
+				everyone.defined |= x;
+			}
+		} else if (richace_is_group(ace)) {
+			x = ace->e_mask & ~group.defined;
+			if (richace_is_allow(ace))
+				group.allowed |= x;
+			group.defined |= x;
+		} else
+			return -1;
+	}
+
+	if (group.allowed & ~owner.defined)
+		return -1;
+
+	if (acl->a_flags & RICHACL_MASKED) {
+		if (acl->a_flags & RICHACL_WRITE_THROUGH) {
+			owner.allowed = acl->a_owner_mask;
+			everyone.allowed = acl->a_other_mask;
+		} else {
+			owner.allowed &= acl->a_owner_mask;
+			everyone.allowed &= acl->a_other_mask;
+		}
+		group.allowed &= acl->a_group_mask;
+	}
+
+	mode = (mode & ~S_IRWXUGO) |
+	       (richacl_mask_to_mode(owner.allowed) << 6) |
+	       (richacl_mask_to_mode(group.allowed) << 3) |
+		richacl_mask_to_mode(everyone.allowed);
+
+	/* Mask flags we can ignore */
+	x = S_ISDIR(mode) ? 0 : RICHACE_DELETE_CHILD;
+
+	if (((richacl_mode_to_mask(mode >> 6) ^ owner.allowed)    & ~x) ||
+	    ((richacl_mode_to_mask(mode >> 3) ^ group.allowed)    & ~x) ||
+	    ((richacl_mode_to_mask(mode)      ^ everyone.allowed) & ~x))
+		return -1;
+
+	*mode_p = mode;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(richacl_equiv_mode);
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index db82fab..9212edb 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -191,5 +191,6 @@ extern unsigned int richacl_want_to_mask(unsigned int);
 extern void richacl_compute_max_masks(struct richacl *);
 extern int richacl_permission(struct inode *, const struct richacl *, int);
 extern int richacl_chmod(struct inode *, umode_t);
+extern int richacl_equiv_mode(const struct richacl *, umode_t *);
 
 #endif /* __RICHACL_H */
-- 
2.5.5

  parent reply	other threads:[~2016-05-09 22:04 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 ` [PATCH v21 03/22] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD " Andreas Gruenbacher
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 ` Andreas Gruenbacher [this message]
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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