linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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 v26 12/21] richacl: Update the file masks in chmod()
Date: Thu, 29 Sep 2016 01:29:31 +0200	[thread overview]
Message-ID: <1475105380-22837-13-git-send-email-agruenba@redhat.com> (raw)
In-Reply-To: <1475105380-22837-1-git-send-email-agruenba@redhat.com>

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>
Acked-by: Jeff Layton <jlayton@redhat.com>
---
 fs/richacl.c            | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/richacl.h |  1 +
 2 files changed, 72 insertions(+)

diff --git a/fs/richacl.c b/fs/richacl.c
index 731c468..a199245 100644
--- a/fs/richacl.c
+++ b/fs/richacl.c
@@ -541,3 +541,74 @@ 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.
+ */
+static 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;
+}
+
+/**
+ * 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 207fe06..3cd5e53 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -189,5 +189,6 @@ extern int richacl_masks_to_mode(const struct richacl *);
 extern unsigned int richacl_mode_to_mask(umode_t);
 extern int richacl_permission(struct inode *, const struct richacl *, int);
 extern void richacl_compute_max_masks(struct richacl *);
+extern int richacl_chmod(struct inode *, umode_t);
 
 #endif /* __RICHACL_H */
-- 
2.7.4

  parent reply	other threads:[~2016-09-28 23:35 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-28 23:29 [PATCH v25 00/21] Richacls (Core and Ext4) Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 01/21] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 02/21] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 03/21] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD " Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 04/21] vfs: Add permission flags for setting file attributes Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 05/21] richacl: In-memory representation and helper functions Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 06/21] richacl: Permission mapping functions Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 07/21] richacl: Permission check algorithm Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 08/21] richacl: Compute maximum file masks from an acl Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 09/21] vfs: Cache base_acl objects in inodes Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 10/21] vfs: Add get_richacl and set_richacl inode operations Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 11/21] vfs: Cache richacl in struct inode Andreas Gruenbacher
2016-09-28 23:29 ` Andreas Gruenbacher [this message]
2016-09-28 23:29 ` [PATCH v26 13/21] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 14/21] richacl: Create-time inheritance Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 15/21] richacl: Automatic Inheritance Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 16/21] richacl: xattr mapping functions Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 17/21] richacl: Add richacl xattr handler Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 18/21] vfs: Add richacl permission checking Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 19/21] vfs: Move check_posix_acl and check_richacl out of fs/namei.c Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 20/21] ext4: Add richacl support Andreas Gruenbacher
2016-09-28 23:29 ` [PATCH v26 21/21] ext4: Add richacl feature flag Andreas Gruenbacher
2016-09-30 16:11 ` [PATCH v25 00/21] Richacls (Core and Ext4) J. Bruce Fields

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1475105380-22837-13-git-send-email-agruenba@redhat.com \
    --to=agruenba@redhat.com \
    --cc=adilger.kernel@dilger.ca \
    --cc=anna.schumaker@netapp.com \
    --cc=bfields@fieldses.org \
    --cc=david@fromorbit.com \
    --cc=hch@infradead.org \
    --cc=jlayton@poochiereds.net \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-cifs@vger.kernel.org \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nfs@vger.kernel.org \
    --cc=trond.myklebust@primarydata.com \
    --cc=tytso@mit.edu \
    --cc=viro@zeniv.linux.org.uk \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).