linux-api.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-api@vger.kernel.org, samba-technical@lists.samba.org,
	linux-security-module@vger.kernel.org,
	Andreas Gruenbacher <agruenba@redhat.com>
Subject: [PATCH v5 07/39] richacl: Permission mapping functions
Date: Wed, 22 Jul 2015 15:02:57 +0200	[thread overview]
Message-ID: <1437570209-29832-8-git-send-email-andreas.gruenbacher@gmail.com> (raw)
In-Reply-To: <1437570209-29832-1-git-send-email-andreas.gruenbacher@gmail.com>

From: Andreas Gruenbacher <agruenba@redhat.com>

We need to map from POSIX permissions to NFSv4 permissions when a
chmod() is done, from NFSv4 permissions to POSIX permissions when an acl
is set (which implicitly sets the file permission bits), and from the
MAY_READ/MAY_WRITE/MAY_EXEC/MAY_APPEND flags to NFSv4 permissions when
doing an access check in a richacl.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/richacl_base.c       | 113 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/richacl.h |  47 +++++++++++++++++++-
 2 files changed, 159 insertions(+), 1 deletion(-)

diff --git a/fs/richacl_base.c b/fs/richacl_base.c
index 6d9a073..d12f984 100644
--- a/fs/richacl_base.c
+++ b/fs/richacl_base.c
@@ -65,3 +65,116 @@ richace_copy(struct richace *to, const struct richace *from)
 {
 	memcpy(to, from, sizeof(struct richace));
 }
+
+/*
+ * richacl_mask_to_mode  -  compute the file permission bits which correspond to @mask
+ * @mask:	%RICHACE_* permission mask
+ *
+ * See richacl_masks_to_mode().
+ */
+static int
+richacl_mask_to_mode(unsigned int mask)
+{
+	int mode = 0;
+
+	if (mask & RICHACE_POSIX_MODE_READ)
+		mode |= S_IROTH;
+	if (mask & RICHACE_POSIX_MODE_WRITE)
+		mode |= S_IWOTH;
+	if (mask & RICHACE_POSIX_MODE_EXEC)
+		mode |= S_IXOTH;
+
+	return mode;
+}
+
+/**
+ * richacl_masks_to_mode  -  compute the file permission bits from the file masks
+ *
+ * When setting a richacl, we set the file permission bits to indicate maximum
+ * permissions: for example, we set the Write permission when a mask contains
+ * RICHACE_APPEND_DATA even if it does not also contain RICHACE_WRITE_DATA.
+ *
+ * Permissions which are not in RICHACE_POSIX_MODE_READ, RICHACE_POSIX_MODE_WRITE, or
+ * RICHACE_POSIX_MODE_EXEC cannot be represented in the file permission bits.
+ * Such permissions can still be effective, but not for new files or after a
+ * chmod(); they must be explicitly enabled in the richacl.
+ */
+int
+richacl_masks_to_mode(const struct richacl *acl)
+{
+	return richacl_mask_to_mode(acl->a_owner_mask) << 6 |
+	       richacl_mask_to_mode(acl->a_group_mask) << 3 |
+	       richacl_mask_to_mode(acl->a_other_mask);
+}
+EXPORT_SYMBOL_GPL(richacl_masks_to_mode);
+
+/**
+ * richacl_mode_to_mask  - compute a file mask from the lowest three mode bits
+ *
+ * When the file permission bits of a file are set with chmod(), this specifies
+ * the maximum permissions that processes will get.  All permissions beyond
+ * that will be removed from the file masks, and become ineffective.
+ */
+unsigned int
+richacl_mode_to_mask(mode_t mode)
+{
+	unsigned int mask = 0;
+
+	if (mode & S_IROTH)
+		mask |= RICHACE_POSIX_MODE_READ;
+	if (mode & S_IWOTH)
+		mask |= RICHACE_POSIX_MODE_WRITE;
+	if (mode & S_IXOTH)
+		mask |= RICHACE_POSIX_MODE_EXEC;
+
+	return mask;
+}
+
+/**
+ * richacl_want_to_mask  - convert the iop->permission want argument to a mask
+ * @want:	@want argument of the permission inode operation
+ *
+ * When checking for append, @want is (MAY_WRITE | MAY_APPEND).
+ *
+ * Richacls use the iop->may_create and iop->may_delete hooks which are
+ * used for checking if creating and deleting files is allowed.  These hooks do
+ * not use richacl_want_to_mask(), so we do not have to deal with mapping
+ * MAY_WRITE to RICHACE_ADD_FILE, RICHACE_ADD_SUBDIRECTORY, and RICHACE_DELETE_CHILD
+ * here.
+ */
+unsigned int
+richacl_want_to_mask(unsigned int want)
+{
+	unsigned int mask = 0;
+
+	if (want & MAY_READ)
+		mask |= RICHACE_READ_DATA;
+	if (want & MAY_DELETE_SELF)
+		mask |= RICHACE_DELETE;
+	if (want & MAY_TAKE_OWNERSHIP)
+		mask |= RICHACE_WRITE_OWNER;
+	if (want & MAY_CHMOD)
+		mask |= RICHACE_WRITE_ACL;
+	if (want & MAY_SET_TIMES)
+		mask |= RICHACE_WRITE_ATTRIBUTES;
+	if (want & MAY_EXEC)
+		mask |= RICHACE_EXECUTE;
+	/*
+	 * differentiate MAY_WRITE from these request
+	 */
+	if (want & (MAY_APPEND |
+		    MAY_CREATE_FILE | MAY_CREATE_DIR |
+		    MAY_DELETE_CHILD)) {
+		if (want & MAY_APPEND)
+			mask |= RICHACE_APPEND_DATA;
+		if (want & MAY_CREATE_FILE)
+			mask |= RICHACE_ADD_FILE;
+		if (want & MAY_CREATE_DIR)
+			mask |= RICHACE_ADD_SUBDIRECTORY;
+		if (want & MAY_DELETE_CHILD)
+			mask |= RICHACE_DELETE_CHILD;
+	} else if (want & MAY_WRITE)
+		mask |= RICHACE_WRITE_DATA;
+	return mask;
+}
+EXPORT_SYMBOL_GPL(richacl_want_to_mask);
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index 060d5e4..1ae0bf8 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -118,6 +118,49 @@ struct richacl {
 	RICHACE_WRITE_OWNER |					\
 	RICHACE_SYNCHRONIZE)
 
+/*
+ * The POSIX permissions are supersets of the following NFSv4 permissions:
+ *
+ *  - MAY_READ maps to READ_DATA or LIST_DIRECTORY, depending on the type
+ *    of the file system object.
+ *
+ *  - MAY_WRITE maps to WRITE_DATA or RICHACE_APPEND_DATA for files, and to
+ *    ADD_FILE, RICHACE_ADD_SUBDIRECTORY, or RICHACE_DELETE_CHILD for directories.
+ *
+ *  - MAY_EXECUTE maps to RICHACE_EXECUTE.
+ *
+ *  (Some of these NFSv4 permissions have the same bit values.)
+ */
+#define RICHACE_POSIX_MODE_READ (			\
+		RICHACE_READ_DATA |		\
+		RICHACE_LIST_DIRECTORY)
+#define RICHACE_POSIX_MODE_WRITE (			\
+		RICHACE_WRITE_DATA |		\
+		RICHACE_ADD_FILE |			\
+		RICHACE_APPEND_DATA |		\
+		RICHACE_ADD_SUBDIRECTORY |		\
+		RICHACE_DELETE_CHILD)
+#define RICHACE_POSIX_MODE_EXEC RICHACE_EXECUTE
+#define RICHACE_POSIX_MODE_ALL (			\
+		RICHACE_POSIX_MODE_READ |		\
+		RICHACE_POSIX_MODE_WRITE |		\
+		RICHACE_POSIX_MODE_EXEC)
+/*
+ * These permissions are always allowed
+ * no matter what the acl says.
+ */
+#define RICHACE_POSIX_ALWAYS_ALLOWED (	\
+		RICHACE_SYNCHRONIZE |	\
+		RICHACE_READ_ATTRIBUTES |	\
+		RICHACE_READ_ACL)
+/*
+ * The owner is implicitly granted
+ * these permissions under POSIX.
+ */
+#define RICHACE_POSIX_OWNER_ALLOWED (		\
+		RICHACE_WRITE_ATTRIBUTES |		\
+		RICHACE_WRITE_OWNER |		\
+		RICHACE_WRITE_ACL)
 /**
  * richacl_get  -  grab another reference to a richacl handle
  */
@@ -255,6 +298,8 @@ richace_is_same_identifier(const struct richace *a, const struct richace *b)
 extern struct richacl *richacl_alloc(int, gfp_t);
 extern struct richacl *richacl_clone(const struct richacl *, gfp_t);
 extern void richace_copy(struct richace *, const struct richace *);
-
+extern int richacl_masks_to_mode(const struct richacl *);
+extern unsigned int richacl_mode_to_mask(mode_t);
+extern unsigned int richacl_want_to_mask(unsigned int);
 
 #endif /* __RICHACL_H */
-- 
2.4.3

  parent reply	other threads:[~2015-07-22 13:02 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-22 13:02 [PATCH v5 00/39] Richacls Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 01/39] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 03/39] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 04/39] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 05/39] vfs: Add permission flags for setting file attributes Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 06/39] richacl: In-memory representation and helper functions Andreas Gruenbacher
2015-07-22 13:02 ` Andreas Gruenbacher [this message]
2015-07-22 13:02 ` [PATCH v5 08/39] richacl: Compute maximum file masks from an acl Andreas Gruenbacher
2015-07-22 13:02 ` [PATCH v5 09/39] richacl: Update the file masks in chmod() Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 11/39] vfs: Cache base_acl objects in inodes Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 12/39] vfs: Cache richacl in struct inode Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 13/39] richacl: Check if an acl is equivalent to a file mode Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 14/39] richacl: Create-time inheritance Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 15/39] richacl: Automatic Inheritance Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 16/39] richacl: xattr mapping functions Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 17/39] vfs: Add richacl permission checking Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 18/39] ext4: Add richacl support Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 19/39] ext4: Add richacl feature flag Andreas Gruenbacher
     [not found] ` <1437570209-29832-1-git-send-email-andreas.gruenbacher-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-07-22 13:02   ` [PATCH v5 02/39] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher
2015-07-22 13:03   ` [PATCH v5 10/39] richacl: Permission check algorithm Andreas Gruenbacher
2015-07-22 13:03   ` [PATCH v5 20/39] richacl: acl editing helper functions Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 21/39] richacl: Move everyone@ aces down the acl Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 22/39] richacl: Propagate everyone@ permissions to other aces Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 23/39] richacl: Set the owner permissions to the owner mask Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 24/39] richacl: Set the other permissions to the other mask Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 25/39] richacl: Isolate the owner and group classes Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 26/39] richacl: Apply the file masks to a richacl Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 27/39] richacl: Create richacl from mode values Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 28/39] nfsd: Keep list of acls to dispose of in compoundargs Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 29/39] nfsd: Use richacls as internal acl representation Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 30/39] nfsd: Add richacl support Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 31/39] nfsd: Add support for the v4.1 dacl attribute Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 32/39] richacl: Add support for unmapped identifiers Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 33/39] ext4: Don't allow unmapped identifiers in richacls Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 34/39] sunrpc: Allow to demand-allocate pages to encode into Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 35/39] sunrpc: Add xdr_init_encode_pages Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 36/39] nfs: Fix GETATTR bitmap verification Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 37/39] nfs: Remove unused xdr page offsets in getacl/setacl arguments Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 38/39] nfs: Add richacl support Andreas Gruenbacher
2015-07-22 13:03 ` [PATCH v5 39/39] nfs: Add support for the v4.1 dacl attribute Andreas Gruenbacher
2015-07-22 15:57   ` Anna Schumaker
2015-07-22 16:08     ` Andreas Grünbacher

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=1437570209-29832-8-git-send-email-andreas.gruenbacher@gmail.com \
    --to=andreas.gruenbacher@gmail.com \
    --cc=agruenba@redhat.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nfs@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=samba-technical@lists.samba.org \
    /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).