Re: [PATCH] fuse: allow umask processing in userspace

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Hi Miklos,

On my first try, I did not get much far. I could not compile
the kernel module for kernel-2.6.29.5-191 because of
undefined function current_umask(). This function
is nowhere to be found in the kernel source.

Is this a function (or macro) missing from the proposed
patch or part of a kernel upgrade ? In this latter case,
can it be implemented within the patch ? If not, I would
rather avoid installing a specific kernel for this test
and just use a dummy version returning a fixed value.

Anyway, what would be the minimal kernel version ?

Regards

Jean-Pierre


Miklos Szeredi wrote:
On Fri, 19 Jun 2009, Jean-Pierre André wrote:
On the very related issue of having some way of getting
the original permission flags (with umask not applied),
in create(), has there been any progress ?

OK, here's a patch that does this, it applies on top of latest git.
Could you please give it a test?

Even if you are not using git, you can get a "snapshot" of the git
tree from www.kernel.org.

I'll follow up with a patch for libfuse (also against latest CVS or
2.8.0-pre3)

Thanks,
Miklos

---
This patch lets filesystems handle masking the file mode on creation.
This is needed if filesystem is using ACLs.

 - The CREATE, MKDIR and MKNOD requests are extended with a "umask"
   parameter.

 - A new FUSE_DONT_MASK flag is added to the INIT request/reply.  With
   this the filesystem may request that the create mode is not masked.

CC: Jean-Pierre André <jean-pierre.andre@xxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
 fs/fuse/dir.c        |   20 +++++++++++++++++---
 fs/fuse/fuse_i.h     |    3 +++
 fs/fuse/inode.c      |    9 ++++++++-
 include/linux/fuse.h |   20 ++++++++++++++++++--
 4 files changed, 46 insertions(+), 6 deletions(-)

Index: linux-2.6/fs/fuse/dir.c
===================================================================
--- linux-2.6.orig/fs/fuse/dir.c	2009-06-22 20:37:44.000000000 +0200
+++ linux-2.6/fs/fuse/dir.c	2009-06-23 10:06:36.000000000 +0200
@@ -375,7 +375,7 @@ static int fuse_create_open(struct inode
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	struct fuse_req *req;
 	struct fuse_req *forget_req;
-	struct fuse_open_in inarg;
+	struct fuse_create_in inarg;
 	struct fuse_open_out outopen;
 	struct fuse_entry_out outentry;
 	struct fuse_file *ff;
@@ -399,15 +399,20 @@ static int fuse_create_open(struct inode
 	if (!ff)
 		goto out_put_request;
+ if (!fc->dont_mask)
+		mode &= ~current_umask();
+
 	flags &= ~O_NOCTTY;
 	memset(&inarg, 0, sizeof(inarg));
 	memset(&outentry, 0, sizeof(outentry));
 	inarg.flags = flags;
 	inarg.mode = mode;
+	inarg.umask = current_umask();
 	req->in.h.opcode = FUSE_CREATE;
 	req->in.h.nodeid = get_node_id(dir);
 	req->in.numargs = 2;
-	req->in.args[0].size = sizeof(inarg);
+	req->in.args[0].size = fc->minor < 12 ? sizeof(struct fuse_open_in) :
+						sizeof(inarg);
 	req->in.args[0].value = &inarg;
 	req->in.args[1].size = entry->d_name.len + 1;
 	req->in.args[1].value = entry->d_name.name;
@@ -546,12 +551,17 @@ static int fuse_mknod(struct inode *dir,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
+ if (!fc->dont_mask)
+		mode &= ~current_umask();
+
 	memset(&inarg, 0, sizeof(inarg));
 	inarg.mode = mode;
 	inarg.rdev = new_encode_dev(rdev);
+	inarg.umask = current_umask();
 	req->in.h.opcode = FUSE_MKNOD;
 	req->in.numargs = 2;
-	req->in.args[0].size = sizeof(inarg);
+	req->in.args[0].size = fc->minor < 12 ? FUSE_COMPAT_MKNOD_IN_SIZE :
+						sizeof(inarg);
 	req->in.args[0].value = &inarg;
 	req->in.args[1].size = entry->d_name.len + 1;
 	req->in.args[1].value = entry->d_name.name;
@@ -578,8 +588,12 @@ static int fuse_mkdir(struct inode *dir,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
+ if (!fc->dont_mask)
+		mode &= ~current_umask();
+
 	memset(&inarg, 0, sizeof(inarg));
 	inarg.mode = mode;
+	inarg.umask = current_umask();
 	req->in.h.opcode = FUSE_MKDIR;
 	req->in.numargs = 2;
 	req->in.args[0].size = sizeof(inarg);
Index: linux-2.6/fs/fuse/fuse_i.h
===================================================================
--- linux-2.6.orig/fs/fuse/fuse_i.h	2009-06-22 20:37:44.000000000 +0200
+++ linux-2.6/fs/fuse/fuse_i.h	2009-06-22 20:42:59.000000000 +0200
@@ -446,6 +446,9 @@ struct fuse_conn {
 	/** Do multi-page cached writes */
 	unsigned big_writes:1;
+ /** Don't apply umask to creation modes */
+	unsigned dont_mask:1;
+
 	/** The number of requests waiting for completion */
 	atomic_t num_waiting;
Index: linux-2.6/fs/fuse/inode.c
===================================================================
--- linux-2.6.orig/fs/fuse/inode.c	2009-06-22 20:37:44.000000000 +0200
+++ linux-2.6/fs/fuse/inode.c	2009-06-22 20:51:10.000000000 +0200
@@ -725,6 +725,8 @@ static void process_init_reply(struct fu
 			}
 			if (arg->flags & FUSE_BIG_WRITES)
 				fc->big_writes = 1;
+			if (arg->flags & FUSE_DONT_MASK)
+				fc->dont_mask = 1;
 		} else {
 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 			fc->no_lock = 1;
@@ -748,7 +750,7 @@ static void fuse_send_init(struct fuse_c
 	arg->minor = FUSE_KERNEL_MINOR_VERSION;
 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
-		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES;
+		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK;
 	req->in.h.opcode = FUSE_INIT;
 	req->in.numargs = 1;
 	req->in.args[0].size = sizeof(*arg);
@@ -864,6 +866,11 @@ static int fuse_fill_super(struct super_
 	if (err)
 		goto err_put_conn;
+ /* Handle umasking inside the fuse code */
+	if (sb->s_flags & MS_POSIXACL)
+		fc->dont_mask = 1;
+	sb->s_flags |= MS_POSIXACL;
+
 	fc->release = fuse_free_conn;
 	fc->flags = d.flags;
 	fc->user_id = d.user_id;
Index: linux-2.6/include/linux/fuse.h
===================================================================
--- linux-2.6.orig/include/linux/fuse.h	2009-06-22 20:37:44.000000000 +0200
+++ linux-2.6/include/linux/fuse.h	2009-06-23 10:05:45.000000000 +0200
@@ -25,6 +25,9 @@
  *  - add IOCTL message
  *  - add unsolicited notification support
  *  - add POLL message and NOTIFY_POLL notification
+ *
+ * 7.12
+ *  - add umask flag to input argument of open, mknod and mkdir
  */
#ifndef _LINUX_FUSE_H
@@ -36,7 +39,7 @@
 #define FUSE_KERNEL_VERSION 7
/** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 11
+#define FUSE_KERNEL_MINOR_VERSION 12
/** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -112,6 +115,7 @@ struct fuse_file_lock {
  * INIT request/reply flags
  *
  * FUSE_EXPORT_SUPPORT: filesystem handles lookups of "." and ".."
+ * FUSE_DONT_MASK: don't apply umask to file mode on create operations
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -119,6 +123,7 @@ struct fuse_file_lock {
 #define FUSE_ATOMIC_O_TRUNC	(1 << 3)
 #define FUSE_EXPORT_SUPPORT	(1 << 4)
 #define FUSE_BIG_WRITES		(1 << 5)
+#define FUSE_DONT_MASK		(1 << 6)
/**
  * CUSE INIT request/reply flags
@@ -262,14 +267,18 @@ struct fuse_attr_out {
 	struct fuse_attr attr;
 };
+#define FUSE_COMPAT_MKNOD_IN_SIZE 8
+
 struct fuse_mknod_in {
 	__u32	mode;
 	__u32	rdev;
+	__u32	umask;
+	__u32	padding;
 };
struct fuse_mkdir_in {
 	__u32	mode;
-	__u32	padding;
+	__u32	umask;
 };
struct fuse_rename_in {
@@ -301,7 +310,14 @@ struct fuse_setattr_in {
struct fuse_open_in {
 	__u32	flags;
+	__u32	unused;
+};
+
+struct fuse_create_in {
+	__u32	flags;
 	__u32	mode;
+	__u32	umask;
+	__u32	padding;
 };
struct fuse_open_out {


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