Commit 60bcc88a authored by Seth Forshee's avatar Seth Forshee Committed by Miklos Szeredi
Browse files

fuse: Add posix ACL support 



Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support with
userspace.  When it is set in the INIT response, ACL support will be
enabled.  ACL support also implies "default_permissions".

When ACL support is enabled, the kernel will cache and have responsibility
for enforcing ACLs.  ACL xattrs will be passed to userspace, which is
responsible for updating the ACLs in the filesystem, keeping the file mode
in sync, and inheritance of default ACLs when new filesystem nodes are
created.

Signed-off-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 5e940c1d

fs/fuse/Kconfig

+1 −0
Original line number Diff line number Diff line 
config FUSE_FS

	tristate "FUSE (Filesystem in Userspace) support"

	select FS_POSIX_ACL

	help

	  With FUSE it is possible to implement a fully functional filesystem

	  in a userspace program.

fs/fuse/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -5,4 +5,4 @@ 
obj-$(CONFIG_FUSE_FS) += fuse.o

obj-$(CONFIG_CUSE) += cuse.o



fuse-objs := dev.o dir.o file.o inode.o control.o xattr.o
 
fuse-objs := dev.o dir.o file.o inode.o control.o xattr.o acl.o

fs/fuse/acl.c

0 → 100644
+99 −0
Original line number Diff line number Diff line 
/*

 * FUSE: Filesystem in Userspace

 * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>

 *

 * This program can be distributed under the terms of the GNU GPL.

 * See the file COPYING.

 */



#include "fuse_i.h"



#include <linux/posix_acl.h>

#include <linux/posix_acl_xattr.h>



struct posix_acl *fuse_get_acl(struct inode *inode, int type)

{

	struct fuse_conn *fc = get_fuse_conn(inode);

	int size;

	const char *name;

	void *value = NULL;

	struct posix_acl *acl;



	if (!fc->posix_acl || fc->no_getxattr)

		return NULL;



	if (type == ACL_TYPE_ACCESS)

		name = XATTR_NAME_POSIX_ACL_ACCESS;

	else if (type == ACL_TYPE_DEFAULT)

		name = XATTR_NAME_POSIX_ACL_DEFAULT;

	else

		return ERR_PTR(-EOPNOTSUPP);



	value = kmalloc(PAGE_SIZE, GFP_KERNEL);

	if (!value)

		return ERR_PTR(-ENOMEM);

	size = fuse_getxattr(inode, name, value, PAGE_SIZE);

	if (size > 0)

		acl = posix_acl_from_xattr(&init_user_ns, value, size);

	else if ((size == 0) || (size == -ENODATA) ||

		 (size == -EOPNOTSUPP && fc->no_getxattr))

		acl = NULL;

	else if (size == -ERANGE)

		acl = ERR_PTR(-E2BIG);

	else

		acl = ERR_PTR(size);



	kfree(value);

	return acl;

}



int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)

{

	struct fuse_conn *fc = get_fuse_conn(inode);

	const char *name;

	int ret;



	if (!fc->posix_acl || fc->no_setxattr)

		return -EOPNOTSUPP;



	if (type == ACL_TYPE_ACCESS)

		name = XATTR_NAME_POSIX_ACL_ACCESS;

	else if (type == ACL_TYPE_DEFAULT)

		name = XATTR_NAME_POSIX_ACL_DEFAULT;

	else

		return -EINVAL;



	if (acl) {

		/*

		 * Fuse userspace is responsible for updating access

		 * permissions in the inode, if needed. fuse_setxattr

		 * invalidates the inode attributes, which will force

		 * them to be refreshed the next time they are used,

		 * and it also updates i_ctime.

		 */

		size_t size = posix_acl_xattr_size(acl->a_count);

		void *value;



		if (size > PAGE_SIZE)

			return -E2BIG;



		value = kmalloc(size, GFP_KERNEL);

		if (!value)

			return -ENOMEM;



		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);

		if (ret < 0) {

			kfree(value);

			return ret;

		}



		ret = fuse_setxattr(inode, name, value, size, 0);

		kfree(value);

	} else {

		ret = fuse_removexattr(inode, name);

	}

	forget_all_cached_acls(inode);

	fuse_invalidate_attr(inode);



	return ret;

}

fs/fuse/dir.c

+16 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/namei.h>

#include <linux/slab.h>

#include <linux/xattr.h>

#include <linux/posix_acl.h>



static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)

{
@@ -244,6 +245,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags) 
		if (ret || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)

			goto invalid;



		forget_all_cached_acls(inode);

		fuse_change_attributes(inode, &outarg.attr,

				       entry_attr_timeout(&outarg),

				       attr_version);
@@ -918,6 +920,7 @@ int fuse_update_attributes(struct inode *inode, struct kstat *stat, 


	if (time_before64(fi->i_time, get_jiffies_64())) {

		r = true;

		forget_all_cached_acls(inode);

		err = fuse_do_getattr(inode, stat, file);

	} else {

		r = false;
@@ -1065,6 +1068,7 @@ static int fuse_perm_getattr(struct inode *inode, int mask) 
	if (mask & MAY_NOT_BLOCK)

		return -ECHILD;



	forget_all_cached_acls(inode);

	return fuse_do_getattr(inode, NULL, NULL);

}
@@ -1234,6 +1238,7 @@ retry: 
		fi->nlookup++;

		spin_unlock(&fc->lock);



		forget_all_cached_acls(inode);

		fuse_change_attributes(inode, &o->attr,

				       entry_attr_timeout(o),

				       attr_version);
@@ -1748,6 +1753,13 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr) 


	ret = fuse_do_setattr(inode, attr, file);

	if (!ret) {

		/*

		 * If filesystem supports acls it may have updated acl xattrs in

		 * the filesystem, so forget cached acls for the inode.

		 */

		if (fc->posix_acl)

			forget_all_cached_acls(inode);



		/* Directory mode changed, may need to revalidate access */

		if (d_is_dir(entry) && (attr->ia_valid & ATTR_MODE))

			fuse_invalidate_entry_cache(entry);
@@ -1785,6 +1797,8 @@ static const struct inode_operations fuse_dir_inode_operations = { 
	.getxattr	= generic_getxattr,

	.listxattr	= fuse_listxattr,

	.removexattr	= generic_removexattr,

	.get_acl	= fuse_get_acl,

	.set_acl	= fuse_set_acl,

};



static const struct file_operations fuse_dir_operations = {
@@ -1806,6 +1820,8 @@ static const struct inode_operations fuse_common_inode_operations = { 
	.getxattr	= generic_getxattr,

	.listxattr	= fuse_listxattr,

	.removexattr	= generic_removexattr,

	.get_acl	= fuse_get_acl,

	.set_acl	= fuse_set_acl,

};



static const struct inode_operations fuse_symlink_inode_operations = {

fs/fuse/fuse_i.h

+14 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/poll.h>

#include <linux/workqueue.h>

#include <linux/kref.h>

#include <linux/xattr.h>



/** Max number of pages that can be used in a single read request */

#define FUSE_MAX_PAGES_PER_REQ 32
@@ -627,6 +628,9 @@ struct fuse_conn { 
	/** Is lseek not implemented by fs? */

	unsigned no_lseek:1;



	/** Does the filesystem support posix acls? */

	unsigned posix_acl:1;



	/** The number of requests waiting for completion */

	atomic_t num_waiting;
@@ -971,7 +975,17 @@ void fuse_set_initialized(struct fuse_conn *fc); 
void fuse_unlock_inode(struct inode *inode);

void fuse_lock_inode(struct inode *inode);



int fuse_setxattr(struct inode *inode, const char *name, const void *value,

		  size_t size, int flags);

ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,

		      size_t size);

ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);

int fuse_removexattr(struct inode *inode, const char *name);

extern const struct xattr_handler *fuse_xattr_handlers[];

extern const struct xattr_handler *fuse_acl_xattr_handlers[];



struct posix_acl;

struct posix_acl *fuse_get_acl(struct inode *inode, int type);

int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type);



#endif /* _FS_FUSE_I_H */

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