Add a new INIT flag, FUSE_POSIX_ACL, for negotiating ACL support
with userspace. When default_permissions is enabled the kernel
will set this flag in FUSE_INIT, and if it is also set in the
response ACL support will be enabled.
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: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
---
fs/fuse/Kconfig | 1 +
fs/fuse/Makefile | 2 +-
fs/fuse/acl.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dir.c | 25 +++++++++++-
fs/fuse/fuse_i.h | 18 +++++++++
fs/fuse/inode.c | 9 +++++
fs/fuse/xattr.c | 18 ++++++---
include/uapi/linux/fuse.h | 3 ++
8 files changed, 168 insertions(+), 8 deletions(-)
create mode 100644 fs/fuse/acl.c
diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 1b2f6c2c3aaf..76f09ce7e5b2 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -1,5 +1,6 @@
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.
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 448aa27ada00..60da84a86dab 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -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
diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
new file mode 100644
index 000000000000..87220da95e91
--- /dev/null
+++ b/fs/fuse/acl.c
@@ -0,0 +1,100 @@
+/*
+ FUSE: Filesystem in Userspace
+ Copyright (C) 2016 Canonical Ltd. <seth.forshee@xxxxxxxxxxxxx>
+
+ 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 == -ERANGE) {
+ kfree(value);
+ size = fuse_getxattr(inode, name, NULL, 0);
+ value = kmalloc(size, GFP_KERNEL);
+ if (!value)
+ return ERR_PTR(-ENOMEM);
+ size = fuse_getxattr(inode, name, value, 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
+ 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 = 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);
+ }
+ if (ret == 0)
+ set_cached_acl(inode, type, acl);
+ return ret;
+}
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 7490db141dd9..d25e00cfe72d 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -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);
@@ -1703,14 +1708,24 @@ error:
static int fuse_setattr(struct dentry *entry, struct iattr *attr)
{
struct inode *inode = d_inode(entry);
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ int ret;
if (!fuse_allow_current_process(get_fuse_conn(inode)))
return -EACCES;
if (attr->ia_valid & ATTR_FILE)
- return fuse_do_setattr(inode, attr, attr->ia_file);
+ ret = fuse_do_setattr(inode, attr, attr->ia_file);
else
- return fuse_do_setattr(inode, attr, NULL);
+ ret = fuse_do_setattr(inode, attr, NULL);
+
+ /*
+ * If filesystem supports acls it may have updated acl xattrs in
+ * the filesystem, so forget cached acls for the inode.
+ */
+ if (!ret && fc->posix_acl)
+ forget_all_cached_acls(inode);
+ return ret;
}
static int fuse_getattr(struct vfsmount *mnt, struct dentry *entry,
@@ -1743,6 +1758,8 @@ 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 = {
@@ -1764,6 +1781,8 @@ 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 = {
@@ -1775,6 +1794,8 @@ static const struct inode_operations fuse_symlink_inode_operations = {
.getxattr = generic_getxattr,
.listxattr = fuse_listxattr,
.removexattr = generic_removexattr,
+ .get_acl = fuse_get_acl,
+ .set_acl = fuse_set_acl,
};
void fuse_init_common(struct inode *inode)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 6db54d0bd81b..5d8a6bf6594d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -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
@@ -624,6 +625,9 @@ 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;
@@ -968,7 +972,21 @@ 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;
+
+extern const struct xattr_handler fuse_xattr_acl_access_handler;
+extern const struct xattr_handler fuse_xattr_acl_default_handler;
+
+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 */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 1e535f31fed0..a3cfcb541243 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -20,6 +20,7 @@
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/exportfs.h>
+#include <linux/posix_acl.h>
MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
MODULE_DESCRIPTION("Filesystem in Userspace");
@@ -340,6 +341,7 @@ int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
return -ENOENT;
fuse_invalidate_attr(inode);
+ forget_all_cached_acls(inode);
if (offset >= 0) {
pg_start = offset >> PAGE_SHIFT;
if (len <= 0)
@@ -912,6 +914,11 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
fc->parallel_dirops = 1;
if (arg->time_gran && arg->time_gran <= 1000000000)
fc->sb->s_time_gran = arg->time_gran;
+ if ((arg->flags & FUSE_POSIX_ACL) &&
+ (fc->flags & FUSE_DEFAULT_PERMISSIONS)) {
+ fc->posix_acl = 1;
+ fc->sb->s_xattr = fuse_acl_xattr_handlers;
+ }
} else {
ra_pages = fc->max_read / PAGE_SIZE;
fc->no_lock = 1;
@@ -942,6 +949,8 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
FUSE_PARALLEL_DIROPS;
+ if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
+ arg->flags |= FUSE_POSIX_ACL;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);
diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 9929cbe8cf03..855e701f8c11 100644
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -9,9 +9,10 @@
#include "fuse_i.h"
#include <linux/xattr.h>
+#include <linux/posix_acl_xattr.h>
-static int fuse_setxattr(struct inode *inode, const char *name,
- const void *value, size_t size, int flags)
+int fuse_setxattr(struct inode *inode, const char *name, const void *value,
+ size_t size, int flags)
{
struct fuse_conn *fc = get_fuse_conn(inode);
FUSE_ARGS(args);
@@ -45,8 +46,8 @@ static int fuse_setxattr(struct inode *inode, const char *name,
return err;
}
-static ssize_t fuse_getxattr(struct inode *inode, const char *name,
- void *value, size_t size)
+ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,
+ size_t size)
{
struct fuse_conn *fc = get_fuse_conn(inode);
FUSE_ARGS(args);
@@ -128,7 +129,7 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
return ret;
}
-static int fuse_removexattr(struct inode *inode, const char *name)
+int fuse_removexattr(struct inode *inode, const char *name)
{
struct fuse_conn *fc = get_fuse_conn(inode);
FUSE_ARGS(args);
@@ -182,3 +183,10 @@ const struct xattr_handler *fuse_xattr_handlers[] = {
&fuse_xattr_handler,
NULL
};
+
+const struct xattr_handler *fuse_acl_xattr_handlers[] = {
+ &posix_acl_access_xattr_handler,
+ &posix_acl_default_xattr_handler,
+ &fuse_xattr_handler,
+ NULL
+};
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 27e17363263a..cb48ec4546ce 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -108,6 +108,7 @@
*
* 7.25
* - add FUSE_PARALLEL_DIROPS
+ * - add FUSE_POSIX_ACL
*/
#ifndef _LINUX_FUSE_H
@@ -238,6 +239,7 @@ struct fuse_file_lock {
* FUSE_WRITEBACK_CACHE: use writeback cache for buffered writes
* FUSE_NO_OPEN_SUPPORT: kernel supports zero-message opens
* FUSE_PARALLEL_DIROPS: allow parallel lookups and readdir
+ * FUSE_POSIX_ACL: filesystem supports posix acls
*/
#define FUSE_ASYNC_READ (1 << 0)
#define FUSE_POSIX_LOCKS (1 << 1)
@@ -258,6 +260,7 @@ struct fuse_file_lock {
#define FUSE_WRITEBACK_CACHE (1 << 16)
#define FUSE_NO_OPEN_SUPPORT (1 << 17)
#define FUSE_PARALLEL_DIROPS (1 << 18)
+#define FUSE_POSIX_ACL (1 << 19)
/**
* CUSE INIT request/reply flags
--
2.7.4
--
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