lkml.org 
[lkml]   [2004]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 7/13] Filesystem in Userspace
From
Date
This patch adds miscellaneous mount options to the FUSE filesystem.

The following mount options are added:

o default_permissions: check permissions with generic_permission()
o allow_other: allow other users to access files
o allow_root: allow root to access files
o kernel_cache: don't invalidate page cache on open

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
--- linux-2.6.10-rc2/fs/fuse/dir.c 2004-11-20 22:56:23.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/dir.c 2004-11-20 22:56:23.000000000 +0100
@@ -519,7 +519,10 @@ static int fuse_revalidate(struct dentry
struct fuse_conn *fc = INO_FC(inode);

if (fi->nodeid == FUSE_ROOT_ID) {
- if (current->fsuid != fc->uid)
+ if (!(fc->flags & FUSE_ALLOW_OTHER) &&
+ current->fsuid != fc->uid &&
+ (!(fc->flags & FUSE_ALLOW_ROOT) ||
+ current->fsuid != 0))
return -EACCES;
} else if (!fi->i_time || time_before_eq(jiffies, fi->i_time))
return 0;
@@ -531,9 +534,34 @@ static int fuse_permission(struct inode
{
struct fuse_conn *fc = INO_FC(inode);

- if (current->fsuid != fc->uid)
+ if (!(fc->flags & FUSE_ALLOW_OTHER) && current->fsuid != fc->uid &&
+ (!(fc->flags & FUSE_ALLOW_ROOT) || current->fsuid != 0))
return -EACCES;
- else
+ else if (fc->flags & FUSE_DEFAULT_PERMISSIONS) {
+ int err;
+ err = generic_permission(inode, mask, NULL);
+
+ /* If permission is denied, try to refresh file
+ attributes. This is also needed, because the root
+ node will at first have no permissions */
+
+ if (err == -EACCES) {
+ err = fuse_do_getattr(inode);
+ if (!err)
+ err = generic_permission(inode, mask, NULL);
+ }
+
+ /* FIXME: Need some mechanism to revoke permissions:
+ currently if the filesystem suddenly changes the
+ file mode, we will not be informed about it, and
+ continue to allow access to the file/directory.
+
+ This is actually not so grave, since the user can
+ simply keep access to the file/directory anyway by
+ keeping it open... */
+
+ return err;
+ } else
return 0;
}

@@ -750,6 +778,12 @@ static int fuse_setattr(struct dentry *e
int err;
int is_truncate = 0;

+ if (fc->flags & FUSE_DEFAULT_PERMISSIONS) {
+ err = inode_change_ok(inode, attr);
+ if (err)
+ return err;
+ }
+
if (attr->ia_valid & ATTR_SIZE) {
unsigned long limit;
is_truncate = 1;
--- linux-2.6.10-rc2/fs/fuse/fuse_i.h 2004-11-20 22:56:23.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/fuse_i.h 2004-11-20 22:56:23.000000000 +0100
@@ -17,6 +17,24 @@
/* If more requests are outstanding, then the operation will block */
#define FUSE_MAX_OUTSTANDING 10

+
+/** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
+module will check permissions based on the file mode. Otherwise no
+permission checking is done in the kernel */
+#define FUSE_DEFAULT_PERMISSIONS (1 << 0)
+
+/** If the FUSE_ALLOW_OTHER flag is given, then not only the user
+ doing the mount will be allowed to access the filesystem */
+#define FUSE_ALLOW_OTHER (1 << 1)
+
+/** If the FUSE_KERNEL_CACHE flag is given, then files will be cached
+ until the INVALIDATE operation is invoked */
+#define FUSE_KERNEL_CACHE (1 << 2)
+
+/** Allow root and setuid-root programs to access fuse-mounted
+ filesystems */
+#define FUSE_ALLOW_ROOT (1 << 4)
+
/** FUSE specific inode data */
struct fuse_inode {
unsigned long nodeid;
@@ -108,6 +126,9 @@ struct fuse_conn {
/** The user id for this mount */
uid_t uid;

+ /** The fuse mount flags for this mount */
+ unsigned int flags;
+
/** Readers of the connection are waiting on this */
wait_queue_head_t waitq;

--- linux-2.6.10-rc2/fs/fuse/inode.c 2004-11-20 22:56:23.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/inode.c 2004-11-20 22:56:23.000000000 +0100
@@ -20,12 +20,17 @@

static kmem_cache_t *fuse_inode_cachep;

+static int user_allow_other;
+module_param(user_allow_other, int, 0644);
+MODULE_PARM_DESC(user_allow_other, "Allow non root user to specify the \"allow_other\" or \"allow_root\" mount options");
+
#define FUSE_SUPER_MAGIC 0x65735546

struct fuse_mount_data {
int fd;
unsigned int rootmode;
unsigned int uid;
+ unsigned int flags;
};

static struct inode *fuse_alloc_inode(struct super_block *sb)
@@ -92,6 +97,7 @@ static void fuse_put_super(struct super_
spin_lock(&fuse_lock);
fc->sb = NULL;
fc->uid = 0;
+ fc->flags = 0;
/* Flush all readers on this fs */
wake_up_all(&fc->waitq);
fuse_release_conn(fc);
@@ -140,6 +146,10 @@ enum {
OPT_FD,
OPT_ROOTMODE,
OPT_UID,
+ OPT_DEFAULT_PERMISSIONS,
+ OPT_ALLOW_OTHER,
+ OPT_ALLOW_ROOT,
+ OPT_KERNEL_CACHE,
OPT_ERR
};

@@ -147,6 +157,10 @@ static match_table_t tokens = {
{OPT_FD, "fd=%u"},
{OPT_ROOTMODE, "rootmode=%o"},
{OPT_UID, "uid=%u"},
+ {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
+ {OPT_ALLOW_OTHER, "allow_other"},
+ {OPT_ALLOW_ROOT, "allow_root"},
+ {OPT_KERNEL_CACHE, "kernel_cache"},
{OPT_ERR, NULL}
};

@@ -183,6 +197,22 @@ static int parse_fuse_opt(char *opt, str
d->uid = value;
break;

+ case OPT_DEFAULT_PERMISSIONS:
+ d->flags |= FUSE_DEFAULT_PERMISSIONS;
+ break;
+
+ case OPT_ALLOW_OTHER:
+ d->flags |= FUSE_ALLOW_OTHER;
+ break;
+
+ case OPT_ALLOW_ROOT:
+ d->flags |= FUSE_ALLOW_ROOT;
+ break;
+
+ case OPT_KERNEL_CACHE:
+ d->flags |= FUSE_KERNEL_CACHE;
+ break;
+
default:
return 0;
}
@@ -198,6 +228,14 @@ static int fuse_show_options(struct seq_
struct fuse_conn *fc = SB_FC(mnt->mnt_sb);

seq_printf(m, ",uid=%u", fc->uid);
+ if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
+ seq_puts(m, ",default_permissions");
+ if (fc->flags & FUSE_ALLOW_OTHER)
+ seq_puts(m, ",allow_other");
+ if (fc->flags & FUSE_ALLOW_ROOT)
+ seq_puts(m, ",allow_root");
+ if (fc->flags & FUSE_KERNEL_CACHE)
+ seq_puts(m, ",kernel_cache");
return 0;
}

@@ -229,6 +267,7 @@ static struct fuse_conn *new_conn(void)
memset(fc, 0, sizeof(*fc));
fc->sb = NULL;
fc->file = NULL;
+ fc->flags = 0;
fc->uid = 0;
init_waitqueue_head(&fc->waitq);
INIT_LIST_HEAD(&fc->pending);
@@ -306,6 +345,11 @@ static int fuse_read_super(struct super_
if (!parse_fuse_opt((char *) data, &d))
return -EINVAL;

+ if (!user_allow_other &&
+ (d.flags & (FUSE_ALLOW_OTHER | FUSE_ALLOW_ROOT)) &&
+ current->uid != 0)
+ return -EPERM;
+
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = FUSE_SUPER_MAGIC;
@@ -321,6 +365,7 @@ static int fuse_read_super(struct super_
if (fc == NULL)
return -EINVAL;

+ fc->flags = d.flags;
fc->uid = d.uid;

SB_FC(sb) = fc;
--- linux-2.6.10-rc2/fs/fuse/file.c 2004-11-20 22:56:23.000000000 +0100
+++ linux-2.6.10-rc2-fuse/fs/fuse/file.c 2004-11-20 22:56:23.000000000 +0100
@@ -63,7 +63,7 @@ static int fuse_open(struct inode *inode
req->out.args[0].value = &outarg;
request_send(fc, req);
err = req->out.h.error;
- if (!err) {
+ if (!err && !(fc->flags & FUSE_KERNEL_CACHE)) {
invalidate_inode_pages(inode->i_mapping);
}
if (err) {
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 14:08    [from the cache]
©2003-2011 Jasper Spaans