[PATCH] FUSE: tighten check for processes allowed access
This patch tightens the check for allowing processes to access non-privileged
mounts. The rational is that the filesystem implementation can control the
behavior or get otherwise unavailable information of the filesystem user. If
the filesystem user process has the same uid, gid, and is not suid or sgid
application, then access is safe. Otherwise access is not allowed unless the
"allow_other" mount option is given (for which policy is controlled by the
userspace mount utility).
Thanks to everyone linux-fsdevel, especially Martin Mares who helped uncover
problems with the previous approach.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 0b75c73..c8e54c0 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -31,6 +31,7 @@
int fd;
unsigned rootmode;
unsigned user_id;
+ unsigned group_id;
unsigned flags;
unsigned max_read;
};
@@ -199,6 +200,7 @@
spin_lock(&fuse_lock);
fc->mounted = 0;
fc->user_id = 0;
+ fc->group_id = 0;
fc->flags = 0;
/* Flush all readers on this fs */
wake_up_all(&fc->waitq);
@@ -248,6 +250,7 @@
OPT_FD,
OPT_ROOTMODE,
OPT_USER_ID,
+ OPT_GROUP_ID,
OPT_DEFAULT_PERMISSIONS,
OPT_ALLOW_OTHER,
OPT_KERNEL_CACHE,
@@ -259,6 +262,7 @@
{OPT_FD, "fd=%u"},
{OPT_ROOTMODE, "rootmode=%o"},
{OPT_USER_ID, "user_id=%u"},
+ {OPT_GROUP_ID, "group_id=%u"},
{OPT_DEFAULT_PERMISSIONS, "default_permissions"},
{OPT_ALLOW_OTHER, "allow_other"},
{OPT_KERNEL_CACHE, "kernel_cache"},
@@ -300,6 +304,12 @@
d->user_id = value;
break;
+ case OPT_GROUP_ID:
+ if (match_int(&args[0], &value))
+ return 0;
+ d->group_id = value;
+ break;
+
case OPT_DEFAULT_PERMISSIONS:
d->flags |= FUSE_DEFAULT_PERMISSIONS;
break;
@@ -333,6 +343,7 @@
struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
seq_printf(m, ",user_id=%u", fc->user_id);
+ seq_printf(m, ",group_id=%u", fc->group_id);
if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
seq_puts(m, ",default_permissions");
if (fc->flags & FUSE_ALLOW_OTHER)
@@ -465,6 +476,7 @@
fc->flags = d.flags;
fc->user_id = d.user_id;
+ fc->group_id = d.group_id;
fc->max_read = d.max_read;
if (fc->max_read / PAGE_CACHE_SIZE < fc->bdi.ra_pages)
fc->bdi.ra_pages = fc->max_read / PAGE_CACHE_SIZE;