[PATCH] r/o bind mounts: elevate write count for ncp_ioctl()
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ncpfs/ioctl.c b/fs/ncpfs/ioctl.c
index c67b4bd..ad8f167 100644
--- a/fs/ncpfs/ioctl.c
+++ b/fs/ncpfs/ioctl.c
@@ -14,6 +14,7 @@
#include <linux/ioctl.h>
#include <linux/time.h>
#include <linux/mm.h>
+#include <linux/mount.h>
#include <linux/highuid.h>
#include <linux/smp_lock.h>
#include <linux/vmalloc.h>
@@ -261,7 +262,7 @@
}
#endif /* CONFIG_NCPFS_NLS */
-int ncp_ioctl(struct inode *inode, struct file *filp,
+static int __ncp_ioctl(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct ncp_server *server = NCP_SERVER(inode);
@@ -822,6 +823,57 @@
return -EINVAL;
}
+static int ncp_ioctl_need_write(unsigned int cmd)
+{
+ switch (cmd) {
+ case NCP_IOC_GET_FS_INFO:
+ case NCP_IOC_GET_FS_INFO_V2:
+ case NCP_IOC_NCPREQUEST:
+ case NCP_IOC_SETDENTRYTTL:
+ case NCP_IOC_SIGN_INIT:
+ case NCP_IOC_LOCKUNLOCK:
+ case NCP_IOC_SET_SIGN_WANTED:
+ return 1;
+ case NCP_IOC_GETOBJECTNAME:
+ case NCP_IOC_SETOBJECTNAME:
+ case NCP_IOC_GETPRIVATEDATA:
+ case NCP_IOC_SETPRIVATEDATA:
+ case NCP_IOC_SETCHARSETS:
+ case NCP_IOC_GETCHARSETS:
+ case NCP_IOC_CONN_LOGGED_IN:
+ case NCP_IOC_GETDENTRYTTL:
+ case NCP_IOC_GETMOUNTUID2:
+ case NCP_IOC_SIGN_WANTED:
+ case NCP_IOC_GETROOT:
+ case NCP_IOC_SETROOT:
+ return 0;
+ default:
+ /* unkown IOCTL command, assume write */
+ return 1;
+ }
+}
+
+int ncp_ioctl(struct inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+ int ret;
+
+ if (ncp_ioctl_need_write(cmd)) {
+ /*
+ * inside the ioctl(), any failures which
+ * are because of file_permission() are
+ * -EACCESS, so it seems consistent to keep
+ * that here.
+ */
+ if (mnt_want_write(filp->f_path.mnt))
+ return -EACCES;
+ }
+ ret = __ncp_ioctl(inode, filp, cmd, arg);
+ if (ncp_ioctl_need_write(cmd))
+ mnt_drop_write(filp->f_path.mnt);
+ return ret;
+}
+
#ifdef CONFIG_COMPAT
long ncp_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{