fuse: fix ioctl ABI

In kernel ABI version 7.16 and later FUSE_IOCTL_RETRY reply from a
unrestricted IOCTL request shall return with an array of 'struct
fuse_ioctl_iovec' instead of 'struct iovec'.  This fixes the ABI
ambiguity of 32bit vs. 64bit.

Reported-by: "ccmail111" <ccmail111@yahoo.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Tejun Heo <tj@kernel.org>

2 files changed, 58 insertions, 5 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ca3b6bbb3790..95da1bc1c826 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1634,9 +1634,9 @@ static int fuse_ioctl_copy_user(struct page **pages, struct iovec *iov,
  * and 64bit.  Fortunately we can determine which structure the server
  * used from the size of the reply.
  */
-static int fuse_copy_ioctl_iovec(struct iovec *dst, void *src,
-                                 size_t transferred, unsigned count,
-                                 bool is_compat)
+static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
+                                     size_t transferred, unsigned count,
+                                     bool is_compat)
 {
 #ifdef CONFIG_COMPAT
         if (count * sizeof(struct compat_iovec) == transferred) {
@@ -1680,6 +1680,42 @@ static int fuse_verify_ioctl_iov(struct iovec *iov, size_t count)
         return 0;
 }
 
+static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
+                                 void *src, size_t transferred, unsigned count,
+                                 bool is_compat)
+{
+        unsigned i;
+        struct fuse_ioctl_iovec *fiov = src;
+
+        if (fc->minor < 16) {
+                return fuse_copy_ioctl_iovec_old(dst, src, transferred,
+                                                 count, is_compat);
+        }
+
+        if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
+                return -EIO;
+
+        for (i = 0; i < count; i++) {
+                /* Did the server supply an inappropriate value? */
+                if (fiov[i].base != (unsigned long) fiov[i].base ||
+                    fiov[i].len != (unsigned long) fiov[i].len)
+                        return -EIO;
+
+                dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
+                dst[i].iov_len = (size_t) fiov[i].len;
+
+#ifdef CONFIG_COMPAT
+                if (is_compat &&
+                    (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
+                     (compat_size_t) dst[i].iov_len != fiov[i].len))
+                        return -EIO;
+#endif
+        }
+
+        return 0;
+}
+
+
 /*
  * For ioctls, there is no generic way to determine how much memory
  * needs to be read and/or written.  Furthermore, ioctls are allowed
@@ -1746,8 +1782,15 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
         size_t in_size, out_size, transferred;
         int err;
 
+#if BITS_PER_LONG == 32
+        inarg.flags |= FUSE_IOCTL_32BIT;
+#else
+        if (flags & FUSE_IOCTL_COMPAT)
+                inarg.flags |= FUSE_IOCTL_32BIT;
+#endif
+
         /* assume all the iovs returned by client always fits in a page */
-        BUILD_BUG_ON(sizeof(struct iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
+        BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
 
         err = -ENOMEM;
         pages = kzalloc(sizeof(pages[0]) * FUSE_MAX_PAGES_PER_REQ, GFP_KERNEL);
@@ -1862,7 +1905,7 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
                         goto out;
 
                 vaddr = kmap_atomic(pages[0], KM_USER0);
-                err = fuse_copy_ioctl_iovec(iov_page, vaddr,
+                err = fuse_copy_ioctl_iovec(fc, iov_page, vaddr,
                                             transferred, in_iovs + out_iovs,
                                             (flags & FUSE_IOCTL_COMPAT) != 0);
                 kunmap_atomic(vaddr, KM_USER0);
diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index cf11881f4938..d464de53db43 100644
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -44,6 +44,9 @@
  *
  * 7.16
  *  - add BATCH_FORGET request
+ *  - FUSE_IOCTL_UNRESTRICTED shall now return with array of 'struct
+ *    fuse_ioctl_iovec' instead of ambiguous 'struct iovec'
+ *  - add FUSE_IOCTL_32BIT flag
  */
 
 #ifndef _LINUX_FUSE_H
@@ -203,12 +206,14 @@ struct fuse_file_lock {
  * FUSE_IOCTL_COMPAT: 32bit compat ioctl on 64bit machine
  * FUSE_IOCTL_UNRESTRICTED: not restricted to well-formed ioctls, retry allowed
  * FUSE_IOCTL_RETRY: retry with new iovecs
+ * FUSE_IOCTL_32BIT: 32bit ioctl
  *
  * FUSE_IOCTL_MAX_IOV: maximum of in_iovecs + out_iovecs
  */
 #define FUSE_IOCTL_COMPAT       (1 << 0)
 #define FUSE_IOCTL_UNRESTRICTED (1 << 1)
 #define FUSE_IOCTL_RETRY        (1 << 2)
+#define FUSE_IOCTL_32BIT        (1 << 3)
 
 #define FUSE_IOCTL_MAX_IOV      256
 
@@ -524,6 +529,11 @@ struct fuse_ioctl_in {
         __u32   out_size;
 };
 
+struct fuse_ioctl_iovec {
+        __u64   base;
+        __u64   len;
+};
+
 struct fuse_ioctl_out {
         __s32   result;
         __u32   flags;