aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector()

A cleanup of rw_copy_check_uvector and compat_rw_copy_check_uvector after
changes made to support CMA in an earlier patch.

Rather than having an additional check_access parameter to these
functions, the first paramater type is overloaded to allow the caller to
specify CHECK_IOVEC_ONLY which means check that the contents of the iovec
are valid, but do not check the memory that they point to.  This is used
by process_vm_readv/writev where we need to validate that a iovec passed
to the syscall is valid but do not want to check the memory that it points
to at this point because it refers to an address space in another process.

Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 8 insertions, 9 deletions

diff --git a/fs/aio.c b/fs/aio.c
index e7f2fad7b4ce..8c7c8b805372 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1446,13 +1446,13 @@ static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
                 ret = compat_rw_copy_check_uvector(type,
                                 (struct compat_iovec __user *)kiocb->ki_buf,
                                 kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
-                                &kiocb->ki_iovec, 1);
+                                &kiocb->ki_iovec);
         else
 #endif
                 ret = rw_copy_check_uvector(type,
                                 (struct iovec __user *)kiocb->ki_buf,
                                 kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
-                                &kiocb->ki_iovec, 1);
+                                &kiocb->ki_iovec);
         if (ret < 0)
                 goto out;
 
diff --git a/fs/compat.c b/fs/compat.c
index 0781e619a62a..6556a9ce8a28 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -532,7 +532,7 @@ out:
 ssize_t compat_rw_copy_check_uvector(int type,
                 const struct compat_iovec __user *uvector, unsigned long nr_segs,
                 unsigned long fast_segs, struct iovec *fast_pointer,
-                struct iovec **ret_pointer, int check_access)
+                struct iovec **ret_pointer)
 {
         compat_ssize_t tot_len;
         struct iovec *iov = *ret_pointer = fast_pointer;
@@ -579,7 +579,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
                 }
                 if (len < 0)    /* size_t not fitting in compat_ssize_t .. */
                         goto out;
-                if (check_access &&
+                if (type >= 0 &&
                     !access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
                         ret = -EFAULT;
                         goto out;
@@ -1094,7 +1094,7 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
                 goto out;
 
         tot_len = compat_rw_copy_check_uvector(type, uvector, nr_segs,
-                                               UIO_FASTIOV, iovstack, &iov, 1);
+                                               UIO_FASTIOV, iovstack, &iov);
         if (tot_len == 0) {
                 ret = 0;
                 goto out;
diff --git a/fs/read_write.c b/fs/read_write.c
index ffc99d22e0a3..c20614f86c01 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -633,8 +633,7 @@ ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
                               unsigned long nr_segs, unsigned long fast_segs,
                               struct iovec *fast_pointer,
-                              struct iovec **ret_pointer,
-                              int check_access)
+                              struct iovec **ret_pointer)
 {
         unsigned long seg;
         ssize_t ret;
@@ -690,7 +689,7 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
                         ret = -EINVAL;
                         goto out;
                 }
-                if (check_access
+                if (type >= 0
                     && unlikely(!access_ok(vrfy_dir(type), buf, len))) {
                         ret = -EFAULT;
                         goto out;
@@ -723,7 +722,7 @@ static ssize_t do_readv_writev(int type, struct file *file,
         }
 
         ret = rw_copy_check_uvector(type, uvector, nr_segs,
-                                    ARRAY_SIZE(iovstack), iovstack, &iov, 1);
+                                    ARRAY_SIZE(iovstack), iovstack, &iov);
         if (ret <= 0)
                 goto out;