splice: move f_mode checks to do_{splice,tee}()

do_splice() is used by io_uring, as will be do_tee(). Move f_mode
checks from sys_{splice,tee}() to do_{splice,tee}(), so they're
enforced for io_uring as well.

Fixes: 7d67af2c0134 ("io_uring: add splice(2) support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/splice.c b/fs/splice.c
index 4735def..fd0a1e7 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1118,6 +1118,10 @@ long do_splice(struct file *in, loff_t __user *off_in,
        loff_t offset;
        long ret;
 
+       if (unlikely(!(in->f_mode & FMODE_READ) ||
+                    !(out->f_mode & FMODE_WRITE)))
+               return -EBADF;
+
        ipipe = get_pipe_info(in);
        opipe = get_pipe_info(out);
 
@@ -1125,12 +1129,6 @@ long do_splice(struct file *in, loff_t __user *off_in,
                if (off_in || off_out)
                        return -ESPIPE;
 
-               if (!(in->f_mode & FMODE_READ))
-                       return -EBADF;
-
-               if (!(out->f_mode & FMODE_WRITE))
-                       return -EBADF;
-
                /* Splicing to self would be fun, but... */
                if (ipipe == opipe)
                        return -EINVAL;
@@ -1153,9 +1151,6 @@ long do_splice(struct file *in, loff_t __user *off_in,
                        offset = out->f_pos;
                }
 
-               if (unlikely(!(out->f_mode & FMODE_WRITE)))
-                       return -EBADF;
-
                if (unlikely(out->f_flags & O_APPEND))
                        return -EINVAL;
 
@@ -1440,15 +1435,11 @@ SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
        error = -EBADF;
        in = fdget(fd_in);
        if (in.file) {
-               if (in.file->f_mode & FMODE_READ) {
-                       out = fdget(fd_out);
-                       if (out.file) {
-                               if (out.file->f_mode & FMODE_WRITE)
-                                       error = do_splice(in.file, off_in,
-                                                         out.file, off_out,
-                                                         len, flags);
-                               fdput(out);
-                       }
+               out = fdget(fd_out);
+               if (out.file) {
+                       error = do_splice(in.file, off_in, out.file, off_out,
+                                         len, flags);
+                       fdput(out);
                }
                fdput(in);
        }
@@ -1770,6 +1761,10 @@ static long do_tee(struct file *in, struct file *out, size_t len,
        struct pipe_inode_info *opipe = get_pipe_info(out);
        int ret = -EINVAL;
 
+       if (unlikely(!(in->f_mode & FMODE_READ) ||
+                    !(out->f_mode & FMODE_WRITE)))
+               return -EBADF;
+
        /*
         * Duplicate the contents of ipipe to opipe without actually
         * copying the data.
@@ -1795,7 +1790,7 @@ static long do_tee(struct file *in, struct file *out, size_t len,
 
 SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
 {
-       struct fd in;
+       struct fd in, out;
        int error;
 
        if (unlikely(flags & ~SPLICE_F_ALL))
@@ -1807,14 +1802,10 @@ SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
        error = -EBADF;
        in = fdget(fdin);
        if (in.file) {
-               if (in.file->f_mode & FMODE_READ) {
-                       struct fd out = fdget(fdout);
-                       if (out.file) {
-                               if (out.file->f_mode & FMODE_WRITE)
-                                       error = do_tee(in.file, out.file,
-                                                       len, flags);
-                               fdput(out);
-                       }
+               out = fdget(fdout);
+               if (out.file) {
+                       error = do_tee(in.file, out.file, len, flags);
+                       fdput(out);
                }
                fdput(in);
        }