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Subject[PATCH for-5.7] splice: move f_mode checks to do_{splice,tee}()
Date
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>
---
fs/splice.c | 45 ++++++++++++++++++---------------------------
1 file changed, 18 insertions(+), 27 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 4735defc46ee..fd0a1e7e5959 100644
--- 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);
}
--
2.24.0
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