[PATCH] fs: split receive_fd_replace from __receive_fd

From: Christoph Hellwig
Date: Thu Mar 25 2021 - 04:23:21 EST


receive_fd_replace shares almost no code with the general case, so split
it out. Also remove the "Bump the sock usage counts" comment from
both copies, as that is now what __receive_sock actually does.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/file.c | 39 +++++++++++++++++++--------------------
include/linux/file.h | 11 ++++-------
2 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index f3a4bac2cbe915..d8ccb95a7f4138 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -1068,8 +1068,6 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)

/**
* __receive_fd() - Install received file into file descriptor table
- *
- * @fd: fd to install into (if negative, a new fd will be allocated)
* @file: struct file that was received from another process
* @ufd: __user pointer to write new fd number to
* @o_flags: the O_* flags to apply to the new fd entry
@@ -1083,7 +1081,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
*
* Returns newly install fd or -ve on error.
*/
-int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags)
+int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)
{
int new_fd;
int error;
@@ -1092,32 +1090,33 @@ int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flag
if (error)
return error;

- if (fd < 0) {
- new_fd = get_unused_fd_flags(o_flags);
- if (new_fd < 0)
- return new_fd;
- } else {
- new_fd = fd;
- }
+ new_fd = get_unused_fd_flags(o_flags);
+ if (new_fd < 0)
+ return new_fd;

if (ufd) {
error = put_user(new_fd, ufd);
if (error) {
- if (fd < 0)
- put_unused_fd(new_fd);
+ put_unused_fd(new_fd);
return error;
}
}

- if (fd < 0) {
- fd_install(new_fd, get_file(file));
- } else {
- error = replace_fd(new_fd, file, o_flags);
- if (error)
- return error;
- }
+ fd_install(new_fd, get_file(file));
+ __receive_sock(file);
+ return new_fd;
+}

- /* Bump the sock usage counts, if any. */
+int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)
+{
+ int error;
+
+ error = security_file_receive(file);
+ if (error)
+ return error;
+ error = replace_fd(new_fd, file, o_flags);
+ if (error)
+ return error;
__receive_sock(file);
return new_fd;
}
diff --git a/include/linux/file.h b/include/linux/file.h
index 225982792fa20e..2de2e4613d7bc3 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -92,23 +92,20 @@ extern void put_unused_fd(unsigned int fd);

extern void fd_install(unsigned int fd, struct file *file);

-extern int __receive_fd(int fd, struct file *file, int __user *ufd,
+extern int __receive_fd(struct file *file, int __user *ufd,
unsigned int o_flags);
static inline int receive_fd_user(struct file *file, int __user *ufd,
unsigned int o_flags)
{
if (ufd == NULL)
return -EFAULT;
- return __receive_fd(-1, file, ufd, o_flags);
+ return __receive_fd(file, ufd, o_flags);
}
static inline int receive_fd(struct file *file, unsigned int o_flags)
{
- return __receive_fd(-1, file, NULL, o_flags);
-}
-static inline int receive_fd_replace(int fd, struct file *file, unsigned int o_flags)
-{
- return __receive_fd(fd, file, NULL, o_flags);
+ return __receive_fd(file, NULL, o_flags);
}
+int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags);

extern void flush_delayed_fput(void);
extern void __fput_sync(struct file *);
--
2.30.1