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Subject[PATCH v3 1/4] net: add accept helper not installing fd
Date
Introduce and reuse a helper that acts similarly to __sys_accept4_file()
but returns struct file instead of installing file descriptor. Will be
used by io_uring.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
include/linux/socket.h | 3 ++
net/socket.c | 71 ++++++++++++++++++++++--------------------
2 files changed, 40 insertions(+), 34 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 0d8e3dcb7f88..d3c1a42a2edd 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -421,6 +421,9 @@ extern int __sys_accept4_file(struct file *file, unsigned file_flags,
struct sockaddr __user *upeer_sockaddr,
int __user *upeer_addrlen, int flags,
unsigned long nofile);
+extern struct file *do_accept(struct file *file, unsigned file_flags,
+ struct sockaddr __user *upeer_sockaddr,
+ int __user *upeer_addrlen, int flags);
extern int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,
int __user *upeer_addrlen, int flags);
extern int __sys_socket(int family, int type, int protocol);
diff --git a/net/socket.c b/net/socket.c
index 0b2dad3bdf7f..532fff5a3684 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1722,32 +1722,22 @@ SYSCALL_DEFINE2(listen, int, fd, int, backlog)
return __sys_listen(fd, backlog);
}

-int __sys_accept4_file(struct file *file, unsigned file_flags,
+struct file *do_accept(struct file *file, unsigned file_flags,
struct sockaddr __user *upeer_sockaddr,
- int __user *upeer_addrlen, int flags,
- unsigned long nofile)
+ int __user *upeer_addrlen, int flags)
{
struct socket *sock, *newsock;
struct file *newfile;
- int err, len, newfd;
+ int err, len;
struct sockaddr_storage address;

- if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
- return -EINVAL;
-
- if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
- flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
-
sock = sock_from_file(file);
- if (!sock) {
- err = -ENOTSOCK;
- goto out;
- }
+ if (!sock)
+ return ERR_PTR(-ENOTSOCK);

- err = -ENFILE;
newsock = sock_alloc();
if (!newsock)
- goto out;
+ return ERR_PTR(-ENFILE);

newsock->type = sock->type;
newsock->ops = sock->ops;
@@ -1758,18 +1748,9 @@ int __sys_accept4_file(struct file *file, unsigned file_flags,
*/
__module_get(newsock->ops->owner);

- newfd = __get_unused_fd_flags(flags, nofile);
- if (unlikely(newfd < 0)) {
- err = newfd;
- sock_release(newsock);
- goto out;
- }
newfile = sock_alloc_file(newsock, flags, sock->sk->sk_prot_creator->name);
- if (IS_ERR(newfile)) {
- err = PTR_ERR(newfile);
- put_unused_fd(newfd);
- goto out;
- }
+ if (IS_ERR(newfile))
+ return newfile;

err = security_socket_accept(sock, newsock);
if (err)
@@ -1794,16 +1775,38 @@ int __sys_accept4_file(struct file *file, unsigned file_flags,
}

/* File flags are not inherited via accept() unlike another OSes. */
-
- fd_install(newfd, newfile);
- err = newfd;
-out:
- return err;
+ return newfile;
out_fd:
fput(newfile);
- put_unused_fd(newfd);
- goto out;
+ return ERR_PTR(err);
+}
+
+int __sys_accept4_file(struct file *file, unsigned file_flags,
+ struct sockaddr __user *upeer_sockaddr,
+ int __user *upeer_addrlen, int flags,
+ unsigned long nofile)
+{
+ struct file *newfile;
+ int newfd;

+ if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
+ return -EINVAL;
+
+ if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
+ flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
+
+ newfd = __get_unused_fd_flags(flags, nofile);
+ if (unlikely(newfd < 0))
+ return newfd;
+
+ newfile = do_accept(file, file_flags, upeer_sockaddr, upeer_addrlen,
+ flags);
+ if (IS_ERR(newfile)) {
+ put_unused_fd(newfd);
+ return PTR_ERR(newfile);
+ }
+ fd_install(newfd, newfile);
+ return newfd;
}

/*
--
2.32.0
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