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Commit 39d8c1b6 authored by David S. Miller's avatar David S. Miller
Browse files

[NET]: Do not lose accepted socket when -ENFILE/-EMFILE. 



Try to allocate the struct file and an unused file
descriptor before we try to pull a newly accepted
socket out of the protocol layer.

Based upon a patch by Prassana Meda.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 77d2ca35

net/socket.c

+71 −42
Original line number Diff line number Diff line
@@ -348,8 +348,8 @@ static struct dentry_operations sockfs_dentry_operations = { 
/*

 *	Obtains the first available file descriptor and sets it up for use.

 *

 *	This function creates file structure and maps it to fd space

 *	of current process. On success it returns file descriptor

 *	These functions create file structures and maps them to fd space

 *	of the current process. On success it returns file descriptor

 *	and file struct implicitly stored in sock->file.

 *	Note that another thread may close file descriptor before we return

 *	from this function. We use the fact that now we do not refer
@@ -362,37 +362,37 @@ static struct dentry_operations sockfs_dentry_operations = { 
 *	but we take care of internal coherence yet.

 */



int sock_map_fd(struct socket *sock)

static int sock_alloc_fd(struct file **filep)

{

	int fd;

	struct qstr this;

	char name[32];



	/*

	 *	Find a file descriptor suitable for return to the user. 

	 */



	fd = get_unused_fd();

	if (fd >= 0) {

	if (likely(fd >= 0)) {

		struct file *file = get_empty_filp();



		if (!file) {

		*filep = file;

		if (unlikely(!file)) {

			put_unused_fd(fd);

			fd = -ENFILE;

			goto out;

			return -ENFILE;

		}

	} else

		*filep = NULL;

	return fd;

}



static int sock_attach_fd(struct socket *sock, struct file *file)

{

	struct qstr this;

	char name[32];



	this.len = sprintf(name, "[%lu]", SOCK_INODE(sock)->i_ino);

	this.name = name;

	this.hash = SOCK_INODE(sock)->i_ino;



	file->f_dentry = d_alloc(sock_mnt->mnt_sb->s_root, &this);

		if (!file->f_dentry) {

			put_filp(file);

			put_unused_fd(fd);

			fd = -ENOMEM;

			goto out;

		}

	if (unlikely(!file->f_dentry))

		return -ENOMEM;



	file->f_dentry->d_op = &sockfs_dentry_operations;

	d_add(file->f_dentry, SOCK_INODE(sock));

	file->f_vfsmnt = mntget(sock_mnt);
@@ -404,10 +404,25 @@ int sock_map_fd(struct socket *sock) 
	file->f_flags = O_RDWR;

	file->f_pos = 0;

	file->private_data = sock;

		fd_install(fd, file);



	return 0;

}



out:

int sock_map_fd(struct socket *sock)

{

	struct file *newfile;

	int fd = sock_alloc_fd(&newfile);



	if (likely(fd >= 0)) {

		int err = sock_attach_fd(sock, newfile);



		if (unlikely(err < 0)) {

			put_filp(newfile);

			put_unused_fd(fd);

			return err;

		}

		fd_install(fd, newfile);

	}

	return fd;

}
@@ -1349,7 +1364,8 @@ asmlinkage long sys_listen(int fd, int backlog) 
asmlinkage long sys_accept(int fd, struct sockaddr __user *upeer_sockaddr, int __user *upeer_addrlen)

{

	struct socket *sock, *newsock;

	int err, len;

	struct file *newfile;

	int err, len, newfd;

	char address[MAX_SOCK_ADDR];



	sock = sockfd_lookup(fd, &err);
@@ -1369,28 +1385,38 @@ asmlinkage long sys_accept(int fd, struct sockaddr __user *upeer_sockaddr, int _ 
	 */

	__module_get(newsock->ops->owner);



	newfd = sock_alloc_fd(&newfile);

	if (unlikely(newfd < 0)) {

		err = newfd;

		goto out_release;

	}



	err = sock_attach_fd(newsock, newfile);

	if (err < 0)

		goto out_fd;



	err = security_socket_accept(sock, newsock);

	if (err)

		goto out_release;

		goto out_fd;



	err = sock->ops->accept(sock, newsock, sock->file->f_flags);

	if (err < 0)

		goto out_release;

		goto out_fd;



	if (upeer_sockaddr) {

		if(newsock->ops->getname(newsock, (struct sockaddr *)address, &len, 2)<0) {

			err = -ECONNABORTED;

			goto out_release;

			goto out_fd;

		}

		err = move_addr_to_user(address, len, upeer_sockaddr, upeer_addrlen);

		if (err < 0)

			goto out_release;

			goto out_fd;

	}



	/* File flags are not inherited via accept() unlike another OSes. */



	if ((err = sock_map_fd(newsock)) < 0)

		goto out_release;

	fd_install(newfd, newfile);

	err = newfd;



	security_socket_post_accept(sock, newsock);
@@ -1398,6 +1424,9 @@ asmlinkage long sys_accept(int fd, struct sockaddr __user *upeer_sockaddr, int _ 
	sockfd_put(sock);

out:

	return err;

out_fd:

	put_filp(newfile);

	put_unused_fd(newfd);

out_release:

	sock_release(newsock);

	goto out_put;