[PATCH v4 05/11] fs: Expand __fd_install_received() to accept fd
From: Kees Cook <hidden>
Date: 2020-06-16 03:26:55
Also in:
linux-fsdevel, linux-kselftest, lkml, netdev
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Expand __fd_install_received() with support for replace_fd() for the coming seccomp "addfd" ioctl(). Add new wrapper fd_replace_received() for the new mode and update existing wrappers to retain old mode. Signed-off-by: Kees Cook <redacted> --- fs/file.c | 22 ++++++++++++++++------ include/linux/file.h | 10 +++++++--- 2 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 14a8ef74efb2..b583e7c60571 100644
--- a/fs/file.c
+++ b/fs/file.c@@ -950,8 +950,8 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) * * Returns newly install fd or -ve on error. */ -int __fd_install_received(struct file *file, bool ufd_required, int __user *ufd, - unsigned int o_flags) +int __fd_install_received(int fd, struct file *file, bool ufd_required, + int __user *ufd, unsigned int o_flags) { struct socket *sock; int new_fd;
@@ -961,9 +961,11 @@ int __fd_install_received(struct file *file, bool ufd_required, int __user *ufd, if (error) return error; - new_fd = get_unused_fd_flags(o_flags); - if (new_fd < 0) - return new_fd; + if (fd < 0) { + new_fd = get_unused_fd_flags(o_flags); + if (new_fd < 0) + return new_fd; + } if (ufd_required) { error = put_user(new_fd, ufd);
@@ -973,6 +975,15 @@ int __fd_install_received(struct file *file, bool ufd_required, int __user *ufd, } } + if (fd < 0) + fd_install(new_fd, get_file(file)); + else { + new_fd = fd; + error = replace_fd(new_fd, file, o_flags); + if (error) + return error; + } + /* Bump the usage count and install the file. The resulting value of * "error" is ignored here since we only need to take action when * the file is a socket and testing "sock" for NULL is sufficient.
@@ -982,7 +993,6 @@ int __fd_install_received(struct file *file, bool ufd_required, int __user *ufd, sock_update_netprioidx(&sock->sk->sk_cgrp_data); sock_update_classid(&sock->sk->sk_cgrp_data); } - fd_install(new_fd, get_file(file)); return new_fd; }
diff --git a/include/linux/file.h b/include/linux/file.h
index 999a2c56db07..f1d16e24a12e 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h@@ -91,16 +91,20 @@ extern void put_unused_fd(unsigned int fd); extern void fd_install(unsigned int fd, struct file *file); -extern int __fd_install_received(struct file *file, bool ufd_required, +extern int __fd_install_received(int fd, struct file *file, bool ufd_required, int __user *ufd, unsigned int o_flags); static inline int fd_install_received_user(struct file *file, int __user *ufd, unsigned int o_flags) { - return __fd_install_received(file, true, ufd, o_flags); + return __fd_install_received(-1, file, true, ufd, o_flags); } static inline int fd_install_received(struct file *file, unsigned int o_flags) { - return __fd_install_received(file, false, NULL, o_flags); + return __fd_install_received(-1, file, false, NULL, o_flags); +} +static inline int fd_replace_received(int fd, struct file *file, unsigned int o_flags) +{ + return __fd_install_received(fd, file, false, NULL, o_flags); } extern void flush_delayed_fput(void);
--
2.25.1