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 keescook@chromium.org --- fs/file.c | 22 +++++++++++++++++----- include/linux/file.h | 10 +++++++--- 2 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/fs/file.c b/fs/file.c index de85a42defe2..9568bcfd1f44 100644 --- a/fs/file.c +++ b/fs/file.c @@ -937,6 +937,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) /** * __fd_install_received() - 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 @@ -947,7 +948,8 @@ 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, int __user *ufd, unsigned int o_flags) +int __fd_install_received(int fd, struct file *file, int __user *ufd, + unsigned int o_flags) { struct socket *sock; int new_fd; @@ -957,9 +959,11 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla 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) { error = put_user(new_fd, ufd); @@ -969,6 +973,15 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla } }
+ 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. @@ -978,7 +991,6 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla 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 e19974ed9322..04389b0da11b 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -92,18 +92,22 @@ 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, int __user *ufd, +extern int __fd_install_received(int fd, struct file *file, int __user *ufd, unsigned int o_flags); static inline int fd_install_received_user(struct file *file, int __user *ufd, unsigned int o_flags) { if (ufd == NULL) return -EFAULT; - return __fd_install_received(file, ufd, o_flags); + return __fd_install_received(-1, file, ufd, o_flags); } static inline int fd_install_received(struct file *file, unsigned int o_flags) { - return __fd_install_received(file, NULL, o_flags); + return __fd_install_received(-1, file, NULL, o_flags); +} +static inline int fd_replace_received(int fd, struct file *file, unsigned int o_flags) +{ + return __fd_install_received(fd, file, NULL, o_flags); }
extern void flush_delayed_fput(void);