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, 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);