On Tue, Jul 07, 2020 at 02:38:54PM +0200, Christian Brauner wrote:
On Mon, Jul 06, 2020 at 01:17:18PM -0700, Kees Cook wrote:
Expand __receive_fd() with support for replace_fd() for the coming seccomp "addfd" ioctl(). Add new wrapper receive_fd_replace() for the new behavior and update existing wrappers to retain old behavior.
Thanks to Colin Ian King colin.king@canonical.com for pointing out an uninitialized variable exposure in an earlier version of this patch.
Reviewed-by: Sargun Dhillon sargun@sargun.me Signed-off-by: Kees Cook keescook@chromium.org
Thanks! (One tiny-nit below.) Acked-by: Christian Brauner christian.brauner@ubuntu.com
fs/file.c | 24 ++++++++++++++++++------ include/linux/file.h | 10 +++++++--- 2 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/fs/file.c b/fs/file.c index 0efdcf413210..11313ff36802 100644 --- a/fs/file.c +++ b/fs/file.c @@ -937,6 +937,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) /**
- __receive_fd() - 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
@@ -950,7 +951,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
- Returns newly install fd or -ve on error.
*/ -int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) +int __receive_fd(int fd, struct file *file, int __user *ufd, unsigned int o_flags) { struct socket *sock; int new_fd; @@ -960,18 +961,30 @@ int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) 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;- } else
new_fd = fd;This is nitpicky but coding style technically wants us to use braces around both branches if one of them requires them. ;)
Ah yeah, good point. Fixed. Thanks!