Re: [PATCH] sandbox/seunshare: switch seunshare_mount_file() to use open()

[Petr Lautrbach <plautrba@redhat.com>]

Stephen Smalley <stephen.smalley.work@gmail.com> writes:

> seunshare_mount_file() currently uses fopen() to create the dst
> if it doesn't already exist. Switch to using open() with
> explicitly specified flags including O_NOFOLLOW and an explicitly
> specified mode for the new file.
>
> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>

Acked-by: Petr Lautrbach <lautrbach@redhat.com>

> ---
>  sandbox/seunshare.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/sandbox/seunshare.c b/sandbox/seunshare.c
> index a1900eaa..17a727e7 100644
> --- a/sandbox/seunshare.c
> +++ b/sandbox/seunshare.c
> @@ -304,18 +304,20 @@ static int seunshare_mount(const char *src, const char *dst, struct stat *src_st
>   */
>  static int seunshare_mount_file(const char *src, const char *dst)
>  {
> -	int flags = 0;
> -
>  	if (verbose)
>  		printf(_("Mounting %s on %s\n"), src, dst);
>  
>  	if (access(dst, F_OK) == -1) {
> -		 FILE *fptr;
> -         fptr = fopen(dst, "w");
> -		 fclose(fptr);
> +		int fd = open(dst, O_WRONLY | O_CREAT | O_NOFOLLOW | O_CLOEXEC, 0600);
> +		if (fd < 0) {
> +			fprintf(stderr, _("Failed to create mount point %s: %m\n"), dst);
> +			return -1;
> +		}
> +		close(fd);
>  	}
> +
>  	/* mount file */
> -	if (mount(src, dst, NULL, MS_BIND | flags, NULL) < 0) {
> +	if (mount(src, dst, NULL, MS_BIND, NULL) < 0) {
>  		fprintf(stderr, _("Failed to mount %s on %s: %s\n"), src, dst, strerror(errno));
>  		return -1;
>  	}
> -- 
> 2.54.0