On Wed, Oct 22, 2014 at 4:44 AM, David Drysdale <drysdale@xxxxxxxxxx> wrote:
> Add a new system execveat(2) syscall. execveat() is to execve() as
> openat() is to open(): it takes a file descriptor that refers to a
> directory, and resolves the filename relative to that.
>
> bprm->file = file;
> - bprm->filename = bprm->interp = filename->name;
> + if (fd == AT_FDCWD || filename->name[0] == '/') {
> + bprm->filename = filename->name;
> + } else {
> + /*
> + * Build a pathname that reflects how we got to the file,
> + * either "/dev/fd/<fd>" (for an empty filename) or
> + * "/dev/fd/<fd>/<filename>".
> + */
> + pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
> + if (!pathbuf) {
> + retval = -ENOMEM;
> + goto out_unmark;
> + }
> + bprm->filename = pathbuf;
> + if (filename->name[0] == '\0')
> + sprintf(pathbuf, "/dev/fd/%d", fd);
If the fd is O_CLOEXEC, then this will result in a confused child
process. Should we fail exec attempts like that for non-static
programs? (E.g. set filename to "" or something and fix up the binfmt
drivers to handle that?)
> + else
> + snprintf(pathbuf, PATH_MAX,
> + "/dev/fd/%d/%s", fd, filename->name);
Does this need to handle the case where the result exceeds PATH_MAX?
--Andy
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