Florian Obser <flor...@openbsd.org> wrote:
> On 2022-05-03 17:41 +0430, Ali Farzanrad <ali_farzan...@riseup.net> wrote:
> >
> > Hi Florian,
> >
> > Yes, I read the RFC, it should work, but I couldn't test it yet, because
> > my domain manager is a little lazy (I've registeret 2 subdomains for my
> > domain, but it is not listed in name servers yet). I'll probably test
> > it tomorrow.
> >
> > I read the isalnum man page, it said that isalnum might have different
> > behavior based on locale, so I decide to not use that. Is it OK?
>
> No, please do a
> setlocale(LC_CTYPE, "");
> at the beginning of chngproc, before the unveil and then use isalnum
> instead of handrolling it. It will fit into chngproc, so no need for
> another function
>
> --
> I'm not entirely sure you are real.
>
OK, I've tested following diff on my own domain and it works.
I did 2 modifications:
1. I explicitly call setlocate with "C" to ensure C locale,
2. I did a string length check. According to RFC it must have 128 bit
of random entropy, so it should have at least 22 base64 characters,
but I was unsure. So I only check for empty strings.
Index: chngproc.c
===================================================================
RCS file: /cvs/src/usr.sbin/acme-client/chngproc.c,v
retrieving revision 1.16
diff -u -p -r1.16 chngproc.c
--- chngproc.c 12 Jul 2021 15:09:20 -0000 1.16
+++ chngproc.c 4 May 2022 08:37:32 -0000
@@ -16,9 +16,11 @@
*/
#include <assert.h>
+#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
+#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -42,6 +44,11 @@ chngproc(int netsock, const char *root)
goto out;
}
+ if (setlocale(LC_CTYPE, "C") == NULL) {
+ warnx("setlocale");
+ goto out;
+ }
+
if (pledge("stdio cpath wpath", NULL) == -1) {
warn("pledge");
goto out;
@@ -77,6 +84,18 @@ chngproc(int netsock, const char *root)
goto out;
else if ((tok = readstr(netsock, COMM_TOK)) == NULL)
goto out;
+ else if (strlen(tok) < 1) {
+ warnx("token is too short");
+ goto out;
+ }
+
+ for (i = 0; tok[i]; ++i) {
+ int ch = (unsigned char)tok[i];
+ if (!isalnum(ch) && ch != '-' && ch != '_') {
+ warnx("token is not a valid base64url");
+ goto out;
+ }
+ }
if (asprintf(&fmt, "%s.%s", tok, th) == -1) {
warn("asprintf");
