applied - thanks!
On Tue, 25 Jan 2022, Fabian Stelzer wrote:
> ---
> ssh-keygen -Y find-principals will fail to return any matches if a
> certificate signature is used and the allowed principals file contains a
> wildcard principal (e.g.: *@example.com). Since we need to specify the full
> princpal for -Y verify, find-principals should return the matching ones.
> Instead of adjusting the heavily used function sshkey_cert_check_authority()
> we instead duplicate a little bit of the cert princpal matching code into
> cert_filter_principals() and no longer have the former verify the principal.
> This makes for a much simpler diff and a more constrained change.
> The explicit deny on wildcards is dropped as well.
>
> regress/sshsig.sh | 17 +++++++++++++++++
> sshsig.c | 24 +++++++++++++-----------
> 2 files changed, 30 insertions(+), 11 deletions(-)
>
> diff --git a/regress/sshsig.sh b/regress/sshsig.sh
> index f8d85c2f..dcfd2e78 100644
> --- a/regress/sshsig.sh
> +++ b/regress/sshsig.sh
> @@ -342,6 +342,23 @@ for t in $SIGNKEYS; do
> -f $OBJ/allowed_signers >/dev/null 2>&1 || \
> fail "failed find-principals for $t with ca key"
>
> + # CA with wildcard principal
> + (printf "*@example.com cert-authority " ;
> + cat $CA_PUB) > $OBJ/allowed_signers
> + # find-principals CA with wildcard principal
> + ${SSHKEYGEN} -vvv -Y find-principals -s $sigfile \
> + -Overify-time=19850101 \
> + -f $OBJ/allowed_signers 2>/dev/null | \
> + fgrep "$sig_principal" >/dev/null || \
> + fail "failed find-principals for $t with ca key using wildcard principal"
> +
> + # verify CA with wildcard principal
> + ${SSHKEYGEN} -vvv -Y verify -s $sigfile -n $sig_namespace \
> + -I $sig_principal -f $OBJ/allowed_signers \
> + -Overify-time=19850101 \
> + < $DATA >/dev/null 2>&1 || \
> + fail "failed signature for $t cert using wildcard principal"
> +
> # signing key listed as cert-authority
> (printf "$sig_principal cert-authority " ;
> cat $pubkey) > $OBJ/allowed_signers
> diff --git a/sshsig.c b/sshsig.c
> index f8c63f7b..1a61bbc6 100644
> --- a/sshsig.c
> +++ b/sshsig.c
> @@ -820,6 +820,7 @@ cert_filter_principals(const char *path, u_long linenum,
> const char *reason;
> struct sshbuf *nprincipals;
> int r = SSH_ERR_INTERNAL_ERROR, success = 0;
> + u_int i;
>
> oprincipals = principals = *principalsp;
> *principalsp = NULL;
> @@ -830,22 +831,23 @@ cert_filter_principals(const char *path, u_long linenum,
> }
>
> while ((cp = strsep(&principals, ",")) != NULL && *cp != '\0') {
> - if (strcspn(cp, "!?*") != strlen(cp)) {
> - debug("%s:%lu: principal \"%s\" not authorized: "
> - "contains wildcards", path, linenum, cp);
> - continue;
> - }
> - /* Check against principals list in certificate */
> + /* Check certificate validity */
> if ((r = sshkey_cert_check_authority(cert, 0, 1, 0,
> - verify_time, cp, &reason)) != 0) {
> + verify_time, NULL, &reason)) != 0) {
> debug("%s:%lu: principal \"%s\" not authorized: %s",
> path, linenum, cp, reason);
> continue;
> }
> - if ((r = sshbuf_putf(nprincipals, "%s%s",
> - sshbuf_len(nprincipals) != 0 ? "," : "", cp)) != 0) {
> - error_f("buffer error");
> - goto out;
> + /* Return all matching principal names from the cert */
> + for (i = 0; i < cert->cert->nprincipals; i++) {
> + if (match_pattern(cert->cert->principals[i], cp)) {
> + if ((r = sshbuf_putf(nprincipals, "%s%s",
> + sshbuf_len(nprincipals) != 0 ? "," : "",
> + cert->cert->principals[i])) != 0) {
> + error_f("buffer error");
> + goto out;
> + }
> + }
> }
> }
> if (sshbuf_len(nprincipals) == 0) {
> --
> 2.34.1
>
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