degrade semi-gracefully when libfido2 is too old

diff --git a/configure.ac b/configure.ac
index 0f15ef2bfbd0e8b8e5965d4186f5b60c73e95539..756e26572c2aa68255f8fbf6d4696444a9535aec 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3180,9 +3180,14 @@ if test "x$enable_sk" = "xyes" -a "x$enable_sk_internal" = "xyes" ; then
                ], [ AC_MSG_ERROR([no usable libfido2 found]) ],
                [ $OTHERLIBS ]
        )
-       AC_CHECK_LIB([fido2], [fido_cred_set_prot], [],
-               [ AC_MSG_ERROR([libfido2 missing fido_cred_set_prot; please use libfido2 >= 1.4.0]) ],
-       )
+       saved_LIBS="$LIBS"
+       LIBS="$LIBS $LIBFIDO2"
+       AC_CHECK_FUNCS([ \
+               fido_cred_set_prot \
+               fido_dev_get_touch_status \
+               fido_dev_supports_cred_prot \
+       ])
+       LIBS="$saved_LIBS"
        AC_CHECK_HEADER([fido.h], [],
                AC_MSG_ERROR([missing fido.h from libfido2]))
        AC_CHECK_HEADER([fido/credman.h], [],

diff --git a/sk-usbhid.c b/sk-usbhid.c
index 0305683febc7916ec0bb4bcc333e9dee955c9017..0b11e40aa6a536c46f166ba3113ce995949d357f 100644 (file)
--- a/sk-usbhid.c
+++ b/sk-usbhid.c
@@ -41,6 +41,17 @@
 #include <fido.h>
 #include <fido/credman.h>
 
+/* backwards compat for libfido2 */
+#ifndef HAVE_FIDO_DEV_SUPPORTS_CRED_PROT
+#define fido_dev_supports_cred_prot(x) (0)
+#endif
+#ifndef HAVE_FIDO_DEV_GET_TOUCH_BEGIN
+#define fido_dev_get_touch_begin(x) (FIDO_ERR_UNSUPPORTED_OPTION)
+#endif
+#ifndef HAVE_FIDO_DEV_GET_TOUCH_STATUS
+#define fido_dev_get_touch_status(x, y, z) (FIDO_ERR_UNSUPPORTED_OPTION)
+#endif
+
 #ifndef SK_STANDALONE
 # include "log.h"
 # include "xmalloc.h"
@@ -377,6 +388,11 @@ sk_select_by_touch(const fido_dev_info_t *devlist, size_t ndevs)
        size_t skvcnt, idx;
        int touch, ms_remain;
 
+#ifndef HAVE_FIDO_DEV_GET_TOUCH_STATUS
+       skdebug(__func__, "libfido2 version does not support a feature needed for multiple tokens. Please upgrade to >=1.5.0");
+       return NULL;
+#endif
+
        if ((skv = sk_openv(devlist, ndevs, &skvcnt)) == NULL) {
                skdebug(__func__, "sk_openv failed");
                return NULL;
@@ -705,6 +721,11 @@ sk_enroll(uint32_t alg, const uint8_t *challenge, size_t challenge_len,
                goto out;
        }
        if ((flags & (SSH_SK_RESIDENT_KEY|SSH_SK_USER_VERIFICATION_REQD)) != 0) {
+#ifndef HAVE_FIDO_DEV_SUPPORTS_CRED_PROT
+               skdebug(__func__, "libfido2 version does not support a feature required for this operation. Please upgrade to >=1.5.0");
+               ret = SSH_SK_ERR_UNSUPPORTED;
+               goto out;
+#endif
                if (!fido_dev_supports_cred_prot(sk->dev)) {
                        skdebug(__func__, "%s does not support credprot, "
                            "refusing to create unprotected "