]> git.ipfire.org Git - thirdparty/openssh-portable.git/commitdiff
upstream: resident keys support in SK API
authordjm@openbsd.org <djm@openbsd.org>
Mon, 30 Dec 2019 09:21:16 +0000 (09:21 +0000)
committerDamien Miller <djm@mindrot.org>
Mon, 30 Dec 2019 09:58:19 +0000 (20:58 +1100)
Adds a sk_load_resident_keys() function to the security key
API that accepts a security key provider and a PIN and returns
a list of keys.

Implement support for this in the usbhid middleware.

feedback and ok markus@

OpenBSD-Commit-ID: 67e984e4e87f4999ce447a6178c4249a9174eff0

sk-api.h
sk-usbhid.c
ssh-sk.c
ssh-sk.h

index 5947e0ed7a97231fe7d888caa61fbaee17af9f5d..10f1fdb1086e877c41102123aacfee9b76aea5eb 100644 (file)
--- a/sk-api.h
+++ b/sk-api.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sk-api.h,v 1.3 2019/12/30 09:19:52 djm Exp $ */
+/* $OpenBSD: sk-api.h,v 1.4 2019/12/30 09:21:16 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -52,6 +52,13 @@ struct sk_sign_response {
        size_t sig_s_len;
 };
 
+struct sk_resident_key {
+       uint8_t alg;
+       size_t slot;
+       char *application;
+       struct sk_enroll_response key;
+};
+
 #define SSH_SK_VERSION_MAJOR           0x00020000 /* current API version */
 #define SSH_SK_VERSION_MAJOR_MASK      0xffff0000
 
@@ -68,4 +75,8 @@ int sk_sign(int alg, const uint8_t *message, size_t message_len,
     const char *application, const uint8_t *key_handle, size_t key_handle_len,
     uint8_t flags, struct sk_sign_response **sign_response);
 
+/* Enumerate all resident keys */
+int sk_load_resident_keys(const char *pin,
+    struct sk_resident_key ***rks, size_t *nrks);
+
 #endif /* _SK_API_H */
index 61b52bbb9b6e80cbf2e5076b6737089897e396b1..fa44244834ebe7c071dc92daf14a0c99352ba2fb 100644 (file)
@@ -34,6 +34,7 @@
 #endif /* WITH_OPENSSL */
 
 #include <fido.h>
+#include <fido/credman.h>
 
 #ifndef SK_STANDALONE
 #include "log.h"
@@ -84,11 +85,19 @@ struct sk_sign_response {
        size_t sig_s_len;
 };
 
+struct sk_resident_key {
+       uint8_t alg;
+       size_t slot;
+       char *application;
+       struct sk_enroll_response key;
+};
+
 /* If building as part of OpenSSH, then rename exported functions */
 #if !defined(SK_STANDALONE)
-#define sk_api_version ssh_sk_api_version
-#define sk_enroll      ssh_sk_enroll
-#define sk_sign                ssh_sk_sign
+#define sk_api_version         ssh_sk_api_version
+#define sk_enroll              ssh_sk_enroll
+#define sk_sign                        ssh_sk_sign
+#define sk_load_resident_keys  ssh_sk_load_resident_keys
 #endif
 
 /* Return the version of the middleware API */
@@ -104,6 +113,10 @@ int sk_sign(int alg, const uint8_t *message, size_t message_len,
     const char *application, const uint8_t *key_handle, size_t key_handle_len,
     uint8_t flags, struct sk_sign_response **sign_response);
 
+/* Load resident keys */
+int sk_load_resident_keys(const char *pin,
+    struct sk_resident_key ***rks, size_t *nrks);
+
 static void skdebug(const char *func, const char *fmt, ...)
     __attribute__((__format__ (printf, 2, 3)));
 
@@ -281,7 +294,8 @@ find_device(const uint8_t *message, size_t message_len, const char *application,
  * but the API expects a SEC1 octet string.
  */
 static int
-pack_public_key_ecdsa(fido_cred_t *cred, struct sk_enroll_response *response)
+pack_public_key_ecdsa(const fido_cred_t *cred,
+    struct sk_enroll_response *response)
 {
        const uint8_t *ptr;
        BIGNUM *x = NULL, *y = NULL;
@@ -351,7 +365,8 @@ pack_public_key_ecdsa(fido_cred_t *cred, struct sk_enroll_response *response)
 #endif /* WITH_OPENSSL */
 
 static int
-pack_public_key_ed25519(fido_cred_t *cred, struct sk_enroll_response *response)
+pack_public_key_ed25519(const fido_cred_t *cred,
+    struct sk_enroll_response *response)
 {
        const uint8_t *ptr;
        size_t len;
@@ -382,7 +397,8 @@ pack_public_key_ed25519(fido_cred_t *cred, struct sk_enroll_response *response)
 }
 
 static int
-pack_public_key(int alg, fido_cred_t *cred, struct sk_enroll_response *response)
+pack_public_key(int alg, const fido_cred_t *cred,
+    struct sk_enroll_response *response)
 {
        switch(alg) {
 #ifdef WITH_OPENSSL
@@ -715,4 +731,214 @@ sk_sign(int alg, const uint8_t *message, size_t message_len,
        }
        return ret;
 }
+
+static int
+read_rks(const char *devpath, const char *pin,
+    struct sk_resident_key ***rksp, size_t *nrksp)
+{
+       int r = -1;
+       fido_dev_t *dev = NULL;
+       fido_credman_metadata_t *metadata = NULL;
+       fido_credman_rp_t *rp = NULL;
+       fido_credman_rk_t *rk = NULL;
+       size_t i, j, nrp, nrk;
+       const fido_cred_t *cred;
+       struct sk_resident_key *srk = NULL, **tmp;
+
+       if ((dev = fido_dev_new()) == NULL) {
+               skdebug(__func__, "fido_dev_new failed");
+               return -1;
+       }
+       if ((r = fido_dev_open(dev, devpath)) != FIDO_OK) {
+               skdebug(__func__, "fido_dev_open %s failed: %s",
+                   devpath, fido_strerr(r));
+               fido_dev_free(&dev);
+               return -1;
+       }
+       if ((metadata = fido_credman_metadata_new()) == NULL) {
+               r = -1;
+               skdebug(__func__, "alloc failed");
+               goto out;
+       }
+
+       if ((r = fido_credman_get_dev_metadata(dev, metadata, pin)) != 0) {
+               if (r == FIDO_ERR_INVALID_COMMAND) {
+                       skdebug(__func__, "device %s does not support "
+                           "resident keys", devpath);
+                       r = 0;
+                       goto out;
+               }
+               skdebug(__func__, "get metadata for %s failed: %s",
+                   devpath, fido_strerr(r));
+               goto out;
+       }
+       skdebug(__func__, "existing %llu, remaining %llu",
+           (unsigned long long)fido_credman_rk_existing(metadata),
+           (unsigned long long)fido_credman_rk_remaining(metadata));
+       if ((rp = fido_credman_rp_new()) == NULL) {
+               r = -1;
+               skdebug(__func__, "alloc rp failed");
+               goto out;
+       }
+       if ((r = fido_credman_get_dev_rp(dev, rp, pin)) != 0) {
+               skdebug(__func__, "get RPs for %s failed: %s",
+                   devpath, fido_strerr(r));
+               goto out;
+       }
+       nrp = fido_credman_rp_count(rp);
+       skdebug(__func__, "Device %s has resident keys for %zu RPs",
+           devpath, nrp);
+
+       /* Iterate over RP IDs that have resident keys */
+       for (i = 0; i < nrp; i++) {
+               skdebug(__func__, "rp %zu: name=\"%s\" id=\"%s\" hashlen=%zu",
+                   i, fido_credman_rp_name(rp, i), fido_credman_rp_id(rp, i),
+                   fido_credman_rp_id_hash_len(rp, i));
+
+               /* Skip non-SSH RP IDs */
+               if (strncasecmp(fido_credman_rp_id(rp, i), "ssh:", 4) != 0)
+                       continue;
+
+               fido_credman_rk_free(&rk);
+               if ((rk = fido_credman_rk_new()) == NULL) {
+                       r = -1;
+                       skdebug(__func__, "alloc rk failed");
+                       goto out;
+               }
+               if ((r = fido_credman_get_dev_rk(dev, fido_credman_rp_id(rp, i),
+                   rk, pin)) != 0) {
+                       skdebug(__func__, "get RKs for %s slot %zu failed: %s",
+                           devpath, i, fido_strerr(r));
+                       goto out;
+               }
+               nrk = fido_credman_rk_count(rk);
+               skdebug(__func__, "RP \"%s\" has %zu resident keys",
+                   fido_credman_rp_id(rp, i), nrk);
+
+               /* Iterate over resident keys for this RP ID */
+               for (j = 0; j < nrk; j++) {
+                       if ((cred = fido_credman_rk(rk, j)) == NULL) {
+                               skdebug(__func__, "no RK in slot %zu", j);
+                               continue;
+                       }
+                       skdebug(__func__, "Device %s RP \"%s\" slot %zu: "
+                           "type %d", devpath, fido_credman_rp_id(rp, i), j,
+                           fido_cred_type(cred));
+
+                       /* build response entry */
+                       if ((srk = calloc(1, sizeof(*srk))) == NULL ||
+                           (srk->key.key_handle = calloc(1,
+                           fido_cred_id_len(cred))) == NULL ||
+                           (srk->application = strdup(fido_credman_rp_id(rp,
+                           i))) == NULL) {
+                               r = -1;
+                               skdebug(__func__, "alloc sk_resident_key");
+                               goto out;
+                       }
+
+                       srk->key.key_handle_len = fido_cred_id_len(cred);
+                       memcpy(srk->key.key_handle,
+                           fido_cred_id_ptr(cred),
+                           srk->key.key_handle_len);
+
+                       switch (fido_cred_type(cred)) {
+                       case COSE_ES256:
+                               srk->alg = SK_ECDSA;
+                               break;
+                       case COSE_EDDSA:
+                               srk->alg = SK_ED25519;
+                               break;
+                       default:
+                               skdebug(__func__, "unsupported key type %d",
+                                   fido_cred_type(cred));
+                               goto out;
+                       }
+
+                       if ((r = pack_public_key(srk->alg, cred,
+                           &srk->key)) != 0) {
+                               skdebug(__func__, "pack public key failed");
+                               goto out;
+                       }
+                       /* append */
+                       if ((tmp = recallocarray(*rksp, *nrksp, (*nrksp) + 1,
+                           sizeof(**rksp))) == NULL) {
+                               r = -1;
+                               skdebug(__func__, "alloc rksp");
+                               goto out;
+                       }
+                       *rksp = tmp;
+                       (*rksp)[(*nrksp)++] = srk;
+                       srk = NULL;
+               }
+       }
+       /* Success */
+       r = 0;
+ out:
+       if (srk != NULL) {
+               free(srk->application);
+               freezero(srk->key.public_key, srk->key.public_key_len);
+               freezero(srk->key.key_handle, srk->key.key_handle_len);
+               freezero(srk, sizeof(*srk));
+       }
+       fido_credman_rp_free(&rp);
+       fido_credman_rk_free(&rk);
+       fido_dev_close(dev);
+       fido_dev_free(&dev);
+       fido_credman_metadata_free(&metadata);
+       return r;
+}
+
+int
+sk_load_resident_keys(const char *pin,
+    struct sk_resident_key ***rksp, size_t *nrksp)
+{
+       int r = -1;
+       fido_dev_info_t *devlist = NULL;
+       size_t i, ndev = 0, nrks = 0;
+       const fido_dev_info_t *di;
+       struct sk_resident_key **rks = NULL;
+       *rksp = NULL;
+       *nrksp = 0;
+
+       if ((devlist = fido_dev_info_new(MAX_FIDO_DEVICES)) == NULL) {
+               skdebug(__func__, "fido_dev_info_new failed");
+               goto out;
+       }
+       if ((r = fido_dev_info_manifest(devlist,
+           MAX_FIDO_DEVICES, &ndev)) != FIDO_OK) {
+               skdebug(__func__, "fido_dev_info_manifest failed: %s",
+                   fido_strerr(r));
+               goto out;
+       }
+       for (i = 0; i < ndev; i++) {
+               if ((di = fido_dev_info_ptr(devlist, i)) == NULL) {
+                       skdebug(__func__, "no dev info at %zu", i);
+                       continue;
+               }
+               skdebug(__func__, "trying %s", fido_dev_info_path(di));
+               if ((r = read_rks(fido_dev_info_path(di), pin,
+                   &rks, &nrks)) != 0) {
+                       skdebug(__func__, "read_rks failed for %s",
+                           fido_dev_info_path(di));
+                       continue;
+               }
+       }
+       /* success */
+       r = 0;
+       *rksp = rks;
+       *nrksp = nrks;
+       rks = NULL;
+       nrks = 0;
+ out:
+       for (i = 0; i < nrks; i++) {
+               free(rks[i]->application);
+               freezero(rks[i]->key.public_key, rks[i]->key.public_key_len);
+               freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len);
+               freezero(rks[i], sizeof(*rks[i]));
+       }
+       free(rks);
+       fido_dev_info_free(&devlist, MAX_FIDO_DEVICES);
+       return r;
+}
+
 #endif /* ENABLE_SK_INTERNAL */
index 01927669e4f444a72a409100a197d8eb6b4ff4a5..d48f34e30ea7c8b712a412d205fe1bf8b50591fe 100644 (file)
--- a/ssh-sk.c
+++ b/ssh-sk.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-sk.c,v 1.19 2019/12/30 09:20:36 djm Exp $ */
+/* $OpenBSD: ssh-sk.c,v 1.20 2019/12/30 09:21:16 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -60,6 +60,10 @@ struct sshsk_provider {
            const char *application,
            const uint8_t *key_handle, size_t key_handle_len,
            uint8_t flags, struct sk_sign_response **sign_response);
+
+       /* Enumerate resident keys */
+       int (*sk_load_resident_keys)(const char *pin,
+           struct sk_resident_key ***rks, size_t *nrks);
 };
 
 /* Built-in version */
@@ -70,6 +74,8 @@ int ssh_sk_sign(int alg, const uint8_t *message, size_t message_len,
     const char *application,
     const uint8_t *key_handle, size_t key_handle_len,
     uint8_t flags, struct sk_sign_response **sign_response);
+int ssh_sk_load_resident_keys(const char *pin,
+    struct sk_resident_key ***rks, size_t *nrks);
 
 static void
 sshsk_free(struct sshsk_provider *p)
@@ -101,6 +107,7 @@ sshsk_open(const char *path)
 #ifdef ENABLE_SK_INTERNAL
                ret->sk_enroll = ssh_sk_enroll;
                ret->sk_sign = ssh_sk_sign;
+               ret->sk_load_resident_keys = ssh_sk_load_resident_keys;
 #else
                error("internal security key support not enabled");
 #endif
@@ -136,6 +143,12 @@ sshsk_open(const char *path)
                    path, dlerror());
                goto fail;
        }
+       if ((ret->sk_load_resident_keys = dlsym(ret->dlhandle,
+           "sk_load_resident_keys")) == NULL) {
+               error("Security key provider %s dlsym(sk_load_resident_keys) "
+                   "failed: %s", path, dlerror());
+               goto fail;
+       }
        /* success */
        return ret;
 fail:
@@ -264,9 +277,7 @@ sshsk_key_from_response(int alg, const char *application, uint8_t flags,
        *keyp = NULL;
 
        /* Check response validity */
-       if (resp->public_key == NULL || resp->key_handle == NULL ||
-           resp->signature == NULL ||
-           (resp->attestation_cert == NULL && resp->attestation_cert_len != 0)) {
+       if (resp->public_key == NULL || resp->key_handle == NULL) {
                error("%s: sk_enroll response invalid", __func__);
                r = SSH_ERR_INVALID_FORMAT;
                goto out;
@@ -595,4 +606,101 @@ sshsk_sign(const char *provider_path, struct sshkey *key,
        sshbuf_free(inner_sig);
        return r;
 }
+
+static void
+sshsk_free_sk_resident_keys(struct sk_resident_key **rks, size_t nrks)
+{
+       size_t i;
+
+       if (nrks == 0 || rks == NULL)
+               return;
+       for (i = 0; i < nrks; i++) {
+               free(rks[i]->application);
+               freezero(rks[i]->key.key_handle, rks[i]->key.key_handle_len);
+               freezero(rks[i]->key.public_key, rks[i]->key.public_key_len);
+               freezero(rks[i]->key.signature, rks[i]->key.signature_len);
+               freezero(rks[i]->key.attestation_cert,
+                   rks[i]->key.attestation_cert_len);
+               freezero(rks[i], sizeof(**rks));
+       }
+       free(rks);
+}
+
+int
+sshsk_load_resident(const char *provider_path, const char *pin,
+    struct sshkey ***keysp, size_t *nkeysp)
+{
+       struct sshsk_provider *skp = NULL;
+       int r = SSH_ERR_INTERNAL_ERROR;
+       struct sk_resident_key **rks = NULL;
+       size_t i, nrks = 0, nkeys = 0;
+       struct sshkey *key = NULL, **keys = NULL, **tmp;
+       uint8_t flags;
+
+       debug("%s: provider \"%s\"%s", __func__, provider_path,
+           (pin != NULL && *pin != '\0') ? ", have-pin": "");
+
+       if (keysp == NULL || nkeysp == NULL)
+               return SSH_ERR_INVALID_ARGUMENT;
+       *keysp = NULL;
+       *nkeysp = 0;
+
+       if ((skp = sshsk_open(provider_path)) == NULL) {
+               r = SSH_ERR_INVALID_FORMAT; /* XXX sshsk_open return code? */
+               goto out;
+       }
+       if ((r = skp->sk_load_resident_keys(pin, &rks, &nrks)) != 0) {
+               error("Security key provider %s returned failure %d",
+                   provider_path, r);
+               r = SSH_ERR_INVALID_FORMAT; /* XXX error codes in API? */
+               goto out;
+       }
+       for (i = 0; i < nrks; i++) {
+               debug3("%s: rk %zu: slot = %zu, alg = %d, application = \"%s\"",
+                   __func__, i, rks[i]->slot, rks[i]->alg,
+                   rks[i]->application);
+               /* XXX need better filter here */
+               if (strncmp(rks[i]->application, "ssh:", 4) != 0)
+                       continue;
+               switch (rks[i]->alg) {
+               case SSH_SK_ECDSA:
+               case SSH_SK_ED25519:
+                       break;
+               default:
+                       continue;
+               }
+               /* XXX where to get flags? */
+               flags = SSH_SK_USER_PRESENCE_REQD|SSH_SK_RESIDENT_KEY;
+               if ((r = sshsk_key_from_response(rks[i]->alg,
+                   rks[i]->application, flags, &rks[i]->key, &key)) != 0)
+                       goto out;
+               if ((tmp = recallocarray(keys, nkeys, nkeys + 1,
+                   sizeof(*tmp))) == NULL) {
+                       error("%s: recallocarray failed", __func__);
+                       r = SSH_ERR_ALLOC_FAIL;
+                       goto out;
+               }
+               keys = tmp;
+               keys[nkeys++] = key;
+               key = NULL;
+               /* XXX synthesise comment */
+       }
+       /* success */
+       *keysp = keys;
+       *nkeysp = nkeys;
+       keys = NULL;
+       nkeys = 0;
+       r = 0;
+ out:
+       sshsk_free(skp);
+       sshsk_free_sk_resident_keys(rks, nrks);
+       sshkey_free(key);
+       if (nkeys != 0) {
+               for (i = 0; i < nkeys; i++)
+                       sshkey_free(keys[i]);
+               free(keys);
+       }
+       return r;
+}
+
 #endif /* ENABLE_SK */
index 4d667884ec20314f1d24aa5180de640227af6cf4..1afe839db28c023b1f07e13d79818afc9991ff63 100644 (file)
--- a/ssh-sk.h
+++ b/ssh-sk.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-sk.h,v 1.6 2019/12/13 19:09:10 djm Exp $ */
+/* $OpenBSD: ssh-sk.h,v 1.7 2019/12/30 09:21:16 djm Exp $ */
 /*
  * Copyright (c) 2019 Google LLC
  *
@@ -45,5 +45,14 @@ int sshsk_sign(const char *provider_path, struct sshkey *key,
     u_char **sigp, size_t *lenp, const u_char *data, size_t datalen,
     u_int compat);
 
+/*
+ * Enumerates and loads all SSH-compatible resident keys from a security
+ * key.
+ *
+ * Returns 0 on success or a ssherr.h error code on failure.
+ */
+int sshsk_load_resident(const char *provider_path, const char *pin,
+    struct sshkey ***keysp, size_t *nkeysp);
+
 #endif /* _SSH_SK_H */