1 files changed, 281 insertions, 45 deletions

diff --git a/sshsig.c b/sshsig.c
index b19cd077d..e63a36e1e 100644
--- a/sshsig.c
+++ b/sshsig.c
@@ -151,8 +151,9 @@ done:
 
 static int
 sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
-    const struct sshbuf *h_message, const char *sig_namespace,
-    struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
+    const char *sk_provider, const struct sshbuf *h_message,
+    const char *sig_namespace, struct sshbuf **out,
+    sshsig_signer *signer, void *signer_ctx)
 {
         int r;
         size_t slen = 0;
@@ -184,14 +185,14 @@ sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
         if (signer != NULL) {
                 if ((r = signer(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, 0, signer_ctx)) != 0) {
+                    sign_alg, sk_provider, 0, signer_ctx)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
         } else {
                 if ((r = sshkey_sign(key, &sig, &slen,
                     sshbuf_ptr(tosign), sshbuf_len(tosign),
-                    sign_alg, 0)) != 0) {
+                    sign_alg, sk_provider, 0)) != 0) {
                         error("Couldn't sign message: %s", ssh_err(r));
                         goto done;
                 }
@@ -285,7 +286,7 @@ sshsig_peek_hashalg(struct sshbuf *signature, char **hashalgp)
 static int
 sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
     const struct sshbuf *h_message, const char *expect_namespace,
-    struct sshkey **sign_keyp)
+    struct sshkey **sign_keyp, struct sshkey_sig_details **sig_details)
 {
         int r = SSH_ERR_INTERNAL_ERROR;
         struct sshbuf *buf = NULL, *toverify = NULL;
@@ -295,6 +296,8 @@ sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
         size_t siglen;
 
         debug("%s: verify message length %zu", __func__, sshbuf_len(h_message));
+        if (sig_details != NULL)
+                *sig_details = NULL;
         if (sign_keyp != NULL)
                 *sign_keyp = NULL;
 
@@ -360,7 +363,7 @@ sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
                 }
         }
         if ((r = sshkey_verify(key, sig, siglen, sshbuf_ptr(toverify),
-            sshbuf_len(toverify), NULL, 0)) != 0) {
+            sshbuf_len(toverify), NULL, 0, sig_details)) != 0) {
                 error("Signature verification failed: %s", ssh_err(r));
                 goto done;
         }
@@ -425,7 +428,7 @@ hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_signb(struct sshkey *key, const char *hashalg,
+sshsig_signb(struct sshkey *key, const char *hashalg, const char *sk_provider,
     const struct sshbuf *message, const char *sig_namespace,
     struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
 {
@@ -440,8 +443,8 @@ sshsig_signb(struct sshkey *key, const char *hashalg,
                 error("%s: hash_buffer failed: %s", __func__, ssh_err(r));
                 goto out;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, b, sig_namespace, out,
-            signer, signer_ctx)) != 0)
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+            sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */
         r = 0;
@@ -452,15 +455,17 @@ sshsig_signb(struct sshkey *key, const char *hashalg,
 
 int
 sshsig_verifyb(struct sshbuf *signature, const struct sshbuf *message,
-    const char *expect_namespace, struct sshkey **sign_keyp)
+    const char *expect_namespace, struct sshkey **sign_keyp,
+    struct sshkey_sig_details **sig_details)
 {
         struct sshbuf *b = NULL;
         int r = SSH_ERR_INTERNAL_ERROR;
         char *hashalg = NULL;
 
+        if (sig_details != NULL)
+                *sig_details = NULL;
         if (sign_keyp != NULL)
                 *sign_keyp = NULL;
-
         if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
                 return r;
         debug("%s: signature made with hash \"%s\"", __func__, hashalg);
@@ -469,7 +474,7 @@ sshsig_verifyb(struct sshbuf *signature, const struct sshbuf *message,
                 goto out;
         }
         if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
-            sign_keyp)) != 0)
+            sign_keyp, sig_details)) != 0)
                 goto out;
         /* success */
         r = 0;
@@ -551,7 +556,7 @@ hash_file(int fd, const char *hashalg, struct sshbuf **bp)
 }
 
 int
-sshsig_sign_fd(struct sshkey *key, const char *hashalg,
+sshsig_sign_fd(struct sshkey *key, const char *hashalg, const char *sk_provider,
     int fd, const char *sig_namespace, struct sshbuf **out,
     sshsig_signer *signer, void *signer_ctx)
 {
@@ -566,8 +571,8 @@ sshsig_sign_fd(struct sshkey *key, const char *hashalg,
                 error("%s: hash_file failed: %s", __func__, ssh_err(r));
                 return r;
         }
-        if ((r = sshsig_wrap_sign(key, hashalg, b, sig_namespace, out,
-            signer, signer_ctx)) != 0)
+        if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, b,
+            sig_namespace, out, signer, signer_ctx)) != 0)
                 goto out;
         /* success */
         r = 0;
@@ -578,15 +583,17 @@ sshsig_sign_fd(struct sshkey *key, const char *hashalg,
 
 int
 sshsig_verify_fd(struct sshbuf *signature, int fd,
-    const char *expect_namespace, struct sshkey **sign_keyp)
+    const char *expect_namespace, struct sshkey **sign_keyp,
+    struct sshkey_sig_details **sig_details)
 {
         struct sshbuf *b = NULL;
         int r = SSH_ERR_INTERNAL_ERROR;
         char *hashalg = NULL;
 
+        if (sig_details != NULL)
+                *sig_details = NULL;
         if (sign_keyp != NULL)
                 *sign_keyp = NULL;
-
         if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
                 return r;
         debug("%s: signature made with hash \"%s\"", __func__, hashalg);
@@ -595,7 +602,7 @@ sshsig_verify_fd(struct sshbuf *signature, int fd,
                 goto out;
         }
         if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
-            sign_keyp)) != 0)
+            sign_keyp, sig_details)) != 0)
                 goto out;
         /* success */
         r = 0;
@@ -672,56 +679,116 @@ sshsigopt_free(struct sshsigopt *opts)
 }
 
 static int
-check_allowed_keys_line(const char *path, u_long linenum, char *line,
-    const struct sshkey *sign_key, const char *principal,
-    const char *sig_namespace)
+parse_principals_key_and_options(const char *path, u_long linenum, char *line,
+    const char *required_principal, char **principalsp, struct sshkey **keyp,
+    struct sshsigopt **sigoptsp)
 {
-        struct sshkey *found_key = NULL;
-        char *cp, *opts = NULL, *identities = NULL;
-        int r, found = 0;
+        char *opts = NULL, *tmp, *cp, *principals = NULL;
         const char *reason = NULL;
         struct sshsigopt *sigopts = NULL;
+        struct sshkey *key = NULL;
+        int r = SSH_ERR_INTERNAL_ERROR;
 
-        if ((found_key = sshkey_new(KEY_UNSPEC)) == NULL) {
-                error("%s: sshkey_new failed", __func__);
-                return SSH_ERR_ALLOC_FAIL;
-        }
+        if (principalsp != NULL)
+                *principalsp = NULL;
+        if (sigoptsp != NULL)
+                *sigoptsp = NULL;
+        if (keyp != NULL)
+                *keyp = NULL;
 
-        /* format: identity[,identity...] [option[,option...]] key */
         cp = line;
         cp = cp + strspn(cp, " \t"); /* skip leading whitespace */
         if (*cp == '#' || *cp == '\0')
-                goto done;
-        if ((identities = strdelimw(&cp)) == NULL) {
+                return SSH_ERR_KEY_NOT_FOUND; /* blank or all-comment line */
+
+        /* format: identity[,identity...] [option[,option...]] key */
+        if ((tmp = strdelimw(&cp)) == NULL) {
                 error("%s:%lu: invalid line", path, linenum);
-                goto done;
+                r = SSH_ERR_INVALID_FORMAT;
+                goto out;
         }
-        if (match_pattern_list(principal, identities, 0) != 1) {
-                /* principal didn't match */
-                goto done;
+        if ((principals = strdup(tmp)) == NULL) {
+                error("%s: strdup failed", __func__);
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        /*
+         * Bail out early if we're looking for a particular principal and this
+         * line does not list it.
+         */
+        if (required_principal != NULL) {
+                if (match_pattern_list(required_principal,
+                    principals, 0) != 1) {
+                        /* principal didn't match */
+                        r = SSH_ERR_KEY_NOT_FOUND;
+                        goto out;
+                }
+                debug("%s: %s:%lu: matched principal \"%s\"",
+                    __func__, path, linenum, required_principal);
         }
-        debug("%s: %s:%lu: matched principal \"%s\"",
-            __func__, path, linenum, principal);
 
-        if (sshkey_read(found_key, &cp) != 0) {
+        if ((key = sshkey_new(KEY_UNSPEC)) == NULL) {
+                error("%s: sshkey_new failed", __func__);
+                r = SSH_ERR_ALLOC_FAIL;
+                goto out;
+        }
+        if (sshkey_read(key, &cp) != 0) {
                 /* no key? Check for options */
                 opts = cp;
                 if (sshkey_advance_past_options(&cp) != 0) {
-                        error("%s:%lu: invalid options",
-                            path, linenum);
-                        goto done;
+                        error("%s:%lu: invalid options", path, linenum);
+                        r = SSH_ERR_INVALID_FORMAT;
+                        goto out;
                 }
                 *cp++ = '\0';
                 skip_space(&cp);
-                if (sshkey_read(found_key, &cp) != 0) {
-                        error("%s:%lu: invalid key", path,
-                            linenum);
-                        goto done;
+                if (sshkey_read(key, &cp) != 0) {
+                        error("%s:%lu: invalid key", path, linenum);
+                        r = SSH_ERR_INVALID_FORMAT;
+                        goto out;
                 }
         }
         debug3("%s:%lu: options %s", path, linenum, opts == NULL ? "" : opts);
         if ((sigopts = sshsigopt_parse(opts, path, linenum, &reason)) == NULL) {
                 error("%s:%lu: bad options: %s", path, linenum, reason);
+                r = SSH_ERR_INVALID_FORMAT;
+                goto out;
+        }
+        /* success */
+        if (principalsp != NULL) {
+                *principalsp = principals;
+                principals = NULL; /* transferred */
+        }
+        if (sigoptsp != NULL) {
+                *sigoptsp = sigopts;
+                sigopts = NULL; /* transferred */
+        }
+        if (keyp != NULL) {
+                *keyp = key;
+                key = NULL; /* transferred */
+        }
+        r = 0;
+ out:
+        free(principals);
+        sshsigopt_free(sigopts);
+        sshkey_free(key);
+        return r;
+}
+
+static int
+check_allowed_keys_line(const char *path, u_long linenum, char *line,
+    const struct sshkey *sign_key, const char *principal,
+    const char *sig_namespace)
+{
+        struct sshkey *found_key = NULL;
+        int r, found = 0;
+        const char *reason = NULL;
+        struct sshsigopt *sigopts = NULL;
+
+        /* Parse the line */
+        if ((r = parse_principals_key_and_options(path, linenum, line,
+            principal, NULL, &found_key, &sigopts)) != 0) {
+                /* error already logged */
                 goto done;
         }
 
@@ -799,3 +866,172 @@ sshsig_check_allowed_keys(const char *path, const struct sshkey *sign_key,
         free(line);
         return r == 0 ? SSH_ERR_KEY_NOT_FOUND : r;
 }
+
+static int
+cert_filter_principals(const char *path, u_long linenum,
+    char **principalsp, const struct sshkey *cert)
+{
+        char *cp, *oprincipals, *principals;
+        const char *reason;
+        struct sshbuf *nprincipals;
+        int r = SSH_ERR_INTERNAL_ERROR, success = 0;
+
+        oprincipals = principals = *principalsp;
+        *principalsp = NULL;
+
+        if ((nprincipals = sshbuf_new()) == NULL)
+                return SSH_ERR_ALLOC_FAIL;
+
+        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 */
+                if ((r = sshkey_cert_check_authority(cert, 0, 1,
+                    cp, &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("%s: buffer error", __func__);
+                        goto out;
+                }
+        }
+        if (sshbuf_len(nprincipals) == 0) {
+                error("%s:%lu: no valid principals found", path, linenum);
+                r = SSH_ERR_KEY_CERT_INVALID;
+                goto out;
+        }
+        if ((principals = sshbuf_dup_string(nprincipals)) == NULL) {
+                error("%s: buffer error", __func__);
+                goto out;
+        }
+        /* success */
+        success = 1;
+        *principalsp = principals;
+ out:
+        sshbuf_free(nprincipals);
+        free(oprincipals);
+        return success ? 0 : r;
+}
+
+static int
+get_matching_principals_from_line(const char *path, u_long linenum, char *line,
+    const struct sshkey *sign_key, char **principalsp)
+{
+        struct sshkey *found_key = NULL;
+        char *principals = NULL;
+        int r, found = 0;
+        struct sshsigopt *sigopts = NULL;
+
+        if (principalsp != NULL)
+                *principalsp = NULL;
+
+        /* Parse the line */
+        if ((r = parse_principals_key_and_options(path, linenum, line,
+            NULL, &principals, &found_key, &sigopts)) != 0) {
+                /* error already logged */
+                goto done;
+        }
+
+        if (!sigopts->ca && sshkey_equal(found_key, sign_key)) {
+                /* Exact match of key */
+                debug("%s:%lu: matched key", path, linenum);
+                /* success */
+                found = 1;
+        } else if (sigopts->ca && sshkey_is_cert(sign_key) &&
+            sshkey_equal_public(sign_key->cert->signature_key, found_key)) {
+                /* Remove principals listed in file but not allowed by cert */
+                if ((r = cert_filter_principals(path, linenum,
+                    &principals, sign_key)) != 0) {
+                        /* error already displayed */
+                        debug("%s:%lu: cert_filter_principals: %s",
+                            path, linenum, ssh_err(r));
+                        goto done;
+                }
+                debug("%s:%lu: matched certificate CA key", path, linenum);
+                /* success */
+                found = 1;
+        } else {
+                /* Key didn't match */
+                goto done;
+        }
+ done:
+        if (found) {
+                *principalsp = principals;
+                principals = NULL; /* transferred */
+        }
+        free(principals);
+        sshkey_free(found_key);
+        sshsigopt_free(sigopts);
+        return found ? 0 : SSH_ERR_KEY_NOT_FOUND;
+}
+
+int
+sshsig_find_principals(const char *path, const struct sshkey *sign_key,
+    char **principals)
+{
+        FILE *f = NULL;
+        char *line = NULL;
+        size_t linesize = 0;
+        u_long linenum = 0;
+        int r, oerrno;
+
+        if ((f = fopen(path, "r")) == NULL) {
+                oerrno = errno;
+                error("Unable to open allowed keys file \"%s\": %s",
+                    path, strerror(errno));
+                errno = oerrno;
+                return SSH_ERR_SYSTEM_ERROR;
+        }
+
+        while (getline(&line, &linesize, f) != -1) {
+                linenum++;
+                r = get_matching_principals_from_line(path, linenum, line,
+                    sign_key, principals);
+                free(line);
+                line = NULL;
+                if (r == SSH_ERR_KEY_NOT_FOUND)
+                        continue;
+                else if (r == 0) {
+                        /* success */
+                        fclose(f);
+                        return 0;
+                } else
+                        break;
+        }
+        free(line);
+        /* Either we hit an error parsing or we simply didn't find the key */
+        if (ferror(f) != 0) {
+                oerrno = errno;
+                fclose(f);
+                error("Unable to read allowed keys file \"%s\": %s",
+                    path, strerror(errno));
+                errno = oerrno;
+                return SSH_ERR_SYSTEM_ERROR;
+        }
+        fclose(f);
+        return r == 0 ? SSH_ERR_KEY_NOT_FOUND : r;
+}
+
+int
+sshsig_get_pubkey(struct sshbuf *signature, struct sshkey **pubkey)
+{
+        struct sshkey *pk = NULL;
+        int r = SSH_ERR_SIGNATURE_INVALID;
+
+        if (pubkey != NULL)
+                *pubkey = NULL;
+        if ((r = sshsig_parse_preamble(signature)) != 0)
+                return r;
+        if ((r = sshkey_froms(signature, &pk)) != 0)
+                return r;
+
+        *pubkey = pk;
+        pk = NULL;
+        return 0;
+}