irmd: Fix OAP re-key header encode

The oap_hdr_encode() function validated its own output by re-decoding
with rekey hardcoded false. The case where the client signs a re-key
failed its own self-check because the cert is not sent again. Now uses
a flag on the encode() to signal the signed re-key without
certificate.

Also fixes a double free after a failed self-decode check.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

4 files changed, 27 insertions, 9 deletions

diff --git a/src/irmd/oap/cli.c b/src/irmd/oap/cli.c
index 689d67ca..3518b4d1 100644
--- a/src/irmd/oap/cli.c
+++ b/src/irmd/oap/cli.c
@@ -250,6 +250,7 @@ int oap_cli_prepare(void **                  ctx,
         void *               crt = NULL;
         buffer_t             no_tag = BUF_INIT;
         ssize_t              ret;
+        int                  enc_flags = 0;
 
         assert(ctx != NULL);
         assert(info != NULL);
@@ -302,6 +303,9 @@ int oap_cli_prepare(void **                  ctx,
                 crt = NULL;
         }
 
+        if (rekey)
+                enc_flags = OAP_ENC_REKEY;
+
         oap_hdr_init(&s->local_hdr, s->id, s->kex_buf, data, s->scfg.c.nid);
 
         if (do_client_kex_prepare(info->name, s) < 0) {
@@ -310,7 +314,7 @@ int oap_cli_prepare(void **                  ctx,
         }
 
         if (oap_hdr_encode(&s->local_hdr, pkp, crt, &s->scfg,
-                           no_tag, NID_undef, NULL)) {
+                           no_tag, NID_undef, NULL, enc_flags)) {
                 log_err_id(s->id.data, "Failed to create OAP request header.");
                 goto fail_hdr;
         }
diff --git a/src/irmd/oap/hdr.c b/src/irmd/oap/hdr.c
index f8400b46..6f355133 100644
--- a/src/irmd/oap/hdr.c
+++ b/src/irmd/oap/hdr.c
@@ -397,7 +397,8 @@ static int oap_hdr_encode_sealed(struct oap_hdr *    hdr,
                                  struct sec_config * scfg,
                                  buffer_t            rsp_tag,
                                  int                 req_md_nid,
-                                 const uint8_t *     seal_key)
+                                 const uint8_t *     seal_key,
+                                 int                 flags)
 {
         struct timespec now;
         uint64_t        stamp;
@@ -449,7 +450,8 @@ static int oap_hdr_encode_sealed(struct oap_hdr *    hdr,
         free(prefix.data);
         freebuf(der);
 
-        if (oap_hdr_decode(hdr, hdr->hdr, req_md_nid, false) < 0)
+        if (oap_hdr_decode(hdr, hdr->hdr, req_md_nid,
+                           flags & OAP_ENC_REKEY) < 0)
                 goto fail_decode;
 
         return 0;
@@ -472,7 +474,8 @@ int oap_hdr_encode(struct oap_hdr *    hdr,
                    struct sec_config * scfg,
                    buffer_t            rsp_tag,
                    int                 req_md_nid,
-                   const uint8_t *     seal_key)
+                   const uint8_t *     seal_key,
+                   int                 flags)
 {
         struct timespec now;
         uint64_t        stamp;
@@ -488,7 +491,7 @@ int oap_hdr_encode(struct oap_hdr *    hdr,
 
         if (seal_key != NULL)
                 return oap_hdr_encode_sealed(hdr, pkp, crt, scfg, rsp_tag,
-                                             req_md_nid, seal_key);
+                                             req_md_nid, seal_key, flags);
 
         clock_gettime(CLOCK_REALTIME, &now);
         stamp = hton64(TS_TO_UINT64(now));
@@ -550,10 +553,13 @@ int oap_hdr_encode(struct oap_hdr *    hdr,
                         goto fail_realloc;
 
                 memcpy(hdr->hdr.data + offset, sig.data, sig.len);
-                clrbuf(out);
         }
 
-        if (oap_hdr_decode(hdr, hdr->hdr, req_md_nid, false) < 0)
+        /* Ownership moved to hdr->hdr; drop the alias to avoid double-free. */
+        clrbuf(out);
+
+        if (oap_hdr_decode(hdr, hdr->hdr, req_md_nid,
+                           flags & OAP_ENC_REKEY) < 0)
                 goto fail_decode;
 
         freebuf(der);
diff --git a/src/irmd/oap/hdr.h b/src/irmd/oap/hdr.h
index 1a599727..66fbac9a 100644
--- a/src/irmd/oap/hdr.h
+++ b/src/irmd/oap/hdr.h
@@ -168,13 +168,17 @@ void oap_hdr_init(struct oap_hdr * hdr,
 
 void oap_hdr_fini(struct oap_hdr * oap_hdr);
 
+/* oap_hdr_encode option flags */
+#define OAP_ENC_REKEY (1U << 0) /* signed, cert-less re-key packet */
+
 int  oap_hdr_encode(struct oap_hdr *    hdr,
                     void *              pkp,
                     void *              crt,
                     struct sec_config * scfg,
                     buffer_t            rsp_tag,
                     int                 req_md_nid,
-                    const uint8_t *     seal_key);
+                    const uint8_t *     seal_key,
+                    int                 flags);
 
 int  oap_hdr_decode(struct oap_hdr * hdr,
                     buffer_t         buf,
diff --git a/src/irmd/oap/srv.c b/src/irmd/oap/srv.c
index 5d631618..cc3dec5b 100644
--- a/src/irmd/oap/srv.c
+++ b/src/irmd/oap/srv.c
@@ -400,6 +400,7 @@ int oap_srv_process(const struct name_info * info,
         void *                pkp = NULL;
         void *                crt = NULL;
         int                   req_md_nid;
+        int                   enc_flags = 0;
         int                   ret;
 
         assert(info != NULL);
@@ -426,6 +427,9 @@ int oap_srv_process(const struct name_info * info,
                 crt = NULL;
         }
 
+        if (rekey)
+                enc_flags = OAP_ENC_REKEY;
+
         if (load_srv_sec_config(info, &scfg) < 0) {
                 log_err("Failed to load security config for %s.", info->name);
                 goto fail_kex;
@@ -535,7 +539,7 @@ int oap_srv_process(const struct name_info * info,
         }
 
         ret = oap_hdr_encode(&local_hdr, pkp, crt, &scfg,
-                             rsp_tag, req_md_nid, seal_key);
+                             rsp_tag, req_md_nid, seal_key, enc_flags);
 
         crypt_secure_clear(hs_key, SYMMKEYSZ);