From d447376aa2bf66a5d5b6a928fb0c6e65189910ba Mon Sep 17 00:00:00 2001
From: Jes Sorensen <jsorensen@fb.com>
Date: Fri, 3 Apr 2020 16:38:08 -0400
Subject: [PATCH 19/33] Implement rpmSignVerity()

This generates the root Merkle tree hash and signs it using the
specified key and certificate.

Signed-off-by: Jes Sorensen <jsorensen@fb.com>
---
 sign/rpmgensig.c     |  36 +++++++++++++
 sign/rpmsignverity.c | 121 +++++++++++++++++++++++++++++++++++++++++++
 sign/rpmsignverity.h |  29 +++++++++++
 3 files changed, 186 insertions(+)
 create mode 100644 sign/rpmsignverity.c
 create mode 100644 sign/rpmsignverity.h

diff --git a/sign/rpmgensig.c b/sign/rpmgensig.c
index a6e37e71b..8d5c5858f 100644
--- a/sign/rpmgensig.c
+++ b/sign/rpmgensig.c
@@ -22,6 +22,7 @@
 #include "lib/signature.h"
 #include "lib/rpmvs.h"
 #include "sign/rpmsignfiles.h"
+#include "sign/rpmsignverity.h"
 
 #include "debug.h"
 
@@ -446,6 +447,36 @@ static rpmRC includeFileSignatures(Header *sigp, Header *hdrp)
 #endif
 }
 
+static rpmRC includeVeritySignatures(FD_t fd, Header *sigp, Header *hdrp)
+{
+#ifdef WITH_FSVERITY
+    rpmRC rc;
+    char *key = rpmExpand("%{?_file_signing_key}", NULL);
+    char *keypass = rpmExpand("%{?_file_signing_key_password}", NULL);
+    char *cert = rpmExpand("%{?_file_signing_cert}", NULL);
+
+    if (rstreq(keypass, "")) {
+	free(keypass);
+	keypass = NULL;
+    }
+
+    if (key && cert) {
+	rc = rpmSignVerity(fd, *sigp, *hdrp, key, keypass, cert);
+    } else {
+	rpmlog(RPMLOG_ERR, _("fsverity signatures requires a key and a cert\n"));
+	rc = RPMRC_FAIL;
+    }
+
+    free(keypass);
+    free(key);
+    free(cert);
+    return rc;
+#else
+    rpmlog(RPMLOG_ERR, _("fsverity signing support not built in\n"));
+    return RPMRC_FAIL;
+#endif
+}
+
 static int msgCb(struct rpmsinfo_s *sinfo, void *cbdata)
 {
     char **msg = cbdata;
@@ -544,6 +575,11 @@ static int rpmSign(const char *rpm, int deleting, int flags)
 	    goto exit;
     }
 
+    if (flags & RPMSIGN_FLAG_FSVERITY) {
+	if (includeVeritySignatures(fd, &sigh, &h))
+	    goto exit;
+    }
+
     if (deleting) {	/* Nuke all the signature tags. */
 	deleteSigs(sigh);
     } else {
diff --git a/sign/rpmsignverity.c b/sign/rpmsignverity.c
new file mode 100644
index 000000000..5346c3bc8
--- /dev/null
+++ b/sign/rpmsignverity.c
@@ -0,0 +1,121 @@
+/**
+ * Copyright (C) 2020 Facebook
+ *
+ * Author: Jes Sorensen <jsorensen@fb.com>
+ */
+
+#include "system.h"
+
+#include <rpm/rpmlib.h>		/* RPMSIGTAG & related */
+#include <rpm/rpmlog.h>		/* rpmlog */
+#include <rpm/rpmfi.h>
+#include <rpm/rpmpgp.h>		/* rpmDigestLength */
+#include "lib/header.h"		/* HEADERGET_MINMEM */
+#include "lib/header_internal.h"
+#include "lib/rpmtypes.h"	/* rpmRC */
+#include <libfsverity.h>
+#include "rpmio/rpmio_internal.h"
+#include "lib/rpmvs.h"
+
+#include "sign/rpmsignverity.h"
+
+#define MAX_SIGNATURE_LENGTH 1024
+
+static int rpmVerityRead(void *opaque, void *buf, size_t size)
+{
+	int retval;
+	rpmfi fi = (rpmfi)opaque;
+
+	retval = rpmfiArchiveRead(fi, buf, size);
+
+	if (retval > 0)
+		retval = 0;
+	return retval;
+}
+
+rpmRC rpmSignVerity(FD_t fd, Header sigh, Header h, char *key,
+		    char *keypass, char *cert)
+{
+    int rc, status;
+    FD_t gzdi;
+    rpmfiles files = NULL;
+    rpmfi fi = NULL;
+    rpmts ts = rpmtsCreate();
+    struct libfsverity_digest *digest = NULL;
+    struct libfsverity_merkle_tree_params params;
+    struct libfsverity_signature_params sig_params;
+    rpm_loff_t file_size;
+    off_t offset = Ftell(fd);
+    const char *compr;
+    char *rpmio_flags = NULL;
+    char *digest_hex;
+    uint8_t *sig;
+    size_t sig_size;
+
+    Fseek(fd, 0, SEEK_SET);
+    rpmtsSetVSFlags(ts, RPMVSF_MASK_NODIGESTS | RPMVSF_MASK_NOSIGNATURES |
+		    RPMVSF_NOHDRCHK);
+    rc = rpmReadPackageFile(ts, fd, "fsverity", &h);
+    if (rc != RPMRC_OK) {
+	rpmlog(RPMLOG_DEBUG, _("%s: rpmReadPackageFile returned %i\n"),
+	       __func__, rc);
+	goto out;
+    }
+
+    rpmlog(RPMLOG_DEBUG, _("key: %s\n"), key);
+    rpmlog(RPMLOG_DEBUG, _("cert: %s\n"), cert);
+
+    compr = headerGetString(h, RPMTAG_PAYLOADCOMPRESSOR);
+    rpmio_flags = rstrscat(NULL, "r.", compr ? compr : "gzip", NULL);
+
+    gzdi = Fdopen(fdDup(Fileno(fd)), rpmio_flags);
+    free(rpmio_flags);
+
+    files = rpmfilesNew(NULL, h, RPMTAG_BASENAMES, RPMFI_FLAGS_QUERY);
+    fi = rpmfiNewArchiveReader(gzdi, files,
+			       RPMFI_ITER_READ_ARCHIVE_OMIT_HARDLINKS);
+
+    while (rpmfiNext(fi) >= 0) {
+	if (!S_ISREG(rpmfiFMode(fi)))
+	    continue;
+	file_size = rpmfiFSize(fi);
+	rpmlog(RPMLOG_DEBUG, _("file: %s, (size %li)\n"),
+	       rpmfiFN(fi), file_size);
+
+	memset(&params, 0, sizeof(struct libfsverity_merkle_tree_params));
+	params.version = 1;
+	params.hash_algorithm = FS_VERITY_HASH_ALG_SHA256;
+	params.block_size = sysconf(_SC_PAGESIZE);
+	params.salt_size = 0 /* salt_size */;
+	params.salt = NULL /* salt */;
+	params.file_size = file_size;
+	status = libfsverity_compute_digest(fi, rpmVerityRead,
+					    &params, &digest);
+	if (!status) {
+	    digest_hex = pgpHexStr(digest->digest, digest->digest_size);
+	    rpmlog(RPMLOG_DEBUG, _("digest(%i): %s\n"),
+		   digest->digest_size, digest_hex);
+	    free(digest_hex);
+	}
+	memset(&sig_params, 0, sizeof(struct libfsverity_signature_params));
+	sig_params.keyfile = key;
+	sig_params.certfile = cert;
+	if (libfsverity_sign_digest(digest, &sig_params, &sig, &sig_size)) {
+	    rpmlog(RPMLOG_DEBUG, _("failed to sign digest\n"));
+	    rc = RPMRC_FAIL;
+	    goto out;
+	}
+	rpmlog(RPMLOG_DEBUG, _("digest signing success\n"));
+
+	free(digest);
+	free(sig);
+    }
+
+out:
+    Fseek(fd, offset, SEEK_SET);
+
+    rpmfilesFree(files);
+    rpmfiFree(fi);
+    rpmtsFree(ts);
+    return rc;
+}
diff --git a/sign/rpmsignverity.h b/sign/rpmsignverity.h
new file mode 100644
index 000000000..f3ad3bb18
--- /dev/null
+++ b/sign/rpmsignverity.h
@@ -0,0 +1,29 @@
+#ifndef H_RPMSIGNVERITY
+#define H_RPMSIGNVERITY
+
+#include <rpm/rpmtypes.h>
+#include <rpm/rpmutil.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Sign file digests in header into signature header
+ * @param fd		file descriptor of RPM
+ * @param sigh		package signature header
+ * @param h		package header
+ * @param key		signing key
+ * @param keypass	signing key password
+ * @param cert		signing cert
+ * @return		RPMRC_OK on success
+ */
+RPM_GNUC_INTERNAL
+rpmRC rpmSignVerity(FD_t fd, Header sigh, Header h, char *key,
+		    char *keypass, char *cert);
+
+#ifdef _cplusplus
+}
+#endif
+
+#endif /* H_RPMSIGNVERITY */
-- 
2.27.0