Verify FILE_CKSUM (sha256) in pkg_summary(5) on download.

This is important for detecting version rollback attacks -- verifying
a signature on the package itself doesn't help, because the old one
also has a valid signature.

Author: Taylor R Campbell

Makefile.am

@@ -24,10 +24,11 @@ pkg_install_SOURCES=	external/automatic.c external/dewey.c
 pkg_install_SOURCES+=	external/fexec.c external/iterate.c external/lpkg.c
 pkg_install_SOURCES+=	external/opattern.c external/pkgdb.c external/plist.c
 pkg_install_SOURCES+=	external/var.c external/xwrapper.c
+pkg_install_SOURCES+=	external/sha2.c
 
 pkgin_SOURCES=		actions.c autoremove.c depends.c download.c fsops.c impact.c
 pkgin_SOURCES+=		main.c order.c pkg_check.c pkg_infos.c pkg_install.c
-pkgin_SOURCES+=		pkg_str.c pkgindb.c pkgindb_queries.c pkglist.c preferred.c
+pkgin_SOURCES+=		pkg_str.c pkghash.c pkgindb.c pkgindb_queries.c pkglist.c preferred.c
 pkgin_SOURCES+=		selection.c sqlite_callbacks.c summary.c tools.c
 pkgin_SOURCES+=		$(openssh_SOURCES) $(pkg_install_SOURCES)
 

actions.c

@@ -29,6 +29,7 @@
 
 #include <sqlite3.h>
 #include "pkgin.h"
+#include "pkghash.h"
 #include <sys/ioctl.h>
 #include <time.h>
 #include <unistd.h>
@@ -99,6 +100,13 @@ pkg_download(Plisthead *installhead)
 				continue;
 			}
 
+			if (p->ipkg->rpkg->hash) {
+				if (!pkghash_verify_file(p->ipkg->rpkg->hash,
+					pkgurl))
+					errx(EXIT_FAILURE, "Hash mismatch %s",
+					    p->ipkg->pkgfs);
+			}
+
 			if (symlink(pkgurl, p->ipkg->pkgfs) < 0) {
 				errx(EXIT_FAILURE,
 				    "Failed to create symlink %s",
@@ -116,7 +124,8 @@ pkg_download(Plisthead *installhead)
 				err(EXIT_FAILURE, MSG_ERR_OPEN, p->ipkg->pkgfs);
 
 			p->ipkg->file_size =
-			    download_pkg(p->ipkg->pkgurl, fp, i++, count);
+			    download_pkg(p->ipkg->pkgurl, fp, i++, count,
+				p->ipkg->rpkg->hash);
 
 			if (p->ipkg->file_size == -1) {
 				(void) fclose(fp);
@@ -748,12 +757,15 @@ pkgin_install(char **pkgargs, int do_inst, int upgrade)
 
 		/*
 		 * If the binary package has not already been downloaded, or
-		 * its size does not match pkg_summary, then mark it to be
+		 * its size/hash do not match pkg_summary, then mark it to be
 		 * downloaded.
 		 */
 		if (stat(p->pkgfs, &st) < 0 || st.st_size != p->rpkg->file_size)
 			p->download = 1;
-		else {
+		else if (p->rpkg->hash != NULL &&
+		    pkghash_verify_file(p->rpkg->hash, p->pkgfs)) {
+			/* exact match, no further check needed */
+		} else {
 			/*
 			 * If the cached package has the correct size, we must
 			 * verify that the BUILD_DATE has not changed, in case

download.c

@@ -28,6 +28,7 @@
  */
 
 #include "pkgin.h"
+#include "pkghash.h"
 #include "external/progressmeter.h"
 
 extern char fetchflags[3];
@@ -159,7 +160,8 @@ sum_close(struct archive *a, void *data)
  * Download a package to the local cache.
  */
 off_t
-download_pkg(char *pkg_url, FILE *fp, int cur, int total)
+download_pkg(char *pkg_url, FILE *fp, int cur, int total,
+    const struct pkghash *hash)
 {
 	struct url_stat st;
 	size_t size, wrote;
@@ -168,6 +170,7 @@ download_pkg(char *pkg_url, FILE *fp, int cur, int total)
 	struct url *url;
 	fetchIO *f = NULL;
 	char buf[4096];
+	struct pkghash_ctx *hash_ctx = NULL;
 	char *pkg, *ptr, *msg = NULL;
 
 	if ((url = fetchParseURL(pkg_url)) == NULL)
@@ -177,7 +180,8 @@ download_pkg(char *pkg_url, FILE *fp, int cur, int total)
 		fprintf(stderr, "download error: %s %s\n", pkg_url,
 		    fetchLastErrString);
 		fetchFreeURL(url);
-		return -1;
+		written = -1;
+		goto out;
 	}
 	fetchFreeURL(url);
 
@@ -194,6 +198,9 @@ download_pkg(char *pkg_url, FILE *fp, int cur, int total)
 		start_progress_meter(msg, st.size, &statsize);
 	}
 
+	if (hash)
+		hash_ctx = pkghash_verify_init(hash);
+
 	while (written < st.size) {
 		if ((fetched = fetchIO_read(f, buf, sizeof(buf))) == 0)
 			break;
@@ -202,12 +209,17 @@ download_pkg(char *pkg_url, FILE *fp, int cur, int total)
 		if (fetched < 0) {
 			fprintf(stderr, "download error: %s",
 			    fetchLastErrString);
-			return -1;
+			written = -1;
+			goto out;
 		}
 
 		statsize += fetched;
 		size = (size_t)fetched;
 
+		if (hash) {
+			pkghash_verify_update(hash_ctx, (const void *)buf,
+			    size);
+		}
 		for (ptr = buf; size > 0; ptr += wrote, size -= wrote) {
 			if ((wrote = fwrite(ptr, 1, size, fp)) < size) {
 				if (ferror(fp) && errno == EINTR)
@@ -230,8 +242,20 @@ download_pkg(char *pkg_url, FILE *fp, int cur, int total)
 
 	if (written != st.size) {
 		fprintf(stderr, "download error: %s truncated\n", pkg_url);
-		return -1;
+		written = -1;
+		goto out;
+	}
+
+	if (hash) {
+		if (!pkghash_verify_final(hash_ctx)) {
+			fprintf(stderr, "download error: %s corrupted\n",
+			    pkg_url);
+			written = -1;
+			goto out;
+		}
 	}
 
+out:	if (hash)
+		free(hash_ctx);
 	return written;
 }