Add package signing infrastructure

Add package signing key and certificate configuration options to the
"Image configuration" submenu. If enabled, the Packages.gz list will
be signed as file Packages.sig. The passphrase for the signing key can
be sourced from a file or entered by the user. The signing certificate
is automatically added to the firmware image if opkg-smime is selected.

Signed-off-by: Evan Hunt <each@isc.org>
Signed-off-by: Steven Barth <steven@midlink.org>

SVN-Revision: 38284

include/prereq-build.mk

@@ -168,6 +168,10 @@ $(eval $(call RequireCommand,svn, \
 	Please install the subversion client. \
 ))
 
+$(eval $(call RequireCommand,openssl, \
+	Please install openssl. \
+))
+
 define Require/gnu-find
 	$(FIND) --version 2>/dev/null
 endef

package/Makefile

@@ -120,10 +120,35 @@ $(curdir)/install: $(TMP_DIR)/.build
 	$(if $(CONFIG_CLEAN_IPKG),rm -rf $(TARGET_DIR)/usr/lib/opkg)
 	$(call mklibs)
 
+PASSOPT=""
+PASSARG=""
+ifndef CONFIG_OPKGSMIME_PASSPHRASE
+  ifneq ($(call qstrip,$(CONFIG_OPKGSMIME_PASSFILE)),)
+    PASSOPT="-passin"
+    PASSARG="file:$(call qstrip,$(CONFIG_OPKGSMIME_PASSFILE))"
+  endif
+endif
+
 $(curdir)/index: FORCE
-	@(cd $(PACKAGE_DIR); $(SCRIPT_DIR)/ipkg-make-index.sh . 2>&1 > Packages && \
-		gzip -9c Packages > Packages.gz \
-	)
+ifeq ($(call qstrip,$(CONFIG_OPKGSMIME_KEY)),)
+	@echo Signing key has not been configured
+else
+ifeq ($(call qstrip,$(CONFIG_OPKGSMIME_CERT)),)
+	@echo Certificate has not been configured
+else
+	@echo Generating package index...
+	@(cd $(PACKAGE_DIR); \
+		$(SCRIPT_DIR)/ipkg-make-index.sh . 2>&1 > Packages && \
+		gzip -9c Packages > Packages.gz )
+	@echo Signing package index...
+	@(cd $(PACKAGE_DIR); \
+		openssl smime -binary -in Packages.gz \
+			-out Packages.sig -outform PEM -sign \
+			-signer $(CONFIG_OPKGSMIME_CERT) \
+			-inkey $(CONFIG_OPKGSMIME_KEY) \
+			$(PASSOPT) $(PASSARG) )
+endif
+endif
 
 $(curdir)/preconfig:
 

package/base-files/image-config.in

@@ -183,3 +183,41 @@ menuconfig VERSIONOPT
 			 %d .. Distribution name or "openwrt", lowercase
 			 %T .. Target name
 			 %S .. Target/Subtarget name
+
+menuconfig SMIMEOPT
+	bool "Package signing options" if IMAGEOPT
+        default n
+	help
+		These options configure the signing key and certificate to
+		be used for signing and verifying packages.
+
+	config OPKGSMIME_CERT
+		string
+		prompt "Path to certificate (PEM certificate format)" if SMIMEOPT
+		help
+		  Path to the certificate to use for signature verification
+
+	config OPKGSMIME_KEY
+		string
+		prompt "Path to signing key (PEM private key format)" if SMIMEOPT
+		help
+		  Path to the key to use for signing packages
+
+	config OPKGSMIME_PASSPHRASE
+		bool
+		default y
+		prompt "Wait for a passphrase when signing packages?" if SMIMEOPT
+		help
+		  If this value is set, then the build will pause and request a passphrase
+                  from the command line when signing packages. This SHOULD NOT be used with
+                  automatic builds. If this value is not set, a file can be specified from
+                  which the passphrase will be read.
+
+	config OPKGSMIME_PASSFILE
+		string
+		prompt "Path to a file containing the passphrase" if SMIMEOPT
+                depends on !OPKGSMIME_PASSPHRASE
+		help
+		  Path to a file containing the passphrase for the signing key.
+                  If the signing key is not encrypted and does not require a passphrase,
+                  this option may be left blank.

package/system/opkg/Makefile

@@ -109,8 +109,12 @@ define Package/opkg/Default/install
 endef
 
 Package/opkg/install = $(call Package/opkg/Default/install,$(1),)
-Package/opkg-smime/install = $(call Package/opkg/Default/install,$(1),-smime)
 
+define Package/opkg-smime/install
+	$(call Package/opkg/Default/install,$(1),-smime)
+	$(INSTALL_DIR) $(1)/etc/ssl/certs
+	$(if $(CONFIG_OPKGSMIME_CERT),$(INSTALL_DATA) $(call qstrip,$(CONFIG_OPKGSMIME_CERT)) $(1)/etc/ssl/certs/opkg.pem,)
+endef
 
 define Build/InstallDev
 	mkdir -p $(1)/usr/include

package/system/opkg/files/opkg-smime.conf

@@ -4,4 +4,4 @@ dest ram /tmp
 lists_dir ext /var/opkg-lists
 option overlay_root /overlay
 option check_signature 1
-option signature_ca_path /etc/ssl/certs/
+option signature_ca_file /etc/ssl/certs/opkg.pem