better nonce generation and session credentials verification

based on the patch from Chris Davies

Signed-off-by: Michael Krelin <hacker@klever.net>

4 files changed, 36 insertions, 7 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 09f698e..b5b7d5c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -2,25 +2,25 @@ sbin_PROGRAMS=iiid
 noinst_HEADERS = \
 	eyefi.h \
 	eyekinfig.h eyetil.h \
 	eyefiworker.h
 
 AM_CPPFLAGS = ${CPPFLAGS_DEBUG} \
 	      -DEYEKIN_CONF_DIR=\"${sysconfdir}/${PACKAGE}\"
 DEFAULT_INCLUDES = -I${top_builddir} -I${builddir} -I${srcdir}
-INCLUDES = ${MODULES_CFLAGS}
+INCLUDES = ${MODULES_CFLAGS} ${UUID_CFLAGS}
 
 iiid_SOURCES = iiid.cc \
 	eyekinfig.cc eyetil.cc \
 	eyefiservice.cc eyefiworker.cc
 nodist_iiid_SOURCES = \
 	${builddir}/soapC.cpp ${builddir}/soapeyefiService.cpp \
 	COPYING.cc
-iiid_LDADD = ${MODULES_LIBS}
+iiid_LDADD = ${MODULES_LIBS} ${UUID_LIBS}
 
 COPYING.cc: ${top_srcdir}/COPYING
 	echo "const char * COPYING = " >$@ || (rm $@;exit 1)
 	sed -e 's/"/\\"/g' -e 's/^/\"/' -e 's/$$/\\n\"/' $< >>$@ || (rm $@;exit 1)
 	echo ';' >>$@ || (rm $@;exit 1)
 
 ${srcdir}/eyefiservice.cc: ${builddir}/soapeyefiService.h
 ${srcdir}/iiid.cc: ${builddir}/eyefi.nsmap
diff --git a/src/eyefiservice.cc b/src/eyefiservice.cc
index d233a07..1a21c02 100644
--- a/src/eyefiservice.cc
+++ b/src/eyefiservice.cc
@@ -1,20 +1,23 @@
 #include <cassert>
 #include <iostream>
 #include <fstream>
 #include <stdexcept>
 #include <iterator>
 #include <syslog.h>
 #include <sys/wait.h>
 #include <autosprintf.h>
+#include <openssl/rand.h>
 #include "eyekinfig.h"
 #include "eyetil.h"
 #include "soapeyefiService.h"
 
+static binary_t session_nonce;
+
 static bool detached_child() {
     pid_t p = fork();
     if(p<0) throw std::runtime_error("failed to fork()");
     if(!p) {
 	p = fork();
 	if(p<0) {
 	    syslog(LOG_ERR,"Failed to re-fork child process");
 	    _exit(-1);
@@ -41,19 +44,18 @@ int eyefiService::StartSession(
 	int transfermode,long transfermodetimestamp,
 	struct rns__StartSessionResponse &r ) {
 #ifndef NDEBUG
     syslog(LOG_DEBUG,
 	    "StartSession request from %s with cnonce=%s, transfermode=%d, transfermodetimestamp=%ld",
 	    macaddress.c_str(), cnonce.c_str(), transfermode, transfermodetimestamp );
 #endif
     r.credential = binary_t(macaddress+cnonce+eyekinfig_t(macaddress).get_upload_key()).md5().hex();
-    /* TODO: better nonce generator */
-    time_t t = time(0);
-    r.snonce = binary_t(&t,sizeof(t)).md5().hex();
+
+    r.snonce = session_nonce.make_nonce().hex();
     r.transfermode=transfermode;
     r.transfermodetimestamp=transfermodetimestamp;
     r.upsyncallowed=false;
 
     std::string cmd = eyekinfig_t(macaddress).get_on_start_session();
     if(!cmd.empty()) {
 	if(detached_child()) {
 	    putenv( gnu::autosprintf("EYEFI_MACADDRESS=%s",macaddress.c_str()) );
@@ -69,19 +71,28 @@ int eyefiService::StartSession(
 }
 
 int eyefiService::GetPhotoStatus(
 	std::string credential, std::string macaddress,
 	std::string filename, long filesize, std::string filesignature,
 	struct rns__GetPhotoStatusResponse &r ) {
 #ifndef NDEBUG
     syslog(LOG_DEBUG,
-	    "GetPhotoStatus request from %s with credential=%s, filename=%s, filesize=%ld, filesignature=%s",
-	    macaddress.c_str(), credential.c_str(), filename.c_str(), filesize, filesignature.c_str() );
+	    "GetPhotoStatus request from %s with credential=%s, filename=%s, filesize=%ld, filesignature=%s; session nonce=%s",
+	    macaddress.c_str(), credential.c_str(), filename.c_str(), filesize, filesignature.c_str(), session_nonce.hex().c_str() );
+#endif
+
+    std::string computed_credential = binary_t(macaddress+eyekinfig_t(macaddress).get_upload_key()+session_nonce.hex()).md5().hex();
+
+#ifndef NDEBUG
+    syslog(LOG_DEBUG, " computed credential=%s", computed_credential.c_str());
 #endif
+
+    if (credential != computed_credential) throw std::runtime_error("card authentication failed");
+
     r.fileid = 1; r.offset = 0;
     return SOAP_OK;
 }
 
 int eyefiService::MarkLastPhotoInRoll(
 	std::string macaddress, int mergedelta,
 	struct rns__MarkLastPhotoInRollResponse &r ) {
 #ifndef NDEBUG
diff --git a/src/eyetil.cc b/src/eyetil.cc
index fe816a6..7669cb6 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -4,16 +4,21 @@
 #include <iostream>
 #include <cassert>
 #include <stdexcept>
 #include <algorithm>
 #include <numeric>
 #include <openssl/md5.h>
 #include "eyetil.h"
 
+#include "config.h"
+#ifdef HAVE_LIBUUID
+# include <uuid/uuid.h>
+#endif
+
 binary_t& binary_t::from_hex(const std::string& h) {
     std::string::size_type hs = h.length();
     if(hs&1)
 	throw std::runtime_error("odd number of characters in hexadecimal number");
     int rvs = hs>>1;
     resize(rvs);
     const unsigned char *hp = (const unsigned char*)h.data();
     iterator oi=begin();
@@ -27,16 +32,28 @@ binary_t& binary_t::from_hex(const std::string& h) {
 
 binary_t& binary_t::from_data(const void *d,size_t s) {
     resize(s);
     std::copy((const unsigned char*)d,(const unsigned char *)d+s,
 	    begin() );
     return *this;
 }
 
+binary_t& binary_t::make_nonce() {
+#ifdef HAVE_LIBUUID
+    uuid_t uuid;
+    uuid_generate(uuid);
+    from_data((unsigned char*)uuid,sizeof(uuid));
+#else
+    resize(16);
+    std::generate_n(begin(),16,rand);
+#endif /* HAVE_LIBUUID */
+    return *this;
+}
+
 std::string binary_t::hex() const {
     std::string rv;
     rv.reserve((size()<<1)+1);
     char t[3] = {0,0,0};
     for(const_iterator i=begin(),ie=end();i!=ie;++i) {
 	int rc = snprintf(t,sizeof(t),"%02x",*i);
 	assert(rc<sizeof(t));
 	rv += t;
diff --git a/src/eyetil.h b/src/eyetil.h
index 378f703..d946e71 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -10,16 +10,17 @@ class binary_t : public std::vector<unsigned char> {
     public:
 	binary_t() { }
 	binary_t(size_type  n) : std::vector<unsigned char>(n) { }
 	binary_t(const std::string& h) { from_hex(h); }
 	binary_t(const void *d,size_t s) { from_data(d,s); }
 
 	binary_t& from_hex(const std::string& h);
 	binary_t& from_data(const void *d,size_t s);
+	binary_t& make_nonce();
 
 	std::string hex() const;
 	binary_t md5() const;
 };
 
 class tmpdir_t {
     public:
 	std::string dir;