better nonce generation and session credentials verification

based on the patch from Chris Davies

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

6 files changed, 43 insertions, 7 deletions

diff --git a/AUTHORS b/AUTHORS
index 257669f..e7f9101 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -4,6 +4,7 @@ Klever dissected:
 
 
 Thanks to:
 
 cdavies of Eye-Fi forums for integrity digest verification algorithm.
         See http://forums.eye.fi/viewtopic.php?f=4&t=270&p=4074#p4074
+        and session nonce verification patch
diff --git a/configure.ac b/configure.ac
index 2e66fc4..515d465 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,12 +12,18 @@ AC_HEADER_STDC
 
 AC_PATH_PROG([XSLTPROC],[xsltproc],[true])
 
 PKG_CHECK_MODULES([MODULES],[gsoap++ openssl libconfuse],,[
  AC_MSG_ERROR([one of the build dependencies isn't satisfied])
 ])
+PKG_CHECK_MODULES([UUID],[uuid],[have_uuid=true],[have_uuid=false])
+AM_CONDITIONAL([HAVE_UUID],[$have_uuid])
+if $have_uuid ; then
+ AC_DEFINE([HAVE_LIBUUID],,[defined in presence of libuuid])
+ AC_SUBST([UUID_UUID],[uuid])
+fi
 
 AC_PATH_PROG([SOAPCPP2],[soapcpp2],[false])
 test "$SOAPCPP2" = "false" && AC_MSG_ERROR([no soapcpp2 tool, part of gsoap package, found.])
 
 notfound=false
 AC_CHECK_HEADERS([archive.h],[
diff --git a/src/Makefile.am b/src/Makefile.am
index 09f698e..b5b7d5c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,21 +4,21 @@ noinst_HEADERS = \
         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)
 
diff --git a/src/eyefiservice.cc b/src/eyefiservice.cc
index d233a07..1a21c02 100644
--- a/src/eyefiservice.cc
+++ b/src/eyefiservice.cc
@@ -3,16 +3,19 @@
 #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) {
@@ -43,15 +46,14 @@ int eyefiService::StartSession(
 #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()) {
@@ -71,15 +73,24 @@ 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,
diff --git a/src/eyetil.cc b/src/eyetil.cc
index fe816a6..7669cb6 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -6,12 +6,17 @@
 #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);
@@ -29,12 +34,24 @@ 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);
diff --git a/src/eyetil.h b/src/eyetil.h
index 378f703..d946e71 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -12,12 +12,13 @@ class binary_t : public std::vector<unsigned char> {
         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 {