better nonce generation and session credentials verification

based on the patch from Chris Davies

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

1 files changed, 16 insertions, 5 deletions

diff --git a/src/eyefiservice.cc b/src/eyefiservice.cc
index d233a07..1a21c02 100644
--- a/src/eyefiservice.cc
+++ b/src/eyefiservice.cc
@@ -1,28 +1,31 @@
 #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);
         }
         if(!p) {
             setsid();
             for(int i=getdtablesize();i>=0;--i) close(i);
             int i=open("/dev/null",O_RDWR); assert(i==0);
             i = dup(i); assert(i==1);
             i = dup(i); assert(i==2);
             return true;
@@ -33,63 +36,71 @@ static bool detached_child() {
     if(waitpid(p,&rc,0)<0) throw std::runtime_error("failed to waitpid()");
     if(!WIFEXITED(rc)) throw std::runtime_error("error in forked process");
     if(WEXITSTATUS(rc)) throw std::runtime_error("forked process signalled error");
     return false;
 }
 
 int eyefiService::StartSession(
         std::string macaddress,std::string cnonce,
         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()) );
             putenv( gnu::autosprintf("EYEFI_TRANSFERMODE=%d",transfermode) );
             putenv( gnu::autosprintf("EYEFI_TRANSFERMODETIMESTAMP=%ld",transfermodetimestamp) );
             char *argv[] = { (char*)"/bin/sh", (char*)"-c", (char*)cmd.c_str(), 0 };
             execv("/bin/sh",argv);
             syslog(LOG_ERR,"Failed to execute '%s'",cmd.c_str());
             _exit(-1);
         }
     }
     return SOAP_OK;
 }
 
 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
     syslog(LOG_DEBUG,
             "MarkLastPhotoInRoll request from %s with mergedelta=%d",
             macaddress.c_str(), mergedelta );
 #endif
     std::string cmd = eyekinfig_t(macaddress).get_on_mark_last_photo_in_roll();
     if(!cmd.empty()) {
         if(detached_child()) {
             putenv( gnu::autosprintf("EYEFI_MACADDRESS=%s",macaddress.c_str()) );