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
@@ -1,9 +1,10 @@
 Klever dissected:
         Michael 'hacker' Krelin <hacker@klever.net>
         Leonid Ivanov <kamel@klever.net>
 
 
 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
@@ -1,71 +1,77 @@
 AC_INIT([iii], [0.1], [iii-bugs@klever.net])
 AC_CONFIG_SRCDIR([src/iiid.cc])
 AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([dist-bzip2])
 
 AC_PROG_INSTALL
 AC_PROG_CXX
 AC_PROG_CC
 PKG_PROG_PKG_CONFIG
 
 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],[
  AC_CHECK_LIB([archive],[archive_read_new],,[notfound=true])
 ],[notfound=true])
 $notfound && AC_MSG_ERROR([no required libarchive library found. get one from http://people.freebsd.org/~kientzle/libarchive/])
 
 notfound=false
 AC_LANG_PUSH([C++])
 AC_CHECK_HEADERS([autosprintf.h],[
  AC_CHECK_LIB([asprintf],[main],,[notfound=true])
 ],[notfound=true])
 $notfound && AC_MSG_ERROR([no autosprintf, part of gettext, found])
 AC_LANG_POP([C++])
 
 nitpick=false
 AC_ARG_ENABLE([nitpicking],
  AC_HELP_STRING([--enable-nitpicking],[make compiler somewhat overly fastidious about the code it deals with]),
  [ test "$enableval" = "no" || nitpick=true ]
 )
 if $nitpick ; then
  CPP_NITPICK="-pedantic -Wall -Wextra -Wundef -Wshadow \
   -Wunsafe-loop-optimizations -Wconversion -Wmissing-format-attribute \
   -Wredundant-decls -ansi -Wlogical-op -Wmissing-noreturn"
  C_NITPICK="$CPP_NITPICK"
  CXX_NITPICK="$C_NITPICK"
 
  CPPFLAGS="$CPPFLAGS $CPP_NITPICK"
  CFLAGS="$CFLAGS $C_NITPICK"
  CXXFLAGS="$CXXFLAGS $CXX_NITPICK"
 fi
 
 ndebug=true
 AC_ARG_ENABLE([debug],
  AC_HELP_STRING([--enable-debug],[enable debugging code]),
  [ test "$enableval" = "no" || ndebug=false ]
 )
 if $ndebug ; then
  CPPFLAGS_DEBUG="-DNDEBUG"
 else
  CPPFLAGS_DEBUG="-DDEBUG"
 fi
 AC_SUBST([CPPFLAGS_DEBUG])
 
 AC_CONFIG_FILES([
  Makefile
  src/Makefile
  doc/Makefile
   doc/iiid.8
 ])
 AC_OUTPUT
diff --git a/src/Makefile.am b/src/Makefile.am
index 09f698e..b5b7d5c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,32 +1,32 @@
 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
 
 ${builddir}soapC.cpp ${builddir}/soapeyefiService.cpp ${builddir}/eyefi.nsmap ${builddir}/soapeyefiService.h: ${srcdir}/eyefi.h
         ${SOAPCPP2} -d${builddir} -S -L -a -i -w -x $<
 
 clean-local:
         rm -f soap{{H,Stub,eyefiService}.h,{C,eyefiService}.cpp} eyefi.nsmap COPYING.cc
diff --git a/src/eyefiservice.cc b/src/eyefiservice.cc
index d233a07..1a21c02 100644
--- a/src/eyefiservice.cc
+++ b/src/eyefiservice.cc
@@ -1,202 +1,213 @@
 #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;
         }
         _exit(0);
     }
     int rc;
     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()) );
             putenv( gnu::autosprintf("EYEFI_MERGEDELTA=%d",mergedelta) );
             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::UploadPhoto(
         int fileid, std::string macaddress,
         std::string filename, long filesize, std::string filesignature,
         std::string encryption, int flags,
         struct rns__UploadPhotoResponse& r ) {
 #ifndef NDEBUG
     syslog(LOG_DEBUG,
             "UploadPhoto request from %s with fileid=%d, filename=%s, filesize=%ld,"
             " filesignature=%s, encryption=%s, flags=%04X",
             macaddress.c_str(), fileid, filename.c_str(), filesize,
             filesignature.c_str(), encryption.c_str(), flags );
 #endif
     eyekinfig_t eyekinfig(macaddress);
 
     umask(eyekinfig.get_umask());
 
     std::string td = eyekinfig.get_targetdir();
     tmpdir_t indir(td+"/.incoming.XXXXXX");
 
     std::string jf;
     binary_t digest, idigest;
 
     for(soap_multipart::iterator i=mime.begin(),ie=mime.end();i!=ie;++i) {
 #ifndef NDEBUG
         syslog(LOG_DEBUG,
                 " MIME attachment with id=%s, type=%s, size=%ld",
                 (*i).id, (*i).type, (long)(*i).size );
 #endif
 
         if((*i).id && !strcmp((*i).id,"INTEGRITYDIGEST")) {
             std::string idigestr((*i).ptr,(*i).size);
 #ifndef NDEBUG
             syslog(LOG_DEBUG, " INTEGRITYDIGEST=%s", idigestr.c_str());
 #endif
             idigest.from_hex(idigestr);
         }
         if( (*i).id && !strcmp((*i).id,"FILENAME") ) {
             assert( (*i).type && !strcmp((*i).type,"application/x-tar") );
 #ifdef III_SAVE_TARS
             std::string tarfile = indir.get_file(filename);
             {
                 std::ofstream(tarfile.c_str(),std::ios::out|std::ios::binary).write((*i).ptr,(*i).size);
             }
 #endif
 
             if(!jf.empty()) throw std::runtime_error("already seen tarball");
             if(!digest.empty()) throw std::runtime_error("already have integrity digest");
             digest = integrity_digest((*i).ptr,(*i).size,eyekinfig.get_upload_key());
 #ifndef NDEBUG
             syslog(LOG_DEBUG," computed integrity digest=%s", digest.hex().c_str());
 #endif
 
             tarchive_t a((*i).ptr,(*i).size);
             if(!a.read_next_header())
                 throw std::runtime_error("failed to tarchive_t::read_next_header())");
             jf = indir.get_file(a.entry_pathname());
             int fd=open(jf.c_str(),O_CREAT|O_WRONLY,0666);
             assert(fd>0);
             a.read_data_into_fd(fd);
             close(fd);
         }
     }
 
     if(jf.empty()) throw std::runtime_error("haven't seen jpeg file");
     if(digest!=idigest) throw std::runtime_error("integrity digest verification failed");
 
     std::string::size_type ls = jf.rfind('/');
     std::string jbn = (ls==std::string::npos)?jf:jf.substr(ls+1);
     std::string tf = td+'/'+jbn;
     bool success = false;
     if(!link(jf.c_str(), tf.c_str())) {
         unlink(jf.c_str()); success = true;
     }else{
         for(int i=1;i<32767;++i) {
             tf = (const char*)gnu::autosprintf( "%s/(%05d)%s",
                     td.c_str(), i, jbn.c_str() );
             if(!link(jf.c_str(), tf.c_str())) {
                 unlink(jf.c_str()); success = true;
                 break;
             }
         }
     }
     std::string cmd = eyekinfig.get_on_upload_photo();
     if(success && !cmd.empty()) {
         if(detached_child()) {
             putenv( gnu::autosprintf("EYEFI_MACADDRESS=%s",macaddress.c_str()) );
             putenv( gnu::autosprintf("EYEFI_UPLOADED=%s",tf.c_str()) );
             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);
         }
     }
 
     r.success = true;
     return SOAP_OK;
 }
diff --git a/src/eyetil.cc b/src/eyetil.cc
index fe816a6..7669cb6 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -1,146 +1,163 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <syslog.h>
 #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();
     char t[3] = { 0,0,0 };
     for(int i=0;i<rvs;++i) {
         t[0]=*(hp++); t[1]=*(hp++);
         *(oi++) = strtol(t,0,16);
     }
     return *this;
 }
 
 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;
     }
     return rv;
 }
 
 binary_t binary_t::md5() const {
     binary_t rv(MD5_DIGEST_LENGTH);
     if(!MD5(
                 (const unsigned char*)&(front()),size(),
                 (unsigned char*)&(rv.front()) ))
         throw std::runtime_error("failed to md5()");
     return rv;
 }
 
 static void make_path_for_template(const std::string& p,mode_t m) {
     struct stat st;
     std::string pp;
     for(std::string::size_type sl=p.find('/',1);
             sl!=std::string::npos;
             sl=p.find('/',sl+1)) {
         if(stat( (pp=p.substr(0,sl)).c_str() ,&st)
                 || !S_ISDIR(st.st_mode)) {
             if(mkdir(pp.c_str(),m))
                 throw std::runtime_error("failed to mkdir()");
         }
     }
 }
 
 tmpdir_t::tmpdir_t(const std::string& dt) : dir(dt) {
     make_path_for_template(dt,0777);
     if(!mkdtemp((char*)dir.data()))
         throw std::runtime_error("failed to mkdtmp()");
 }
 tmpdir_t::~tmpdir_t() {
     assert(!dir.empty());
     if(rmdir(dir.c_str())) {
         syslog(LOG_WARNING,"Failed to remove '%s' directory",dir.c_str());
     }
 }
 
 std::string tmpdir_t::get_file(const std::string& f) {
     std::string::size_type ls = f.rfind('/');
     return dir+'/'+(
             (ls==std::string::npos)
             ? f
             : f.substr(ls+1)
         );
 }
 
 tarchive_t::tarchive_t(void *p,size_t s) : a(archive_read_new()), e(0) {
     if(!a) throw std::runtime_error("failed to archive_read_new()");
     if(archive_read_support_format_tar(a)) {
         archive_read_finish(a);
         throw std::runtime_error("failed to archive_read_support_format_tar()");
     }
     if(archive_read_open_memory(a,p,s)) {
         archive_read_finish(a);
         throw std::runtime_error("failed to archive_read_open_memory()");
     }
 }
 tarchive_t::~tarchive_t() {
     assert(a);
     archive_read_finish(a);
 }
 
 bool tarchive_t::read_next_header() {
     assert(a);
     return archive_read_next_header(a,&e)==ARCHIVE_OK;
 }
 
 std::string tarchive_t::entry_pathname() {
     assert(a); assert(e);
     return archive_entry_pathname(e);
 }
 
 bool tarchive_t::read_data_into_fd(int fd) {
     assert(a);
     return archive_read_data_into_fd(a,fd)==ARCHIVE_OK;
 }
 
 #pragma pack(1)
 struct block512_t {
     enum { words = 512 / sizeof(uint16_t) };
     uint16_t data[words];
 
     static uint16_t tcpcksum(block512_t& data) {
         uint32_t sum = std::accumulate(data.data,data.data+words,0);
         while(uint32_t hw = sum>>16) sum = (sum&0xffff)+hw;
         return ~sum;
     }
 
 };
 #pragma pack()
 
 binary_t integrity_digest(const void *ptr,size_t size,const std::string& ukey) {
     binary_t key; key.from_hex(ukey);
     std::vector<uint16_t> blksums; blksums.reserve(size/sizeof(block512_t));
     block512_t *db = (block512_t*)ptr,
                *de = db + size/sizeof(block512_t);
     std::transform( db, de, std::back_inserter(blksums), block512_t::tcpcksum );
     binary_t subject;
     subject.from_data((void*)&(blksums.front()),blksums.size()*sizeof(uint16_t));
     std::copy( key.begin(), key.end(), std::back_inserter(subject) );
     return subject.md5();
 }
diff --git a/src/eyetil.h b/src/eyetil.h
index 378f703..d946e71 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -1,51 +1,52 @@
 #ifndef __EYETIL_H
 #define __EYETIL_H
 
 #include <vector>
 #include <string>
 #include <archive.h>
 #include <archive_entry.h>
 
 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;
 
         tmpdir_t(const std::string& dt);
         ~tmpdir_t();
 
         std::string get_file(const std::string& f);
 };
 
 class tarchive_t {
     public:
         struct archive *a;
         struct archive_entry *e;
 
         tarchive_t(void *p,size_t s);
         ~tarchive_t();
 
         bool read_next_header();
 
         std::string entry_pathname();
 
         bool read_data_into_fd(int fd);
 };
 
 binary_t integrity_digest(const void *ptr,size_t size,
         const std::string& ukey);
 
 #endif /* __EYETIL_H */