Check keyUsage and extended key usage extensions

This commit prints the contents of the keyUsage and extended key usage extensions in certificates and checks the public keys in the certificates are not being used in a manner that is inconsistent with these extensions.

testssl.sh

@@ -6346,11 +6346,12 @@ certificate_info() {
      local -i number_of_certificates=$2
      local cipher=$3
      local cert_keysize=$4
-     local ocsp_response=$5
+     local cert_type="$5"
-     local ocsp_response_status=$6
+     local ocsp_response=$6
-     local sni_used=$7
+     local ocsp_response_status=$7
-     local ct="$8"
+     local sni_used=$8
-     local cert_sig_algo cert_sig_hash_algo cert_key_algo
+     local ct="$9"
+     local cert_sig_algo cert_sig_hash_algo cert_key_algo cert_keyusage cert_ext_keyusage
      local expire days2expire secs2warn ocsp_uri crl
      local startdate enddate issuer_CN issuer_C issuer_O issuer sans san all_san="" cn
      local issuer_DC issuerfinding cn_nosni=""
@@ -6568,6 +6569,36 @@ certificate_info() {
           fi
      fi
 
+     out "$indent"; pr_bold " Server key usage             ";
+     cert_keyusage=$($OPENSSL x509 -text -noout -in $HOSTCERT 2>>$ERRFILE | grep -A 1 "X509v3 Key Usage:" | tail -n +2 | sed 's/^[ \t]*//')
+     if [[ -n "$cert_keyusage" ]]; then
+          outln "$cert_keyusage"
+          if ( [[ " $cert_type " =~ " RSASig " ]] || [[ " $cert_type " =~ " DSA " ]] || [[ " $cert_type " =~ " ECDSA " ]] ) && \
+             [[ ! "$cert_keyusage" =~ "Digital Signature" ]]; then
+               prln_svrty_high "$indent                              -- certificate incorrectly used for digital signatures"
+          fi
+          if [[ " $cert_type " =~ " RSAKMK " ]] && [[ ! "$cert_keyusage" =~ "Key Encipherment" ]]; then
+               prln_svrty_high "$indent                              -- certificate incorrectly used for key encipherment"
+          fi
+          if ( [[ " $cert_type " =~ " DH " ]] || [[ " $cert_type " =~ " ECDH " ]] ) && \
+             [[ ! "$cert_keyusage" =~ "Key Agreement" ]]; then
+               prln_svrty_high "$indent                              -- certificate incorrectly used for key agreement"
+          fi
+     else
+          outln "(absent)"
+     fi
+
+     out "$indent"; pr_bold " Server extended key usage    ";
+     cert_ext_keyusage="$($OPENSSL x509 -noout -text -in $HOSTCERT 2>>$ERRFILE | grep -A 1 "X509v3 Extended Key Usage: " | tail -1 | sed 's/^[ \t]*//')"
+     if [[ -n "$cert_ext_keyusage" ]]; then
+          outln "$cert_ext_keyusage"
+          if [[ ! "$cert_ext_keyusage" =~ "TLS Web Server Authentication" ]] && [[ ! "$cert_ext_keyusage" =~ "Any Extended Key Usage" ]]; then
+               prln_svrty_high "$indent                              -- certificate incorrectly used for TLS Web Server Authentication"
+          fi
+     else
+          outln "(absent)"
+     fi
+
      out "$indent"; pr_bold " Fingerprint / Serial         "
      cert_fingerprint_sha1="$($OPENSSL x509 -noout -in $HOSTCERT -fingerprint -sha1 2>>$ERRFILE | sed 's/Fingerprint=//' | sed 's/://g')"
      cert_fingerprint_serial="$($OPENSSL x509 -noout -in $HOSTCERT -serial 2>>$ERRFILE | sed 's/serial=//')"
@@ -7005,9 +7036,9 @@ run_server_defaults() {
      local sessticket_lifetime_hint="" lifetime unit
      local -i i n
      local -i certs_found=0
-     local -a previous_hostcert previous_intermediates keysize cipher
+     local -a previous_hostcert previous_hostcert_type previous_intermediates keysize cipher
      local -a ocsp_response ocsp_response_status sni_used tls_version ct
-     local -a ciphers_to_test
+     local -a ciphers_to_test certificate_type
      local -a -i success
      local cn_nosni cn_sni sans_nosni sans_sni san tls_extensions
 
@@ -7035,6 +7066,10 @@ run_server_defaults() {
      ciphers_to_test[5]="aECDH"
      ciphers_to_test[6]="aECDSA"
      ciphers_to_test[7]="aGOST"
+     certificate_type[1]="RSASig" ; certificate_type[2]="RSAKMK"
+     certificate_type[3]="DSA"; certificate_type[4]="DH"
+     certificate_type[5]="ECDH" ; certificate_type[6]="ECDSA"
+     certificate_type[7]="GOST"
 
      for (( n=1; n <= 14 ; n++ )); do
           # Some servers use a different certificate if the ClientHello
@@ -7043,7 +7078,7 @@ run_server_defaults() {
           # try again, but only with TLSv1.1 and without SNI.
           if [[ $n -ge 8 ]]; then
                ciphers_to_test[n]=""
-               [[ ${success[n-7]} -eq 0 ]] && ciphers_to_test[n]="${ciphers_to_test[n-7]}"
+               [[ ${success[n-7]} -eq 0 ]] && ciphers_to_test[n]="${ciphers_to_test[n-7]}" && certificate_type[n]="${certificate_type[n-7]}"
           fi
 
           if [[ -n "${ciphers_to_test[n]}" ]] && [[ $(count_ciphers $($OPENSSL ciphers "${ciphers_to_test[n]}" 2>>$ERRFILE)) -ge 1 ]]; then
@@ -7129,6 +7164,9 @@ run_server_defaults() {
                          previous_intermediates[certs_found]=$(cat $TEMPDIR/intermediatecerts.pem)
                          [[ $n -ge 8 ]] && sni_used[certs_found]="" || sni_used[certs_found]="$SNI"
                          tls_version[certs_found]="$DETECTED_TLS_VERSION"
+                         previous_hostcert_type[certs_found]=" ${certificate_type[n]}"
+                    else
+                         previous_hostcert_type[i]+=" ${certificate_type[n]}"
                     fi
                fi
           fi
@@ -7260,7 +7298,7 @@ run_server_defaults() {
      for (( i=1; i <= certs_found; i++ )); do
           echo "${previous_hostcert[i]}" > $HOSTCERT
           echo "${previous_intermediates[i]}" > $TEMPDIR/intermediatecerts.pem
-          certificate_info "$i" "$certs_found" "${cipher[i]}" "${keysize[i]}" "${ocsp_response[i]}" "${ocsp_response_status[i]}" "${sni_used[i]}" "${ct[i]}"
+          certificate_info "$i" "$certs_found" "${cipher[i]}" "${keysize[i]}" "${previous_hostcert_type[i]}" "${ocsp_response[i]}" "${ocsp_response_status[i]}" "${sni_used[i]}" "${ct[i]}"
      done
 }