Merge pull request #2287 from x448/strong-tls-option

kinnison · web-flow · commit c022b922b165 · 2020-04-22T07:20:35.000+01:00
Force strong TLS cipher suite in rustup-init.sh for curl and wget if support is detected
diff --git a/rustup-init.sh b/rustup-init.sh
@@ -376,6 +376,7 @@ ignore() {
 # use wget instead.
 downloader() {
     local _dld
+    local _ciphersuites
     if check_cmd curl; then
         _dld=curl
     elif check_cmd wget; then
@@ -387,18 +388,32 @@ downloader() {
     if [ "$1" = --check ]; then
         need_cmd "$_dld"
     elif [ "$_dld" = curl ]; then
-        if ! check_help_for "$3" curl --proto --tlsv1.2; then
-            echo "Warning: Not forcing TLS v1.2, this is potentially less secure"
-            curl --silent --show-error --fail --location "$1" --output "$2"
+        get_ciphersuites_for_curl
+        _ciphersuites="$RETVAL"
+        if [ -n "$_ciphersuites" ]; then
+            curl --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2"
         else
-            curl --proto '=https' --tlsv1.2 --silent --show-error --fail --location "$1" --output "$2"
+            echo "Warning: Not forcing strong cipher suites for TLS, this is potentially less secure"
+            if ! check_help_for "$3" curl --proto --tlsv1.2; then
+                echo "Warning: Not forcing TLS v1.2, this is potentially less secure"
+                curl --silent --show-error --fail --location "$1" --output "$2"
+            else
+                curl --proto '=https' --tlsv1.2 --silent --show-error --fail --location "$1" --output "$2"
+            fi
         fi
     elif [ "$_dld" = wget ]; then
-        if ! check_help_for "$3" wget --https-only --secure-protocol; then
-            echo "Warning: Not forcing TLS v1.2, this is potentially less secure"
-            wget "$1" -O "$2"
+        get_ciphersuites_for_wget
+        _ciphersuites="$RETVAL"
+        if [ -n "$_ciphersuites" ]; then
+            wget --https-only --secure-protocol=TLSv1_2 --ciphers "$_ciphersuites" "$1" -O "$2"
         else
-            wget --https-only --secure-protocol=TLSv1_2 "$1" -O "$2"
+            echo "Warning: Not forcing strong cipher suites for TLS, this is potentially less secure"
+            if ! check_help_for "$3" wget --https-only --secure-protocol; then
+                echo "Warning: Not forcing TLS v1.2, this is potentially less secure"
+                wget "$1" -O "$2"
+            else
+                wget --https-only --secure-protocol=TLSv1_2 "$1" -O "$2"
+            fi
         fi
     else
         err "Unknown downloader"   # should not reach here
@@ -441,4 +456,91 @@ check_help_for() {
     test "$_ok" = "y"
 }
 
+# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
+# if support by local tools is detected. Detection currently supports these curl backends: 
+# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
+get_ciphersuites_for_curl() {
+    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
+        # user specified custom cipher suites, assume they know what they're doing
+        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
+        return
+    fi
+
+    local _openssl_syntax="no"
+    local _gnutls_syntax="no"
+    local _backend_supported="yes"
+    if curl -V | grep -q ' OpenSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' LibreSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' BoringSSL/'; then
+        _openssl_syntax="yes"
+    elif curl -V | grep -iq ' GnuTLS/'; then
+        _gnutls_syntax="yes"
+    else
+        _backend_supported="no"
+    fi
+
+    local _args_supported="no"
+    if [ "$_backend_supported" = "yes" ]; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "curl" "--tlsv1.2" "--ciphers" "--proto"; then
+            _args_supported="yes"
+        fi
+    fi
+
+    local _cs=""
+    if [ "$_args_supported" = "yes" ]; then
+        if [ "$_openssl_syntax" = "yes" ]; then
+            _cs=$(get_strong_ciphersuites_for "openssl")
+        elif [ "$_gnutls_syntax" = "yes" ]; then
+            _cs=$(get_strong_ciphersuites_for "gnutls")
+        fi
+    fi
+
+    RETVAL="$_cs"
+}
+
+# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
+# if support by local tools is detected. Detection currently supports these wget backends: 
+# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
+get_ciphersuites_for_wget() {
+    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
+        # user specified custom cipher suites, assume they know what they're doing
+        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
+        return
+    fi
+
+    local _cs=""
+    if wget -V | grep -q '\-DHAVE_LIBSSL'; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
+            _cs=$(get_strong_ciphersuites_for "openssl")
+        fi
+    elif wget -V | grep -q '\-DHAVE_LIBGNUTLS'; then
+        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
+        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
+            _cs=$(get_strong_ciphersuites_for "gnutls")
+        fi
+    fi
+
+    RETVAL="$_cs"
+}
+
+# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2 
+# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad 
+# DH params often found on servers (see RFC 7919). Sequence matches or is
+# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.  
+# $1 must be openssl or gnutls.
+get_strong_ciphersuites_for() {
+    if [ "$1" = "openssl" ]; then
+        # OpenSSL is forgiving of unknown values, no problems with TLS 1.3 values on versions that don't support it yet.
+        echo "TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384"
+    elif [ "$1" = "gnutls" ]; then
+        # GnuTLS isn't forgiving of unknown values, so this may require a GnuTLS version that supports TLS 1.3 even if wget doesn't.
+        # Begin with SECURE128 (and higher) then remove/add to build cipher suites. Produces same 9 cipher suites as OpenSSL but in slightly different order.
+        echo "SECURE128:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS-ALL:-CIPHER-ALL:-MAC-ALL:-KX-ALL:+AEAD:+ECDHE-ECDSA:+ECDHE-RSA:+AES-128-GCM:+CHACHA20-POLY1305:+AES-256-GCM"
+    fi 
+}
+
 main "$@" || exit 1
