From 4e4470f15e6da4a4dc5f0c5cd906432e317d111e Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Mon, 23 Sep 2024 15:09:44 +0200 Subject: [PATCH 1/5] builtin:fetchurl: Enable TLS verification This is better for privacy and to avoid leaking netrc credentials in a MITM attack, but also the assumption that we check the hash no longer holds in some cases (in particular for impure derivations). Partially reverts https://github.com/NixOS/nix/commit/5db358d4d78aea7204a8f22c5bf2a309267ee038. (cherry picked from commit c04bc17a5a0fdcb725a11ef6541f94730112e7b6) --- src/libstore/builtins/fetchurl.cc | 3 --- 1 file changed, 3 deletions(-) diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc index 357800333..9e2f85503 100644 --- a/src/libstore/builtins/fetchurl.cc +++ b/src/libstore/builtins/fetchurl.cc @@ -34,10 +34,7 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData) auto source = sinkToSource([&](Sink & sink) { - /* No need to do TLS verification, because we check the hash of - the result anyway. */ FileTransferRequest request(url); - request.verifyTLS = false; request.decompress = false; auto decompressor = makeDecompressionSink( From 5b427197542315e4d8630ab3095b32dbd7d33b16 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Tue, 24 Sep 2024 16:13:28 +0200 Subject: [PATCH 2/5] Add a test for builtin:fetchurl cert verification (cherry picked from commit f2f47fa725fc87bfb536de171a2ea81f2789c9fb) # Conflicts: # tests/nixos/default.nix --- tests/nixos/default.nix | 11 ++++++ tests/nixos/fetchurl.nix | 78 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 89 insertions(+) create mode 100644 tests/nixos/fetchurl.nix diff --git a/tests/nixos/default.nix b/tests/nixos/default.nix index 88698338c..dc2c4b385 100644 --- a/tests/nixos/default.nix +++ b/tests/nixos/default.nix @@ -44,4 +44,15 @@ in ca-fd-leak = runNixOSTestFor "x86_64-linux" ./ca-fd-leak; user-sandboxing = runNixOSTestFor "x86_64-linux" ./user-sandboxing; +<<<<<<< HEAD +======= + + s3-binary-cache-store = runNixOSTestFor "x86_64-linux" ./s3-binary-cache-store.nix; + + fsync = runNixOSTestFor "x86_64-linux" ./fsync.nix; + + cgroups = runNixOSTestFor "x86_64-linux" ./cgroups; + + fetchurl = runNixOSTestFor "x86_64-linux" ./fetchurl.nix; +>>>>>>> f2f47fa72 (Add a test for builtin:fetchurl cert verification) } diff --git a/tests/nixos/fetchurl.nix b/tests/nixos/fetchurl.nix new file mode 100644 index 000000000..476f779bc --- /dev/null +++ b/tests/nixos/fetchurl.nix @@ -0,0 +1,78 @@ +# Test whether builtin:fetchurl properly performs TLS certificate +# checks on HTTPS servers. + +{ lib, config, pkgs, ... }: + +let + + makeTlsCert = name: pkgs.runCommand name { + nativeBuildInputs = with pkgs; [ openssl ]; + } '' + mkdir -p $out + openssl req -x509 \ + -subj '/CN=${name}/' -days 49710 \ + -addext 'subjectAltName = DNS:${name}' \ + -keyout "$out/key.pem" -newkey ed25519 \ + -out "$out/cert.pem" -noenc + ''; + + goodCert = makeTlsCert "good"; + badCert = makeTlsCert "bad"; + +in + +{ + name = "nss-preload"; + + nodes = { + machine = { lib, pkgs, ... }: { + services.nginx = { + enable = true; + + virtualHosts."good" = { + addSSL = true; + sslCertificate = "${goodCert}/cert.pem"; + sslCertificateKey = "${goodCert}/key.pem"; + root = pkgs.runCommand "nginx-root" {} '' + mkdir "$out" + echo 'hello world' > "$out/index.html" + ''; + }; + + virtualHosts."bad" = { + addSSL = true; + sslCertificate = "${badCert}/cert.pem"; + sslCertificateKey = "${badCert}/key.pem"; + root = pkgs.runCommand "nginx-root" {} '' + mkdir "$out" + echo 'foobar' > "$out/index.html" + ''; + }; + }; + + security.pki.certificateFiles = [ "${goodCert}/cert.pem" ]; + + networking.hosts."127.0.0.1" = [ "good" "bad" ]; + + virtualisation.writableStore = true; + + nix.settings.experimental-features = "nix-command"; + }; + }; + + testScript = { nodes, ... }: '' + machine.wait_for_unit("nginx") + machine.wait_for_open_port(443) + + out = machine.succeed("curl https://good/index.html") + assert out == "hello world\n" + + # Fetching from a server with a trusted cert should work. + machine.succeed("nix build --no-substitute --expr 'import { url = \"https://good/index.html\"; hash = \"sha256-qUiQTy8PR5uPgZdpSzAYSw0u0cHNKh7A+4XSmaGSpEc=\"; }'") + + # Fetching from a server with an untrusted cert should fail. + err = machine.fail("nix build --no-substitute --expr 'import { url = \"https://bad/index.html\"; hash = \"sha256-rsBwZF/lPuOzdjBZN2E08FjMM3JHyXit0Xi2zN+wAZ8=\"; }' 2>&1") + print(err) + assert "SSL certificate problem: self-signed certificate" in err + ''; +} From a99baf767e0fd03c6252f27e8c836fe759516168 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 25 Sep 2024 22:33:50 +0200 Subject: [PATCH 3/5] Add release note (cherry picked from commit 7b39cd631e0d3c3d238015c6f450c59bbc9cbc5b) --- doc/manual/rl-next/verify-tls.md | 8 ++++++++ 1 file changed, 8 insertions(+) create mode 100644 doc/manual/rl-next/verify-tls.md diff --git a/doc/manual/rl-next/verify-tls.md b/doc/manual/rl-next/verify-tls.md new file mode 100644 index 000000000..489941d5b --- /dev/null +++ b/doc/manual/rl-next/verify-tls.md @@ -0,0 +1,8 @@ +--- +synopsis: "`` uses TLS verification" +prs: [11585] +--- + +Previously `` did not do TLS verification. This was because the Nix sandbox in the past did not have access to TLS certificates, and Nix checks the hash of the fetched file anyway. However, this can expose authentication data from `netrc` and URLs to man-in-the-middle attackers. In addition, Nix now in some cases (such as when using impure derivations) does *not* check the hash. Therefore we have now enabled TLS verification. This means that downloads by `` will now fail if you're fetching from a HTTPS server that does not have a valid certificate. + +`` is also known as the builtin derivation builder `builtin:fetchurl`. It's not to be confused with the evaluation-time function `builtins.fetchurl`, which was not affected by this issues. From 233a91464db0e48ffbc44ba6e4d4bc9bfee4f5ce Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 26 Sep 2024 00:15:04 +0200 Subject: [PATCH 4/5] Typo (cherry picked from commit ef8987955be337976ae229c44870cf6adc43bba5) --- doc/manual/rl-next/verify-tls.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/doc/manual/rl-next/verify-tls.md b/doc/manual/rl-next/verify-tls.md index 489941d5b..afc689f46 100644 --- a/doc/manual/rl-next/verify-tls.md +++ b/doc/manual/rl-next/verify-tls.md @@ -5,4 +5,4 @@ prs: [11585] Previously `` did not do TLS verification. This was because the Nix sandbox in the past did not have access to TLS certificates, and Nix checks the hash of the fetched file anyway. However, this can expose authentication data from `netrc` and URLs to man-in-the-middle attackers. In addition, Nix now in some cases (such as when using impure derivations) does *not* check the hash. Therefore we have now enabled TLS verification. This means that downloads by `` will now fail if you're fetching from a HTTPS server that does not have a valid certificate. -`` is also known as the builtin derivation builder `builtin:fetchurl`. It's not to be confused with the evaluation-time function `builtins.fetchurl`, which was not affected by this issues. +`` is also known as the builtin derivation builder `builtin:fetchurl`. It's not to be confused with the evaluation-time function `builtins.fetchurl`, which was not affected by this issue. From aca7a73bc24c8fb91e6f59f3fe08e56bed70b76d Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 26 Sep 2024 00:17:03 +0200 Subject: [PATCH 5/5] Resolve conflict --- tests/nixos/default.nix | 9 --------- 1 file changed, 9 deletions(-) diff --git a/tests/nixos/default.nix b/tests/nixos/default.nix index dc2c4b385..b58c17731 100644 --- a/tests/nixos/default.nix +++ b/tests/nixos/default.nix @@ -44,15 +44,6 @@ in ca-fd-leak = runNixOSTestFor "x86_64-linux" ./ca-fd-leak; user-sandboxing = runNixOSTestFor "x86_64-linux" ./user-sandboxing; -<<<<<<< HEAD -======= - - s3-binary-cache-store = runNixOSTestFor "x86_64-linux" ./s3-binary-cache-store.nix; - - fsync = runNixOSTestFor "x86_64-linux" ./fsync.nix; - - cgroups = runNixOSTestFor "x86_64-linux" ./cgroups; fetchurl = runNixOSTestFor "x86_64-linux" ./fetchurl.nix; ->>>>>>> f2f47fa72 (Add a test for builtin:fetchurl cert verification) }