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Implement home-manager support

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Closes #62
Closes #163
This commit is contained in:
Janne Heß 2022-03-29 19:14:06 +02:00 committed by Pogobanane
parent a81ce6c961
commit acaf36a1bf
4 changed files with 314 additions and 23 deletions
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35
README.md
View file

@ -19,6 +19,7 @@ environment variables that can be passed to sops.
- Compatible with all NixOS deployment frameworks: [NixOps](https://github.com/NixOS/nixops), nixos-rebuild, [krops](https://github.com/krebs/krops/), [morph](https://github.com/DBCDK/morph), [nixus](https://github.com/Infinisil/nixus), etc.
- Version-control friendly: Since all files are encrypted they can be directly committed to version control without worry. Diffs of the secrets are readable, and [can be shown in cleartext](https://github.com/mozilla/sops#showing-diffs-in-cleartext-in-git).
- CI friendly: Since sops files can be added to the Nix store without leaking secrets, a machine definition can be built as a whole from a repository, without needing to rely on external secrets or services.
- Home-manager friendly: Provides a home-manager module
- Works well in teams: sops-nix comes with `nix-shell` hooks that allows multiple people to quickly import all GPG keys.
The cryptography used in sops is designed to be scalable: Secrets are only encrypted once with a master key
instead of encrypted per machine/developer key.
@ -34,7 +35,7 @@ There is a `configuration.nix` example in the [deployment step](#deploy-example)
## Supported encryption methods
sops-nix supports two basic ways of encryption, GPG and `age`.
sops-nix supports two basic ways of encryption, GPG and `age`.
GPG is based on [GnuPG](https://gnupg.org/) and encrypts against GPG public keys. Private GPG keys may
be used to decrypt the secrets on the target machine. The tool [`ssh-to-pgp`](https://github.com/Mic92/ssh-to-pgp) can
@ -733,6 +734,38 @@ This is how it can be included in your `configuration.nix`:
}
```
## Use with home manager
sops-nix also provides a home-manager module.
This module provides a subset of features provided by the system-wide sops-nix since features like the creation of the ramfs and changing the owner of the secrets are not available for non-root users.
Instead of running as an activation script, sops-nix runs as a systemd user service called `sops-nix.service`.
And instead of decrypting to `/run/secrets`, the secrets are decrypted to `$XDG_RUNTIME_DIR/secrets`.
Usage example:
```nix
{
# NixOS home-manager configuration
home-manager.sharedModules = [
/path/to/sops-nix/modules/home-manager/sops.nix
];
# Configuration via home.nix
imports = [
/path/to/sops-nix/modules/home-manager/sops.nix
];
# Configuration of secrets
sops = {
age.sshKeyPaths = [ "/home/user/path-to-ssh-key" ]; # must have no password!
sops.secrets.test = {
sopsFile = ./secrets.yml.enc;
path = "%r/test.txt"; # %r gets replaced with your $XDG_RUNTIME_DIR
};
};
}
```
## Use with GPG instead of SSH keys
If you prefer having a separate GPG key, sops-nix also comes with a helper tool, `sops-init-gpg-key`:

226
modules/home-manager/sops.nix Normal file
View file

@ -0,0 +1,226 @@
{ config, lib, pkgs, ... }:
let
cfg = config.sops;
sops-install-secrets = (pkgs.callPackage ../.. {}).sops-install-secrets;
secretType = lib.types.submodule ({ config, name, ... }: {
options = {
name = lib.mkOption {
type = lib.types.str;
default = name;
description = ''
Name of the file used in /run/user/*/secrets
'';
};
key = lib.mkOption {
type = lib.types.str;
default = name;
description = ''
Key used to lookup in the sops file.
No tested data structures are supported right now.
This option is ignored if format is binary.
'';
};
path = lib.mkOption {
type = lib.types.str;
default = "%r/secrets/${name}";
description = ''
Path where secrets are symlinked to.
If the default is kept no symlink is created.
'';
};
format = lib.mkOption {
type = lib.types.enum [ "yaml" "json" "binary" ];
default = cfg.defaultSopsFormat;
description = ''
File format used to decrypt the sops secret.
Binary files are written to the target file as is.
'';
};
mode = lib.mkOption {
type = lib.types.str;
default = "0400";
description = ''
Permissions mode of the in octal.
'';
};
sopsFile = lib.mkOption {
type = lib.types.path;
default = cfg.defaultSopsFile;
defaultText = "\${config.sops.defaultSopsFile}";
description = ''
Sops file the secret is loaded from.
'';
};
};
});
manifestFor = suffix: secrets: pkgs.writeTextFile {
name = "manifest${suffix}.json";
text = builtins.toJSON {
secrets = builtins.attrValues secrets;
secretsMountPoint = "%r/secrets.d";
symlinkPath = "%r/secrets";
keepGenerations = cfg.keepGenerations;
gnupgHome = cfg.gnupg.home;
sshKeyPaths = cfg.gnupg.sshKeyPaths;
ageKeyFile = cfg.age.keyFile;
ageSshKeyPaths = cfg.age.sshKeyPaths;
userMode = true;
logging = {
keyImport = builtins.elem "keyImport" cfg.log;
secretChanges = builtins.elem "secretChanges" cfg.log;
};
};
checkPhase = ''
${sops-install-secrets}/bin/sops-install-secrets -check-mode=${if cfg.validateSopsFiles then "sopsfile" else "manifest"} "$out"
'';
};
manifest = manifestFor "" cfg.secrets;
in {
options.sops = {
secrets = lib.mkOption {
type = lib.types.attrsOf secretType;
default = {};
description = ''
Secrets to decrypt.
'';
};
defaultSopsFile = lib.mkOption {
type = lib.types.path;
description = ''
Default sops file used for all secrets.
'';
};
defaultSopsFormat = lib.mkOption {
type = lib.types.str;
default = "yaml";
description = ''
Default sops format used for all secrets.
'';
};
validateSopsFiles = lib.mkOption {
type = lib.types.bool;
default = true;
description = ''
Check all sops files at evaluation time.
This requires sops files to be added to the nix store.
'';
};
keepGenerations = lib.mkOption {
type = lib.types.ints.unsigned;
default = 1;
description = ''
Number of secrets generations to keep. Setting this to 0 disables pruning.
'';
};
log = lib.mkOption {
type = lib.types.listOf (lib.types.enum [ "keyImport" "secretChanges" ]);
default = [ "keyImport" "secretChanges" ];
description = "What to log";
};
age = {
keyFile = lib.mkOption {
type = lib.types.nullOr lib.types.path;
default = null;
example = "/var/lib/sops-nix/key.txt";
description = ''
Path to age key file used for sops decryption.
'';
};
generateKey = lib.mkOption {
type = lib.types.bool;
default = false;
description = ''
Whether or not to generate the age key. If this
option is set to false, the key must already be
present at the specified location.
'';
};
sshKeyPaths = lib.mkOption {
type = lib.types.listOf lib.types.path;
default = [];
defaultText = lib.literalDocBook "The ed25519 keys from <option>config.services.openssh.hostKeys</option>";
description = ''
Paths to ssh keys added as age keys during sops description.
'';
};
};
gnupg = {
home = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "/root/.gnupg";
description = ''
Path to gnupg database directory containing the key for decrypting the sops file.
'';
};
sshKeyPaths = lib.mkOption {
type = lib.types.listOf lib.types.path;
default = [];
defaultText = lib.literalDocBook "The rsa keys from <option>config.services.openssh.hostKeys</option>";
description = ''
Path to ssh keys added as GPG keys during sops description.
This option must be explicitly unset if <literal>config.sops.gnupg.sshKeyPaths</literal> is set.
'';
};
};
};
config = lib.mkIf (cfg.secrets != {}) {
assertions = [{
assertion = cfg.gnupg.home != null || cfg.gnupg.sshKeyPaths != [] || cfg.age.keyFile != null || cfg.age.sshKeyPaths != [];
message = "No key source configurated for sops";
} {
assertion = !(cfg.gnupg.home != null && cfg.gnupg.sshKeyPaths != []);
message = "Exactly one of sops.gnupg.home and sops.gnupg.sshKeyPaths must be set";
}] ++ lib.optionals cfg.validateSopsFiles (
lib.concatLists (lib.mapAttrsToList (name: secret: [{
assertion = builtins.pathExists secret.sopsFile;
message = "Cannot find path '${secret.sopsFile}' set in sops.secrets.${lib.strings.escapeNixIdentifier name}.sopsFile";
} {
assertion =
builtins.isPath secret.sopsFile ||
(builtins.isString secret.sopsFile && lib.hasPrefix builtins.storeDir secret.sopsFile);
message = "'${secret.sopsFile}' is not in the Nix store. Either add it to the Nix store or set sops.validateSopsFiles to false";
}]) cfg.secrets)
);
systemd.user.services.sops-nix = {
Unit = {
Description = "sops-nix activation";
};
Service = {
Environment = lib.mkIf (cfg.gnupg.home != null) [ "SOPS_GPG_EXEC=${pkgs.gnupg}/bin/gpg" ];
Type = "oneshot";
ExecStart = toString (pkgs.writeShellScript "sops-nix-user" (lib.optionalString cfg.age.generateKey ''
if [[ ! -f '${cfg.age.keyFile}' ]]; then
echo generating machine-specific age key...
mkdir -p $(dirname ${cfg.age.keyFile})
# age-keygen sets 0600 by default, no need to chmod.
${pkgs.age}/bin/age-keygen -o ${cfg.age.keyFile}
fi
'' + ''
${sops-install-secrets}/bin/sops-install-secrets -ignore-passwd '${manifest}'
''));
};
Install.WantedBy = [ "default.target" ];
};
};
}

1
modules/sops/default.nix
View file

@ -126,6 +126,7 @@ let
sshKeyPaths = cfg.gnupg.sshKeyPaths;
ageKeyFile = cfg.age.keyFile;
ageSshKeyPaths = cfg.age.sshKeyPaths;
userMode = false;
logging = {
keyImport = builtins.elem "keyImport" cfg.log;
secretChanges = builtins.elem "secretChanges" cfg.log;

75
pkgs/sops-install-secrets/main.go
View file

@ -58,6 +58,7 @@ type manifest struct {
GnupgHome string `json:"gnupgHome"`
AgeKeyFile string `json:"ageKeyFile"`
AgeSshKeyPaths []string `json:"ageSshKeyPaths"`
UserMode bool `json:"userMode"`
Logging loggingConfig `json:"logging"`
}
@ -179,15 +180,17 @@ func linksAreEqual(linkTarget, targetFile string, info os.FileInfo, secret *secr
return linkTarget == targetFile && validUG
}
func symlinkSecret(targetFile string, secret *secret) error {
func symlinkSecret(targetFile string, secret *secret, userMode bool) error {
for {
stat, err := os.Lstat(secret.Path)
if os.IsNotExist(err) {
if err := os.Symlink(targetFile, secret.Path); err != nil {
return fmt.Errorf("Cannot create symlink '%s': %w", secret.Path, err)
}
if err := secureSymlinkChown(secret.Path, targetFile, secret.owner, secret.group); err != nil {
return fmt.Errorf("Cannot chown symlink '%s': %w", secret.Path, err)
if !userMode {
if err := secureSymlinkChown(secret.Path, targetFile, secret.owner, secret.group); err != nil {
return fmt.Errorf("Cannot chown symlink '%s': %w", secret.Path, err)
}
}
return nil
} else if err != nil {
@ -209,7 +212,7 @@ func symlinkSecret(targetFile string, secret *secret) error {
}
}
func symlinkSecrets(targetDir string, secrets []secret) error {
func symlinkSecrets(targetDir string, secrets []secret, userMode bool) error {
for _, secret := range secrets {
targetFile := filepath.Join(targetDir, secret.Name)
if targetFile == secret.Path {
@ -219,7 +222,7 @@ func symlinkSecrets(targetDir string, secrets []secret) error {
if err := os.MkdirAll(parent, os.ModePerm); err != nil {
return fmt.Errorf("Cannot create parent directory of '%s': %w", secret.Path, err)
}
if err := symlinkSecret(targetFile, &secret); err != nil {
if err := symlinkSecret(targetFile, &secret, userMode); err != nil {
return fmt.Errorf("Failed to symlink secret '%s': %w", secret.Path, err)
}
}
@ -328,11 +331,16 @@ func decryptSecrets(secrets []secret) error {
const RAMFS_MAGIC int32 = -2054924042
func mountSecretFs(mountpoint string, keysGid int) error {
func mountSecretFs(mountpoint string, keysGid int, userMode bool) error {
if err := os.MkdirAll(mountpoint, 0751); err != nil {
return fmt.Errorf("Cannot create directory '%s': %w", mountpoint, err)
}
// We can't create a ramfs as user
if userMode {
return nil
}
buf := unix.Statfs_t{}
if err := unix.Statfs(mountpoint, &buf); err != nil {
return fmt.Errorf("Cannot get statfs for directory '%s': %w", mountpoint, err)
@ -350,7 +358,7 @@ func mountSecretFs(mountpoint string, keysGid int) error {
return nil
}
func prepareSecretsDir(secretMountpoint string, linkName string, keysGid int) (*string, error) {
func prepareSecretsDir(secretMountpoint string, linkName string, keysGid int, userMode bool) (*string, error) {
var generation uint64
linkTarget, err := os.Readlink(linkName)
if err == nil {
@ -374,13 +382,15 @@ func prepareSecretsDir(secretMountpoint string, linkName string, keysGid int) (*
if err := os.Mkdir(dir, os.FileMode(0751)); err != nil {
return nil, fmt.Errorf("mkdir(): %w", err)
}
if err := os.Chown(dir, 0, int(keysGid)); err != nil {
return nil, fmt.Errorf("Cannot change owner/group of '%s' to 0/%d: %w", dir, keysGid, err)
if !userMode {
if err := os.Chown(dir, 0, int(keysGid)); err != nil {
return nil, fmt.Errorf("Cannot change owner/group of '%s' to 0/%d: %w", dir, keysGid, err)
}
}
return &dir, nil
}
func writeSecrets(secretDir string, secrets []secret, keysGid int) error {
func writeSecrets(secretDir string, secrets []secret, keysGid int, userMode bool) error {
for _, secret := range secrets {
fp := filepath.Join(secretDir, secret.Name)
@ -391,16 +401,20 @@ func writeSecrets(secretDir string, secrets []secret, keysGid int) error {
if err := os.MkdirAll(pathSoFar, 0751); err != nil {
return fmt.Errorf("Cannot create directory '%s' for %s: %w", pathSoFar, fp, err)
}
if err := os.Chown(pathSoFar, 0, int(keysGid)); err != nil {
return fmt.Errorf("Cannot own directory '%s' for %s: %w", pathSoFar, fp, err)
if !userMode {
if err := os.Chown(pathSoFar, 0, int(keysGid)); err != nil {
return fmt.Errorf("Cannot own directory '%s' for %s: %w", pathSoFar, fp, err)
}
}
}
if err := ioutil.WriteFile(fp, []byte(secret.value), secret.mode); err != nil {
return fmt.Errorf("Cannot write %s: %w", fp, err)
}
if err := os.Chown(fp, secret.owner, secret.group); err != nil {
return fmt.Errorf("Cannot change owner/group of '%s' to %d/%d: %w", fp, secret.owner, secret.group, err)
if !userMode {
if err := os.Chown(fp, secret.owner, secret.group); err != nil {
return fmt.Errorf("Cannot change owner/group of '%s' to %d/%d: %w", fp, secret.owner, secret.group, err)
}
}
}
return nil
@ -488,7 +502,7 @@ func (app *appContext) validateSecret(secret *secret) error {
if app.ignorePasswd || os.Getenv("NIXOS_ACTION") == "dry-activate" {
secret.owner = 0
secret.group = 0
} else if app.checkMode == Off {
} else if app.checkMode == Off || app.ignorePasswd {
// we only access to the user/group during deployment
owner, err := user.Lookup(secret.Owner)
if err != nil {
@ -873,7 +887,7 @@ func parseFlags(args []string) (*options, error) {
}
var checkMode string
fs.StringVar(&checkMode, "check-mode", "off", `Validate configuration without installing it (possible values: "manifest","sopsfile","off")`)
fs.BoolVar(&opts.ignorePasswd, "ignore-passwd", false, `Don't look up anything in /etc/passwd. Causes everything to be owned by root:root`)
fs.BoolVar(&opts.ignorePasswd, "ignore-passwd", false, `Don't look up anything in /etc/passwd. Causes everything to be owned by root:root or the user executing the tool in user mode`)
if err := fs.Parse(args[1:]); err != nil {
return nil, err
}
@ -904,6 +918,21 @@ func installSecrets(args []string) error {
return err
}
if manifest.UserMode {
rundir, ok := os.LookupEnv("XDG_RUNTIME_DIR")
if !ok {
rundir = fmt.Sprintf("/run/user/%d", os.Getuid())
}
manifest.SecretsMountPoint = strings.ReplaceAll(manifest.SecretsMountPoint, "%r", rundir)
manifest.SymlinkPath = strings.ReplaceAll(manifest.SymlinkPath, "%r", rundir)
var newSecrets []secret
for _, secret := range manifest.Secrets {
secret.Path = strings.ReplaceAll(secret.Path, "%r", rundir)
newSecrets = append(newSecrets, secret)
}
manifest.Secrets = newSecrets
}
app := appContext{
manifest: *manifest,
checkMode: opts.checkMode,
@ -931,7 +960,7 @@ func installSecrets(args []string) error {
isDry := os.Getenv("NIXOS_ACTION") == "dry-activate"
if err := mountSecretFs(manifest.SecretsMountPoint, keysGid); err != nil {
if err := mountSecretFs(manifest.SecretsMountPoint, keysGid, manifest.UserMode); err != nil {
return fmt.Errorf("Failed to mount filesystem for secrets: %w", err)
}
@ -983,21 +1012,23 @@ func installSecrets(args []string) error {
return err
}
secretDir, err := prepareSecretsDir(manifest.SecretsMountPoint, manifest.SymlinkPath, keysGid)
secretDir, err := prepareSecretsDir(manifest.SecretsMountPoint, manifest.SymlinkPath, keysGid, manifest.UserMode)
if err != nil {
return fmt.Errorf("Failed to prepare new secrets directory: %w", err)
}
if err := writeSecrets(*secretDir, manifest.Secrets, keysGid); err != nil {
if err := writeSecrets(*secretDir, manifest.Secrets, keysGid, manifest.UserMode); err != nil {
return fmt.Errorf("Cannot write secrets: %w", err)
}
if err := handleModifications(isDry, manifest.Logging, manifest.SymlinkPath, *secretDir, manifest.Secrets); err != nil {
return fmt.Errorf("Cannot request units to restart: %w", err)
if !manifest.UserMode {
if err := handleModifications(isDry, manifest.Logging, manifest.SymlinkPath, *secretDir, manifest.Secrets); err != nil {
return fmt.Errorf("Cannot request units to restart: %w", err)
}
}
// No need to perform the actual symlinking
if isDry {
return nil
}
if err := symlinkSecrets(manifest.SymlinkPath, manifest.Secrets); err != nil {
if err := symlinkSecrets(manifest.SymlinkPath, manifest.Secrets, manifest.UserMode); err != nil {
return fmt.Errorf("Failed to prepare symlinks to secret store: %w", err)
}
if err := atomicSymlink(*secretDir, manifest.SymlinkPath); err != nil {