Tyler King
043b9b9bdc
New crate: bascule-shell (471 lines, 1.8MB binary) Login shell that detects identity + platform attestation at startup. Wraps bash/zsh/fish — operator works normally, identity travels with them. Identity detection (priority order): 1. Entra via WSL2 interop 2. Azure CLI 3. Kerberos TGT 4. Cached OIDC token 5. System user (fallback) Platform attestation: TPM 2.0 PCR values via tpm2_pcrread (PCRs 0,1,2,7,10,14) IMA measurement log hash + count Keylime agent state Entra device compliance (WSL2 only) Composite SHA-256 hash over all evidence Shell features: Banner with identity + attestation summary BASCULE_* env vars injected into inner shell --info mode for dry-run display --json mode for machine-readable output --exec mode for single-command execution Configurable via ~/.config/bascule/shell.toml Tested on Fedora with real TPM 2.0: 6 PCRs successfully read from hardware All env vars propagated to inner shell 1.8MB binary, 0 substrate deps Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
80 lines
2.2 KiB
Markdown
80 lines
2.2 KiB
Markdown
# Authentication
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Bascule supports multiple authentication methods. Configure via `[auth]` in your TOML config.
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## accept-all (Development Only)
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Accepts any SSH key or password. **Never use in production.**
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```toml
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[auth]
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mode = "accept-all"
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```
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## authorized-keys
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Standard SSH authorized_keys file, same format as OpenSSH.
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```toml
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[auth]
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mode = "authorized-keys"
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authorized_keys_path = "/etc/bascule/authorized_keys"
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```
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The file format is identical to `~/.ssh/authorized_keys`:
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```
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ssh-ed25519 AAAAC3NzaC1l... user@host
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ssh-rsa AAAAB3NzaC1yc2... another-user@host
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```
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The `authorized_keys_path` can point to either:
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- A single file (all users share the same key list)
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- A directory with per-user key files: `{dir}/{username}/authorized_keys`
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## Entra Agent ID (AI Agents)
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Microsoft Entra Agent ID authentication for AI agents. Requires the `agent-id` feature flag.
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Agents present their OAuth token as the SSH password.
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```toml
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[auth]
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mode = "authorized-keys"
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[auth.agent_id]
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tenant_id = "your-entra-tenant-id"
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audiences = ["api://bascule-proxy"]
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multi_tenant = false
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```
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When both `authorized-keys` and `[auth.agent_id]` are configured, Bascule composes them: SSH key auth for humans, token-as-password auth for agents.
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### How agents authenticate
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1. Agent obtains an OAuth token from Entra via `client_credentials` flow
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2. Agent connects via SSH: `ssh agent-name@proxy -p 2222`
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3. Agent provides the OAuth token as the SSH password
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4. Bascule validates the token against Entra's JWKS
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5. Session created with `auth_method: "agent-id"` and full agent metadata
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### Agent metadata extracted
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From the validated token, Bascule extracts:
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- Agent application ID
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- Display name
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- Agent type (from custom claims)
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- Blueprint ID (Entra Agent ID template)
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- Sponsor (human/org that registered the agent)
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- On-behalf-of (if agent is delegated)
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- Scopes and roles
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Your `SessionHandler` receives this in `SessionInfo` and can apply different policies for human vs agent sessions.
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## Composing Auth Providers
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Bascule tries auth methods in order:
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1. SSH public key (if configured)
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2. Password / token-as-password (if configured)
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Humans use SSH keys. Agents use token-as-password. Both work through the same SSH server.
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