tor_hsservice/publish/
descriptor.rs

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1//! Helpers for building and representing hidden service descriptors.
2
3use super::*;
4use crate::config::OnionServiceConfigPublisherView;
5use tor_cell::chancell::msg::HandshakeType;
6use tor_llcrypto::rng::EntropicRng;
7
8/// Build the descriptor.
9///
10/// The `now` argument is used for computing the expiry of the `intro_{auth, enc}_key_cert`
11/// certificates included in the descriptor. The expiry will be set to 54 hours from `now`.
12///
13/// Note: `blind_id_kp` is the blinded hidden service signing keypair used to sign descriptor
14/// signing keys (KP_hs_blind_id, KS_hs_blind_id).
15#[allow(clippy::too_many_arguments)]
16pub(super) fn build_sign<Rng: RngCore + CryptoRng, KeyRng: RngCore + EntropicRng, R: Runtime>(
17    keymgr: &Arc<KeyMgr>,
18    pow_manager: &Arc<PowManager<R>>,
19    config: &Arc<OnionServiceConfigPublisherView>,
20    authorized_clients: Option<&RestrictedDiscoveryKeys>,
21    ipt_set: &IptSet,
22    period: TimePeriod,
23    revision_counter: RevisionCounter,
24    rng: &mut Rng,
25    key_rng: &mut KeyRng,
26    now: SystemTime,
27) -> Result<VersionedDescriptor, FatalError> {
28    // TODO: should this be configurable? If so, we should read it from the svc config.
29    //
30    /// The CREATE handshake type we support.
31    const CREATE2_FORMATS: &[HandshakeType] = &[HandshakeType::NTOR];
32
33    /// Lifetime of the intro_{auth, enc}_key_cert certificates in the descriptor.
34    ///
35    /// From C-Tor src/feature/hs/hs_descriptor.h:
36    ///
37    /// "This defines the lifetime of the descriptor signing key and the cross certification cert of
38    /// that key. It is set to 54 hours because a descriptor can be around for 48 hours and because
39    /// consensuses are used after the hour, add an extra 6 hours to give some time for the service
40    /// to stop using it."
41    const HS_DESC_CERT_LIFETIME_SEC: Duration = Duration::from_secs(54 * 60 * 60);
42
43    let intro_points = ipt_set
44        .ipts
45        .iter()
46        .map(|ipt_in_set| ipt_in_set.ipt.clone())
47        .collect::<Vec<_>>();
48
49    let nickname = &config.nickname;
50
51    let svc_key_spec = HsIdPublicKeySpecifier::new(nickname.clone());
52    let hsid = keymgr
53        .get::<HsIdKey>(&svc_key_spec)?
54        .ok_or_else(|| FatalError::MissingHsIdKeypair(nickname.clone()))?;
55
56    // TODO: make the keystore selector configurable
57    let keystore_selector = Default::default();
58    let blind_id_kp = read_blind_id_keypair(keymgr, nickname, period)?
59        .ok_or_else(|| internal!("hidden service offline mode not supported"))?;
60
61    let blind_id_key = HsBlindIdKey::from(&blind_id_kp);
62    let subcredential = hsid.compute_subcredential(&blind_id_key, period);
63
64    let hs_desc_sign_key_spec = DescSigningKeypairSpecifier::new(nickname.clone(), period);
65    let hs_desc_sign = keymgr.get_or_generate::<HsDescSigningKeypair>(
66        &hs_desc_sign_key_spec,
67        keystore_selector,
68        key_rng,
69    )?;
70
71    // TODO #1028: support introduction-layer authentication.
72    let auth_required = None;
73
74    // TODO(#727): add support for single onion services
75    let is_single_onion_service = false;
76
77    // TODO (#955): perhaps the certificates should be read from the keystore, rather than created
78    // when building the descriptor. See #1048
79    let intro_auth_key_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
80    let intro_enc_key_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
81    let hs_desc_sign_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
82
83    cfg_if::cfg_if! {
84        if #[cfg(feature = "restricted-discovery")] {
85            let auth_clients: Option<Vec<curve25519::PublicKey>> = authorized_clients
86                .as_ref()
87                .map(|authorized_clients| {
88                    if authorized_clients.is_empty() {
89                        return Err(internal!("restricted discovery enabled, but no authorized clients?!"));
90                    }
91                    let auth_clients = authorized_clients
92                        .iter()
93                        .map(|(nickname, key)| {
94                            trace!("encrypting descriptor for client {nickname}");
95                            (*key).clone().into()
96                        })
97                        .collect_vec();
98                    Ok(auth_clients)
99                })
100                .transpose()?;
101        } else {
102            let auth_clients: Option<Vec<curve25519::PublicKey>> = None;
103        }
104    }
105
106    if let Some(ref auth_clients) = auth_clients {
107        debug!("Encrypting descriptor for {} clients", auth_clients.len());
108    }
109
110    let desc_signing_key_cert = create_desc_sign_key_cert(
111        &hs_desc_sign.as_ref().verifying_key(),
112        &blind_id_kp,
113        hs_desc_sign_cert_expiry,
114    )
115    .map_err(into_bad_api_usage!(
116        "failed to sign the descriptor signing key"
117    ))?;
118
119    let blind_id_kp = (&blind_id_kp).into();
120
121    let mut desc = HsDescBuilder::default()
122        .blinded_id(&blind_id_kp)
123        .hs_desc_sign(hs_desc_sign.as_ref())
124        .hs_desc_sign_cert(desc_signing_key_cert)
125        .create2_formats(CREATE2_FORMATS)
126        .auth_required(auth_required)
127        .is_single_onion_service(is_single_onion_service)
128        .intro_points(&intro_points[..])
129        .intro_auth_key_cert_expiry(intro_auth_key_cert_expiry)
130        .intro_enc_key_cert_expiry(intro_enc_key_cert_expiry)
131        .lifetime(((ipt_set.lifetime.as_secs() / 60) as u16).into())
132        .revision_counter(revision_counter)
133        .subcredential(subcredential)
134        .auth_clients(auth_clients.as_deref());
135
136    cfg_if::cfg_if! {
137        if #[cfg(feature = "hs-pow-full")] {
138            let pow_params = pow_manager.get_pow_params(period);
139            match pow_params {
140                Ok(ref pow_params) => {
141                    desc = desc.pow_params(Some(pow_params));
142                },
143                Err(err) => {
144                    warn!(?err, "Couldn't get PoW params");
145                }
146            }
147        }
148    }
149
150    let desc = desc
151        .build_sign(rng)
152        .map_err(|e| into_internal!("failed to build descriptor")(e))?;
153
154    Ok(VersionedDescriptor {
155        desc,
156        revision_counter,
157    })
158}
159
160/// The freshness status of a descriptor at a particular HsDir.
161#[derive(Copy, Clone, Debug, Default, PartialEq)]
162pub(super) enum DescriptorStatus {
163    #[default]
164    /// Dirty, needs to be (re)uploaded.
165    Dirty,
166    /// Clean, does not need to be reuploaded.
167    Clean,
168}
169
170/// A descriptor and its revision.
171#[derive(Clone)]
172pub(super) struct VersionedDescriptor {
173    /// The serialized descriptor.
174    pub(super) desc: String,
175    /// The revision counter.
176    pub(super) revision_counter: RevisionCounter,
177}
tor_hsservice/publish/descriptor.rs

tor_hsservice/publish/
descriptor.rs
