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    max_hsdesc_len: usize,
28) -> Result<VersionedDescriptor, FatalError> {
29    // TODO: should this be configurable? If so, we should read it from the svc config.
30    //
31    /// The CREATE handshake type we support.
32    const CREATE2_FORMATS: &[HandshakeType] = &[HandshakeType::NTOR];
33
34    /// Lifetime of the intro_{auth, enc}_key_cert certificates in the descriptor.
35    ///
36    /// From C-Tor src/feature/hs/hs_descriptor.h:
37    ///
38    /// "This defines the lifetime of the descriptor signing key and the cross certification cert of
39    /// that key. It is set to 54 hours because a descriptor can be around for 48 hours and because
40    /// consensuses are used after the hour, add an extra 6 hours to give some time for the service
41    /// to stop using it."
42    const HS_DESC_CERT_LIFETIME_SEC: Duration = Duration::from_secs(54 * 60 * 60);
43
44    let intro_points = ipt_set
45        .ipts
46        .iter()
47        .map(|ipt_in_set| ipt_in_set.ipt.clone())
48        .collect::<Vec<_>>();
49
50    let nickname = &config.nickname;
51
52    let svc_key_spec = HsIdPublicKeySpecifier::new(nickname.clone());
53    let hsid = keymgr
54        .get::<HsIdKey>(&svc_key_spec)?
55        .ok_or_else(|| FatalError::MissingHsIdKeypair(nickname.clone()))?;
56
57    // TODO: make the keystore selector configurable
58    let keystore_selector = Default::default();
59    let blind_id_kp = read_blind_id_keypair(keymgr, nickname, period)?
60        .ok_or_else(|| internal!("hidden service offline mode not supported"))?;
61
62    let blind_id_key = HsBlindIdKey::from(&blind_id_kp);
63    let subcredential = hsid.compute_subcredential(&blind_id_key, period);
64
65    let hs_desc_sign_key_spec = DescSigningKeypairSpecifier::new(nickname.clone(), period);
66    let hs_desc_sign = keymgr.get_or_generate::<HsDescSigningKeypair>(
67        &hs_desc_sign_key_spec,
68        keystore_selector,
69        key_rng,
70    )?;
71
72    // TODO #1028: support introduction-layer authentication.
73    let auth_required = None;
74
75    // TODO(#727): add support for single onion services
76    let is_single_onion_service = false;
77
78    // TODO (#955): perhaps the certificates should be read from the keystore, rather than created
79    // when building the descriptor. See #1048
80    let intro_auth_key_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
81    let intro_enc_key_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
82    let hs_desc_sign_cert_expiry = now + HS_DESC_CERT_LIFETIME_SEC;
83
84    cfg_if::cfg_if! {
85        if #[cfg(feature = "restricted-discovery")] {
86            let auth_clients: Option<Vec<curve25519::PublicKey>> = authorized_clients
87                .as_ref()
88                .map(|authorized_clients| {
89                    if authorized_clients.is_empty() {
90                        return Err(internal!("restricted discovery enabled, but no authorized clients?!"));
91                    }
92                    let auth_clients = authorized_clients
93                        .iter()
94                        .map(|(nickname, key)| {
95                            trace!("encrypting descriptor for client {nickname}");
96                            (*key).clone().into()
97                        })
98                        .collect_vec();
99                    Ok(auth_clients)
100                })
101                .transpose()?;
102        } else {
103            let auth_clients: Option<Vec<curve25519::PublicKey>> = None;
104        }
105    }
106
107    if let Some(ref auth_clients) = auth_clients {
108        debug!("Encrypting descriptor for {} clients", auth_clients.len());
109    }
110
111    let desc_signing_key_cert = create_desc_sign_key_cert(
112        &hs_desc_sign.as_ref().verifying_key(),
113        &blind_id_kp,
114        hs_desc_sign_cert_expiry,
115    )
116    .map_err(into_bad_api_usage!(
117        "failed to sign the descriptor signing key"
118    ))?;
119
120    let blind_id_kp = (&blind_id_kp).into();
121
122    let mut desc = HsDescBuilder::default()
123        .blinded_id(&blind_id_kp)
124        .hs_desc_sign(hs_desc_sign.as_ref())
125        .hs_desc_sign_cert(desc_signing_key_cert)
126        .create2_formats(CREATE2_FORMATS)
127        .auth_required(auth_required)
128        .is_single_onion_service(is_single_onion_service)
129        .intro_points(&intro_points[..])
130        .intro_auth_key_cert_expiry(intro_auth_key_cert_expiry)
131        .intro_enc_key_cert_expiry(intro_enc_key_cert_expiry)
132        .lifetime(((ipt_set.lifetime.as_secs() / 60) as u16).into())
133        .revision_counter(revision_counter)
134        .subcredential(subcredential)
135        .auth_clients(auth_clients.as_deref())
136        .max_generated_len(max_hsdesc_len);
137
138    cfg_if::cfg_if! {
139        if #[cfg(feature = "hs-pow-full")] {
140            let pow_params = pow_manager.get_pow_params(period);
141            match pow_params {
142                Ok(ref pow_params) => {
143                    desc = desc.pow_params(Some(pow_params));
144                },
145                Err(err) => {
146                    warn!(?err, "Couldn't get PoW params");
147                }
148            }
149        }
150    }
151
152    let desc = desc.build_sign(rng).map_err(|e| match e {
153        tor_bytes::EncodeError::BadLengthValue => FatalError::HsDescTooLong,
154        e => into_internal!("failed to build descriptor")(e).into(),
155    })?;
156
157    Ok(VersionedDescriptor {
158        desc,
159        revision_counter,
160    })
161}
162
163/// The freshness status of a descriptor at a particular HsDir.
164#[derive(Copy, Clone, Debug, Default, PartialEq)]
165pub(super) enum DescriptorStatus {
166    #[default]
167    /// Dirty, needs to be (re)uploaded.
168    Dirty,
169    /// Clean, does not need to be reuploaded.
170    Clean,
171}
172
173/// A descriptor and its revision.
174#[derive(Clone)]
175pub(super) struct VersionedDescriptor {
176    /// The serialized descriptor.
177    pub(super) desc: String,
178    /// The revision counter.
179    pub(super) revision_counter: RevisionCounter,
180}
tor_hsservice/publish/descriptor.rs

tor_hsservice/publish/
descriptor.rs
