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|
use std::collections::HashSet;
use axum::http;
use chrono::{DateTime, Utc};
use gitolfs3_common::{generate_tag, Claims, Digest, Oid, Operation, SpecificClaims};
use crate::{
api::{make_error_resp, GitLfsErrorResponse, REPO_NOT_FOUND},
config::AuthorizationConfig,
};
pub struct Trusted(pub bool);
pub fn authorize_batch(
conf: &AuthorizationConfig,
repo_path: &str,
public: bool,
operation: Operation,
headers: &http::HeaderMap,
) -> Result<Trusted, GitLfsErrorResponse<'static>> {
// - No authentication required for downloading exported repos
// - When authenticated:
// - Download / upload over presigned URLs
// - When accessing over Tailscale:
// - No authentication required for downloading from any repo
let claims = VerifyClaimsInput {
specific_claims: SpecificClaims::BatchApi(operation),
repo_path,
};
if !verify_claims(conf, &claims, headers)? {
return authorize_batch_unauthenticated(conf, public, operation, headers);
}
Ok(Trusted(true))
}
fn authorize_batch_unauthenticated(
conf: &AuthorizationConfig,
public: bool,
operation: Operation,
headers: &http::HeaderMap,
) -> Result<Trusted, GitLfsErrorResponse<'static>> {
let trusted = forwarded_from_trusted_host(headers, &conf.trusted_forwarded_hosts)?;
match operation {
Operation::Upload => {
// Trusted users can clone all repositories (by virtue of accessing the server via a
// trusted network). However, they can not push without proper authentication. Untrusted
// users who are also not authenticated should not need to know which repositories exists.
// Therefore, we tell untrusted && unauthenticated users that the repo doesn't exist, but
// tell trusted users that they need to authenticate.
if !trusted {
return Err(REPO_NOT_FOUND);
}
Err(make_error_resp(
http::StatusCode::FORBIDDEN,
"Authentication required to upload",
))
}
Operation::Download => {
// Again, trusted users can see all repos. For untrusted users, we first need to check
// whether the repo is public before we authorize. If the user is untrusted and the
// repo isn't public, we just act like it doesn't even exist.
if !trusted {
if !public {
return Err(REPO_NOT_FOUND);
}
return Ok(Trusted(false));
}
Ok(Trusted(true))
}
}
}
pub fn authorize_get(
conf: &AuthorizationConfig,
repo_path: &str,
oid: Oid,
headers: &http::HeaderMap,
) -> Result<(), GitLfsErrorResponse<'static>> {
let claims = VerifyClaimsInput {
specific_claims: SpecificClaims::Download(oid),
repo_path,
};
if !verify_claims(conf, &claims, headers)? {
return Err(make_error_resp(
http::StatusCode::UNAUTHORIZED,
"Repository not found",
));
}
Ok(())
}
fn forwarded_from_trusted_host(
headers: &http::HeaderMap,
trusted: &HashSet<String>,
) -> Result<bool, GitLfsErrorResponse<'static>> {
if let Some(forwarded_host) = headers.get("X-Forwarded-Host") {
if let Ok(forwarded_host) = forwarded_host.to_str() {
if trusted.contains(forwarded_host) {
return Ok(true);
}
} else {
return Err(make_error_resp(
http::StatusCode::NOT_FOUND,
"Invalid X-Forwarded-Host header",
));
}
}
Ok(false)
}
struct VerifyClaimsInput<'a> {
specific_claims: SpecificClaims,
repo_path: &'a str,
}
fn verify_claims(
conf: &AuthorizationConfig,
claims: &VerifyClaimsInput,
headers: &http::HeaderMap,
) -> Result<bool, GitLfsErrorResponse<'static>> {
const INVALID_AUTHZ_HEADER: GitLfsErrorResponse = make_error_resp(
http::StatusCode::BAD_REQUEST,
"Invalid authorization header",
);
let Some(authz) = headers.get(http::header::AUTHORIZATION) else {
return Ok(false);
};
let authz = authz.to_str().map_err(|_| INVALID_AUTHZ_HEADER)?;
let val = authz
.strip_prefix("Gitolfs3-Hmac-Sha256 ")
.ok_or(INVALID_AUTHZ_HEADER)?;
let (tag, expires_at) = val.split_once(' ').ok_or(INVALID_AUTHZ_HEADER)?;
let tag: Digest<32> = tag.parse().map_err(|_| INVALID_AUTHZ_HEADER)?;
let expires_at: i64 = expires_at.parse().map_err(|_| INVALID_AUTHZ_HEADER)?;
let expires_at = DateTime::<Utc>::from_timestamp(expires_at, 0).ok_or(INVALID_AUTHZ_HEADER)?;
let expected_tag = generate_tag(
Claims {
specific_claims: claims.specific_claims,
repo_path: claims.repo_path,
expires_at,
},
&conf.key,
)
.ok_or_else(|| {
make_error_resp(
http::StatusCode::INTERNAL_SERVER_ERROR,
"Internal server error",
)
})?;
if tag != expected_tag {
return Err(INVALID_AUTHZ_HEADER);
}
Ok(true)
}
#[test]
fn test_validate_claims() {
use gitolfs3_common::Key;
let key = "00232f7a019bd34e3921ee6c5f04caf48a4489d1be5d1999038950a7054e0bfea369ce2becc0f13fd3c69f8af2384a25b7ac2d52eb52c33722f3c00c50d4c9c2";
let key: Key = key.parse().unwrap();
let claims = Claims {
expires_at: Utc::now() + std::time::Duration::from_secs(5 * 60),
repo_path: "lfs-test.git",
specific_claims: SpecificClaims::BatchApi(Operation::Download),
};
let tag = generate_tag(claims, &key).unwrap();
let header_value = format!(
"Gitolfs3-Hmac-Sha256 {tag} {}",
claims.expires_at.timestamp()
);
let conf = AuthorizationConfig {
key,
trusted_forwarded_hosts: HashSet::new(),
};
let verification_claims = VerifyClaimsInput {
repo_path: claims.repo_path,
specific_claims: claims.specific_claims,
};
let mut headers = http::HeaderMap::new();
headers.insert(
http::header::AUTHORIZATION,
header_value.try_into().unwrap(),
);
assert!(verify_claims(&conf, &verification_claims, &headers).unwrap());
}
|
