[pve-devel] [PATCH proxmox v7 2/4] fix #5207: apt: check signature of repos with proxmox-pgp

[Nicolas Frey <n.frey@proxmox.com>]

If POM is set up to mirror the PVE repository and only this repository
is added on a PVE host, the `Repositories` panel will show an `Error`
status with the message:

`No Proxmox VE repository is enabled, you do not get any updates!`

This is because the current implementation only checks if the uri of
the repo matches that of one of the standard repos.

This commit aims to fix this issue by verifying it through signature
info via `proxmox-pgp`. The InRelease file cached at
`/var/lib/apt/lists/` is used to check whether the package is of
Proxmox Origin.

Fixes: https://bugzilla.proxmox.com/show_bug.cgi?id=5207
Signed-off-by: Nicolas Frey <n.frey@proxmox.com>
---
Changes since v6:
* removed logging from verification, as it is only invoked to check
  whether a repository is a Proxmox standard repository, where
  logging is not warranted
* switched from 2 match expressions to one let-else in
  `is_signed_by_key`

 proxmox-apt/Cargo.toml                     |  1 +
 proxmox-apt/src/repositories/repository.rs | 42 ++++++++++++++++------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/proxmox-apt/Cargo.toml b/proxmox-apt/Cargo.toml
index 59bb4906..2eaf588d 100644
--- a/proxmox-apt/Cargo.toml
+++ b/proxmox-apt/Cargo.toml
@@ -23,6 +23,7 @@ rfc822-like = "0.2.1"
 proxmox-apt-api-types.workspace = true
 proxmox-config-digest = { workspace = true, features = ["openssl"] }
 proxmox-sys.workspace = true
+proxmox-pgp.workspace = true
 
 apt-pkg-native = { version = "0.3.2", optional = true }
 regex = { workspace = true, optional = true }
diff --git a/proxmox-apt/src/repositories/repository.rs b/proxmox-apt/src/repositories/repository.rs
index 24e7943b..88e6cccf 100644
--- a/proxmox-apt/src/repositories/repository.rs
+++ b/proxmox-apt/src/repositories/repository.rs
@@ -2,6 +2,7 @@ use std::io::{BufRead, BufReader, Write};
 use std::path::{Path, PathBuf};
 
 use anyhow::{bail, format_err, Error};
+use proxmox_pgp::{verify_signature, WeakCryptoConfig};
 
 use crate::repositories::standard::APTRepositoryHandleImpl;
 use proxmox_apt_api_types::{
@@ -122,21 +123,24 @@ impl APTRepositoryImpl for APTRepository {
         product: &str,
         suite: &str,
     ) -> bool {
-        let (package_type, handle_uris, component, _key) = handle.info(product);
-
-        let mut found_uri = false;
-
-        for uri in self.uris.iter() {
-            let uri = uri.trim_end_matches('/');
-
-            found_uri = found_uri || handle_uris.iter().any(|handle_uri| handle_uri == uri);
-        }
+        let (package_type, handle_uris, component, key) = handle.info(product);
+
+        let found_uri_or_signed = || {
+            let mut found = false;
+            for uri in self.uris.iter() {
+                let uri = uri.trim_end_matches('/');
+                found = found
+                    || handle_uris.iter().any(|handle_uri| handle_uri == uri)
+                    || is_signed_by_key(uri, suite, key);
+            }
+            found
+        };
 
         self.types.contains(&package_type)
-            && found_uri
             // using contains would require a &String
             && self.suites.iter().any(|self_suite| self_suite == suite)
             && self.components.contains(&component)
+            && found_uri_or_signed()
     }
 
     fn origin_from_uris(&self) -> Option<String> {
@@ -389,6 +393,24 @@ fn write_stanza(repo: &APTRepository, w: &mut dyn Write) -> Result<(), Error> {
     Ok(())
 }
 
+/// Reads file contents of cached/local POM InRelease file from uri
+/// and key to verify pgp signature
+fn is_signed_by_key(uri: &str, suite: &str, key_path: &str) -> bool {
+    let (Ok(data), Ok(key)) = (
+        std::fs::read(release_filename(
+            Path::new("/var/lib/apt/lists"),
+            uri,
+            suite,
+            false,
+        )),
+        std::fs::read(key_path),
+    ) else {
+        return false;
+    };
+
+    verify_signature(&data, &key, None, &WeakCryptoConfig::default()).is_ok()
+}
+
 #[test]
 fn test_uri_to_filename() {
     let filename = uri_to_filename("https://some_host/some/path");
-- 
2.47.3


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