Re: [PATCH proxmox-backup v3 3/3] fix #6990: server: drop verify state on non-decrypt pull job

[Christian Ebner <c.ebner@proxmox.com>]

Two comments and a note inline.

On 9/22/26 3:11 PM, Jakob Klocker wrote:
> On a non-decrypt pull the source manifest is written to the target
> as-is, so the target inherits the source's verify_state flag instead of
> being verified independently on its own storage. Because a snapshot
> carrying a verify_state is skipped by verify jobs, the target's copy can
> never be checked.
> 
> The decrypt path already drops verify_state; do the same on the
> non-decrypt path when the snapshot is newly pulled or re-synced due to
> corruption. Also factor the manifest blob encoding and writing into a
> helper, shared by both paths.
> 
> Additionally, refactor `cleanup_unreferenced_files` to accept the set of
> expected files (built by new `expected_files` helper) rather than the
> manifest itself, avoiding the need to share the manifest across the
> write and cleanup steps.

comment: This should be it's own preparatory patch, as it has nothing to 
do with the dropping of the verify state by itself.

> Link: https://bugzilla.proxmox.com/show_bug.cgi?id=6990
> Signed-off-by: Jakob Klocker <j.klocker@proxmox.com>
> ---
>   pbs-datastore/src/backup_info.rs | 21 ++++++-------
>   pbs-datastore/src/manifest.rs    | 50 +++++++++++++++++++++++++++--
>   src/server/pull.rs               | 54 ++++++++++++++++++++------------
>   3 files changed, 91 insertions(+), 34 deletions(-)
> 
> diff --git a/pbs-datastore/src/backup_info.rs b/pbs-datastore/src/backup_info.rs
> index be4ec8b3e..0c146533e 100644
> --- a/pbs-datastore/src/backup_info.rs
> +++ b/pbs-datastore/src/backup_info.rs
> @@ -1,3 +1,4 @@
> +use std::collections::HashSet;
>   use std::fmt;
>   use std::os::unix::io::{AsRawFd, RawFd};
>   use std::os::unix::prelude::OsStrExt;
> @@ -16,8 +17,7 @@ use proxmox_systemd::escape_unit;
>   
>   use pbs_api_types::{
>       ArchiveType, Authid, BACKUP_DATE_REGEX, BackupArchiveName, BackupGroupDeleteStats,
> -    BackupNamespace, BackupType, CLIENT_LOG_BLOB_NAME, GroupFilter, MANIFEST_BLOB_NAME,
> -    VerifyState,
> +    BackupNamespace, BackupType, GroupFilter, MANIFEST_BLOB_NAME, VerifyState,
>   };
>   use pbs_config::{BackupLockGuard, open_backup_lockfile};
>   
> @@ -1029,17 +1029,14 @@ impl BackupDir {
>           Ok(())
>       }
>   
> -    /// Cleans up the backup directory by removing any file not mentioned in the manifest.
> -    pub fn cleanup_unreferenced_files(&self, manifest: &BackupManifest) -> Result<(), Error> {
> +    /// Removes any file in the backup directory not present in `files_to_keep`.
> +    ///
> +    /// The set is supplied by the caller (see `BackupManifest::expected_files`)
> +    /// rather than derived here, so passing an incomplete set will delete files
> +    /// that should be retained.
> +    pub fn cleanup_unreferenced_files(&self, files_to_keep: &HashSet<String>) -> Result<(), Error> {

comment: Instead of a plain String with no further restrictions in 
HashSet, I would prefer the additionally restricted archive name and 
type checked HashSet<BackupArchiveName> here.

This does require to extend the type in pbs-api-types by implementation 
of Hash and Borrow traits by the following diff and adaption of the 
expected_files() method as defined on BackupManifest as described below:

```
diff --git a/pbs-api-types/src/datastore.rs b/pbs-api-types/src/datastore.rs
index 93ccaf07..39ff5e9a 100644
--- a/pbs-api-types/src/datastore.rs
+++ b/pbs-api-types/src/datastore.rs
@@ -1,5 +1,7 @@
+use std::borrow::Borrow;
  use std::convert::{AsRef, TryFrom};
  use std::fmt;
+use std::hash::{Hash, Hasher};
  use std::path::{Path, PathBuf};
  use std::str::FromStr;
  use std::sync::LazyLock;
@@ -2139,6 +2141,18 @@ impl AsRef<str> for BackupArchiveName {
      }
  }

+impl Borrow<str> for BackupArchiveName {
+    fn borrow(&self) -> &str {
+        &self.name
+    }
+}
+
+impl Hash for BackupArchiveName {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.name.hash(state)
+    }
+}
+
  impl BackupArchiveName {
      pub fn from_path(path: impl AsRef<Path>) -> Result<Self, Error> {
          let path = path.as_ref();
```

>           let full_path = self.full_path();
>   
> -        let mut wanted_files = std::collections::HashSet::new();
> -        wanted_files.insert(MANIFEST_BLOB_NAME.to_string());
> -        wanted_files.insert(CLIENT_LOG_BLOB_NAME.to_string());
> -        manifest.files().iter().for_each(|item| {
> -            wanted_files.insert(item.filename.to_string());
> -        });
> -
>           for item in proxmox_sys::fs::read_subdir(libc::AT_FDCWD, &full_path)?.flatten() {
>               if let Some(file_type) = item.file_type() {
>                   if file_type != nix::dir::Type::File {
> @@ -1051,7 +1048,7 @@ impl BackupDir {
>                   continue;
>               };
>               if let Ok(name) = std::str::from_utf8(file_name) {
> -                if wanted_files.contains(name) {
> +                if files_to_keep.contains(name) {
>                       continue;
>                   }
>               }
> diff --git a/pbs-datastore/src/manifest.rs b/pbs-datastore/src/manifest.rs
> index 4d482c252..9250ecc97 100644
> --- a/pbs-datastore/src/manifest.rs
> +++ b/pbs-datastore/src/manifest.rs
> @@ -1,9 +1,15 @@
> -use anyhow::{Error, bail, format_err};
> +use std::io::Write;
> +use std::os::fd::AsRawFd;
> +use std::path::Path;
>   
> +use anyhow::{Context, Error, bail, format_err};
>   use serde::{Deserialize, Serialize};
>   use serde_json::{Value, json};
>   
> -use pbs_api_types::{BackupArchiveName, BackupType, CryptMode, Fingerprint, SnapshotVerifyState};
> +use pbs_api_types::{
> +    BackupArchiveName, BackupType, CLIENT_LOG_BLOB_NAME, CryptMode, Fingerprint,
> +    MANIFEST_BLOB_NAME, SnapshotVerifyState,
> +};
>   use pbs_tools::crypt_config::CryptConfig;
>   
>   use super::DataBlob;
> @@ -295,6 +301,46 @@ impl BackupManifest {
>   
>           Ok(Some(Deserialize::deserialize(value)?))
>       }
> +
> +    /// Encode the manifest and write it atomically to `target_path`.
> +    ///
> +    /// The encoded blob is first written to `tmp_path` and fsync'd, then
> +    /// atomically renamed onto `target_path`. Writing via a temp file and
> +    /// rename ensures concurrent readers never observe a partially written,
> +    /// corrupt manifest.
> +    ///
> +    /// Returns the raw blob data.
> +    pub fn write_to_path(&self, tmp_path: &Path, target_path: &Path) -> Result<Vec<u8>, Error> {
> +        let raw_data = self.to_data_blob(None)?.raw_data().to_vec();
> +
> +        let mut file = std::fs::OpenOptions::new()
> +            .write(true)
> +            .create(true)
> +            .truncate(true)
> +            .open(tmp_path)
> +            .with_context(|| format!("failed to open manifest {tmp_path:?}"))?;
> +
> +        file.write_all(&raw_data)?;
> +        file.flush()?;
> +        nix::unistd::fsync(file.as_raw_fd())?;
> +
> +        std::fs::rename(tmp_path, target_path)
> +            .with_context(|| format!("atomic rename manifest {target_path:?} failed"))?;
> +
> +        Ok(raw_data)
> +    }
> +
> +    /// Returns the set of all files expected in a complete snapshot: every
> +    /// manifest entry plus the manifest and client-log blobs themselves.

note: this is not fully correct, as the client log is not required to be 
present but rather optional. It should however never be cleaned up. So 
this should rather state something along the line of `set of all files 
which might be encountered in the snapshot represented by given manifest`.

This could be explicitly encoded, either by a flag which includes the 
client log only if set, or by explicitly inserting the client log 
afterwards on the call site. But not that important given the use-case 
for this, so fine as well if left in place.

> +    pub fn expected_files(&self) -> std::collections::HashSet<String> {
> +        let mut expected = std::collections::HashSet::new();
> +        expected.insert(MANIFEST_BLOB_NAME.to_string());
> +        expected.insert(CLIENT_LOG_BLOB_NAME.to_string());
> +        self.files().iter().for_each(|item| {
> +            expected.insert(item.filename.to_string());
> +        });
> +        expected
> +    }

... with above mentioned implementation of Hash and Borrow on 
BackupArchiveName, this could now return the type checked archive names via:

```
diff --git a/pbs-datastore/src/manifest.rs b/pbs-datastore/src/manifest.rs
index 9250ecc97..00d83b610 100644
--- a/pbs-datastore/src/manifest.rs
+++ b/pbs-datastore/src/manifest.rs
@@ -332,12 +332,12 @@ impl BackupManifest {

      /// Returns the set of all files expected in a complete snapshot: 
every
      /// manifest entry plus the manifest and client-log blobs themselves.
-    pub fn expected_files(&self) -> std::collections::HashSet<String> {
+    pub fn expected_files(&self) -> 
std::collections::HashSet<BackupArchiveN
          let mut expected = std::collections::HashSet::new();
-        expected.insert(MANIFEST_BLOB_NAME.to_string());
-        expected.insert(CLIENT_LOG_BLOB_NAME.to_string());
-        self.files().iter().for_each(|item| {
-            expected.insert(item.filename.to_string());
+        expected.insert(MANIFEST_BLOB_NAME.clone());
+        expected.insert(CLIENT_LOG_BLOB_NAME.clone());
+        self.files.iter().for_each(|item| {
+            expected.insert(item.filename.clone());
          });
          expected
      }
```

>   }
>   
>   impl TryFrom<DataBlob> for BackupManifest {
> diff --git a/src/server/pull.rs b/src/server/pull.rs
> index d4bd07d94..ac2d4065c 100644
> --- a/src/server/pull.rs
> +++ b/src/server/pull.rs
> @@ -3,7 +3,6 @@
>   use std::collections::hash_map::Entry;
>   use std::collections::{HashMap, HashSet};
>   use std::io::Seek;
> -use std::os::fd::AsRawFd;
>   use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
>   use std::sync::{Arc, Mutex};
>   use std::time::{Duration, SystemTime};
> @@ -16,8 +15,6 @@ use super::sync::{
>   use crate::backup::{check_ns_modification_privs, check_ns_privs};
>   use crate::server::sync::SharedGroupProgress;
>   use anyhow::{Context, Error, bail, format_err};
> -use tokio::fs::OpenOptions;
> -use tokio::io::AsyncWriteExt;
>   
>   use pbs_api_types::{
>       ArchiveType, Authid, BackupDir, BackupGroup, BackupNamespace, CLIENT_LOG_BLOB_NAME, CryptMode,
> @@ -741,7 +738,8 @@ async fn pull_snapshot<'a>(
>       };
>   
>       let mut manifest_data = tmp_manifest_blob.raw_data().to_vec();
> -    let manifest = BackupManifest::try_from(tmp_manifest_blob).with_context(|| prefix.clone())?;
> +    let mut manifest =
> +        BackupManifest::try_from(tmp_manifest_blob).with_context(|| prefix.clone())?;
>   
>       if ignore_not_verified_or_encrypted(
>           &manifest,
> @@ -849,6 +847,11 @@ async fn pull_snapshot<'a>(
>           sync_stats.add(stats);
>       }
>   
> +    let target_verify_state = existing_target_manifest
> +        .as_ref()
> +        .and_then(|m| m.unprotected.get("verify_state").cloned());
> +    let files_to_keep = manifest.expected_files();
> +
>       if let Some(new_manifest) = new_manifest {
>           let mut new_manifest = Arc::try_unwrap(new_manifest)
>               .map_err(|_arc| {
> @@ -875,24 +878,35 @@ async fn pull_snapshot<'a>(
>               new_manifest.set_sync_source_signature(expected.bytes())?;
>           }
>   
> -        // keep signature
> -        let manifest_blob = new_manifest.to_data_blob(None)?;
> -        // update contents to be uploaded to backend
> -        manifest_data = manifest_blob.raw_data().to_vec();
> +        manifest_data = tokio::task::spawn_blocking(move || {
> +            new_manifest.write_to_path(&tmp_manifest_name, &manifest_name)
> +        })
> +        .await??;
> +    } else if manifest.unprotected.get("verify_state") != target_verify_state.as_ref() {
> +        // the manifest is copied as-is on the non-decrypted path: never inherit the
> +        // source's verify state, but keep one the target obtained on its own
> +        let Some(unprotected) = manifest.unprotected.as_object_mut() else {
> +            bail!("{prefix}: unexpected manifest without 'unprotected' section");
> +        };
> +        match &target_verify_state {
> +            Some(state) => {
> +                unprotected.insert("verify_state".to_string(), state.clone());
> +            }
> +            None => {
> +                unprotected.remove("verify_state");
> +            }
> +        }
>   
> -        let mut tmp_manifest_file = OpenOptions::new()
> -            .write(true)
> -            .truncate(true) // clear pre-existing manifest content
> -            .open(&tmp_manifest_name)
> -            .await?;
> -        tmp_manifest_file.write_all(&manifest_data).await?;
> -        tmp_manifest_file.flush().await?;
> -        nix::unistd::fsync(tmp_manifest_file.as_raw_fd())?;
> +        manifest_data = tokio::task::spawn_blocking(move || {
> +            manifest.write_to_path(&tmp_manifest_name, &manifest_name)
> +        })
> +        .await??;
> +    } else {
> +        if let Err(err) = tokio::fs::rename(&tmp_manifest_name, &manifest_name).await {
> +            bail!("{prefix}: Atomic rename file {manifest_name:?} failed - {err}");
> +        }
>       }
>   
> -    if let Err(err) = tokio::fs::rename(&tmp_manifest_name, &manifest_name).await {
> -        bail!("{prefix}: Atomic rename file {manifest_name:?} failed - {err}");
> -    }
>       if let DatastoreBackend::S3(s3_client) = backend {
>           let object_key = pbs_datastore::s3::object_key_from_path(
>               &snapshot.relative_path(),
> @@ -911,7 +925,7 @@ async fn pull_snapshot<'a>(
>       fetch_log(crypt_config).await?;
>   
>       let snapshot = snapshot.clone();
> -    tokio::task::spawn_blocking(move || snapshot.cleanup_unreferenced_files(&manifest))
> +    tokio::task::spawn_blocking(move || snapshot.cleanup_unreferenced_files(&files_to_keep))
>           .await?
>           .map_err(|err| format_err!("{prefix}: failed to cleanup unreferenced files - {err}"))?;
>