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fix(webdav): close PATCH gaps found in review (quota, authz, cap, races)

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Fixes to the RFC 5789 PATCH implementation found by review of the
rfc-5789-http-patch branch:

- nextcloud/webdav_handler.rs::handle_patch now enforces storage quota
  before committing, matching the plain WebDAV surface (was a quota
  bypass via the NextCloud endpoint).
- The plain surface's If-Match/If-None-Match comparison reused a
  hand-rolled single-value strong compare that mishandled weak (W/)
  validators and multi-value lists. Moved the correct RFC 7232 helpers
  (already used by the NC surface) into the shared handler file so both
  surfaces use one conformant implementation.
- NC handle_patch resolved the target file via get_file_by_path, which
  performs no authorization check, before any permission-gated call —
  for a full-file-range patch this could leak size/ETag via 412/416
  responses to a caller without Read on that file. Added the same
  explicit authz.require(Read, ...) the plain surface already has.
- ingest_range_patch_to_cas capped the whole spliced stream (prefix +
  edit + suffix) against direct_put_max_bytes, so PATCH became
  permanently unusable on any file at or above that size regardless of
  edit size. The cap now only bounds the edit itself.
- NC handle_patch had no active-lock guard, so a LOCK taken via
  /webdav/ didn't protect the same file reached through
  /remote.php/dav/. Now shares enforce_native_lock with the plain
  surface.
- Added a re-check of the file's ETag immediately before the write on
  both surfaces, narrowing (not eliminating — that would need
  compare-and-swap support in the write path) the window in which two
  concurrent PATCHes to disjoint ranges could silently clobber each
  other.
- NC handle_patch returned 404 for a PATCH on a directory instead of
  409 like the plain surface; now checks folder existence first.
- The Content-Length-vs-X-Update-Range span check only fired when
  Content-Length was present, so a chunked-transfer body could silently
  diverge from the declared span. ingest_range_patch_to_cas now counts
  actual body bytes and validates against the declared span
  regardless, discarding the ingested blob on mismatch.
This commit is contained in:
M.Schmidt
2026-07-14 20:09:15 +02:00
parent 93ae7ab142
commit c390a781bb
3 changed files with 288 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/interfaces/nextcloud/webdav_handler.rs
+108 -57
View File
@@ -24,6 +24,7 @@ use crate::application::ports::file_ports::{
FileManagementUseCase, FileRetrievalUseCase, FileUploadUseCase,
};
use crate::application::ports::folder_ports::FolderUseCase;
use crate::application::ports::storage_ports::StorageUsagePort;
use crate::application::ports::trash_ports::TrashUseCase;
use crate::common::di::AppState;
use crate::common::mime_detect::filename_from_path;
@@ -31,12 +32,15 @@ use crate::domain::services::authorization::{Permission, Resource, Subject};
use crate::infrastructure::services::path_resolver_service::ResolvedResource;
use crate::infrastructure::services::webdav_dead_property_store::ResourceRef;
use crate::interfaces::api::handlers::webdav_handler::{
PROPFIND_BATCH_SIZE, dead_props_for, file_dead_props, files_dead_props_map, folder_dead_props, parse_update_range,
PROPFIND_BATCH_SIZE, dead_props_for, enforce_native_lock, file_dead_props, files_dead_props_map, folder_dead_props,
if_match_precondition_fails, if_none_match_precondition_fails, parse_update_range,
folders_dead_props_map, streamed_file_dead_props,
};
use crate::interfaces::errors::AppError;
use crate::interfaces::range_requests::{not_modified_response, range_response};
use crate::interfaces::upload_ingest::{ingest_body_to_cas, ingest_range_patch_to_cas};
use crate::interfaces::upload_ingest::{
PatchIngestBudget, discard_ingested, ingest_body_to_cas, ingest_range_patch_to_cas,
};
/// Extension trait to map XML write errors to `String` concisely.
trait XmlResultExt<T> {
@@ -793,55 +797,6 @@ async fn handle_proppatch(
// ──────────────────── PUT ────────────────────
/// Strip the optional `W/` weak prefix and surrounding double-quotes
/// from one ETag value in an `If-Match` / `If-None-Match` list. Returns
/// `(is_weak, inner)`.
fn parse_etag_value(raw: &str) -> (bool, &str) {
let trimmed = raw.trim();
if let Some(rest) = trimmed.strip_prefix("W/") {
(true, rest.trim().trim_matches('"'))
} else {
(false, trimmed.trim_matches('"'))
}
}
/// RFC 7232 §3.2 — `If-None-Match` fails for PUT when:
/// - the header value is `*` and a current representation exists, OR
/// - any listed ETag matches the current representation (weak comparison
/// — weak validators in the request are equivalent to strong for the
/// match itself, only If-Match is required to be strong).
fn if_none_match_precondition_fails(header: &str, current_etag: Option<&str>) -> bool {
let v = header.trim();
if v == "*" {
return current_etag.is_some();
}
let Some(current) = current_etag else {
return false;
};
v.split(',').any(|tag| {
let (_, parsed) = parse_etag_value(tag);
!parsed.is_empty() && parsed == current
})
}
/// RFC 7232 §3.1 — `If-Match` fails for PUT when:
/// - the resource doesn't currently exist (no strong validator to match), OR
/// - the header isn't `*` and no listed ETag strong-matches the current one
/// (weak validators in the request never satisfy a strong-match).
fn if_match_precondition_fails(header: &str, current_etag: Option<&str>) -> bool {
let v = header.trim();
let Some(current) = current_etag else {
return true;
};
if v == "*" {
return false;
}
!v.split(',').any(|tag| {
let (is_weak, parsed) = parse_etag_value(tag);
!is_weak && !parsed.is_empty() && parsed == current
})
}
fn precondition_failed_response() -> Response<Body> {
Response::builder()
.status(StatusCode::PRECONDITION_FAILED)
@@ -1034,15 +989,67 @@ async fn handle_patch(
.and_then(|v| v.to_str().ok())
.unwrap_or("application/octet-stream")
.to_string();
let if_header = req
.headers()
.get("If")
.and_then(|v| v.to_str().ok())
.map(|s| s.to_string());
let max_upload = state.core.config.storage.direct_put_max_bytes;
// ── Existence check ───────────────────────────────────────────────
// Unlike PUT, PATCH requires an existing file — a partial update of
// nothing isn't meaningful.
let file = file_service
// nothing isn't meaningful. On lookup failure, distinguish "it's a
// directory" (409, matching the plain WebDAV surface) from "it
// doesn't exist at all" (404) instead of collapsing both to 404.
let file = match file_service
.get_file_by_path(&internal_path, chroot.drive_id)
.await
{
Ok(file) => file,
Err(_) => {
if state
.applications
.folder_service
.get_folder_by_path(&internal_path, chroot.drive_id)
.await
.is_ok()
{
return Err(AppError::conflict("Cannot PATCH a directory"));
}
return Err(AppError::not_found(format!(
"File not found: {}",
internal_path
)));
}
};
// `get_file_by_path` performs no authorization check (see its own
// doc comment) — mirrors the plain WebDAV surface's explicit
// defense-in-depth Read check right after resolving the file, so a
// caller without Read on this specific file can't learn its size or
// ETag via the precondition/range-bounds responses below.
let file_uuid = Uuid::parse_str(&file.id)
.map_err(|_| AppError::not_found(format!("File not found: {}", internal_path)))?;
state
.authorization
.require(
Subject::User(session.user.id),
Permission::Read,
Resource::File(file_uuid),
)
.await?;
// ── Active-lock guard (RFC 4918 §10.4 If: evaluation) ─────────────
// Shared with the plain WebDAV surface so a LOCK taken via /webdav/
// also protects the same file reached through /remote.php/dav/.
if let Some(resp) = enforce_native_lock(
&state.webdav_lock_store,
if_header.as_deref(),
&internal_path,
Some(&file.etag),
) {
return Ok(resp);
}
// ── RFC 7232 conditional preconditions ────────────────────────────
let current_etag = Some(file.etag.as_str());
@@ -1080,6 +1087,10 @@ async fn handle_patch(
.map_err(AppError::from)?,
)
};
let suffix_len = match end {
Some(end) if end + 1 < file.size => file.size - (end + 1),
_ => 0,
};
let suffix_stream: Pin<Box<dyn Stream<Item = Result<Bytes, std::io::Error>> + Send>> = match end
{
Some(end) if end + 1 < file.size => Box::into_pin(
@@ -1090,19 +1101,59 @@ async fn handle_patch(
),
_ => Box::pin(stream::empty()),
};
let filename = filename_from_path(subpath).to_string();
let ingested = ingest_range_patch_to_cas(
prefix_stream,
(prefix_stream, start),
req.into_body(),
suffix_stream,
(suffix_stream, suffix_len),
&state.core.dedup_service,
&filename,
&claimed_type,
max_upload,
PatchIngestBudget {
max_bytes: max_upload,
expected_body_len: end.map(|end| end - start + 1),
},
)
.await?;
// ── Quota enforcement ─────────────────────────────────────────────
if let Some(storage_svc) = state.storage_usage_service.as_ref()
&& let Err(err) = storage_svc
.check_storage_quota(session.user.id, ingested.size)
.await
{
discard_ingested(&state.core.dedup_service, &ingested).await;
tracing::warn!(
"⛔ NC WEBDAV PATCH REJECTED (quota): user={}, file={}, size={}",
session.user.id,
internal_path,
ingested.size
);
return Err(AppError::new(
StatusCode::INSUFFICIENT_STORAGE,
err.message,
"QuotaExceeded",
));
}
// ── Optimistic-concurrency re-check ───────────────────────────────
// `file.etag` was snapshotted before the (potentially slow) splice +
// CAS-ingest above. Re-verify nothing else wrote to this file in the
// meantime, narrowing the window in which two concurrent PATCHes to
// disjoint ranges — each individually passing its own If-Match check
// against the same stale snapshot — could otherwise silently clobber
// each other on the blind-overwrite write path below.
if let Ok(current) = file_service
.get_file_by_path(&internal_path, chroot.drive_id)
.await
&& current.etag != file.etag
{
discard_ingested(&state.core.dedup_service, &ingested).await;
return Err(AppError::precondition_failed(
"File was modified concurrently — retry the PATCH",
));
}
// ── Atomic store ──────────────────────────────────────────────────
let new_size = ingested.size;
let content_type = ingested.content_type.clone();