From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [IPv6:2a01:7e0:0:424::9]) by lore.proxmox.com (Postfix) with ESMTPS id 0C7221FF137 for ; Tue, 17 Feb 2026 12:11:50 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 7645533D08; Tue, 17 Feb 2026 12:12:40 +0100 (CET) From: Samuel Rufinatscha To: pbs-devel@lists.proxmox.com Subject: [PATCH proxmox-backup v5 4/4] pbs-config: add TTL window to token secret cache Date: Tue, 17 Feb 2026 12:12:21 +0100 Message-ID: <20260217111229.78661-5-s.rufinatscha@proxmox.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260217111229.78661-1-s.rufinatscha@proxmox.com> References: <20260217111229.78661-1-s.rufinatscha@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1771326748222 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.263 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Message-ID-Hash: RL2LYPHBYTYTOQIUXLR3XO2BPT4AYTAR X-Message-ID-Hash: RL2LYPHBYTYTOQIUXLR3XO2BPT4AYTAR X-MailFrom: s.rufinatscha@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox Backup Server development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Verify_secret() currently calls refresh_cache_if_file_changed() on every request, which performs a metadata() call on token.shadow each time. Under load this adds unnecessary overhead, considering also the file usually should rarely change. This patch introduces a TTL boundary, controlled by TOKEN_SECRET_CACHE_TTL_SECS. File metadata is only re-loaded once the TTL has expired; documents TTL effects. Signed-off-by: Samuel Rufinatscha --- Changes from v4 to v5: * Rebased * Introduce shadow_check_within_ttl() helper Changes from v3 to v4: * Adjusted commit message Changes from v2 to v3: * Refactored refresh_cache_if_file_changed TTL logic. * Remove had_prior_state check (replaced by last_checked logic). * Improve TTL bound checks. * Reword documentation warning for clarity. Changes from v1 to v2: * Add TOKEN_SECRET_CACHE_TTL_SECS and last_checked. * Implement double-checked TTL: check with try_read first; only attempt refresh with try_write if expired/unknown. * Fix TTL bookkeeping: update last_checked on the “file unchanged” path and after API mutations. * Add documentation warning about TTL-delayed effect of manual token.shadow edits. docs/user-management.rst | 4 ++++ pbs-config/src/token_shadow.rs | 30 +++++++++++++++++++++++++++++- 2 files changed, 33 insertions(+), 1 deletion(-) diff --git a/docs/user-management.rst b/docs/user-management.rst index 41b43d60..8dfae528 100644 --- a/docs/user-management.rst +++ b/docs/user-management.rst @@ -156,6 +156,10 @@ metadata: Similarly, the ``user delete-token`` subcommand can be used to delete a token again. +.. WARNING:: Direct/manual edits to ``token.shadow`` may take up to 60 seconds (or + longer in edge cases) to take effect due to caching. Restart services for + immediate effect of manual edits. + Newly generated API tokens don't have any permissions. Please read the next section to learn how to set access permissions. diff --git a/pbs-config/src/token_shadow.rs b/pbs-config/src/token_shadow.rs index 82c4a7f1..2930465f 100644 --- a/pbs-config/src/token_shadow.rs +++ b/pbs-config/src/token_shadow.rs @@ -31,6 +31,8 @@ static TOKEN_SECRET_CACHE: LazyLock> = LazyLock::new shadow: None, }) }); +/// Max age in seconds of the token secret cache before checking for file changes. +const TOKEN_SECRET_CACHE_TTL_SECS: i64 = 60; #[derive(Serialize, Deserialize)] #[serde(rename_all = "kebab-case")] @@ -72,11 +74,24 @@ fn write_file(data: HashMap) -> Result<(), Error> { fn refresh_cache_if_file_changed() -> bool { let now = epoch_i64(); - // Best-effort refresh under write lock. + // Fast path: cache is fresh if shared-gen matches and TTL not expired. + if let (Some(cache), Some(shared_gen_read)) = + (TOKEN_SECRET_CACHE.try_read(), token_shadow_shared_gen()) + { + if cache.shared_gen == shared_gen_read && cache.shadow_check_within_ttl(now) { + return true; + } + // read lock drops here + } else { + return false; + } + + // Slow path: best-effort refresh under write lock. let Some(mut cache) = TOKEN_SECRET_CACHE.try_write() else { return false; }; + // Re-read generation after acquiring the lock (may have changed meanwhile). let Some(shared_gen_now) = token_shadow_shared_gen() else { return false; }; @@ -86,6 +101,12 @@ fn refresh_cache_if_file_changed() -> bool { cache.reset_and_set_gen(shared_gen_now); } + // TTL check again after acquiring the lock + let now = epoch_i64(); + if cache.shadow_check_within_ttl(now) { + return true; + } + // Stat the file to detect manual edits. let Ok((new_mtime, new_len)) = shadow_mtime_len() else { return false; @@ -234,6 +255,13 @@ impl ApiTokenSecretCache { self.secrets.remove(tokenid); self.shared_gen = gen; } + + /// Returns true if cached token.shadow metadata exists and was checked within the TTL window. + fn shadow_check_within_ttl(&self, now: i64) -> bool { + self.shadow.as_ref().is_some_and(|cached| { + now >= cached.last_checked && (now - cached.last_checked) < TOKEN_SECRET_CACHE_TTL_SECS + }) + } } /// Shadow file info -- 2.47.3