From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) by lore.proxmox.com (Postfix) with ESMTPS id C1A4A1FF139 for ; Tue, 10 Feb 2026 13:58:12 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 480786EB; Tue, 10 Feb 2026 13:58:57 +0100 (CET) Message-ID: Date: Tue, 10 Feb 2026 13:58:52 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [pbs-devel] [PATCH proxmox-backup v4 4/4] pbs-config: add TTL window to token secret cache To: Proxmox Backup Server development discussion , Samuel Rufinatscha References: <20260121151408.731516-1-s.rufinatscha@proxmox.com> <20260121151408.731516-5-s.rufinatscha@proxmox.com> Content-Language: en-US, de-DE From: Christian Ebner In-Reply-To: <20260121151408.731516-5-s.rufinatscha@proxmox.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1770728248440 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.048 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: TREVA633CPBR6XI5WOQO2BOYEWBE6JPC X-Message-ID-Hash: TREVA633CPBR6XI5WOQO2BOYEWBE6JPC X-MailFrom: c.ebner@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: one suggestion inline On 1/21/26 4:13 PM, Samuel Rufinatscha wrote: > 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 v3 to 4: > * 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 | 29 ++++++++++++++++++++++++++++- > 2 files changed, 32 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 a5bd1525..24633f6e 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 +74,29 @@ 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 starting here .. > + && cache.shadow.as_ref().is_some_and(|cached| { > + now >= cached.last_checked > + && (now - cached.last_checked) < TOKEN_SECRET_CACHE_TTL_SECS ... to here is the same as ... > + }) > + { > + 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 +106,13 @@ fn refresh_cache_if_file_changed() -> bool { > invalidate_cache_state_and_set_gen(&mut cache, shared_gen_now); > } > > + // TTL check again after acquiring the lock > + if cache.shadow.as_ref().is_some_and(|cached| { > + now >= cached.last_checked && (now - cached.last_checked) < TOKEN_SECRET_CACHE_TTL_SECS ... this check above. I think this could be defined as method on the cache object so it can be easily reused and the code is more readable. > + }) { > + return true; > + } > + > // Stat the file to detect manual edits. > let Ok((new_mtime, new_len)) = shadow_mtime_len() else { > return false;