From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id A12FB6926E for ; Fri, 11 Mar 2022 13:20:54 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 9853E2466D for ; Fri, 11 Mar 2022 13:20:24 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 0E33B24662 for ; Fri, 11 Mar 2022 13:20:24 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id D4B1E45910 for ; Fri, 11 Mar 2022 13:20:23 +0100 (CET) Message-ID: <717c8999-d3f8-a01b-a8f5-da0f5960d23f@proxmox.com> Date: Fri, 11 Mar 2022 13:20:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:98.0) Gecko/20100101 Thunderbird/98.0 Content-Language: en-US To: Proxmox Backup Server development discussion , Stefan Sterz References: <20220309135031.1995207-1-s.sterz@proxmox.com> From: Thomas Lamprecht In-Reply-To: <20220309135031.1995207-1-s.sterz@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.059 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record T_SCC_BODY_TEXT_LINE -0.01 - Subject: Re: [pbs-devel] [PATCH proxmox-backup] fix #3336: api: remove backup group if the last snapshot is removed X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Mar 2022 12:20:54 -0000 On 09.03.22 14:50, Stefan Sterz wrote: > Signed-off-by: Stefan Sterz > --- > pbs-datastore/src/datastore.rs | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs > index d416c8d8..623b7688 100644 > --- a/pbs-datastore/src/datastore.rs > +++ b/pbs-datastore/src/datastore.rs > @@ -346,6 +346,28 @@ impl DataStore { > ) > })?; > > + // check if this was the last snapshot and if so remove the group > + if backup_dir > + .group() > + .list_backups(&self.base_path())? > + .is_empty() > + { a log::info could be appropriate in the "success" (i.e., delete dir) case. I'd factor the this block below out into a non-pub (or pub(crate)) remove_empty_group_dir fn. > + let group_path = self.group_path(backup_dir.group()); > + let _guard = proxmox_sys::fs::lock_dir_noblock( > + &group_path, > + "backup group", > + "possible running backup", > + )?; > + > + std::fs::remove_dir_all(&group_path).map_err(|err| { this is still unsafe as there's a TOCTOU race, the lock does not protects you from the following sequence with two threads/async-excutions t1 and t1 t1.1 snapshot deleted t1.2 empty dir check holds up, entering "delete group dir" code branch t2.1 create new snapshot in group -> lock group dir t2.2 finish new snapshot in group -> unlock group dir t1.3 lock group dir t1.4 delete all files, including the new snapshot made in-between. Rather, just use the safer "remove_dir" variant, that way the TOCTOU race doesn't matters, the check merely becomes a short cut; if we'd explicitly check for `err.kind() != ErrorKind::DirectoryNotEmpty and silent it we could even do away with the check, should result in the same amount of syscalls in the best-case (one rmdir vs. one readir) and can be better on success (readdir + rmdir vs. rmdir only), not that perfromance matters much in this case. fyi, "remove_backup_group", the place where I think you copied this part, can use the remove_dir_all safely because there's no check to made there, so no TOCTOU. > + format_err!( > + "removing backup group directory {:?} failed - {}", > + group_path, > + err, > + ) > + })?; > + } > + > // the manifest does not exists anymore, we do not need to keep the lock > if let Ok(path) = self.manifest_lock_path(backup_dir) { > // ignore errors