From: "Jan Lübbe" <jlu@pengutronix.de> To: Eric Biggers <ebiggers@kernel.org>, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Cc: linux-integrity@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org, Mimi Zohar <zohar@linux.vnet.ibm.com>, Dmitry Kasatkin <dmitry.kasatkin@gmail.com>, Michael Halcrow <mhalcrow@google.com>, Victor Hsieh <victorhsieh@google.com> Subject: Re: [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Date: Fri, 31 Aug 2018 22:05:23 +0200 [thread overview] Message-ID: <1535745923.25742.1.camel@pengutronix.de> (raw) In-Reply-To: <20180824161642.1144-1-ebiggers@kernel.org> On Fri, 2018-08-24 at 09:16 -0700, Eric Biggers wrote: [...] > Since fs-verity provides the Merkle tree root hash in constant time and > verifies data blocks on-demand, it is useful for efficiently verifying > the authenticity of, or "appraising", large files of which only a small > portion may be accessed -- such as Android application (APK) files. It > can also be useful in "audit" use cases where file hashes are logged. > fs-verity also provides better protection against malicious disk > firmware than an ahead-of-time hash, since fs-verity re-verifies data > each time it's paged in. [...] > Feedback on the design and implementation is greatly appreciated. Hi, I've looked at the series and the slides linked form the recent lwn.net article, but I'm not sure how fs-verity intends to protect against malicious firmware (or offline modification). Similar to IMA/EVM, fs- verity doesn't seem to include the name/location of the file into it's verification. So the firmware/an attacker could replace one fs-verity- protected file with another (maybe a trusted system APK with another one for which a vulnerability was discovered, or /sbin/init with /bin/sh). Is the expected root hash of the file provided from somewhere else, so this is not a problem on Android? Or is this problem out-of-scope for fs-verity? For IMA/EVM, there were patches by Dmitry to address this class of attacks (they were not merged, though): https://lwn.net/Articles/574221/ Thanks, Jan [1] https://events.linuxfoundation.org/wp-content/uploads/2017/11/fs-ve rify_Mike-Halcrow_Eric-Biggers.pdf -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
WARNING: multiple messages have this Message-ID (diff)
From: "Jan Lübbe" <jlu@pengutronix.de> To: Eric Biggers <ebiggers@kernel.org>, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Cc: linux-integrity@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-kernel@vger.kernel.org, Mimi Zohar <zohar@linux.vnet.ibm.com>, Dmitry Kasatkin <dmitry.kasatkin@gmail.com>, Michael Halcrow <mhalcrow@google.com>, Victor Hsieh <victorhsieh@google.com> Subject: Re: [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Date: Fri, 31 Aug 2018 22:05:23 +0200 [thread overview] Message-ID: <1535745923.25742.1.camel@pengutronix.de> (raw) In-Reply-To: <20180824161642.1144-1-ebiggers@kernel.org> On Fri, 2018-08-24 at 09:16 -0700, Eric Biggers wrote: [...] > Since fs-verity provides the Merkle tree root hash in constant time and > verifies data blocks on-demand, it is useful for efficiently verifying > the authenticity of, or "appraising", large files of which only a small > portion may be accessed -- such as Android application (APK) files. It > can also be useful in "audit" use cases where file hashes are logged. > fs-verity also provides better protection against malicious disk > firmware than an ahead-of-time hash, since fs-verity re-verifies data > each time it's paged in. [...] > Feedback on the design and implementation is greatly appreciated. Hi, I've looked at the series and the slides linked form the recent lwn.net article, but I'm not sure how fs-verity intends to protect against malicious firmware (or offline modification). Similar to IMA/EVM, fs- verity doesn't seem to include the name/location of the file into it's verification. So the firmware/an attacker could replace one fs-verity- protected file with another (maybe a trusted system APK with another one for which a vulnerability was discovered, or /sbin/init with /bin/sh). Is the expected root hash of the file provided from somewhere else, so this is not a problem on Android? Or is this problem out-of-scope for fs-verity? For IMA/EVM, there were patches by Dmitry to address this class of attacks (they were not merged, though): https://lwn.net/Articles/574221/ Thanks, Jan [1] https://events.linuxfoundation.org/wp-content/uploads/2017/11/fs-ve rify_Mike-Halcrow_Eric-Biggers.pdf -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
next prev parent reply other threads:[~2018-08-31 20:05 UTC|newest] Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-08-24 16:16 [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Eric Biggers 2018-08-24 16:16 ` [f2fs-dev] [RFC PATCH 01/10] fs-verity: add setup code, UAPI, and Kconfig Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 17:28 ` Randy Dunlap 2018-08-24 17:28 ` Randy Dunlap 2018-08-24 17:42 ` Colin Walters 2018-08-24 22:45 ` Theodore Y. Ts'o 2018-08-25 4:48 ` Eric Biggers 2018-09-14 13:15 ` Colin Walters 2018-09-14 16:21 ` Eric Biggers 2018-09-15 15:27 ` Theodore Y. Ts'o 2018-08-26 16:22 ` Chuck Lever 2018-08-26 16:22 ` Chuck Lever 2018-08-26 17:17 ` Eric Biggers 2018-08-24 16:16 ` [f2fs-dev] [RFC PATCH 02/10] fs-verity: add data verification hooks for ->readpages() Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-25 2:29 ` [f2fs-dev] " Gao Xiang 2018-08-25 2:29 ` Gao Xiang 2018-08-25 2:29 ` Gao Xiang 2018-08-25 3:45 ` Theodore Y. Ts'o 2018-08-25 3:45 ` Theodore Y. Ts'o 2018-08-25 4:00 ` [f2fs-dev] " Gao Xiang 2018-08-25 4:00 ` Gao Xiang 2018-08-25 5:06 ` Theodore Y. Ts'o 2018-08-25 7:33 ` Gao Xiang 2018-08-25 7:33 ` Gao Xiang 2018-08-25 7:33 ` Gao Xiang 2018-08-25 7:33 ` [f2fs-dev] " Gao Xiang 2018-08-25 7:55 ` Gao Xiang 2018-08-25 7:55 ` Gao Xiang 2018-08-25 4:16 ` Eric Biggers 2018-08-25 4:16 ` Eric Biggers 2018-08-25 6:31 ` Gao Xiang 2018-08-25 6:31 ` Gao Xiang 2018-08-25 6:31 ` Gao Xiang 2018-08-25 7:18 ` Eric Biggers 2018-08-25 7:43 ` Gao Xiang 2018-08-25 7:43 ` Gao Xiang 2018-08-25 17:06 ` Theodore Y. Ts'o 2018-08-25 17:06 ` Theodore Y. Ts'o 2018-08-26 13:44 ` Gao Xiang 2018-09-02 2:35 ` Olof Johansson 2018-08-26 15:55 ` Chuck Lever 2018-08-26 17:04 ` Eric Biggers 2018-08-26 17:44 ` Gao Xiang 2018-08-26 17:44 ` Gao Xiang via Linux-f2fs-devel 2018-08-24 16:16 ` [RFC PATCH 03/10] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` [RFC PATCH 04/10] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Eric Biggers 2018-08-24 16:16 ` [RFC PATCH 05/10] fs-verity: add SHA-512 support Eric Biggers 2018-08-24 16:16 ` [f2fs-dev] [RFC PATCH 06/10] fs-verity: add CRC-32C support Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` [f2fs-dev] [RFC PATCH 07/10] fs-verity: support builtin file signatures Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` [RFC PATCH 08/10] ext4: add basic fs-verity support Eric Biggers 2018-08-24 16:16 ` [f2fs-dev] [RFC PATCH 09/10] ext4: add fs-verity read support Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-24 16:16 ` [RFC PATCH 10/10] f2fs: fs-verity support Eric Biggers 2018-08-24 16:16 ` Eric Biggers 2018-08-25 5:54 ` [f2fs-dev] " Chao Yu 2018-08-25 5:54 ` Chao Yu 2018-08-25 5:54 ` Chao Yu 2018-08-26 17:35 ` Eric Biggers 2018-08-27 15:54 ` Chao Yu 2018-08-28 7:27 ` Jaegeuk Kim 2018-08-28 9:20 ` Chao Yu 2018-08-28 9:20 ` Chao Yu 2018-08-28 17:01 ` Jaegeuk Kim 2018-08-29 1:22 ` Chao Yu 2018-08-29 1:22 ` Chao Yu 2018-08-29 1:22 ` Chao Yu 2018-08-29 1:43 ` Jaegeuk Kim 2018-08-31 20:05 ` Jan Lübbe [this message] 2018-08-31 20:05 ` [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Jan Lübbe 2018-08-31 21:39 ` Eric Biggers 2018-08-31 21:39 ` Eric Biggers 2018-08-31 21:39 ` Eric Biggers
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