Messages in this thread | | | Date | Mon, 20 Mar 2023 20:47:18 +0800 | Subject | Re: [PATCH v3 0/3] ceph: fscrypt: fix atomic open bug for encrypted directories | From | Xiubo Li <> |
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On 20/03/2023 19:20, Ilya Dryomov wrote: > On Mon, Mar 20, 2023 at 2:07 AM Xiubo Li <xiubli@redhat.com> wrote: >> >> On 17/03/2023 02:14, Luís Henriques wrote: >>> Hi! >>> >>> I started seeing fstest generic/123 failing in ceph fscrypt, when running it >>> with 'test_dummy_encryption'. This test is quite simple: >>> >>> 1. Creates a directory with write permissions for root only >>> 2. Writes into a file in that directory >>> 3. Uses 'su' to try to modify that file as a different user, and >>> gets -EPERM >>> >>> All the test steps succeed, but the test fails to cleanup: 'rm -rf <dir>' >>> will fail with -ENOTEMPTY. 'strace' shows that calling unlinkat() to remove >>> the file got a -ENOENT and then -ENOTEMPTY for the directory. >>> >>> This is because 'su' does a drop_caches ('su (874): drop_caches: 2' in >>> dmesg), and ceph's atomic open will do: >>> >>> if (IS_ENCRYPTED(dir)) { >>> set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags); >>> if (!fscrypt_has_encryption_key(dir)) { >>> spin_lock(&dentry->d_lock); >>> dentry->d_flags |= DCACHE_NOKEY_NAME; >>> spin_unlock(&dentry->d_lock); >>> } >>> } >>> >>> Although 'dir' has the encryption key available, fscrypt_has_encryption_key() >>> will return 'false' because fscrypt info isn't yet set after the cache >>> cleanup. >>> >>> The first patch will add a new helper for the atomic_open that will force >>> the fscrypt info to be loaded into an inode that has been evicted recently >>> but for which the key is still available. >>> >>> The second patch switches ceph atomic_open to use the new fscrypt helper. >>> >>> Cheers, >>> -- >>> Luís >>> >>> Changes since v2: >>> - Make helper more generic and to be used both in lookup and atomic open >>> operations >>> - Modify ceph_lookup (patch 0002) and ceph_atomic_open (patch 0003) to use >>> the new helper >>> >>> Changes since v1: >>> - Dropped IS_ENCRYPTED() from helper function because kerneldoc says >>> already that it applies to encrypted directories and, most importantly, >>> because it would introduce a different behaviour for >>> CONFIG_FS_ENCRYPTION and !CONFIG_FS_ENCRYPTION. >>> - Rephrased helper kerneldoc >>> >>> Changes since initial RFC (after Eric's review): >>> - Added kerneldoc comments to the new fscrypt helper >>> - Dropped '__' from helper name (now fscrypt_prepare_atomic_open()) >>> - Added IS_ENCRYPTED() check in helper >>> - DCACHE_NOKEY_NAME is not set if fscrypt_get_encryption_info() returns an >>> error >>> - Fixed helper for !CONFIG_FS_ENCRYPTION (now defined 'static inline') >> This series looks good to me. >> >> And I have run the test locally and worked well. >> >> >>> Luís Henriques (3): >>> fscrypt: new helper function - fscrypt_prepare_lookup_partial() >> Eric, >> >> If possible I we can pick this together to ceph repo and need your ack >> about this. Or you can pick it to the crypto repo then please feel free >> to add: >> >> Tested-by: Xiubo Li <xiubli@redhat.com> and Reviewed-by: Xiubo Li >> <xiubli@redhat.com> > I would prefer the fscrypt helper to go through the fscrypt tree.
Sure. This also LGTM.
Thanks
- Xiubo
> Thanks, > > Ilya >
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