Messages in this thread | | | Date | Fri, 4 Aug 2023 11:24:08 +0800 | Subject | Re: [PATCH v8 03/12] ceph: handle idmapped mounts in create_request_message() | From | Xiubo Li <> |
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On 8/4/23 10:26, Xiubo Li wrote: > > On 8/3/23 21:59, Alexander Mikhalitsyn wrote: >> From: Christian Brauner <brauner@kernel.org> >> >> Inode operations that create a new filesystem object such as ->mknod, >> ->create, ->mkdir() and others don't take a {g,u}id argument explicitly. >> Instead the caller's fs{g,u}id is used for the {g,u}id of the new >> filesystem object. >> >> In order to ensure that the correct {g,u}id is used map the caller's >> fs{g,u}id for creation requests. This doesn't require complex changes. >> It suffices to pass in the relevant idmapping recorded in the request >> message. If this request message was triggered from an inode operation >> that creates filesystem objects it will have passed down the relevant >> idmaping. If this is a request message that was triggered from an inode >> operation that doens't need to take idmappings into account the initial >> idmapping is passed down which is an identity mapping. >> >> This change uses a new cephfs protocol extension >> CEPHFS_FEATURE_HAS_OWNER_UIDGID >> which adds two new fields (owner_{u,g}id) to the request head structure. >> So, we need to ensure that MDS supports it otherwise we need to fail >> any IO that comes through an idmapped mount because we can't process it >> in a proper way. MDS server without such an extension will use >> caller_{u,g}id >> fields to set a new inode owner UID/GID which is incorrect because >> caller_{u,g}id >> values are unmapped. At the same time we can't map these fields with an >> idmapping as it can break UID/GID-based permission checks logic on the >> MDS side. This problem was described with a lot of details at [1], [2]. >> >> [1] >> https://lore.kernel.org/lkml/CAEivzxfw1fHO2TFA4dx3u23ZKK6Q+EThfzuibrhA3RKM=ZOYLg@mail.gmail.com/ >> [2] >> https://lore.kernel.org/all/20220104140414.155198-3-brauner@kernel.org/ >> >> https://github.com/ceph/ceph/pull/52575 >> https://tracker.ceph.com/issues/62217 >> >> Cc: Xiubo Li <xiubli@redhat.com> >> Cc: Jeff Layton <jlayton@kernel.org> >> Cc: Ilya Dryomov <idryomov@gmail.com> >> Cc: ceph-devel@vger.kernel.org >> Co-Developed-by: Alexander Mikhalitsyn >> <aleksandr.mikhalitsyn@canonical.com> >> Signed-off-by: Christian Brauner <brauner@kernel.org> >> Signed-off-by: Alexander Mikhalitsyn >> <aleksandr.mikhalitsyn@canonical.com> >> --- >> v7: >> - reworked to use two new fields for owner UID/GID >> (https://github.com/ceph/ceph/pull/52575) >> v8: >> - properly handled case when old MDS used with new kernel client >> --- >> fs/ceph/mds_client.c | 46 +++++++++++++++++++++++++++++++++--- >> fs/ceph/mds_client.h | 5 +++- >> include/linux/ceph/ceph_fs.h | 4 +++- >> 3 files changed, 50 insertions(+), 5 deletions(-) >> >> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c >> index 8829f55103da..7d3106d3b726 100644 >> --- a/fs/ceph/mds_client.c >> +++ b/fs/ceph/mds_client.c >> @@ -2902,6 +2902,17 @@ static void encode_mclientrequest_tail(void >> **p, const struct ceph_mds_request * >> } >> } >> +static inline u16 mds_supported_head_version(struct >> ceph_mds_session *session) >> +{ >> + if (!test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD, >> &session->s_features)) >> + return 1; >> + >> + if (!test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, >> &session->s_features)) >> + return 2; >> + >> + return CEPH_MDS_REQUEST_HEAD_VERSION; >> +} >> + >> static struct ceph_mds_request_head_legacy * >> find_legacy_request_head(void *p, u64 features) >> { >> @@ -2923,6 +2934,7 @@ static struct ceph_msg >> *create_request_message(struct ceph_mds_session *session, >> { >> int mds = session->s_mds; >> struct ceph_mds_client *mdsc = session->s_mdsc; >> + struct ceph_client *cl = mdsc->fsc->client; >> struct ceph_msg *msg; >> struct ceph_mds_request_head_legacy *lhead; >> const char *path1 = NULL; >> @@ -2936,7 +2948,7 @@ static struct ceph_msg >> *create_request_message(struct ceph_mds_session *session, >> void *p, *end; >> int ret; >> bool legacy = !(session->s_con.peer_features & >> CEPH_FEATURE_FS_BTIME); >> - bool old_version = !test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD, >> &session->s_features); >> + u16 request_head_version = mds_supported_head_version(session); >> ret = set_request_path_attr(mdsc, req->r_inode, req->r_dentry, >> req->r_parent, req->r_path1, req->r_ino1.ino, >> @@ -2977,8 +2989,10 @@ static struct ceph_msg >> *create_request_message(struct ceph_mds_session *session, >> */ >> if (legacy) >> len = sizeof(struct ceph_mds_request_head_legacy); >> - else if (old_version) >> + else if (request_head_version == 1) >> len = sizeof(struct ceph_mds_request_head_old); >> + else if (request_head_version == 2) >> + len = offsetofend(struct ceph_mds_request_head, ext_num_fwd); >> else >> len = sizeof(struct ceph_mds_request_head); > > This is not what we suppose to. If we do this again and again when > adding new members it will make the code very complicated to maintain. > > Once the CEPHFS_FEATURE_32BITS_RETRY_FWD has been supported the ceph > should correctly decode it and if CEPHFS_FEATURE_HAS_OWNER_UIDGID is > not supported the decoder should skip it directly. > > Is the MDS side buggy ? Why you last version didn't work ? >
I think the ceph side is buggy. Possibly we should add one new `length` member in struct `struct ceph_mds_request_head` and just skip the extra bytes when decoding it.
Could you fix it together with your ceph PR ?
Thanks
- Xiubo
> Thanks > > - Xiubo > >> @@ -3028,6 +3042,16 @@ static struct ceph_msg >> *create_request_message(struct ceph_mds_session *session, >> lhead = find_legacy_request_head(msg->front.iov_base, >> session->s_con.peer_features); >> + if ((req->r_mnt_idmap != &nop_mnt_idmap) && >> + !test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, >> &session->s_features)) { >> + pr_err_ratelimited_client(cl, >> + "idmapped mount is used and >> CEPHFS_FEATURE_HAS_OWNER_UIDGID" >> + " is not supported by MDS. Fail request with -EIO.\n"); >> + >> + ret = -EIO; >> + goto out_err; >> + } >> + >> /* >> * The ceph_mds_request_head_legacy didn't contain a version >> field, and >> * one was added when we moved the message version from 3->4. >> @@ -3035,17 +3059,33 @@ static struct ceph_msg >> *create_request_message(struct ceph_mds_session *session, >> if (legacy) { >> msg->hdr.version = cpu_to_le16(3); >> p = msg->front.iov_base + sizeof(*lhead); >> - } else if (old_version) { >> + } else if (request_head_version == 1) { >> struct ceph_mds_request_head_old *ohead = msg->front.iov_base; >> msg->hdr.version = cpu_to_le16(4); >> ohead->version = cpu_to_le16(1); >> p = msg->front.iov_base + sizeof(*ohead); >> + } else if (request_head_version == 2) { >> + struct ceph_mds_request_head *nhead = msg->front.iov_base; >> + >> + msg->hdr.version = cpu_to_le16(6); >> + nhead->version = cpu_to_le16(2); >> + >> + p = msg->front.iov_base + offsetofend(struct >> ceph_mds_request_head, ext_num_fwd); >> } else { >> struct ceph_mds_request_head *nhead = msg->front.iov_base; >> + kuid_t owner_fsuid; >> + kgid_t owner_fsgid; >> msg->hdr.version = cpu_to_le16(6); >> nhead->version = cpu_to_le16(CEPH_MDS_REQUEST_HEAD_VERSION); >> + >> + owner_fsuid = from_vfsuid(req->r_mnt_idmap, &init_user_ns, >> + VFSUIDT_INIT(req->r_cred->fsuid)); >> + owner_fsgid = from_vfsgid(req->r_mnt_idmap, &init_user_ns, >> + VFSGIDT_INIT(req->r_cred->fsgid)); >> + nhead->owner_uid = cpu_to_le32(from_kuid(&init_user_ns, >> owner_fsuid)); >> + nhead->owner_gid = cpu_to_le32(from_kgid(&init_user_ns, >> owner_fsgid)); >> p = msg->front.iov_base + sizeof(*nhead); >> } >> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h >> index e3bbf3ba8ee8..8f683e8203bd 100644 >> --- a/fs/ceph/mds_client.h >> +++ b/fs/ceph/mds_client.h >> @@ -33,8 +33,10 @@ enum ceph_feature_type { >> CEPHFS_FEATURE_NOTIFY_SESSION_STATE, >> CEPHFS_FEATURE_OP_GETVXATTR, >> CEPHFS_FEATURE_32BITS_RETRY_FWD, >> + CEPHFS_FEATURE_NEW_SNAPREALM_INFO, >> + CEPHFS_FEATURE_HAS_OWNER_UIDGID, >> - CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_32BITS_RETRY_FWD, >> + CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_HAS_OWNER_UIDGID, >> }; >> #define CEPHFS_FEATURES_CLIENT_SUPPORTED { \ >> @@ -49,6 +51,7 @@ enum ceph_feature_type { >> CEPHFS_FEATURE_NOTIFY_SESSION_STATE, \ >> CEPHFS_FEATURE_OP_GETVXATTR, \ >> CEPHFS_FEATURE_32BITS_RETRY_FWD, \ >> + CEPHFS_FEATURE_HAS_OWNER_UIDGID, \ >> } >> /* >> diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h >> index 5f2301ee88bc..6eb83a51341c 100644 >> --- a/include/linux/ceph/ceph_fs.h >> +++ b/include/linux/ceph/ceph_fs.h >> @@ -499,7 +499,7 @@ struct ceph_mds_request_head_legacy { >> union ceph_mds_request_args args; >> } __attribute__ ((packed)); >> -#define CEPH_MDS_REQUEST_HEAD_VERSION 2 >> +#define CEPH_MDS_REQUEST_HEAD_VERSION 3 >> struct ceph_mds_request_head_old { >> __le16 version; /* struct version */ >> @@ -530,6 +530,8 @@ struct ceph_mds_request_head { >> __le32 ext_num_retry; /* new count retry attempts */ >> __le32 ext_num_fwd; /* new count fwd attempts */ >> + >> + __le32 owner_uid, owner_gid; /* used for OPs which create >> inodes */ >> } __attribute__ ((packed)); >> /* cap/lease release record */
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