Messages in this thread | | | Date | Fri, 4 Aug 2023 10:26:16 +0800 | Subject | Re: [PATCH v8 03/12] ceph: handle idmapped mounts in create_request_message() | From | Xiubo Li <> |
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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 ?
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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