Re: [PATCH v9 03/12] ceph: handle idmapped mounts in create_request_message()

From: Aleksandr Mikhalitsyn
Date: Mon Aug 07 2023 - 07:33:39 EST

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On Mon, Aug 7, 2023 at 1:21 PM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
>
>
> On 8/7/23 18:34, Aleksandr Mikhalitsyn wrote:
> > On Mon, Aug 7, 2023 at 12:28 PM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
> >>
> >> On 8/7/23 14:51, Aleksandr Mikhalitsyn wrote:
> >>> On Mon, Aug 7, 2023 at 3:25 AM Xiubo Li <xiubli@xxxxxxxxxx> wrote:
> >>>> On 8/4/23 16:48, Alexander Mikhalitsyn wrote:
> >>>>> From: Christian Brauner <brauner@xxxxxxxxxx>
> >>>>>
> >>>>> 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@xxxxxxxxxxxxxx/
> >>>>> [2] https://lore.kernel.org/all/20220104140414.155198-3-brauner@xxxxxxxxxx/
> >>>>>
> >>>>> Link: https://github.com/ceph/ceph/pull/52575
> >>>>> Link: https://tracker.ceph.com/issues/62217
> >>>>> Cc: Xiubo Li <xiubli@xxxxxxxxxx>
> >>>>> Cc: Jeff Layton <jlayton@xxxxxxxxxx>
> >>>>> Cc: Ilya Dryomov <idryomov@xxxxxxxxx>
> >>>>> Cc: ceph-devel@xxxxxxxxxxxxxxx
> >>>>> Co-Developed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
> >>>>> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
> >>>>> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
> >>>>> ---
> >>>>> 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 | 47 +++++++++++++++++++++++++++++++++---
> >>>>> fs/ceph/mds_client.h | 5 +++-
> >>>>> include/linux/ceph/ceph_fs.h | 5 +++-
> >>>>> 3 files changed, 52 insertions(+), 5 deletions(-)
> >>>>>
> >>>>> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> >>>>> index 8829f55103da..41e4bf3811c4 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);
> >>>>>
> >>>>> @@ -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 +3059,34 @@ 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);
> >>>>> + nhead->struct_len = sizeof(struct ceph_mds_request_head);
> >>>>> +
> >>>>> + 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..b91699b08f26 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 +530,9 @@ struct ceph_mds_request_head {
> >>>>>
> >>>>> __le32 ext_num_retry; /* new count retry attempts */
> >>>>> __le32 ext_num_fwd; /* new count fwd attempts */
> >>>>> +
> >>>>> + __le32 struct_len; /* to store size of struct ceph_mds_request_head */
> >>>>> + __le32 owner_uid, owner_gid; /* used for OPs which create inodes */
> >>>> Let's also initialize them to -1 for all the other requests as we do in
> >>>> your PR.
> >>> They are always initialized already. As you can see from the code we
> >>> don't have any extra conditions
> >>> on filling these fields. We always fill them with an appropriate
> >>> UID/GID. If mount is not idmapped then it's just == caller_uid/gid,
> >>> if mount idmapped then it's idmapped caller_uid/gid.
> >> Then in kclient all the request will always initialized the
> >> 'owner_{uid/gid}' with 'caller_{uid/gid}'. While in userspace libcephfs
> >> it will only set them for 'create/mknod/mkdir/symlink` instead.
> >>
> >> I'd prefer to make them consistent, which is what I am still focusing
> >> on, to make them easier to read and comparing when troubles hooting.
> > Dear Xiubo,
> >
> > Sure, I will do it.
> >
> > Couldn't you please review all the rest of the patches before I fix
> > this particular thing?
> > It will allow me to fix and send -v10 with all required fixes
> > incorporated in it.
>
> I have gone through them all and they LGTM.

Thanks!

Kind regards,
Alex

>
> Thanks
>
> - Xiubo
>
>
> > Kind regards,
> > Alex
> >
> >> Thanks
> >>
> >> - Xiubo
> >>
> >>> Kind regards,
> >>> Alex
> >>>
> >>>> Thanks
> >>>>
> >>>> - Xiubo
> >>>>
> >>>>
> >>>>
> >>>>> } __attribute__ ((packed));
> >>>>>
> >>>>> /* cap/lease release record */
>

Next message: Hans de Goede: "Re: [PATCH] hp-bioscfg: Update string length calculation"
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In reply to: Xiubo Li: "Re: [PATCH v9 03/12] ceph: handle idmapped mounts in create_request_message()"
Next in thread: Aleksandr Mikhalitsyn: "Re: [PATCH v9 03/12] ceph: handle idmapped mounts in create_request_message()"
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