Re: [RFC PATCH v8 09/24] ceph: add ability to set fscrypt_auth via setattr

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2021-08-31 at 21:22 +0800, Xiubo Li wrote:
> On 8/31/21 8:43 PM, Jeff Layton wrote:
> > On Tue, 2021-08-31 at 13:06 +0800, Xiubo Li wrote:
> > > On 8/27/21 12:19 AM, Jeff Layton wrote:
> > > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > > ---
> > > >    fs/ceph/acl.c                |  4 +--
> > > >    fs/ceph/crypto.h             |  9 +++++-
> > > >    fs/ceph/inode.c              | 33 ++++++++++++++++++++--
> > > >    fs/ceph/mds_client.c         | 54 ++++++++++++++++++++++++++++++------
> > > >    fs/ceph/mds_client.h         |  3 ++
> > > >    fs/ceph/super.h              |  7 ++++-
> > > >    include/linux/ceph/ceph_fs.h | 21 ++++++++------
> > > >    7 files changed, 108 insertions(+), 23 deletions(-)
> > > > 
> > > > diff --git a/fs/ceph/acl.c b/fs/ceph/acl.c
> > > > index 529af59d9fd3..6e716f142022 100644
> > > > --- a/fs/ceph/acl.c
> > > > +++ b/fs/ceph/acl.c
> > > > @@ -136,7 +136,7 @@ int ceph_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
> > > >    		newattrs.ia_ctime = current_time(inode);
> > > >    		newattrs.ia_mode = new_mode;
> > > >    		newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
> > > > -		ret = __ceph_setattr(inode, &newattrs);
> > > > +		ret = __ceph_setattr(inode, &newattrs, NULL);
> > > >    		if (ret)
> > > >    			goto out_free;
> > > >    	}
> > > > @@ -147,7 +147,7 @@ int ceph_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
> > > >    			newattrs.ia_ctime = old_ctime;
> > > >    			newattrs.ia_mode = old_mode;
> > > >    			newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
> > > > -			__ceph_setattr(inode, &newattrs);
> > > > +			__ceph_setattr(inode, &newattrs, NULL);
> > > >    		}
> > > >    		goto out_free;
> > > >    	}
> > > > diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
> > > > index 6c3831c57c8d..6dca674f79b8 100644
> > > > --- a/fs/ceph/crypto.h
> > > > +++ b/fs/ceph/crypto.h
> > > > @@ -14,8 +14,15 @@ struct ceph_fscrypt_auth {
> > > >    	u8	cfa_blob[FSCRYPT_SET_CONTEXT_MAX_SIZE];
> > > >    } __packed;
> > > >    
> > > > -#ifdef CONFIG_FS_ENCRYPTION
> > > >    #define CEPH_FSCRYPT_AUTH_VERSION	1
> > > > +static inline u32 ceph_fscrypt_auth_len(struct ceph_fscrypt_auth *fa)
> > > > +{
> > > > +	u32 ctxsize = le32_to_cpu(fa->cfa_blob_len);
> > > > +
> > > > +	return offsetof(struct ceph_fscrypt_auth, cfa_blob) + ctxsize;
> > > > +}
> > > > +
> > > > +#ifdef CONFIG_FS_ENCRYPTION
> > > >    void ceph_fscrypt_set_ops(struct super_block *sb);
> > > >    
> > > >    #else /* CONFIG_FS_ENCRYPTION */
> > > > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> > > > index a541f5e9c5ed..ae800372e42d 100644
> > > > --- a/fs/ceph/inode.c
> > > > +++ b/fs/ceph/inode.c
> > > > @@ -2083,7 +2083,7 @@ static const struct inode_operations ceph_symlink_iops = {
> > > >    	.listxattr = ceph_listxattr,
> > > >    };
> > > >    
> > > > -int __ceph_setattr(struct inode *inode, struct iattr *attr)
> > > > +int __ceph_setattr(struct inode *inode, struct iattr *attr, struct ceph_iattr *cia)
> > > >    {
> > > >    	struct ceph_inode_info *ci = ceph_inode(inode);
> > > >    	unsigned int ia_valid = attr->ia_valid;
> > > > @@ -2124,6 +2124,34 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
> > > >    
> > > >    	dout("setattr %p issued %s\n", inode, ceph_cap_string(issued));
> > > >    
> > > > +	if (cia && cia->fscrypt_auth) {
> > > > +		u32 len = ceph_fscrypt_auth_len(cia->fscrypt_auth);
> > > > +
> > > > +		if (len > sizeof(*cia->fscrypt_auth)) {
> > > > +			err = -EINVAL;
> > > > +			spin_unlock(&ci->i_ceph_lock);
> > > > +			goto out;
> > > > +		}
> > > > +
> > > > +		dout("setattr %llx:%llx fscrypt_auth len %u to %u)\n",
> > > > +			ceph_vinop(inode), ci->fscrypt_auth_len, len);
> > > > +
> > > > +		/* It should never be re-set once set */
> > > > +		WARN_ON_ONCE(ci->fscrypt_auth);
> > > > +
> > > Maybe this should return -EEXIST if already set ?
> > > 
> > I don't know. In general, once the context is set on an inode, we
> > shouldn't ever reset it. That said, I think we might need to allow
> > admins to override an existing context if it's corrupted.
> > 
> > So, that's the rationale for the WARN_ON_ONCE. The admins should never
> > do this under normal circumstances but they do have the ability to
> > change it if needed (and we'll see a warning in the logs in that case).
> 
> I may miss some code in the fs/crypto/ layer.
> 
> I readed that once the directory/file has set the policy context, it 
> will just return 0 if the new one matches the existence, if not match it 
> will return -EEXIST, or will try to call ceph layer to set it.
> 
> So once this is set, my understanding is that it shouldn't be here ?
> 

Where did you read that? If we have documented semantics we need to
follow here, then we should change it to comply with them.

> 
> > > > +		if (issued & CEPH_CAP_AUTH_EXCL) {
> > > > +			dirtied |= CEPH_CAP_AUTH_EXCL;
> > > > +			kfree(ci->fscrypt_auth);
> > > > +			ci->fscrypt_auth = (u8 *)cia->fscrypt_auth;
> > > > +			ci->fscrypt_auth_len = len;
> > > > +		} else if ((issued & CEPH_CAP_AUTH_SHARED) == 0) {
> > > For this, shouldn't we always set the req->r_fscrypt_auth even the
> > > "CEPH_CAP_AUTH_SHARED" cap is issued ?
> > > 
> > > Maybe this should be:
> > > 
> > > } else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 || !ci->fscrypt_auth) {
> > > 
> > > ??
> > > 
> > ...or maybe we need to memcmp ci->fscrypt_auth and cia->fscrypt_auth?
> 
> My understanding is that, if the 'As' cap is not issued, that means 
> maybe another client has been issued the 'Ax' cap. For the current 
> client, if !ci->fscrypt_auth == true and
> 
> no matter whether the 'As' cap is issued or not it should try to set the 
> fscrypt_auth to MDS. But this could fail if another client also trying 
> to set the fscrypt_auth by holding the 'Ax' cap ?
> 
> Or won't the new one override the old context in MDS side ?
> 

The update to the code that I'm testing now looks like this.

                if (issued & CEPH_CAP_AUTH_EXCL) {
                        dirtied |= CEPH_CAP_AUTH_EXCL;
                        kfree(ci->fscrypt_auth);
                        ci->fscrypt_auth = (u8 *)cia->fscrypt_auth;
                        ci->fscrypt_auth_len = len;
                } else if ((issued & CEPH_CAP_AUTH_SHARED) == 0 ||
                           ci->fscrypt_auth_len != len ||
                           memcmp(ci->fscrypt_auth, cia->fscrypt_auth, len)) {
                        req->r_fscrypt_auth = cia->fscrypt_auth;
                        mask |= CEPH_SETATTR_FSCRYPT_AUTH;
                        release |= CEPH_CAP_AUTH_SHARED;
                }
                cia->fscrypt_auth = NULL;

Basically, the logic is:

If we have Ax caps, we can do the change locally and eventually flush it
to the server in a cap update. If we have As caps then we can skip
issuing a SETATTR if nothing actually changed. If we don't have either,
then we just have to issue the SETATTR since we can't tell.

> 
> 
> > 
> > In any case, you're right that testing for As caps alone is not
> > sufficient. I'll fix that up soon.
> > 
> > > > +			req->r_fscrypt_auth = cia->fscrypt_auth;
> > > > +			mask |= CEPH_SETATTR_FSCRYPT_AUTH;
> > > > +			release |= CEPH_CAP_AUTH_SHARED;
> > > > +		}
> > > > +		cia->fscrypt_auth = NULL;
> > > > +	}
> > > > +
> > > >    	if (ia_valid & ATTR_UID) {
> > > >    		dout("setattr %p uid %d -> %d\n", inode,
> > > >    		     from_kuid(&init_user_ns, inode->i_uid),
> > > > @@ -2284,6 +2312,7 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
> > > >    		req->r_stamp = attr->ia_ctime;
> > > >    		err = ceph_mdsc_do_request(mdsc, NULL, req);
> > > >    	}
> > > > +out:
> > > >    	dout("setattr %p result=%d (%s locally, %d remote)\n", inode, err,
> > > >    	     ceph_cap_string(dirtied), mask);
> > > >    
> > > > @@ -2321,7 +2350,7 @@ int ceph_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> > > >    	    ceph_quota_is_max_bytes_exceeded(inode, attr->ia_size))
> > > >    		return -EDQUOT;
> > > >    
> > > > -	err = __ceph_setattr(inode, attr);
> > > > +	err = __ceph_setattr(inode, attr, NULL);
> > > >    
> > > >    	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
> > > >    		err = posix_acl_chmod(&init_user_ns, inode, attr->ia_mode);
> > > > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> > > > index 240b53d58dda..449b4e78366e 100644
> > > > --- a/fs/ceph/mds_client.c
> > > > +++ b/fs/ceph/mds_client.c
> > > > @@ -15,6 +15,7 @@
> > > >    
> > > >    #include "super.h"
> > > >    #include "mds_client.h"
> > > > +#include "crypto.h"
> > > >    
> > > >    #include <linux/ceph/ceph_features.h>
> > > >    #include <linux/ceph/messenger.h>
> > > > @@ -927,6 +928,7 @@ void ceph_mdsc_release_request(struct kref *kref)
> > > >    	put_cred(req->r_cred);
> > > >    	if (req->r_pagelist)
> > > >    		ceph_pagelist_release(req->r_pagelist);
> > > > +	kfree(req->r_fscrypt_auth);
> > > >    	put_request_session(req);
> > > >    	ceph_unreserve_caps(req->r_mdsc, &req->r_caps_reservation);
> > > >    	WARN_ON_ONCE(!list_empty(&req->r_wait));
> > > > @@ -2618,8 +2620,7 @@ static int set_request_path_attr(struct inode *rinode, struct dentry *rdentry,
> > > >    	return r;
> > > >    }
> > > >    
> > > > -static void encode_timestamp_and_gids(void **p,
> > > > -				      const struct ceph_mds_request *req)
> > > > +static void encode_mclientrequest_tail(void **p, const struct ceph_mds_request *req)
> > > >    {
> > > >    	struct ceph_timespec ts;
> > > >    	int i;16:51 < batrick> done
> > > > @@ -2632,6 +2633,20 @@ static void encode_timestamp_and_gids(void **p,
> > > >    	for (i = 0; i < req->r_cred->group_info->ngroups; i++)load more comments (105 replies)
> > > >    		ceph_encode_64(p, from_kgid(&init_user_ns,
> > > >    					    req->r_cred->group_info->gid[i]));
> > > > +
> > > > +	/* v5: altname (TODO: skip for now) */load more comments (105 replies)
> > > > +	ceph_encode_32(p, 0);
> > > > +
> > > > +	/* v6: fscrypt_auth and fscrypt_file */
> > > > +	if (req->r_fscrypt_auth) {
> > > > +		u32 authlen = ceph_fscrypt_auth_len(req->r_fscrypt_auth);
> > > > +
> > > > +		ceph_encode_32(p, authlen);
> > > > +		ceph_encode_copy(p, req->r_fscrypt_auth, authlen);
> > > > +	} else {
> > > > +		ceph_encode_32(p, 0);
> > > > +	}
> > > > +	ceph_encode_32(p, 0); // fscrypt_file for now
> > > >    }
> > > >    
> > > >    /*
> > > > @@ -2676,12 +2691,14 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
> > > >    		goto out_free1;
> > > >    	}
> > > >    
> > > > +	/* head */
> > > >    	len = legacy ? sizeof(*head) : sizeof(struct ceph_mds_request_head);
> > > > -	len += pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
> > > > -		sizeof(struct ceph_timespec);
> > > > -	len += sizeof(u32) + (sizeof(u64) * req->r_cred->group_info->ngroups);
> > > >    
> > > > -	/* calculate (max) length for cap releases */
> > > > +	/* filepaths */
> > > > +	len += 2 * (1 + sizeof(u32) + sizeof(u64));
> > > > +	len += pathlen1 + pathlen2;
> > > > +
> > > > +	/* cap releases */
> > > >    	len += sizeof(struct ceph_mds_request_release) *
> > > >    		(!!req->r_inode_drop + !!req->r_dentry_drop +
> > > >    		 !!req->r_old_inode_drop + !!req->r_old_dentry_drop);
> > > > @@ -2691,6 +2708,25 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
> > > >    	if (req->r_old_dentry_drop)
> > > >    		len += pathlen2;
> > > >    
> > > > +	/* MClientRequest tail */
> > > > +
> > > > +	/* req->r_stamp */
> > > > +	len += sizeof(struct ceph_timespec);
> > > > +
> > > > +	/* gid list */
> > > > +	len += sizeof(u32) + (sizeof(u64) * req->r_cred->group_info->ngroups);
> > > > +
> > > > +	/* alternate name */
> > > > +	len += sizeof(u32);	// TODO
> > > > +
> > > > +	/* fscrypt_auth */
> > > > +	len += sizeof(u32); // fscrypt_auth
> > > > +	if (req->r_fscrypt_auth)
> > > > +		len += ceph_fscrypt_auth_len(req->r_fscrypt_auth);
> > > > +
> > > > +	/* fscrypt_file */
> > > > +	len += sizeof(u32);
> > > > +
> > > >    	msg = ceph_msg_new2(CEPH_MSG_CLIENT_REQUEST, len, 1, GFP_NOFS, false);
> > > >    	if (!msg) {load more comments (105 replies)
> > > >    		msg = ERR_PTR(-ENOMEM);
> > > > @@ -2710,7 +2746,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
> > > >    	} else {
> > > >    		struct ceph_mds_request_head *new_head = msg->front.iov_base;
> > > >    
> > > > -		msg->hdr.version = cpu_to_le16(4);
> > > > +		msg->hdr.version = cpu_to_le16(6);
> > > >    		new_head->version = cpu_to_le16(CEPH_MDS_REQUEST_HEAD_VERSION);
> > > >    		head = (struct ceph_mds_request_head_old *)&new_head->oldest_client_tid;
> > > >    		p = msg->front.iov_base + sizeof(*new_head);
> > > > @@ -2761,7 +2797,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
> > > >    
> > > >    	head->num_releases = cpu_to_le16(releases);
> > > >    
> > > > -	encode_timestamp_and_gids(&p, req);
> > > > +	encode_mclientrequest_tail(&p, req);
> > > >    
> > > >    	if (WARN_ONCE(p > end, "p=%p end=%p len=%d\n", p, end, len)) {
> > > >    		ceph_msg_put(msg);
> > > > @@ -2870,7 +2906,7 @@ static int __prepare_send_request(struct ceph_mds_session *session,
> > > >    		rhead->num_releases = 0;
> > > >    
> > > >    		p = msg->front.iov_base + req->r_request_release_offset;
> > > > -		encode_timestamp_and_gids(&p, req);
> > > > +		encode_mclientrequest_tail(&p, req);
> > > >    
> > > >    		msg->front.iov_len = p - msg->front.iov_base;
> > > >    		msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
> > > > diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> > > > index 98a8710807d1..e7d2c8a1b9c1 100644
> > > > --- a/fs/ceph/mds_client.h
> > > > +++ b/fs/ceph/mds_client.h
> > > > @@ -278,6 +278,9 @@ struct ceph_mds_request {
> > > >    	struct mutex r_fill_mutex;
> > > >    
> > > >    	union ceph_mds_request_args r_args;
> > > > +
> > > > +	struct ceph_fscrypt_auth *r_fscrypt_auth;
> > > > +
> > > >    	int r_fmode;        /* file mode, if expecting cap */
> > > >    	const struct cred *r_cred;
> > > >    	int r_request_release_offset;
> > > > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > > > index 6bb6f9f9d79a..bc74c0b19c4f 100644
> > > > --- a/fs/ceph/super.h
> > > > +++ b/fs/ceph/super.h
> > > > @@ -1040,7 +1040,12 @@ static inline int ceph_do_getattr(struct inode *inode, int mask, bool force)
> > > >    }
> > > >    extern int ceph_permission(struct user_namespace *mnt_userns,
> > > >    			   struct inode *inode, int mask);
> > > > -extern int __ceph_setattr(struct inode *inode, struct iattr *attr);
> > > > +
> > > > +struct ceph_iattr {
> > > > +	struct ceph_fscrypt_auth	*fscrypt_auth;
> > > > +};
> > > > +
> > > > +extern int __ceph_setattr(struct inode *inode, struct iattr *attr, struct ceph_iattr *cia);
> > > >    extern int ceph_setattr(struct user_namespace *mnt_userns,
> > > >    			struct dentry *dentry, struct iattr *attr);
> > > >    extern int ceph_getattr(struct user_namespace *mnt_userns,
> > > > diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
> > > > index bc2699feddbe..a7d801a6ac88 100644
> > > > --- a/include/linux/ceph/ceph_fs.h
> > > > +++ b/include/linux/ceph/ceph_fs.h
> > > > @@ -356,14 +356,19 @@ enum {
> > > >    
> > > >    extern const char *ceph_mds_op_name(int op);
> > > >    
> > > > -
> > > > -#define CEPH_SETATTR_MODE   1
> > > > -#define CEPH_SETATTR_UID    2
> > > > -#define CEPH_SETATTR_GID    4
> > > > -#define CEPH_SETATTR_MTIME  8
> > > > -#define CEPH_SETATTR_ATIME 16
> > > > -#define CEPH_SETATTR_SIZE  32
> > > > -#define CEPH_SETATTR_CTIME 64
> > > > +#define CEPH_SETATTR_MODE              (1 << 0)
> > > > +#define CEPH_SETATTR_UID               (1 << 1)
> > > > +#define CEPH_SETATTR_GID               (1 << 2)
> > > > +#define CEPH_SETATTR_MTIME             (1 << 3)
> > > > +#define CEPH_SETATTR_ATIME             (1 << 4)
> > > > +#define CEPH_SETATTR_SIZE              (1 << 5)
> > > > +#define CEPH_SETATTR_CTIME             (1 << 6)
> > > > +#define CEPH_SETATTR_MTIME_NOW         (1 << 7)
> > > > +#define CEPH_SETATTR_ATIME_NOW         (1 << 8)
> > > > +#define CEPH_SETATTR_BTIME             (1 << 9)
> > > > +#define CEPH_SETATTR_KILL_SGUID        (1 << 10)
> > > > +#define CEPH_SETATTR_FSCRYPT_AUTH      (1 << 11)
> > > > +#define CEPH_SETATTR_FSCRYPT_FILE      (1 << 12)
> > > >    
> > > >    /*
> > > >     * Ceph setxattr request flags.
> 

-- 
Jeff Layton <jlayton@kernel.org>