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

[Xiubo Li <xiubli@redhat.com>]

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 ?

>>> +		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 ?



>
> 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.