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

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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@xxxxxxxxxx>
---
   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.




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