[RFC PATCH v2 11/18] ceph: add routine to create context prior to RPC

[Jeff Layton <jlayton@xxxxxxxxxx>]

After pre-creating a new inode, do an fscrypt prepare on it, fetch a
new encryption context and then marshal that into the security context
to be sent along with the RPC.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/ceph/crypto.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/crypto.h |  8 ++++++
 fs/ceph/inode.c  | 10 ++++++--
 fs/ceph/super.h  |  3 +++
 4 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 22a09d422b72..f4849f8b32df 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -67,3 +67,66 @@ int ceph_fscrypt_set_ops(struct super_block *sb)
 	}
 	return 0;
 }
+
+int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
+				 struct ceph_acl_sec_ctx *as)
+{
+	int ret, ctxsize;
+	size_t name_len;
+	char *name;
+	struct ceph_pagelist *pagelist = as->pagelist;
+	bool encrypted = false;
+
+	ret = fscrypt_prepare_new_inode(dir, inode, &encrypted);
+	if (ret)
+		return ret;
+	if (!encrypted)
+		return 0;
+
+	inode_set_flags(inode, S_ENCRYPTED, S_ENCRYPTED);
+
+	/* No need to set context for dummy encryption */
+	if (fscrypt_get_dummy_context(inode->i_sb))
+		return 0;
+
+	ctxsize = fscrypt_new_context_from_inode((union fscrypt_context *)&as->fscrypt, inode);
+
+	/* marshal it in page array */
+	if (!pagelist) {
+		pagelist = ceph_pagelist_alloc(GFP_KERNEL);
+		if (!pagelist)
+			return -ENOMEM;
+		ret = ceph_pagelist_reserve(pagelist, PAGE_SIZE);
+		if (ret)
+			goto out;
+		ceph_pagelist_encode_32(pagelist, 1);
+	}
+
+	name = CEPH_XATTR_NAME_ENCRYPTION_CONTEXT;
+	name_len = strlen(name);
+	ret = ceph_pagelist_reserve(pagelist, 4 * 2 + name_len + ctxsize);
+	if (ret)
+		goto out;
+
+	if (as->pagelist) {
+		BUG_ON(pagelist->length <= sizeof(__le32));
+		if (list_is_singular(&pagelist->head)) {
+			le32_add_cpu((__le32*)pagelist->mapped_tail, 1);
+		} else {
+			struct page *page = list_first_entry(&pagelist->head,
+							     struct page, lru);
+			void *addr = kmap_atomic(page);
+			le32_add_cpu((__le32*)addr, 1);
+			kunmap_atomic(addr);
+		}
+	}
+
+	ceph_pagelist_encode_32(pagelist, name_len);
+	ceph_pagelist_append(pagelist, name, name_len);
+	ceph_pagelist_encode_32(pagelist, ctxsize);
+	ceph_pagelist_append(pagelist, as->fscrypt, ctxsize);
+out:
+	if (pagelist && !as->pagelist)
+		ceph_pagelist_release(pagelist);
+	return ret;
+}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index af06dca5f5a6..bf893bd215c3 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -11,6 +11,8 @@
 #define	CEPH_XATTR_NAME_ENCRYPTION_CONTEXT	"encryption.ctx"
 
 int ceph_fscrypt_set_ops(struct super_block *sb);
+int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
+				 struct ceph_acl_sec_ctx *as);
 
 #else /* CONFIG_FS_ENCRYPTION */
 
@@ -19,6 +21,12 @@ static inline int ceph_fscrypt_set_ops(struct super_block *sb)
 	return 0;
 }
 
+static inline int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
+						struct ceph_acl_sec_ctx *as)
+{
+	return 0;
+}
+
 #endif /* CONFIG_FS_ENCRYPTION */
 
 #endif
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index e3c81b950f74..651148194316 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -18,6 +18,7 @@
 #include "super.h"
 #include "mds_client.h"
 #include "cache.h"
+#include "crypto.h"
 #include <linux/ceph/decode.h>
 
 /*
@@ -70,12 +71,17 @@ struct inode *ceph_new_inode(struct inode *dir, struct dentry *dentry,
 			goto out_err;
 	}
 
+	inode->i_state = 0;
+	inode->i_mode = *mode;
+
 	err = ceph_security_init_secctx(dentry, *mode, as_ctx);
 	if (err < 0)
 		goto out_err;
 
-	inode->i_state = 0;
-	inode->i_mode = *mode;
+	err = ceph_fscrypt_prepare_context(dir, inode, as_ctx);
+	if (err)
+		goto out_err;
+
 	return inode;
 out_err:
 	iput(inode);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index d788fa9b3eaa..cf04fcd3de69 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -995,6 +995,9 @@ struct ceph_acl_sec_ctx {
 #ifdef CONFIG_CEPH_FS_SECURITY_LABEL
 	void *sec_ctx;
 	u32 sec_ctxlen;
+#endif
+#ifdef CONFIG_FS_ENCRYPTION
+	u8	fscrypt[FSCRYPT_SET_CONTEXT_MAX_SIZE];
 #endif
 	struct ceph_pagelist *pagelist;
 };
-- 
2.26.2