[RFC PATCH v3 10/16] 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 | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/ceph/crypto.h |  8 +++++++
 fs/ceph/inode.c  | 10 ++++++--
 fs/ceph/super.h  |  3 +++
 4 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 879d9a0d3751..f037a4939026 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -46,3 +46,64 @@ void ceph_fscrypt_set_ops(struct super_block *sb)
 {
 	fscrypt_set_ops(sb, &ceph_fscrypt_ops);
 }
+
+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->i_flags |= S_ENCRYPTED;
+
+	ctxsize = fscrypt_context_for_new_inode(&as->fscrypt, inode);
+	if (ctxsize < 0)
+		return ctxsize;
+
+	/* 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 b5f38ee80553..c1b6ec4b2961 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -11,6 +11,8 @@
 #define	CEPH_XATTR_NAME_ENCRYPTION_CONTEXT	"encryption.ctx"
 
 void 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 f50e7873bf6e..2fda08518312 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>
 
 /*
@@ -73,12 +74,17 @@ 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 c05ed00035ec..5d5283552c03 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1003,6 +1003,9 @@ 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