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Message-Id: <20220322141316.41325-21-jlayton@kernel.org>
Date: Tue, 22 Mar 2022 10:12:45 -0400
From: Jeff Layton <jlayton@...nel.org>
To: idryomov@...il.com, xiubli@...hat.com
Cc: ceph-devel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-fscrypt@...r.kernel.org, linux-kernel@...r.kernel.org,
lhenriques@...e.de
Subject: [RFC PATCH v11 20/51] ceph: add helpers for converting names for userland presentation
Define a new ceph_fname struct that we can use to carry information
about encrypted dentry names. Add helpers for working with these
objects, including ceph_fname_to_usr which formats an encrypted filename
for userland presentation.
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
fs/ceph/crypto.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/ceph/crypto.h | 41 ++++++++++++++++++++++++++
2 files changed, 117 insertions(+)
diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 3e3b12cd3413..86de8483032f 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -174,3 +174,79 @@ int ceph_encode_encrypted_fname(const struct inode *parent, struct dentry *dentr
dout("base64-encoded ciphertext name = %.*s\n", elen, buf);
return elen;
}
+
+/**
+ * ceph_fname_to_usr - convert a filename for userland presentation
+ * @fname: ceph_fname to be converted
+ * @tname: temporary name buffer to use for conversion (may be NULL)
+ * @oname: where converted name should be placed
+ * @is_nokey: set to true if key wasn't available during conversion (may be NULL)
+ *
+ * Given a filename (usually from the MDS), format it for presentation to
+ * userland. If @parent is not encrypted, just pass it back as-is.
+ *
+ * Otherwise, base64 decode the string, and then ask fscrypt to format it
+ * for userland presentation.
+ *
+ * Returns 0 on success or negative error code on error.
+ */
+int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
+ struct fscrypt_str *oname, bool *is_nokey)
+{
+ int ret;
+ struct fscrypt_str _tname = FSTR_INIT(NULL, 0);
+ struct fscrypt_str iname;
+
+ if (!IS_ENCRYPTED(fname->dir)) {
+ oname->name = fname->name;
+ oname->len = fname->name_len;
+ return 0;
+ }
+
+ /* Sanity check that the resulting name will fit in the buffer */
+ if (fname->name_len > FSCRYPT_BASE64URL_CHARS(NAME_MAX))
+ return -EIO;
+
+ ret = __fscrypt_prepare_readdir(fname->dir);
+ if (ret)
+ return ret;
+
+ /*
+ * Use the raw dentry name as sent by the MDS instead of
+ * generating a nokey name via fscrypt.
+ */
+ if (!fscrypt_has_encryption_key(fname->dir)) {
+ memcpy(oname->name, fname->name, fname->name_len);
+ oname->len = fname->name_len;
+ if (is_nokey)
+ *is_nokey = true;
+ return 0;
+ }
+
+ if (fname->ctext_len == 0) {
+ int declen;
+
+ if (!tname) {
+ ret = fscrypt_fname_alloc_buffer(NAME_MAX, &_tname);
+ if (ret)
+ return ret;
+ tname = &_tname;
+ }
+
+ declen = fscrypt_base64url_decode(fname->name, fname->name_len, tname->name);
+ if (declen <= 0) {
+ ret = -EIO;
+ goto out;
+ }
+ iname.name = tname->name;
+ iname.len = declen;
+ } else {
+ iname.name = fname->ctext;
+ iname.len = fname->ctext_len;
+ }
+
+ ret = fscrypt_fname_disk_to_usr(fname->dir, 0, 0, &iname, oname);
+out:
+ fscrypt_fname_free_buffer(&_tname);
+ return ret;
+}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index 9a66a29d5c8b..7e56aded5124 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -13,6 +13,14 @@ struct ceph_fs_client;
struct ceph_acl_sec_ctx;
struct ceph_mds_request;
+struct ceph_fname {
+ struct inode *dir;
+ char *name; // b64 encoded, possibly hashed
+ unsigned char *ctext; // binary crypttext (if any)
+ u32 name_len; // length of name buffer
+ u32 ctext_len; // length of crypttext
+};
+
struct ceph_fscrypt_auth {
__le32 cfa_version;
__le32 cfa_blob_len;
@@ -61,6 +69,22 @@ int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, struct ceph_acl_sec_ctx *as);
int ceph_encode_encrypted_fname(const struct inode *parent, struct dentry *dentry, char *buf);
+static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname)
+{
+ if (!IS_ENCRYPTED(parent))
+ return 0;
+ return fscrypt_fname_alloc_buffer(NAME_MAX, fname);
+}
+
+static inline void ceph_fname_free_buffer(struct inode *parent, struct fscrypt_str *fname)
+{
+ if (IS_ENCRYPTED(parent))
+ fscrypt_fname_free_buffer(fname);
+}
+
+int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
+ struct fscrypt_str *oname, bool *is_nokey);
+
#else /* CONFIG_FS_ENCRYPTION */
static inline void ceph_fscrypt_set_ops(struct super_block *sb)
@@ -89,6 +113,23 @@ static inline int ceph_encode_encrypted_fname(const struct inode *parent,
{
return -EOPNOTSUPP;
}
+
+static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname)
+{
+ return 0;
+}
+
+static inline void ceph_fname_free_buffer(struct inode *parent, struct fscrypt_str *fname)
+{
+}
+
+static inline int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
+ struct fscrypt_str *oname, bool *is_nokey)
+{
+ oname->name = fname->name;
+ oname->len = fname->name_len;
+ return 0;
+}
#endif /* CONFIG_FS_ENCRYPTION */
#endif
--
2.35.1
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