From: Luís Henriques <lhenriques@xxxxxxx>
When creating a snapshot, the .snap directories for every subdirectory will
show the snapshot name in the "long format":
# mkdir .snap/my-snap
# ls my-dir/.snap/
_my-snap_1099511627782
Encrypted snapshots will need to be able to handle these snapshot names by
encrypting/decrypting only the snapshot part of the string ('my-snap').
Also, since the MDS prevents snapshot names to be bigger than 240 characters
it is necessary to adapt CEPH_NOHASH_NAME_MAX to accommodate this extra
limitation.
Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx>
Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/crypto.c | 190 ++++++++++++++++++++++++++++++++++++++++-------
fs/ceph/crypto.h | 4 +-
2 files changed, 165 insertions(+), 29 deletions(-)
diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 590477d6e3ef..d23b3d1c59c5 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -189,16 +189,100 @@ void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, struct ceph_acl_se
swap(req->r_fscrypt_auth, as->fscrypt_auth);
}
-int ceph_encode_encrypted_dname(const struct inode *parent, struct qstr *d_name, char *buf)
+/*
+ * User-created snapshots can't start with '_'. Snapshots that start with this
+ * character are special (hint: there aren't real snapshots) and use the
+ * following format:
+ *
+ * _<SNAPSHOT-NAME>_<INODE-NUMBER>
+ *
+ * where:
+ * - <SNAPSHOT-NAME> - the real snapshot name that may need to be decrypted,
+ * - <INODE-NUMBER> - the inode number (in decimal) for the actual snapshot
+ *
+ * This function parses these snapshot names and returns the inode
+ * <INODE-NUMBER>. 'name_len' will also bet set with the <SNAPSHOT-NAME>
+ * length.
+ */
+static struct inode *parse_longname(const struct inode *parent, const char *name,
+ int *name_len)
+{
+ struct inode *dir = NULL;
+ struct ceph_vino vino = { .snap = CEPH_NOSNAP };
+ char *inode_number;
+ char *name_end;
+ int orig_len = *name_len;
+ int ret = -EIO;
+
+ /* Skip initial '_' */
+ name++;
+ name_end = strrchr(name, '_');
+ if (!name_end) {
+ dout("Failed to parse long snapshot name: %s\n", name);
+ return ERR_PTR(-EIO);
+ }
+ *name_len = (name_end - name);
+ if (*name_len <= 0) {
+ pr_err("Failed to parse long snapshot name\n");
+ return ERR_PTR(-EIO);
+ }
+
+ /* Get the inode number */
+ inode_number = kmemdup_nul(name_end + 1,
+ orig_len - *name_len - 2,
+ GFP_KERNEL);
+ if (!inode_number)
+ return ERR_PTR(-ENOMEM);
+ ret = kstrtou64(inode_number, 10, &vino.ino);
+ if (ret) {
+ dout("Failed to parse inode number: %s\n", name);
+ dir = ERR_PTR(ret);
+ goto out;
+ }
+
+ /* And finally the inode */
+ dir = ceph_find_inode(parent->i_sb, vino);
+ if (!dir) {
+ /* This can happen if we're not mounting cephfs on the root */
+ dir = ceph_get_inode(parent->i_sb, vino, NULL);
+ if (!dir)
+ dir = ERR_PTR(-ENOENT);
+ }
+ if (IS_ERR(dir))
+ dout("Can't find inode %s (%s)\n", inode_number, name);
+
+out:
+ kfree(inode_number);
+ return dir;
+}
+
+int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name, char *buf)
{
+ struct inode *dir = parent;
+ struct qstr iname;
u32 len;
+ int name_len;
int elen;
int ret;
- u8 *cryptbuf;
+ u8 *cryptbuf = NULL;
+
+ iname.name = d_name->name;
+ name_len = d_name->len;
+
+ /* Handle the special case of snapshot names that start with '_' */
+ if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
+ (iname.name[0] == '_')) {
+ dir = parse_longname(parent, iname.name, &name_len);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+ iname.name++; /* skip initial '_' */
+ }
+ iname.len = name_len;
- if (!fscrypt_has_encryption_key(parent)) {
+ if (!fscrypt_has_encryption_key(dir)) {
memcpy(buf, d_name->name, d_name->len);
- return d_name->len;
+ elen = d_name->len;
+ goto out;
}
/*
@@ -207,18 +291,22 @@ int ceph_encode_encrypted_dname(const struct inode *parent, struct qstr *d_name,
*
* See: fscrypt_setup_filename
*/
- if (!fscrypt_fname_encrypted_size(parent, d_name->len, NAME_MAX, &len))
- return -ENAMETOOLONG;
+ if (!fscrypt_fname_encrypted_size(dir, iname.len, NAME_MAX, &len)) {
+ elen = -ENAMETOOLONG;
+ goto out;
+ }
/* Allocate a buffer appropriate to hold the result */
cryptbuf = kmalloc(len > CEPH_NOHASH_NAME_MAX ? NAME_MAX : len, GFP_KERNEL);
- if (!cryptbuf)
- return -ENOMEM;
+ if (!cryptbuf) {
+ elen = -ENOMEM;
+ goto out;
+ }
- ret = fscrypt_fname_encrypt(parent, d_name, cryptbuf, len);
+ ret = fscrypt_fname_encrypt(dir, &iname, cryptbuf, len);
if (ret) {
- kfree(cryptbuf);
- return ret;
+ elen = ret;
+ goto out;
}
/* hash the end if the name is long enough */
@@ -234,12 +322,30 @@ int ceph_encode_encrypted_dname(const struct inode *parent, struct qstr *d_name,
/* base64 encode the encrypted name */
elen = ceph_base64_encode(cryptbuf, len, buf);
- kfree(cryptbuf);
dout("base64-encoded ciphertext name = %.*s\n", elen, buf);
+
+ /* To understand the 240 limit, see CEPH_NOHASH_NAME_MAX comments */
+ WARN_ON(elen > 240);
+ if ((elen > 0) && (dir != parent)) {
+ char tmp_buf[NAME_MAX];
+
+ elen = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
+ elen, buf, dir->i_ino);
+ memcpy(buf, tmp_buf, elen);
+ }
+
+out:
+ kfree(cryptbuf);
+ if (dir != parent) {
+ if ((dir->i_state & I_NEW))
+ discard_new_inode(dir);
+ else
+ iput(dir);
+ }
return elen;
}
-int ceph_encode_encrypted_fname(const struct inode *parent, struct dentry *dentry, char *buf)
+int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry, char *buf)
{
WARN_ON_ONCE(!fscrypt_has_encryption_key(parent));
@@ -264,29 +370,42 @@ int ceph_encode_encrypted_fname(const struct inode *parent, struct dentry *dentr
int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
struct fscrypt_str *oname, bool *is_nokey)
{
- int ret;
+ struct inode *dir = fname->dir;
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;
- }
+ char *name = fname->name;
+ int name_len = fname->name_len;
+ int ret;
/* Sanity check that the resulting name will fit in the buffer */
if (fname->name_len > NAME_MAX || fname->ctext_len > NAME_MAX)
return -EIO;
- ret = __fscrypt_prepare_readdir(fname->dir);
+ /* Handle the special case of snapshot names that start with '_' */
+ if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
+ (name[0] == '_')) {
+ dir = parse_longname(dir, name, &name_len);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+ name++; /* skip initial '_' */
+ }
+
+ if (!IS_ENCRYPTED(dir)) {
+ oname->name = fname->name;
+ oname->len = fname->name_len;
+ ret = 0;
+ goto out_inode;
+ }
+
+ ret = __fscrypt_prepare_readdir(dir);
if (ret)
- return ret;
+ goto out_inode;
/*
* 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)) {
+ if (!fscrypt_has_encryption_key(dir)) {
if (fname->no_copy)
oname->name = fname->name;
else
@@ -294,7 +413,8 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
oname->len = fname->name_len;
if (is_nokey)
*is_nokey = true;
- return 0;
+ ret = 0;
+ goto out_inode;
}
if (fname->ctext_len == 0) {
@@ -303,11 +423,11 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
if (!tname) {
ret = fscrypt_fname_alloc_buffer(NAME_MAX, &_tname);
if (ret)
- return ret;
+ goto out_inode;
tname = &_tname;
}
- declen = ceph_base64_decode(fname->name, fname->name_len, tname->name);
+ declen = ceph_base64_decode(name, name_len, tname->name);
if (declen <= 0) {
ret = -EIO;
goto out;
@@ -319,9 +439,25 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
iname.len = fname->ctext_len;
}
- ret = fscrypt_fname_disk_to_usr(fname->dir, 0, 0, &iname, oname);
+ ret = fscrypt_fname_disk_to_usr(dir, 0, 0, &iname, oname);
+ if (!ret && (dir != fname->dir)) {
+ char tmp_buf[CEPH_BASE64_CHARS(NAME_MAX)];
+
+ name_len = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
+ oname->len, oname->name, dir->i_ino);
+ memcpy(oname->name, tmp_buf, name_len);
+ oname->len = name_len;
+ }
+
out:
fscrypt_fname_free_buffer(&_tname);
+out_inode:
+ if ((dir != fname->dir) && !IS_ERR(dir)) {
+ if ((dir->i_state & I_NEW))
+ discard_new_inode(dir);
+ else
+ iput(dir);
+ }
return ret;
}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index d1726307bdb8..c6ee993f4ec8 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -101,8 +101,8 @@ void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc);
int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
struct ceph_acl_sec_ctx *as);
void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, struct ceph_acl_sec_ctx *as);
-int ceph_encode_encrypted_dname(const struct inode *parent, struct qstr *d_name, char *buf);
-int ceph_encode_encrypted_fname(const struct inode *parent, struct dentry *dentry, char *buf);
+int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name, char *buf);
+int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry, char *buf);
static inline int ceph_fname_alloc_buffer(struct inode *parent, struct fscrypt_str *fname)
{
--
2.35.1
