[RFC PATCH v3 14/16] ceph: add support to readdir for encrypted filenames

Jeff Layton
2020-09-14T19:17:57Z

Add helper functions for buffer management and for decrypting filenames
returned by the MDS. Wire those into the readdir codepaths.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/ceph/crypto.c | 47 +++++++++++++++++++++++++++++++++++++++
fs/ceph/crypto.h | 35 +++++++++++++++++++++++++++++
fs/ceph/dir.c | 58 +++++++++++++++++++++++++++++++++++++++---------
fs/ceph/inode.c | 31 +++++++++++++++++++++++---
4 files changed, 157 insertions(+), 14 deletions(-)

diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index f037a4939026..e3038c88c7a0 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -107,3 +107,50 @@ int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
ceph_pagelist_release(pagelist);
return ret;
}
+
+int ceph_fname_to_usr(struct inode *parent, char *name, u32 len,
+ struct fscrypt_str *tname, struct fscrypt_str *oname,
+ bool *is_nokey)
+{
+ int ret, declen;
+ u32 save_len;
+ struct fscrypt_str myname = FSTR_INIT(NULL, 0);
+
+ if (!IS_ENCRYPTED(parent)) {
+ oname->name = name;
+ oname->len = len;
+ return 0;
+ }
+
+ ret = fscrypt_get_encryption_info(parent);
+ if (ret)
+ return ret;
+
+ if (tname) {
+ save_len = tname->len;
+ } else {
+ int err;
+
+ save_len = 0;
+ err = fscrypt_fname_alloc_buffer(NAME_MAX, &myname);
+ if (err)
+ return err;
+ tname = &myname;
+ }
+
+ declen = fscrypt_base64_decode(name, len, tname->name);
+ if (declen < 0 || declen > NAME_MAX) {
+ ret = -EIO;
+ goto out;
+ }
+
+ tname->len = declen;
+
+ ret = fscrypt_fname_disk_to_usr(parent, 0, 0, tname, oname, is_nokey);
+
+ if (save_len)
+ tname->len = save_len;
+out:
+ fscrypt_fname_free_buffer(&myname);
+ return ret;
+}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index c1b6ec4b2961..df1a093848bb 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -6,6 +6,8 @@
#ifndef _CEPH_CRYPTO_H
#define _CEPH_CRYPTO_H

+#include <linux/fscrypt.h>
+
#ifdef CONFIG_FS_ENCRYPTION

#define CEPH_XATTR_NAME_ENCRYPTION_CONTEXT "encryption.ctx"
@@ -14,6 +16,22 @@ 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);

+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(struct inode *parent, char *name, u32 len, struct fscrypt_str *tname,
+ struct fscrypt_str *oname, bool *is_nokey);
+
#else /* CONFIG_FS_ENCRYPTION */

static inline int ceph_fscrypt_set_ops(struct super_block *sb)
@@ -27,6 +45,23 @@ static inline int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *
return 0;
}

+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(struct inode *inode, char *name, u32 len,
+ struct fscrypt_str *tname, struct fscrypt_str *oname, bool *is_nokey)
+{
+ oname->name = dname;
+ oname->len = dlen;
+ return 0;
+}
+
#endif /* CONFIG_FS_ENCRYPTION */

#endif
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index b6e5d751024d..e9fdb9c07320 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -9,6 +9,7 @@

#include "super.h"
#include "mds_client.h"
+#include "crypto.h"

/*
* Directory operations: readdir, lookup, create, link, unlink,
@@ -241,7 +242,9 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
di = ceph_dentry(dentry);
if (d_unhashed(dentry) ||
d_really_is_negative(dentry) ||
- di->lease_shared_gen != shared_gen) {
+ di->lease_shared_gen != shared_gen ||
+ ((dentry->d_flags & DCACHE_ENCRYPTED_NAME) &&
+ fscrypt_has_encryption_key(dir))) {
spin_unlock(&dentry->d_lock);
dput(dentry);
err = -EAGAIN;
@@ -313,6 +316,8 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
int err;
unsigned frag = -1;
struct ceph_mds_reply_info_parsed *rinfo;
+ struct fscrypt_str tname = FSTR_INIT(NULL, 0);
+ struct fscrypt_str oname = FSTR_INIT(NULL, 0);

dout("readdir %p file %p pos %llx\n", inode, file, ctx->pos);
if (dfi->file_info.flags & CEPH_F_ATEND)
@@ -340,6 +345,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
ctx->pos = 2;
}

+ if (IS_ENCRYPTED(inode)) {
+ err = fscrypt_get_encryption_info(inode);
+ if (err)
+ goto out;
+ }
+
spin_lock(&ci->i_ceph_lock);
/* request Fx cap. if have Fx, we don't need to release Fs cap
* for later create/unlink. */
@@ -360,6 +371,14 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
spin_unlock(&ci->i_ceph_lock);
}

+ err = ceph_fname_alloc_buffer(inode, &tname);
+ if (err < 0)
+ goto out;
+
+ err = ceph_fname_alloc_buffer(inode, &oname);
+ if (err < 0)
+ goto out;
+
/* proceed with a normal readdir */
more:
/* do we have the correct frag content buffered? */
@@ -387,12 +406,14 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
dout("readdir fetching %llx.%llx frag %x offset '%s'\n",
ceph_vinop(inode), frag, dfi->last_name);
req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
- if (IS_ERR(req))
- return PTR_ERR(req);
+ if (IS_ERR(req)) {
+ err = PTR_ERR(req);
+ goto out;
+ }
err = ceph_alloc_readdir_reply_buffer(req, inode);
if (err) {
ceph_mdsc_put_request(req);
- return err;
+ goto out;
}
/* hints to request -> mds selection code */
req->r_direct_mode = USE_AUTH_MDS;
@@ -405,7 +426,8 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
req->r_path2 = kstrdup(dfi->last_name, GFP_KERNEL);
if (!req->r_path2) {
ceph_mdsc_put_request(req);
- return -ENOMEM;
+ err = -ENOMEM;
+ goto out;
}
} else if (is_hash_order(ctx->pos)) {
req->r_args.readdir.offset_hash =
@@ -426,7 +448,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
err = ceph_mdsc_do_request(mdsc, NULL, req);
if (err < 0) {
ceph_mdsc_put_request(req);
- return err;
+ goto out;
}
dout("readdir got and parsed readdir result=%d on "
"frag %x, end=%d, complete=%d, hash_order=%d\n",
@@ -479,7 +501,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
err = note_last_dentry(dfi, rde->name, rde->name_len,
next_offset);
if (err)
- return err;
+ goto out;
} else if (req->r_reply_info.dir_end) {
dfi->next_offset = 2;
/* keep last name */
@@ -506,9 +528,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
}
}
for (; i < rinfo->dir_nr; i++) {
+ bool is_nokey = false;
struct ceph_mds_reply_dir_entry *rde = rinfo->dir_entries + i;
+ u32 olen = oname.len;

BUG_ON(rde->offset < ctx->pos);
+ BUG_ON(!rde->inode.in);

ctx->pos = rde->offset;
dout("readdir (%d/%d) -> %llx '%.*s' %p\n",
@@ -517,12 +542,20 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)

BUG_ON(!rde->inode.in);

- if (!dir_emit(ctx, rde->name, rde->name_len,
+ err = ceph_fname_to_usr(inode, rde->name, rde->name_len, &tname, &oname, &is_nokey);
+ if (err)
+ goto out;
+
+ if (!dir_emit(ctx, oname.name, oname.len,
ceph_present_ino(inode->i_sb, le64_to_cpu(rde->inode.in->ino)),
le32_to_cpu(rde->inode.in->mode) >> 12)) {
dout("filldir stopping us...\n");
- return 0;
+ err = 0;
+ goto out;
}
+
+ /* Reset the lengths to their original allocated vals */
+ oname.len = olen;
ctx->pos++;
}

@@ -577,9 +610,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
dfi->dir_ordered_count);
spin_unlock(&ci->i_ceph_lock);
}
-
+ err = 0;
dout("readdir %p file %p done.\n", inode, file);
- return 0;
+out:
+ ceph_fname_free_buffer(inode, &tname);
+ ceph_fname_free_buffer(inode, &oname);
+ return err;
}

static void reset_readdir(struct ceph_dir_file_info *dfi)
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 2fda08518312..c3a7a9f5603d 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1653,7 +1653,8 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
struct ceph_mds_session *session)
{
struct dentry *parent = req->r_dentry;
- struct ceph_inode_info *ci = ceph_inode(d_inode(parent));
+ struct inode *inode = d_inode(parent);
+ struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
struct qstr dname;
struct dentry *dn;
@@ -1664,6 +1665,8 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
u32 last_hash = 0;
u32 fpos_offset;
struct ceph_readdir_cache_control cache_ctl = {};
+ struct fscrypt_str tname = FSTR_INIT(NULL, 0);
+ struct fscrypt_str oname = FSTR_INIT(NULL, 0);

if (test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags))
return readdir_prepopulate_inodes_only(req, session);
@@ -1715,14 +1718,29 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
cache_ctl.index = req->r_readdir_cache_idx;
fpos_offset = req->r_readdir_offset;

+ err = ceph_fname_alloc_buffer(inode, &tname);
+ if (err < 0)
+ goto out;
+
+ err = ceph_fname_alloc_buffer(inode, &oname);
+ if (err < 0)
+ goto out;
+
/* FIXME: release caps/leases if error occurs */
for (i = 0; i < rinfo->dir_nr; i++) {
+ bool is_nokey = false;
struct ceph_mds_reply_dir_entry *rde = rinfo->dir_entries + i;
struct ceph_vino tvino;
+ u32 olen = oname.len;

- dname.name = rde->name;
- dname.len = rde->name_len;
+ err = ceph_fname_to_usr(inode, rde->name, rde->name_len, &tname, &oname, &is_nokey);
+ if (err)
+ goto out;
+
+ dname.name = oname.name;
+ dname.len = oname.len;
dname.hash = full_name_hash(parent, dname.name, dname.len);
+ oname.len = olen;

tvino.ino = le64_to_cpu(rde->inode.in->ino);
tvino.snap = le64_to_cpu(rde->inode.in->snapid);
@@ -1753,6 +1771,11 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
err = -ENOMEM;
goto out;
}
+ if (is_nokey) {
+ spin_lock(&dn->d_lock);
+ dn->d_flags |= DCACHE_ENCRYPTED_NAME;
+ spin_unlock(&dn->d_lock);
+ }
} else if (d_really_is_positive(dn) &&
(ceph_ino(d_inode(dn)) != tvino.ino ||
ceph_snap(d_inode(dn)) != tvino.snap)) {
@@ -1843,6 +1866,8 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
req->r_readdir_cache_idx = cache_ctl.index;
}
ceph_readdir_cache_release(&cache_ctl);
+ ceph_fname_free_buffer(inode, &tname);
+ ceph_fname_free_buffer(inode, &oname);
dout("readdir_prepopulate done\n");
return err;
}
--
2.26.2