Commit 79f2f6ad authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: create symlinks with encrypted and base64-encoded targets 



When creating symlinks in encrypted directories, encrypt and
base64-encode the target with the new inode's key before sending to the
MDS.

When filling a symlinked inode, base64-decode it into a buffer that
we'll keep in ci->i_symlink. When get_link is called, decrypt the buffer
into a new one that will hang off i_link.

Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-and-tested-by: default avatarLuís Henriques <lhenriques@suse.de>
Reviewed-by: default avatarMilind Changire <mchangir@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent af9ffa6d

fs/ceph/dir.c

+49 −5
Original line number Diff line number Diff line
@@ -948,6 +948,43 @@ static int ceph_create(struct mnt_idmap *idmap, struct inode *dir, 
	return ceph_mknod(idmap, dir, dentry, mode, 0);

}



#if IS_ENABLED(CONFIG_FS_ENCRYPTION)

static int prep_encrypted_symlink_target(struct ceph_mds_request *req,

					 const char *dest)

{

	int err;

	int len = strlen(dest);

	struct fscrypt_str osd_link = FSTR_INIT(NULL, 0);



	err = fscrypt_prepare_symlink(req->r_parent, dest, len, PATH_MAX,

				      &osd_link);

	if (err)

		goto out;



	err = fscrypt_encrypt_symlink(req->r_new_inode, dest, len, &osd_link);

	if (err)

		goto out;



	req->r_path2 = kmalloc(CEPH_BASE64_CHARS(osd_link.len) + 1, GFP_KERNEL);

	if (!req->r_path2) {

		err = -ENOMEM;

		goto out;

	}



	len = ceph_base64_encode(osd_link.name, osd_link.len, req->r_path2);

	req->r_path2[len] = '\0';

out:

	fscrypt_fname_free_buffer(&osd_link);

	return err;

}

#else

static int prep_encrypted_symlink_target(struct ceph_mds_request *req,

					 const char *dest)

{

	return -EOPNOTSUPP;

}

#endif



static int ceph_symlink(struct mnt_idmap *idmap, struct inode *dir,

			struct dentry *dentry, const char *dest)

{
@@ -983,13 +1020,20 @@ static int ceph_symlink(struct mnt_idmap *idmap, struct inode *dir, 
		goto out_req;

	}



	req->r_parent = dir;

	ihold(dir);



	if (IS_ENCRYPTED(req->r_new_inode)) {

		err = prep_encrypted_symlink_target(req, dest);

		if (err)

			goto out_req;

	} else {

		req->r_path2 = kstrdup(dest, GFP_KERNEL);

		if (!req->r_path2) {

			err = -ENOMEM;

			goto out_req;

		}

	req->r_parent = dir;

	ihold(dir);

	}



	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);

	req->r_dentry = dget(dentry);

fs/ceph/inode.c

+101 −12
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
 */



static const struct inode_operations ceph_symlink_iops;

static const struct inode_operations ceph_encrypted_symlink_iops;



static void ceph_inode_work(struct work_struct *work);
@@ -640,6 +641,7 @@ void ceph_free_inode(struct inode *inode) 
#ifdef CONFIG_FS_ENCRYPTION

	kfree(ci->fscrypt_auth);

#endif

	fscrypt_free_inode(inode);

	kmem_cache_free(ceph_inode_cachep, ci);

}
@@ -837,6 +839,34 @@ void ceph_fill_file_time(struct inode *inode, int issued, 
		     inode, time_warp_seq, ci->i_time_warp_seq);

}



#if IS_ENABLED(CONFIG_FS_ENCRYPTION)

static int decode_encrypted_symlink(const char *encsym, int enclen, u8 **decsym)

{

	int declen;

	u8 *sym;



	sym = kmalloc(enclen + 1, GFP_NOFS);

	if (!sym)

		return -ENOMEM;



	declen = ceph_base64_decode(encsym, enclen, sym);

	if (declen < 0) {

		pr_err("%s: can't decode symlink (%d). Content: %.*s\n",

		       __func__, declen, enclen, encsym);

		kfree(sym);

		return -EIO;

	}

	sym[declen + 1] = '\0';

	*decsym = sym;

	return declen;

}

#else

static int decode_encrypted_symlink(const char *encsym, int symlen, u8 **decsym)

{

	return -EOPNOTSUPP;

}

#endif



/*

 * Populate an inode based on info from mds.  May be called on new or

 * existing inodes.
@@ -1071,17 +1101,32 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page, 
		inode->i_fop = &ceph_file_fops;

		break;

	case S_IFLNK:

		inode->i_op = &ceph_symlink_iops;

		if (!ci->i_symlink) {

			u32 symlen = iinfo->symlink_len;

			char *sym;



			spin_unlock(&ci->i_ceph_lock);



			if (IS_ENCRYPTED(inode)) {

				if (symlen != i_size_read(inode))

					pr_err("%s %llx.%llx BAD symlink size %lld\n",

						__func__, ceph_vinop(inode),

						i_size_read(inode));



				err = decode_encrypted_symlink(iinfo->symlink,

							       symlen, (u8 **)&sym);

				if (err < 0) {

					pr_err("%s decoding encrypted symlink failed: %d\n",

						__func__, err);

					goto out;

				}

				symlen = err;

				i_size_write(inode, symlen);

				inode->i_blocks = calc_inode_blocks(symlen);

			} else {

				if (symlen != i_size_read(inode)) {

				pr_err("%s %llx.%llx BAD symlink "

					"size %lld\n", __func__,

					ceph_vinop(inode),

					pr_err("%s %llx.%llx BAD symlink size %lld\n",

						__func__, ceph_vinop(inode),

						i_size_read(inode));

					i_size_write(inode, symlen);

					inode->i_blocks = calc_inode_blocks(symlen);
@@ -1091,6 +1136,7 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page, 
				sym = kstrndup(iinfo->symlink, symlen, GFP_NOFS);

				if (!sym)

					goto out;

			}



			spin_lock(&ci->i_ceph_lock);

			if (!ci->i_symlink)
@@ -1098,7 +1144,17 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page, 
			else

				kfree(sym); /* lost a race */

		}



		if (IS_ENCRYPTED(inode)) {

			/*

			 * Encrypted symlinks need to be decrypted before we can

			 * cache their targets in i_link. Don't touch it here.

			 */

			inode->i_op = &ceph_encrypted_symlink_iops;

		} else {

			inode->i_link = ci->i_symlink;

			inode->i_op = &ceph_symlink_iops;

		}

		break;

	case S_IFDIR:

		inode->i_op = &ceph_dir_iops;
@@ -2126,6 +2182,32 @@ static void ceph_inode_work(struct work_struct *work) 
	iput(inode);

}



static const char *ceph_encrypted_get_link(struct dentry *dentry,

					   struct inode *inode,

					   struct delayed_call *done)

{

	struct ceph_inode_info *ci = ceph_inode(inode);



	if (!dentry)

		return ERR_PTR(-ECHILD);



	return fscrypt_get_symlink(inode, ci->i_symlink, i_size_read(inode),

				   done);

}



static int ceph_encrypted_symlink_getattr(struct mnt_idmap *idmap,

					  const struct path *path,

					  struct kstat *stat, u32 request_mask,

					  unsigned int query_flags)

{

	int ret;



	ret = ceph_getattr(idmap, path, stat, request_mask, query_flags);

	if (ret)

		return ret;

	return fscrypt_symlink_getattr(path, stat);

}



/*

 * symlinks

 */
@@ -2136,6 +2218,13 @@ static const struct inode_operations ceph_symlink_iops = { 
	.listxattr = ceph_listxattr,

};



static const struct inode_operations ceph_encrypted_symlink_iops = {

	.get_link = ceph_encrypted_get_link,

	.setattr = ceph_setattr,

	.getattr = ceph_encrypted_symlink_getattr,

	.listxattr = ceph_listxattr,

};



int __ceph_setattr(struct inode *inode, struct iattr *attr,

		   struct ceph_iattr *cia)

{