Re: [RFC PATCH v4 08/17] ceph: add routine to create fscrypt context prior to RPC

[Luis Henriques <lhenriques@suse.de>]

Jeff Layton <jlayton@kernel.org> writes:

> 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@kernel.org>
> ---
>  fs/ceph/crypto.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/ceph/crypto.h | 12 ++++++++++
>  fs/ceph/inode.c  |  9 +++++--
>  fs/ceph/super.h  |  3 +++
>  4 files changed, 83 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);
> +		}
> +	}
> +

I've been staring at this function for a bit.  And at this point I would
expect something like this:

	} else
		as->pagelist = pagelist;

as I'm not seeing pagelist being used anywhere if it's allocated in this
function.

Cheers,
-- 
Luis

> 
> +	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 0dd043b56096..cc4e481bf13a 100644
> --- a/fs/ceph/crypto.h
> +++ b/fs/ceph/crypto.h
> @@ -18,6 +18,9 @@ static inline void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
>  	fscrypt_free_dummy_policy(&fsc->dummy_enc_policy);
>  }
>  
> +int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
> +				 struct ceph_acl_sec_ctx *as);
> +
>  #else /* CONFIG_FS_ENCRYPTION */
>  
>  static inline void ceph_fscrypt_set_ops(struct super_block *sb)
> @@ -27,6 +30,15 @@ static inline void ceph_fscrypt_set_ops(struct super_block *sb)
>  static inline void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
>  {
>  }
> +
> +static inline int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
> +						struct ceph_acl_sec_ctx *as)
> +{
> +	if (IS_ENCRYPTED(dir))
> +		return -EOPNOTSUPP;
> +	return 0;
> +}
> +
>  #endif /* CONFIG_FS_ENCRYPTION */
>  
>  #endif
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index d004f294a256..2854711e8988 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -83,12 +83,17 @@ 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 7a022c7c38b6..2411813ab552 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -1031,6 +1031,9 @@ 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;
>  };
> -- 
>
> 2.29.2
>