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

Luis Henriques
2021-01-22T17:26:04Z

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
>