Re: [RFC PATCH v11 08/51] ceph: add support for fscrypt_auth/fscrypt_file to cap messages

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2022-03-22 at 10:12 -0400, Jeff Layton wrote:
> Add support for new version 12 cap messages that carry the new
> fscrypt_auth and fscrypt_file fields from the inode.
> 
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/ceph/caps.c | 76 +++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 63 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 7d8ef67a1032..b0b7688331b4 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -13,6 +13,7 @@
>  #include "super.h"
>  #include "mds_client.h"
>  #include "cache.h"
> +#include "crypto.h"
>  #include <linux/ceph/decode.h>
>  #include <linux/ceph/messenger.h>
>  
> @@ -1214,15 +1215,12 @@ struct cap_msg_args {
>  	umode_t			mode;
>  	bool			inline_data;
>  	bool			wake;
> +	u32			fscrypt_auth_len;
> +	u32			fscrypt_file_len;
> +	u8			fscrypt_auth[sizeof(struct ceph_fscrypt_auth)]; // for context
> +	u8			fscrypt_file[sizeof(u64)]; // for size
>  };
>  
> -/*
> - * cap struct size + flock buffer size + inline version + inline data size +
> - * osd_epoch_barrier + oldest_flush_tid
> - */
> -#define CAP_MSG_SIZE (sizeof(struct ceph_mds_caps) + \
> -		      4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4)
> -
>  /* Marshal up the cap msg to the MDS */
>  static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
>  {
> @@ -1238,7 +1236,7 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
>  	     arg->size, arg->max_size, arg->xattr_version,
>  	     arg->xattr_buf ? (int)arg->xattr_buf->vec.iov_len : 0);
>  
> -	msg->hdr.version = cpu_to_le16(10);
> +	msg->hdr.version = cpu_to_le16(12);
>  	msg->hdr.tid = cpu_to_le64(arg->flush_tid);
>  
>  	fc = msg->front.iov_base;
> @@ -1309,6 +1307,21 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
>  
>  	/* Advisory flags (version 10) */
>  	ceph_encode_32(&p, arg->flags);
> +
> +	/* dirstats (version 11) - these are r/o on the client */
> +	ceph_encode_64(&p, 0);
> +	ceph_encode_64(&p, 0);
> +
> +#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
> +	/* fscrypt_auth and fscrypt_file (version 12) */
> +	ceph_encode_32(&p, arg->fscrypt_auth_len);
> +	ceph_encode_copy(&p, arg->fscrypt_auth, arg->fscrypt_auth_len);
> +	ceph_encode_32(&p, arg->fscrypt_file_len);
> +	ceph_encode_copy(&p, arg->fscrypt_file, arg->fscrypt_file_len);
> +#else /* CONFIG_FS_ENCRYPTION */
> +	ceph_encode_32(&p, 0);
> +	ceph_encode_32(&p, 0);
> +#endif /* CONFIG_FS_ENCRYPTION */
>  }
>  
>  /*
> @@ -1430,8 +1443,37 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
>  		}
>  	}
>  	arg->flags = flags;
> +#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
> +	if (ci->fscrypt_auth_len &&
> +	    WARN_ON_ONCE(ci->fscrypt_auth_len != sizeof(struct ceph_fscrypt_auth))) {

The above WARN_ON_ONCE is too strict, and causes the client to reject v1
fscrypt contexts (as well as throw the warning). That should be a ">"
instead. I've fixed this in my tree and pushed the fix into wip-fscrypt.


> +		/* Don't set this if it isn't right size */
> +		arg->fscrypt_auth_len = 0;
> +	} else {
> +		arg->fscrypt_auth_len = ci->fscrypt_auth_len;
> +		memcpy(arg->fscrypt_auth, ci->fscrypt_auth,
> +			min_t(size_t, ci->fscrypt_auth_len, sizeof(arg->fscrypt_auth)));
> +	}
> +	/* FIXME: use this to track "real" size */
> +	arg->fscrypt_file_len = 0;
> +#endif /* CONFIG_FS_ENCRYPTION */
>  }
>  
> +#define CAP_MSG_FIXED_FIELDS (sizeof(struct ceph_mds_caps) + \
> +		      4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4 + 8 + 8 + 4 + 4)
> +
> +#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
> +static inline int cap_msg_size(struct cap_msg_args *arg)
> +{
> +	return CAP_MSG_FIXED_FIELDS + arg->fscrypt_auth_len +
> +			arg->fscrypt_file_len;
> +}
> +#else
> +static inline int cap_msg_size(struct cap_msg_args *arg)
> +{
> +	return CAP_MSG_FIXED_FIELDS;
> +}
> +#endif /* CONFIG_FS_ENCRYPTION */
> +
>  /*
>   * Send a cap msg on the given inode.
>   *
> @@ -1442,7 +1484,7 @@ static void __send_cap(struct cap_msg_args *arg, struct ceph_inode_info *ci)
>  	struct ceph_msg *msg;
>  	struct inode *inode = &ci->vfs_inode;
>  
> -	msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, CAP_MSG_SIZE, GFP_NOFS, false);
> +	msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, cap_msg_size(arg), GFP_NOFS, false);
>  	if (!msg) {
>  		pr_err("error allocating cap msg: ino (%llx.%llx) flushing %s tid %llu, requeuing cap.\n",
>  		       ceph_vinop(inode), ceph_cap_string(arg->dirty),
> @@ -1468,10 +1510,6 @@ static inline int __send_flush_snap(struct inode *inode,
>  	struct cap_msg_args	arg;
>  	struct ceph_msg		*msg;
>  
> -	msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, CAP_MSG_SIZE, GFP_NOFS, false);
> -	if (!msg)
> -		return -ENOMEM;
> -
>  	arg.session = session;
>  	arg.ino = ceph_vino(inode).ino;
>  	arg.cid = 0;
> @@ -1509,6 +1547,18 @@ static inline int __send_flush_snap(struct inode *inode,
>  	arg.flags = 0;
>  	arg.wake = false;
>  
> +	/*
> +	 * No fscrypt_auth changes from a capsnap. It will need
> +	 * to update fscrypt_file on size changes (TODO).
> +	 */
> +	arg.fscrypt_auth_len = 0;
> +	arg.fscrypt_file_len = 0;
> +
> +	msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, cap_msg_size(&arg),
> +			   GFP_NOFS, false);
> +	if (!msg)
> +		return -ENOMEM;
> +
>  	encode_cap_msg(msg, &arg);
>  	ceph_con_send(&arg.session->s_con, msg);
>  	return 0;

-- 
Jeff Layton <jlayton@kernel.org>