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Message-ID: <267f0fe8665d3f7d89893d163a4cb0b5c215d22f.camel@kernel.org>
Subject: Re: [PATCH] NFSD: fix endianness issue in nfsd4_encode_fattr4
From: Jeff Layton <jlayton@kernel.org>
To: Vasily Gorbik <gor@linux.ibm.com>, Chuck Lever <chuck.lever@oracle.com>
Cc: Neil Brown <neilb@suse.de>, Olga Kornievskaia <kolga@netapp.com>, Dai
 Ngo <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>,
 linux-nfs@vger.kernel.org,  linux-kernel@vger.kernel.org
Date: Thu, 11 Apr 2024 06:20:25 -0400
In-Reply-To: <patch.git-0ff58649313e.your-ad-here.call-01712828617-ext-4049@work.hours>
References: 
	<patch.git-0ff58649313e.your-ad-here.call-01712828617-ext-4049@work.hours>
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On Thu, 2024-04-11 at 11:45 +0200, Vasily Gorbik wrote:
> The nfs4 mount fails with EIO on 64-bit big endian architectures since
> v6.7. The issue arises from employing a union in the nfsd4_encode_fattr4(=
)
> function to overlay a 32-bit array with a 64-bit values based bitmap,
> which does not function as intended. Address the endianness issue by
> utilizing bitmap_from_arr32() to copy 32-bit attribute masks into a
> bitmap in an endianness-agnostic manner.
>=20
> Cc: <stable@vger.kernel.org>
> Fixes: fce7913b13d0 ("NFSD: Use a bitmask loop to encode FATTR4 results")
> Link: https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/2060217
> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
> ---
>  fs/nfsd/nfs4xdr.c | 47 +++++++++++++++++++++++------------------------
>  1 file changed, 23 insertions(+), 24 deletions(-)
>=20
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 10439d569d9c..85d43b3249f9 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3519,11 +3519,13 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struc=
t xdr_stream *xdr,
>  		    struct dentry *dentry, const u32 *bmval,
>  		    int ignore_crossmnt)
>  {
> +	DECLARE_BITMAP(attr_bitmap, ARRAY_SIZE(nfsd4_enc_fattr4_encode_ops));
>  	struct nfsd4_fattr_args args;
>  	struct svc_fh *tempfh =3D NULL;
>  	int starting_len =3D xdr->buf->len;
>  	__be32 *attrlen_p, status;
>  	int attrlen_offset;
> +	u32 attrmask[3];
>  	int err;
>  	struct nfsd4_compoundres *resp =3D rqstp->rq_resp;
>  	u32 minorversion =3D resp->cstate.minorversion;
> @@ -3531,10 +3533,6 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct=
 xdr_stream *xdr,
>  		.mnt	=3D exp->ex_path.mnt,
>  		.dentry	=3D dentry,
>  	};
> -	union {
> -		u32		attrmask[3];
> -		unsigned long	mask[2];
> -	} u;
>  	unsigned long bit;
>  	bool file_modified =3D false;
>  	u64 size =3D 0;
> @@ -3550,20 +3548,19 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struc=
t xdr_stream *xdr,
>  	/*
>  	 * Make a local copy of the attribute bitmap that can be modified.
>  	 */
> -	memset(&u, 0, sizeof(u));
> -	u.attrmask[0] =3D bmval[0];
> -	u.attrmask[1] =3D bmval[1];
> -	u.attrmask[2] =3D bmval[2];
> +	attrmask[0] =3D bmval[0];
> +	attrmask[1] =3D bmval[1];
> +	attrmask[2] =3D bmval[2];
> =20
>  	args.rdattr_err =3D 0;
>  	if (exp->ex_fslocs.migrated) {
> -		status =3D fattr_handle_absent_fs(&u.attrmask[0], &u.attrmask[1],
> -						&u.attrmask[2], &args.rdattr_err);
> +		status =3D fattr_handle_absent_fs(&attrmask[0], &attrmask[1],
> +						&attrmask[2], &args.rdattr_err);
>  		if (status)
>  			goto out;
>  	}
>  	args.size =3D 0;
> -	if (u.attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
> +	if (attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
>  		status =3D nfsd4_deleg_getattr_conflict(rqstp, d_inode(dentry),
>  					&file_modified, &size);
>  		if (status)
> @@ -3582,16 +3579,16 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struc=
t xdr_stream *xdr,
> =20
>  	if (!(args.stat.result_mask & STATX_BTIME))
>  		/* underlying FS does not offer btime so we can't share it */
> -		u.attrmask[1] &=3D ~FATTR4_WORD1_TIME_CREATE;
> -	if ((u.attrmask[0] & (FATTR4_WORD0_FILES_AVAIL | FATTR4_WORD0_FILES_FRE=
E |
> +		attrmask[1] &=3D ~FATTR4_WORD1_TIME_CREATE;
> +	if ((attrmask[0] & (FATTR4_WORD0_FILES_AVAIL | FATTR4_WORD0_FILES_FREE =
|
>  			FATTR4_WORD0_FILES_TOTAL | FATTR4_WORD0_MAXNAME)) ||
> -	    (u.attrmask[1] & (FATTR4_WORD1_SPACE_AVAIL | FATTR4_WORD1_SPACE_FRE=
E |
> +	    (attrmask[1] & (FATTR4_WORD1_SPACE_AVAIL | FATTR4_WORD1_SPACE_FREE =
|
>  		       FATTR4_WORD1_SPACE_TOTAL))) {
>  		err =3D vfs_statfs(&path, &args.statfs);
>  		if (err)
>  			goto out_nfserr;
>  	}
> -	if ((u.attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) &&
> +	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) &&
>  	    !fhp) {
>  		tempfh =3D kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
>  		status =3D nfserr_jukebox;
> @@ -3606,10 +3603,10 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struc=
t xdr_stream *xdr,
>  		args.fhp =3D fhp;
> =20
>  	args.acl =3D NULL;
> -	if (u.attrmask[0] & FATTR4_WORD0_ACL) {
> +	if (attrmask[0] & FATTR4_WORD0_ACL) {
>  		err =3D nfsd4_get_nfs4_acl(rqstp, dentry, &args.acl);
>  		if (err =3D=3D -EOPNOTSUPP)
> -			u.attrmask[0] &=3D ~FATTR4_WORD0_ACL;
> +			attrmask[0] &=3D ~FATTR4_WORD0_ACL;
>  		else if (err =3D=3D -EINVAL) {
>  			status =3D nfserr_attrnotsupp;
>  			goto out;
> @@ -3621,17 +3618,17 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struc=
t xdr_stream *xdr,
> =20
>  #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
>  	args.context =3D NULL;
> -	if ((u.attrmask[2] & FATTR4_WORD2_SECURITY_LABEL) ||
> -	     u.attrmask[0] & FATTR4_WORD0_SUPPORTED_ATTRS) {
> +	if ((attrmask[2] & FATTR4_WORD2_SECURITY_LABEL) ||
> +	     attrmask[0] & FATTR4_WORD0_SUPPORTED_ATTRS) {
>  		if (exp->ex_flags & NFSEXP_SECURITY_LABEL)
>  			err =3D security_inode_getsecctx(d_inode(dentry),
>  						&args.context, &args.contextlen);
>  		else
>  			err =3D -EOPNOTSUPP;
>  		args.contextsupport =3D (err =3D=3D 0);
> -		if (u.attrmask[2] & FATTR4_WORD2_SECURITY_LABEL) {
> +		if (attrmask[2] & FATTR4_WORD2_SECURITY_LABEL) {
>  			if (err =3D=3D -EOPNOTSUPP)
> -				u.attrmask[2] &=3D ~FATTR4_WORD2_SECURITY_LABEL;
> +				attrmask[2] &=3D ~FATTR4_WORD2_SECURITY_LABEL;
>  			else if (err)
>  				goto out_nfserr;
>  		}
> @@ -3639,8 +3636,8 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct =
xdr_stream *xdr,
>  #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
> =20
>  	/* attrmask */
> -	status =3D nfsd4_encode_bitmap4(xdr, u.attrmask[0],
> -				      u.attrmask[1], u.attrmask[2]);
> +	status =3D nfsd4_encode_bitmap4(xdr, attrmask[0], attrmask[1],
> +				      attrmask[2]);
>  	if (status)
>  		goto out;
> =20
> @@ -3649,7 +3646,9 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct =
xdr_stream *xdr,
>  	attrlen_p =3D xdr_reserve_space(xdr, XDR_UNIT);
>  	if (!attrlen_p)
>  		goto out_resource;
> -	for_each_set_bit(bit, (const unsigned long *)&u.mask,
> +	bitmap_from_arr32(attr_bitmap, attrmask,
> +			  ARRAY_SIZE(nfsd4_enc_fattr4_encode_ops));
> +	for_each_set_bit(bit, attr_bitmap,
>  			 ARRAY_SIZE(nfsd4_enc_fattr4_encode_ops)) {
>  		status =3D nfsd4_enc_fattr4_encode_ops[bit](xdr, &args);
>  		if (status !=3D nfs_ok)

I learned something new today -- I wasn't aware of lib/bitmap.c! This
looks like a nice cleanup too. The union was sort of nasty.

Reviewed-by: Jeff Layton <jlayton@kernel.org>