Commit 68f74c34 authored by Chuck Lever's avatar Chuck Lever Committed by Li Lingfeng
Browse files

NFSD: Fix the behavior of READ near OFFSET_MAX 

stable inclusion
from stable-v5.10.220
commit 1726a39b0879acfb490b22dca643f26f4f907da9
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IADG80
CVE: CVE-2022-48827

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1726a39b0879acfb490b22dca643f26f4f907da9



--------------------------------

[ Upstream commit 0cb4d23a ]

Dan Aloni reports:
> Due to commit 8cfb9015 ("NFS: Always provide aligned buffers to
> the RPC read layers") on the client, a read of 0xfff is aligned up
> to server rsize of 0x1000.
>
> As a result, in a test where the server has a file of size
> 0x7fffffffffffffff, and the client tries to read from the offset
> 0x7ffffffffffff000, the read causes loff_t overflow in the server
> and it returns an NFS code of EINVAL to the client. The client as
> a result indefinitely retries the request.

The Linux NFS client does not handle NFS?ERR_INVAL, even though all
NFS specifications permit servers to return that status code for a
READ.

Instead of NFS?ERR_INVAL, have out-of-range READ requests succeed
and return a short result. Set the EOF flag in the result to prevent
the client from retrying the READ request. This behavior appears to
be consistent with Solaris NFS servers.

Note that NFSv3 and NFSv4 use u64 offset values on the wire. These
must be converted to loff_t internally before use -- an implicit
type cast is not adequate for this purpose. Otherwise VFS checks
against sb->s_maxbytes do not work properly.

Reported-by: default avatarDan Aloni <dan.aloni@vastdata.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>

Conflicts:
  fs/nfsd/nfs3proc.c
[Commit be63bd2a("NFSD: Update READ3arg decoder to use struct
xdr_stream") modified the method of initializing resp->count]
Signed-off-by: default avatarLi Lingfeng <lilingfeng3@huawei.com>
parent 55fafc5c

fs/nfsd/nfs3proc.c

+6 −2
Original line number Diff line number Diff line
@@ -145,18 +145,22 @@ nfsd3_proc_read(struct svc_rqst *rqstp) 
	struct nfsd3_readargs *argp = rqstp->rq_argp;

	struct nfsd3_readres *resp = rqstp->rq_resp;

	u32	max_blocksize = svc_max_payload(rqstp);

	unsigned long cnt = min(argp->count, max_blocksize);



	dprintk("nfsd: READ(3) %s %lu bytes at %Lu\n",

				SVCFH_fmt(&argp->fh),

				(unsigned long) argp->count,

				(unsigned long long) argp->offset);



	argp->count = min_t(u32, argp->count, max_blocksize);

	if (argp->offset > (u64)OFFSET_MAX)

		argp->offset = (u64)OFFSET_MAX;

	if (argp->offset + argp->count > (u64)OFFSET_MAX)

		argp->count = (u64)OFFSET_MAX - argp->offset;

	/* Obtain buffer pointer for payload.

	 * 1 (status) + 22 (post_op_attr) + 1 (count) + 1 (eof)

	 * + 1 (xdr opaque byte count) = 26

	 */

	resp->count = cnt;

	resp->count = argp->count;

	svc_reserve_auth(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);



	fh_copy(&resp->fh, &argp->fh);

fs/nfsd/nfs4proc.c

+6 −2
Original line number Diff line number Diff line
@@ -772,12 +772,16 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, 
	__be32 status;



	read->rd_nf = NULL;

	if (read->rd_offset >= OFFSET_MAX)

		return nfserr_inval;



	trace_nfsd_read_start(rqstp, &cstate->current_fh,

			      read->rd_offset, read->rd_length);



	read->rd_length = min_t(u32, read->rd_length, svc_max_payload(rqstp));

	if (read->rd_offset > (u64)OFFSET_MAX)

		read->rd_offset = (u64)OFFSET_MAX;

	if (read->rd_offset + read->rd_length > (u64)OFFSET_MAX)

		read->rd_length = (u64)OFFSET_MAX - read->rd_offset;



	/*

	 * If we do a zero copy read, then a client will see read data

	 * that reflects the state of the file *after* performing the

fs/nfsd/nfs4xdr.c

+2 −6
Original line number Diff line number Diff line
@@ -3886,10 +3886,8 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr, 
	}

	xdr_commit_encode(xdr);



	maxcount = svc_max_payload(resp->rqstp);

	maxcount = min_t(unsigned long, maxcount,

	maxcount = min_t(unsigned long, read->rd_length,

			 (xdr->buf->buflen - xdr->buf->len));

	maxcount = min_t(unsigned long, maxcount, read->rd_length);



	if (file->f_op->splice_read &&

	    test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags))
@@ -4714,10 +4712,8 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr, 
		return nfserr_resource;

	xdr_commit_encode(xdr);



	maxcount = svc_max_payload(resp->rqstp);

	maxcount = min_t(unsigned long, maxcount,

	maxcount = min_t(unsigned long, read->rd_length,

			 (xdr->buf->buflen - xdr->buf->len));

	maxcount = min_t(unsigned long, maxcount, read->rd_length);

	count    = maxcount;



	eof = read->rd_offset >= i_size_read(file_inode(file));