Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-15 08:31:55 +00:00
Code Issues Packages Projects Releases Wiki Activity

nfsd: check for oversized NFSv2/v3 arguments

Browse Source 
A client can append random data to the end of an NFSv2 or NFSv3 RPC call
without our complaining; we'll just stop parsing at the end of the
expected data and ignore the rest.

Encoded arguments and replies are stored together in an array of pages,
and if a call is too large it could leave inadequate space for the
reply.  This is normally OK because NFS RPC's typically have either
short arguments and long replies (like READ) or long arguments and short
replies (like WRITE).  But a client that sends an incorrectly long reply
can violate those assumptions.  This was observed to cause crashes.

So, insist that the argument not be any longer than we expect.

Also, several operations increment rq_next_page in the decode routine
before checking the argument size, which can leave rq_next_page pointing
well past the end of the page array, causing trouble later in
svc_free_pages.

As followup we may also want to rewrite the encoding routines to check
more carefully that they aren't running off the end of the page array.

Reported-by: Tuomas Haanpää <thaan@synopsys.com>
Reported-by: Ari Kauppi <ari@synopsys.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2017-04-06 22:36:31 -04:00
parent 13bf9fbff0
commit 51f5677777
3 changed files with 28 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
fs/nfsd/nfs3xdr.c
View File

@ -334,8 +334,11 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
if (!p)
return 0;
p = xdr_decode_hyper(p, &args->offset);
args->count = ntohl(*p++);
if (!xdr_argsize_check(rqstp, p))
return 0;
len = min(args->count, max_blocksize);
/* set up the kvec */
@ -349,7 +352,7 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
v++;
}
args->vlen = v;
return xdr_argsize_check(rqstp, p);
return 1;
}
int
@ -541,9 +544,11 @@ nfs3svc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p,
p = decode_fh(p, &args->fh);
if (!p)
return 0;
if (!xdr_argsize_check(rqstp, p))
return 0;
args->buffer = page_address(*(rqstp->rq_next_page++));
return xdr_argsize_check(rqstp, p);
return 1;
}
int
@ -569,10 +574,14 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p,
args->verf = p; p += 2;
args->dircount = ~0;
args->count = ntohl(*p++);
if (!xdr_argsize_check(rqstp, p))
return 0;
args->count = min_t(u32, args->count, PAGE_SIZE);
args->buffer = page_address(*(rqstp->rq_next_page++));
return xdr_argsize_check(rqstp, p);
return 1;
}
int
@ -590,6 +599,9 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, __be32 *p,
args->dircount = ntohl(*p++);
args->count = ntohl(*p++);
if (!xdr_argsize_check(rqstp, p))
return 0;
len = args->count = min(args->count, max_blocksize);
while (len > 0) {
struct page *p = *(rqstp->rq_next_page++);
@ -597,8 +609,7 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, __be32 *p,
args->buffer = page_address(p);
len -= PAGE_SIZE;
}
return xdr_argsize_check(rqstp, p);
return 1;
}
int

13
fs/nfsd/nfsxdr.c
View File

@ -257,6 +257,9 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
len = args->count = ntohl(*p++);
p++; /* totalcount - unused */
if (!xdr_argsize_check(rqstp, p))
return 0;
len = min_t(unsigned int, len, NFSSVC_MAXBLKSIZE_V2);
/* set up somewhere to store response.
@ -272,7 +275,7 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
v++;
}
args->vlen = v;
return xdr_argsize_check(rqstp, p);
return 1;
}
int
@ -362,9 +365,11 @@ nfssvc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p, struct nfsd_readli
p = decode_fh(p, &args->fh);
if (!p)
return 0;
if (!xdr_argsize_check(rqstp, p))
return 0;
args->buffer = page_address(*(rqstp->rq_next_page++));
return xdr_argsize_check(rqstp, p);
return 1;
}
int
@ -402,9 +407,11 @@ nfssvc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p,
args->cookie = ntohl(*p++);
args->count = ntohl(*p++);
args->count = min_t(u32, args->count, PAGE_SIZE);
if (!xdr_argsize_check(rqstp, p))
return 0;
args->buffer = page_address(*(rqstp->rq_next_page++));
return xdr_argsize_check(rqstp, p);
return 1;
}
/*

3
include/linux/sunrpc/svc.h
View File

@ -336,8 +336,7 @@ xdr_argsize_check(struct svc_rqst *rqstp, __be32 *p)
{
char *cp = (char *)p;
struct kvec *vec = &rqstp->rq_arg.head[0];
return cp >= (char*)vec->iov_base
&& cp <= (char*)vec->iov_base + vec->iov_len;
return cp == (char *)vec->iov_base + vec->iov_len;
}
static inline int