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SUNRPC: fix copying of multiple pages in gss_read_proxy_verf()

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When the passed token is longer than 4032 bytes, the remaining part
of the token must be copied from the rqstp->rq_arg.pages. But the
copy must make sure it happens in a consecutive way.

With the existing code, the first memcpy copies 'length' bytes from
argv->iobase, but since the header is in front, this never fills the
whole first page of in_token->pages.

The mecpy in the loop copies the following bytes, but starts writing at
the next page of in_token->pages.  This leaves the last bytes of page 0
unwritten.

Symptoms were that users with many groups were not able to access NFS
exports, when using Active Directory as the KDC.

Signed-off-by: Martijn de Gouw <martijn.de.gouw@prodrive-technologies.com>
Fixes: 5866efa8cb "SUNRPC: Fix svcauth_gss_proxy_init()"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Martijn de Gouw 2020-10-19 13:42:27 +02:00 committed by J. Bruce Fields
parent 27a1e8a0f7
commit d48c812474
1 changed files with 17 additions and 10 deletions
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27
net/sunrpc/auth_gss/svcauth_gss.c
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@ -1147,9 +1147,9 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp,
struct gssp_in_token *in_token)
{
struct kvec *argv = &rqstp->rq_arg.head[0];
unsigned int page_base, length;
int pages, i, res;
size_t inlen;
unsigned int length, pgto_offs, pgfrom_offs;
int pages, i, res, pgto, pgfrom;
size_t inlen, to_offs, from_offs;
res = gss_read_common_verf(gc, argv, authp, in_handle);
if (res)
@ -1177,17 +1177,24 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp,
memcpy(page_address(in_token->pages[0]), argv->iov_base, length);
inlen -= length;
i = 1;
page_base = rqstp->rq_arg.page_base;
to_offs = length;
from_offs = rqstp->rq_arg.page_base;
while (inlen) {
length = min_t(unsigned int, inlen, PAGE_SIZE);
memcpy(page_address(in_token->pages[i]),
page_address(rqstp->rq_arg.pages[i]) + page_base,
pgto = to_offs >> PAGE_SHIFT;
pgfrom = from_offs >> PAGE_SHIFT;
pgto_offs = to_offs & ~PAGE_MASK;
pgfrom_offs = from_offs & ~PAGE_MASK;
length = min_t(unsigned int, inlen,
min_t(unsigned int, PAGE_SIZE - pgto_offs,
PAGE_SIZE - pgfrom_offs));
memcpy(page_address(in_token->pages[pgto]) + pgto_offs,
page_address(rqstp->rq_arg.pages[pgfrom]) + pgfrom_offs,
length);
to_offs += length;
from_offs += length;
inlen -= length;
page_base = 0;
i++;
}
return 0;
}