From f9e7a5fa51fbb6fcb9c1c7e2c89dd7df9e7fe253 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 6 Jun 2023 14:08:51 +0100 Subject: crypto: af_alg: Pin pages rather than ref'ing if appropriate Convert AF_ALG to use iov_iter_extract_pages() instead of iov_iter_get_pages(). This will pin pages or leave them unaltered rather than getting a ref on them as appropriate to the iterator. The pages need to be pinned for DIO-read rather than having refs taken on them to prevent VM copy-on-write from malfunctioning during a concurrent fork() (the result of the I/O would otherwise end up only visible to the child process and not the parent). Signed-off-by: David Howells cc: Herbert Xu cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: linux-crypto@vger.kernel.org cc: netdev@vger.kernel.org Acked-by: Herbert Xu Signed-off-by: Paolo Abeni --- crypto/af_alg.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'crypto') diff --git a/crypto/af_alg.c b/crypto/af_alg.c index 5f7252a5b7b44a..7caff10df64353 100644 --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -533,14 +533,17 @@ static const struct net_proto_family alg_family = { int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len) { + struct page **pages = sgl->pages; size_t off; ssize_t n; int npages, i; - n = iov_iter_get_pages2(iter, sgl->pages, len, ALG_MAX_PAGES, &off); + n = iov_iter_extract_pages(iter, &pages, len, ALG_MAX_PAGES, 0, &off); if (n < 0) return n; + sgl->need_unpin = iov_iter_extract_will_pin(iter); + npages = DIV_ROUND_UP(off + n, PAGE_SIZE); if (WARN_ON(npages == 0)) return -EINVAL; @@ -573,8 +576,9 @@ void af_alg_free_sg(struct af_alg_sgl *sgl) { int i; - for (i = 0; i < sgl->npages; i++) - put_page(sgl->pages[i]); + if (sgl->need_unpin) + for (i = 0; i < sgl->npages; i++) + unpin_user_page(sgl->pages[i]); } EXPORT_SYMBOL_GPL(af_alg_free_sg); -- cgit 1.2.3-korg