Commit 1ee527a7 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'skb-frag-kmap_atomic-fixes' 

Willem de Bruijn says:

====================
skb frag: kmap_atomic fixes

skb frags may be backed by highmem and/or compound pages. Various
code calls kmap_atomic to safely access highmem pages. But this
needs additional care for compound pages. Fix a few issues:

patch 1 expect kmap mappings with CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
patch 2 fixes kmap_atomic + compound page support in skb_seq_read
patch 3 fixes kmap_atomic + compound page support in esp
====================

Link: https://lore.kernel.org/r/20210109221834.3459768-1-willemdebruijn.kernel@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents e56b3d94 9bd6b629

include/linux/skbuff.h

+2 −1
Original line number Diff line number Diff line
@@ -366,7 +366,7 @@ static inline void skb_frag_size_sub(skb_frag_t *frag, int delta) 
static inline bool skb_frag_must_loop(struct page *p)

{

#if defined(CONFIG_HIGHMEM)

	if (PageHighMem(p))

	if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) || PageHighMem(p))

		return true;

#endif

	return false;
@@ -1203,6 +1203,7 @@ struct skb_seq_state { 
	struct sk_buff	*root_skb;

	struct sk_buff	*cur_skb;

	__u8		*frag_data;

	__u32		frag_off;

};



void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,

net/core/skbuff.c

+23 −5
Original line number Diff line number Diff line
@@ -3442,6 +3442,7 @@ void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from, 
	st->root_skb = st->cur_skb = skb;

	st->frag_idx = st->stepped_offset = 0;

	st->frag_data = NULL;

	st->frag_off = 0;

}

EXPORT_SYMBOL(skb_prepare_seq_read);
@@ -3496,14 +3497,27 @@ unsigned int skb_seq_read(unsigned int consumed, const u8 **data, 
		st->stepped_offset += skb_headlen(st->cur_skb);



	while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {

		unsigned int pg_idx, pg_off, pg_sz;



		frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];

		block_limit = skb_frag_size(frag) + st->stepped_offset;



		pg_idx = 0;

		pg_off = skb_frag_off(frag);

		pg_sz = skb_frag_size(frag);



		if (skb_frag_must_loop(skb_frag_page(frag))) {

			pg_idx = (pg_off + st->frag_off) >> PAGE_SHIFT;

			pg_off = offset_in_page(pg_off + st->frag_off);

			pg_sz = min_t(unsigned int, pg_sz - st->frag_off,

						    PAGE_SIZE - pg_off);

		}



		block_limit = pg_sz + st->stepped_offset;

		if (abs_offset < block_limit) {

			if (!st->frag_data)

				st->frag_data = kmap_atomic(skb_frag_page(frag));

				st->frag_data = kmap_atomic(skb_frag_page(frag) + pg_idx);



			*data = (u8 *) st->frag_data + skb_frag_off(frag) +

			*data = (u8 *)st->frag_data + pg_off +

				(abs_offset - st->stepped_offset);



			return block_limit - abs_offset;
@@ -3514,8 +3528,12 @@ unsigned int skb_seq_read(unsigned int consumed, const u8 **data, 
			st->frag_data = NULL;

		}



		st->stepped_offset += pg_sz;

		st->frag_off += pg_sz;

		if (st->frag_off == skb_frag_size(frag)) {

			st->frag_off = 0;

			st->frag_idx++;

		st->stepped_offset += skb_frag_size(frag);

		}

	}



	if (st->frag_data) {

net/ipv4/esp4.c

+1 −6
Original line number Diff line number Diff line
@@ -443,7 +443,6 @@ static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb, 
int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)

{

	u8 *tail;

	u8 *vaddr;

	int nfrags;

	int esph_offset;

	struct page *page;
@@ -485,14 +484,10 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * 
			page = pfrag->page;

			get_page(page);



			vaddr = kmap_atomic(page);



			tail = vaddr + pfrag->offset;

			tail = page_address(page) + pfrag->offset;



			esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);



			kunmap_atomic(vaddr);



			nfrags = skb_shinfo(skb)->nr_frags;



			__skb_fill_page_desc(skb, nfrags, page, pfrag->offset,

net/ipv6/esp6.c

+1 −6
Original line number Diff line number Diff line
@@ -478,7 +478,6 @@ static int esp6_output_encap(struct xfrm_state *x, struct sk_buff *skb, 
int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)

{

	u8 *tail;

	u8 *vaddr;

	int nfrags;

	int esph_offset;

	struct page *page;
@@ -519,14 +518,10 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info 
			page = pfrag->page;

			get_page(page);



			vaddr = kmap_atomic(page);



			tail = vaddr + pfrag->offset;

			tail = page_address(page) + pfrag->offset;



			esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);



			kunmap_atomic(vaddr);



			nfrags = skb_shinfo(skb)->nr_frags;



			__skb_fill_page_desc(skb, nfrags, page, pfrag->offset,