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Merge branch 'skb-frag-kmap_atomic-fixes'

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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: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2021-01-11 18:20:12 -08:00
commit 1ee527a79f
4 changed files with 28 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/skbuff.h
View File

@ -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,

30
net/core/skbuff.c
View File

@ -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 @@ next_skb:
st->stepped_offset += skb_headlen(st->cur_skb);
while (st->frag_idx < skb_shinfo(st->cur_skb)->nr_frags) {
frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
block_limit = skb_frag_size(frag) + st->stepped_offset;
unsigned int pg_idx, pg_off, pg_sz;
frag = &skb_shinfo(st->cur_skb)->frags[st->frag_idx];
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 @@ next_skb:
st->frag_data = NULL;
}
st->frag_idx++;
st->stepped_offset += skb_frag_size(frag);
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++;
}
}
if (st->frag_data) {

7
net/ipv4/esp4.c
View File

@ -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,

7
net/ipv6/esp6.c
View File

@ -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,