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cls_u32: use skb_header_pointer() to dereference data safely 

use skb_header_pointer() to dereference data safely

the original skb->data dereference isn't safe, as there isn't any skb->len or
skb_is_nonlinear() check. skb_header_pointer() is used instead in this patch.
And when the skb isn't long enough, we terminate the function u32_classify()
immediately with -1.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Changli Gao 2010-06-02 07:32:42 -07:00 committed by David S. Miller
parent edafe50240
commit fbc2e7d9cf
1 changed files with 34 additions and 11 deletions
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45
net/sched/cls_u32.c
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@ -98,11 +98,11 @@ static int u32_classify(struct sk_buff *skb, struct tcf_proto *tp, struct tcf_re
{
struct {
struct tc_u_knode *knode;
u8 *ptr;
unsigned int off;
} stack[TC_U32_MAXDEPTH];
struct tc_u_hnode *ht = (struct tc_u_hnode*)tp->root;
u8 *ptr = skb_network_header(skb);
unsigned int off = skb_network_offset(skb);
struct tc_u_knode *n;
int sdepth = 0;
int off2 = 0;
@ -134,8 +134,14 @@ next_knode:
#endif
for (i = n->sel.nkeys; i>0; i--, key++) {
unsigned int toff;
__be32 *data, _data;
if ((*(__be32*)(ptr+key->off+(off2&key->offmask))^key->val)&key->mask) {
toff = off + key->off + (off2 & key->offmask);
data = skb_header_pointer(skb, toff, 4, &_data);
if (!data)
goto out;
if ((*data ^ key->val) & key->mask) {
n = n->next;
goto next_knode;
}
@ -174,29 +180,45 @@ check_terminal:
if (sdepth >= TC_U32_MAXDEPTH)
goto deadloop;
stack[sdepth].knode = n;
stack[sdepth].ptr = ptr;
stack[sdepth].off = off;
sdepth++;
ht = n->ht_down;
sel = 0;
if (ht->divisor)
sel = ht->divisor&u32_hash_fold(*(__be32*)(ptr+n->sel.hoff), &n->sel,n->fshift);
if (ht->divisor) {
__be32 *data, _data;
data = skb_header_pointer(skb, off + n->sel.hoff, 4,
&_data);
if (!data)
goto out;
sel = ht->divisor & u32_hash_fold(*data, &n->sel,
n->fshift);
}
if (!(n->sel.flags&(TC_U32_VAROFFSET|TC_U32_OFFSET|TC_U32_EAT)))
goto next_ht;
if (n->sel.flags&(TC_U32_OFFSET|TC_U32_VAROFFSET)) {
off2 = n->sel.off + 3;
if (n->sel.flags&TC_U32_VAROFFSET)
off2 += ntohs(n->sel.offmask & *(__be16*)(ptr+n->sel.offoff)) >>n->sel.offshift;
if (n->sel.flags & TC_U32_VAROFFSET) {
__be16 *data, _data;
data = skb_header_pointer(skb,
off + n->sel.offoff,
2, &_data);
if (!data)
goto out;
off2 += ntohs(n->sel.offmask & *data) >>
n->sel.offshift;
}
off2 &= ~3;
}
if (n->sel.flags&TC_U32_EAT) {
ptr += off2;
off += off2;
off2 = 0;
}
if (ptr < skb_tail_pointer(skb))
if (off < skb->len)
goto next_ht;
}
@ -204,9 +226,10 @@ check_terminal:
if (sdepth--) {
n = stack[sdepth].knode;
ht = n->ht_up;
ptr = stack[sdepth].ptr;
off = stack[sdepth].off;
goto check_terminal;
}
out:
return -1;
deadloop: