Commit 790e5ef5 authored by David S. Miller's avatar David S. Miller

Merge branch 'sk_filter-trim-limit'

Willem de Bruijn says:

====================
limit sk_filter trim to payload

Sockets can apply a filter to incoming packets to drop or trim them.
Fix two codepaths that call skb_pull/__skb_pull after sk_filter
without checking for packet length.

Reading beyond skb->tail after trimming happens in more codepaths, but
safety of reading in the linear segment is based on minimum allocation
size (MAX_HEADER, GRO_MAX_HEAD, ..).
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 22cb99fb 4f0c40d9
......@@ -467,7 +467,11 @@ static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
}
#endif /* CONFIG_DEBUG_SET_MODULE_RONX */
int sk_filter(struct sock *sk, struct sk_buff *skb);
int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap);
static inline int sk_filter(struct sock *sk, struct sk_buff *skb)
{
return sk_filter_trim_cap(sk, skb, 1);
}
struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err);
void bpf_prog_free(struct bpf_prog *fp);
......
......@@ -1576,7 +1576,13 @@ static inline void sock_put(struct sock *sk)
*/
void sock_gen_put(struct sock *sk);
int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested);
int __sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested,
unsigned int trim_cap);
static inline int sk_receive_skb(struct sock *sk, struct sk_buff *skb,
const int nested)
{
return __sk_receive_skb(sk, skb, nested, 1);
}
static inline void sk_tx_queue_set(struct sock *sk, int tx_queue)
{
......
......@@ -53,9 +53,10 @@
#include <net/sock_reuseport.h>
/**
* sk_filter - run a packet through a socket filter
* sk_filter_trim_cap - run a packet through a socket filter
* @sk: sock associated with &sk_buff
* @skb: buffer to filter
* @cap: limit on how short the eBPF program may trim the packet
*
* Run the eBPF program and then cut skb->data to correct size returned by
* the program. If pkt_len is 0 we toss packet. If skb->len is smaller
......@@ -64,7 +65,7 @@
* be accepted or -EPERM if the packet should be tossed.
*
*/
int sk_filter(struct sock *sk, struct sk_buff *skb)
int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
{
int err;
struct sk_filter *filter;
......@@ -85,14 +86,13 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
filter = rcu_dereference(sk->sk_filter);
if (filter) {
unsigned int pkt_len = bpf_prog_run_save_cb(filter->prog, skb);
err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
err = pkt_len ? pskb_trim(skb, max(cap, pkt_len)) : -EPERM;
}
rcu_read_unlock();
return err;
}
EXPORT_SYMBOL(sk_filter);
EXPORT_SYMBOL(sk_filter_trim_cap);
static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
{
......
......@@ -452,11 +452,12 @@ int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
}
EXPORT_SYMBOL(sock_queue_rcv_skb);
int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)
int __sk_receive_skb(struct sock *sk, struct sk_buff *skb,
const int nested, unsigned int trim_cap)
{
int rc = NET_RX_SUCCESS;
if (sk_filter(sk, skb))
if (sk_filter_trim_cap(sk, skb, trim_cap))
goto discard_and_relse;
skb->dev = NULL;
......@@ -492,7 +493,7 @@ int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)
kfree_skb(skb);
goto out;
}
EXPORT_SYMBOL(sk_receive_skb);
EXPORT_SYMBOL(__sk_receive_skb);
struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
{
......
......@@ -868,7 +868,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
goto discard_and_relse;
nf_reset(skb);
return sk_receive_skb(sk, skb, 1);
return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4);
no_dccp_socket:
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
......
......@@ -732,7 +732,7 @@ static int dccp_v6_rcv(struct sk_buff *skb)
if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
return sk_receive_skb(sk, skb, 1) ? -1 : 0;
return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4) ? -1 : 0;
no_dccp_socket:
if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
......
......@@ -164,7 +164,8 @@ static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int framety
rose_frames_acked(sk, nr);
if (ns == rose->vr) {
rose_start_idletimer(sk);
if (sock_queue_rcv_skb(sk, skb) == 0) {
if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 &&
__sock_queue_rcv_skb(sk, skb) == 0) {
rose->vr = (rose->vr + 1) % ROSE_MODULUS;
queued = 1;
} else {
......
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