evie/android_kernel_oneplus_msm8998
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rose: limit sk_filter trim to payload

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Sockets can have a filter program attached that drops or trims
incoming packets based on the filter program return value.

Rose requires data packets to have at least ROSE_MIN_LEN bytes. It
verifies this on arrival in rose_route_frame and unconditionally pulls
the bytes in rose_recvmsg. The filter can trim packets to below this
value in-between, causing pull to fail, leaving the partial header at
the time of skb_copy_datagram_msg.

Place a lower bound on the size to which sk_filter may trim packets
by introducing sk_filter_trim_cap and call this for rose packets.

CRs-Fixed: 1089895
Change-Id: Idc52737bc96097a9220dfe47bb76e94ff1026a05
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: f4979fcea7fd36d8e2f556abef86f80e0d5af1ba
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[subashab@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
This commit is contained in:
Willem de Bruijn 2016-11-15 14:43:27 -07:00 • committed by Subash Abhinov Kasiviswanathan
parent 1e17007652
commit f36f22a49d
3 changed files with 12 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/filter.h
View file

@ -421,7 +421,11 @@ 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);
}
int bpf_prog_select_runtime(struct bpf_prog *fp);
void bpf_prog_free(struct bpf_prog *fp);

9
net/core/filter.c
View file

@ -52,9 +52,10 @@
#include <net/dst.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
@ -63,7 +64,7 @@
* 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;
@ -85,13 +86,13 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
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)
{

3
net/rose/rose_in.c
View file

@ -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 {