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authorAlexei Starovoitov <ast@kernel.org>2019-01-28 18:43:34 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2019-01-31 23:14:55 +0100
commit6cab5e90ab2bd323c9f3811b6c70a4687df51e27 (patch)
tree0fc39a3f8010ea54edab9f8d70014b447ccb6bd2 /include
parent1bb54c4071f585ebef56ce8fdfe6026fa2cbcddd (diff)
downloadlinux-6cab5e90ab2bd323c9f3811b6c70a4687df51e27.tar.bz2
bpf: run bpf programs with preemption disabled
Disabled preemption is necessary for proper access to per-cpu maps from BPF programs. But the sender side of socket filters didn't have preemption disabled: unix_dgram_sendmsg->sk_filter->sk_filter_trim_cap->bpf_prog_run_save_cb->BPF_PROG_RUN and a combination of af_packet with tun device didn't disable either: tpacket_snd->packet_direct_xmit->packet_pick_tx_queue->ndo_select_queue-> tun_select_queue->tun_ebpf_select_queue->bpf_prog_run_clear_cb->BPF_PROG_RUN Disable preemption before executing BPF programs (both classic and extended). Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/filter.h21
1 files changed, 18 insertions, 3 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h
index ad106d845b22..e532fcc6e4b5 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -591,8 +591,8 @@ static inline u8 *bpf_skb_cb(struct sk_buff *skb)
return qdisc_skb_cb(skb)->data;
}
-static inline u32 bpf_prog_run_save_cb(const struct bpf_prog *prog,
- struct sk_buff *skb)
+static inline u32 __bpf_prog_run_save_cb(const struct bpf_prog *prog,
+ struct sk_buff *skb)
{
u8 *cb_data = bpf_skb_cb(skb);
u8 cb_saved[BPF_SKB_CB_LEN];
@@ -611,15 +611,30 @@ static inline u32 bpf_prog_run_save_cb(const struct bpf_prog *prog,
return res;
}
+static inline u32 bpf_prog_run_save_cb(const struct bpf_prog *prog,
+ struct sk_buff *skb)
+{
+ u32 res;
+
+ preempt_disable();
+ res = __bpf_prog_run_save_cb(prog, skb);
+ preempt_enable();
+ return res;
+}
+
static inline u32 bpf_prog_run_clear_cb(const struct bpf_prog *prog,
struct sk_buff *skb)
{
u8 *cb_data = bpf_skb_cb(skb);
+ u32 res;
if (unlikely(prog->cb_access))
memset(cb_data, 0, BPF_SKB_CB_LEN);
- return BPF_PROG_RUN(prog, skb);
+ preempt_disable();
+ res = BPF_PROG_RUN(prog, skb);
+ preempt_enable();
+ return res;
}
static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,