[PATCH net 0/2] Minor fix in bpf_convert_ctx_access

[PATCH net 0/2] Minor fix in bpf_convert_ctx_access

[Daniel Borkmann]

First one was found while trying to compile the kernel
with !CONFIG_NET_RX_BUSY_POLL.

Thanks!

Daniel Borkmann (2):
  net: fix compilation when busy poll is not enabled
  bpf: fix two missing target_size settings in bpf_convert_ctx_access

 include/net/busy_poll.h | 12 ++++++------
 net/core/filter.c       |  2 ++
 2 files changed, 8 insertions(+), 6 deletions(-)

-- 
1.9.3

[PATCH net 1/2] net: fix compilation when busy poll is not enabled

[Daniel Borkmann]

MIN_NAPI_ID is used in various places outside of
CONFIG_NET_RX_BUSY_POLL wrapping, so when it's not set
we run into build errors such as:

  net/core/dev.c: In function 'dev_get_by_napi_id':
  net/core/dev.c:886:16: error: ‘MIN_NAPI_ID’ undeclared (first use in this function)
    if (napi_id < MIN_NAPI_ID)
                  ^~~~~~~~~~~

Thus, have MIN_NAPI_ID always defined to fix these errors.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 include/net/busy_poll.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index 8ffd434..71c72a9 100644
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -29,18 +29,18 @@
 #include <linux/sched/signal.h>
 #include <net/ip.h>
 
-#ifdef CONFIG_NET_RX_BUSY_POLL
-
-struct napi_struct;
-extern unsigned int sysctl_net_busy_read __read_mostly;
-extern unsigned int sysctl_net_busy_poll __read_mostly;
-
 /*		0 - Reserved to indicate value not set
  *     1..NR_CPUS - Reserved for sender_cpu
  *  NR_CPUS+1..~0 - Region available for NAPI IDs
  */
 #define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
 
+#ifdef CONFIG_NET_RX_BUSY_POLL
+
+struct napi_struct;
+extern unsigned int sysctl_net_busy_read __read_mostly;
+extern unsigned int sysctl_net_busy_poll __read_mostly;
+
 static inline bool net_busy_loop_on(void)
 {
 	return sysctl_net_busy_poll;
-- 
1.9.3

[PATCH net 2/2] bpf: fix two missing target_size settings in bpf_convert_ctx_access

[Daniel Borkmann]

When CONFIG_NET_SCHED or CONFIG_NET_RX_BUSY_POLL is /not/ set and
we try a narrow __sk_buff load of tc_index or napi_id, respectively,
then verifier rightfully complains that it's misconfigured, because
we need to set target_size in each of the two cases. The rewrite
for the ctx access is just a dummy op, but needs to pass, so fix
this up.

Fixes: f96da09473b5 ("bpf: simplify narrower ctx access")
Reported-by: Shubham Bansal <illusionist.neo@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 net/core/filter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index f44fc22..6280a60 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3505,6 +3505,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
 					      bpf_target_off(struct sk_buff, tc_index, 2,
 							     target_size));
 #else
+		*target_size = 2;
 		if (type == BPF_WRITE)
 			*insn++ = BPF_MOV64_REG(si->dst_reg, si->dst_reg);
 		else
@@ -3520,6 +3521,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
 		*insn++ = BPF_JMP_IMM(BPF_JGE, si->dst_reg, MIN_NAPI_ID, 1);
 		*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);
 #else
+		*target_size = 4;
 		*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);
 #endif
 		break;
-- 
1.9.3

Re: [PATCH net 0/2] Minor fix in bpf_convert_ctx_access

[David Miller]

From: Daniel Borkmann <daniel@iogearbox.net>
Date: Fri, 11 Aug 2017 18:31:23 +0200

> First one was found while trying to compile the kernel
> with !CONFIG_NET_RX_BUSY_POLL.

Series applied, thanks Daniel.