Minor fix in bpf_convert_ctx_access

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

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.

---
 include/net/busy_poll.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

index 8ffd434..71c72a9 100644
@@ -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

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.

---
 net/core/filter.c | 2 ++
 1 file changed, 2 insertions(+)

index f44fc22..6280a60 100644
@@ -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

From: Daniel Borkmann <[email protected]>
Date: Fri, 11 Aug 2017 18:31:23 +0200

Series applied, thanks Daniel.