* [PATCH bpf-next] libbpf: fix compilation errors on ubuntu 16.04
@ 2021-07-12 16:30 Yonghong Song
0 siblings, 0 replies; only message in thread
From: Yonghong Song @ 2021-07-12 16:30 UTC (permalink / raw)
To: bpf
Cc: Alexei Starovoitov, Andrii Nakryiko, Daniel Borkmann,
kernel-team, Kumar Kartikeya Dwivedi
libbpf is used as a submodule in bcc.
When importing latest libbpf repo in bcc, I observed the
following compilation errors when compiling on ubuntu 16.04.
.../netlink.c:416:23: error: ‘TC_H_CLSACT’ undeclared (first use in this function)
*parent = TC_H_MAKE(TC_H_CLSACT,
^
.../netlink.c:418:9: error: ‘TC_H_MIN_INGRESS’ undeclared (first use in this function)
TC_H_MIN_INGRESS : TC_H_MIN_EGRESS);
^
.../netlink.c:418:28: error: ‘TC_H_MIN_EGRESS’ undeclared (first use in this function)
TC_H_MIN_INGRESS : TC_H_MIN_EGRESS);
^
.../netlink.c: In function ‘__get_tc_info’:
.../netlink.c:522:11: error: ‘TCA_BPF_ID’ undeclared (first use in this function)
if (!tbb[TCA_BPF_ID])
^
In ubuntu 16.04, TCA_BPF_* enumerator looks like below
enum {
TCA_BPF_UNSPEC,
TCA_BPF_ACT,
...
TCA_BPF_NAME,
TCA_BPF_FLAGS,
__TCA_BPF_MAX,
};
#define TCA_BPF_MAX (__TCA_BPF_MAX - 1)
while in latest bpf-next, the enumerator looks like
enum {
TCA_BPF_UNSPEC,
...
TCA_BPF_FLAGS,
TCA_BPF_FLAGS_GEN,
TCA_BPF_TAG,
TCA_BPF_ID,
__TCA_BPF_MAX,
};
So if TCA_BPF_MAX indicates TCA_BPF_ID is not defined, TCA_BPF_ID will be defined
properly.
I also added a comparison "TCA_BPF_MAX < TCA_BPF_ID" in function __get_tc_info()
such that if the compare result if true, returns -EOPNOTSUPP. This is used to
prevent otherwise array overflows:
.../netlink.c:538:10: warning: array subscript is above array bounds [-Warray-bounds]
if (!tbb[TCA_BPF_ID])
^
Fixes: 715c5ce454a6 ("libbpf: Add low level TC-BPF management API")
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
---
tools/lib/bpf/netlink.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index 39f25e09b51e..1a88e3e7c231 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -22,6 +22,22 @@
#define SOL_NETLINK 270
#endif
+#ifndef TC_H_CLSACT
+#define TC_H_CLSACT TC_H_INGRESS
+#endif
+
+#ifndef TC_H_MIN_INGRESS
+#define TC_H_MIN_INGRESS 0xFFF2U
+#endif
+
+#ifndef TC_H_MIN_EGRESS
+#define TC_H_MIN_EGRESS 0xFFF3U
+#endif
+
+#if TCA_BPF_MAX <= 10
+#define TCA_BPF_ID 11
+#endif
+
typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
@@ -504,6 +520,8 @@ static int __get_tc_info(void *cookie, struct tcmsg *tc, struct nlattr **tb,
return -EINVAL;
if (!tb[TCA_OPTIONS])
return NL_CONT;
+ if (TCA_BPF_MAX < TCA_BPF_ID)
+ return -EOPNOTSUPP;
libbpf_nla_parse_nested(tbb, TCA_BPF_MAX, tb[TCA_OPTIONS], NULL);
if (!tbb[TCA_BPF_ID])
--
2.30.2
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