From: Eric Leblond <eric@regit•org>
To: netdev@vger•kernel.org, daniel@iogearbox•net
Cc: linux-kernel@vger•kernel.org, ast@kernel•org,
Eric Leblond <eric@regit•org>
Subject: [PATCH bpf-next 2/3] libbpf: add error reporting in XDP
Date: Mon, 25 Dec 2017 23:13:24 +0100 [thread overview]
Message-ID: <20171225221325.9680-3-eric@regit.org> (raw)
In-Reply-To: <20171225221325.9680-1-eric@regit.org>
Parse netlink ext attribute to get the error message returned by
the card.
Signed-off-by: Eric Leblond <eric@regit•org>
---
tools/lib/bpf/Build | 2 +-
tools/lib/bpf/bpf.c | 9 +++
tools/lib/bpf/nlattr.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/nlattr.h | 164 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 362 insertions(+), 1 deletion(-)
create mode 100644 tools/lib/bpf/nlattr.c
create mode 100644 tools/lib/bpf/nlattr.h
diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build
index d8749756352d..64c679d67109 100644
--- a/tools/lib/bpf/Build
+++ b/tools/lib/bpf/Build
@@ -1 +1 @@
-libbpf-y := libbpf.o bpf.o
+libbpf-y := libbpf.o bpf.o nlattr.o
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 1e3cfe6b9fce..cfd30a0cbce4 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -26,6 +26,7 @@
#include <linux/bpf.h>
#include "bpf.h"
#include "libbpf.h"
+#include "nlattr.h"
#include <linux/rtnetlink.h>
#include <sys/socket.h>
#include <errno.h>
@@ -436,6 +437,7 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
struct nlmsghdr *nh;
struct nlmsgerr *err;
socklen_t addrlen;
+ int one;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
@@ -445,6 +447,12 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
return -errno;
}
+ if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
+ &one, sizeof(one)) < 0) {
+ /* debug/verbose message that it is not supported */
+ fprintf(stderr, "Netlink error reporting not supported\n");
+ }
+
if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
ret = -errno;
goto cleanup;
@@ -521,6 +529,7 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
if (!err->error)
continue;
ret = err->error;
+ nla_dump_errormsg(nh);
goto cleanup;
case NLMSG_DONE:
break;
diff --git a/tools/lib/bpf/nlattr.c b/tools/lib/bpf/nlattr.c
new file mode 100644
index 000000000000..962de14f74e3
--- /dev/null
+++ b/tools/lib/bpf/nlattr.c
@@ -0,0 +1,188 @@
+
+/*
+ * NETLINK Netlink attributes
+ *
+ * Authors: Thomas Graf <tgraf@suug•ch>
+ * Alexey Kuznetsov <kuznet@ms2•inr.ac.ru>
+ */
+
+#include <errno.h>
+#include "nlattr.h"
+#include <linux/rtnetlink.h>
+#include <string.h>
+#include <stdio.h>
+
+static const __u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
+ [NLA_U8] = sizeof(__u8),
+ [NLA_U16] = sizeof(__u16),
+ [NLA_U32] = sizeof(__u32),
+ [NLA_U64] = sizeof(__u64),
+ [NLA_MSECS] = sizeof(__u64),
+ [NLA_NESTED] = NLA_HDRLEN,
+ [NLA_S8] = sizeof(__s8),
+ [NLA_S16] = sizeof(__s16),
+ [NLA_S32] = sizeof(__s32),
+ [NLA_S64] = sizeof(__s64),
+};
+
+static int validate_nla(const struct nlattr *nla, int maxtype,
+ const struct nla_policy *policy)
+{
+ const struct nla_policy *pt;
+ int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
+
+ if (type <= 0 || type > maxtype)
+ return 0;
+
+ pt = &policy[type];
+
+ if (pt->type > NLA_TYPE_MAX)
+ return -EINVAL;
+
+ switch (pt->type) {
+ case NLA_FLAG:
+ if (attrlen > 0)
+ return -ERANGE;
+ break;
+
+ case NLA_NUL_STRING:
+ if (pt->len)
+ minlen = min(attrlen, pt->len + 1);
+ else
+ minlen = attrlen;
+
+ if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
+ return -EINVAL;
+ /* fall through */
+
+ case NLA_STRING:
+ if (attrlen < 1)
+ return -ERANGE;
+
+ if (pt->len) {
+ char *buf = nla_data(nla);
+
+ if (buf[attrlen - 1] == '\0')
+ attrlen--;
+
+ if (attrlen > pt->len)
+ return -ERANGE;
+ }
+ break;
+
+ case NLA_BINARY:
+ if (pt->len && attrlen > pt->len)
+ return -ERANGE;
+ break;
+
+ case NLA_NESTED_COMPAT:
+ if (attrlen < pt->len)
+ return -ERANGE;
+ if (attrlen < NLA_ALIGN(pt->len))
+ break;
+ if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
+ return -ERANGE;
+ nla = nla_data(nla) + NLA_ALIGN(pt->len);
+ if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
+ return -ERANGE;
+ break;
+ case NLA_NESTED:
+ /* a nested attributes is allowed to be empty; if its not,
+ * it must have a size of at least NLA_HDRLEN.
+ */
+ if (attrlen == 0)
+ break;
+ default:
+ if (pt->len)
+ minlen = pt->len;
+ else if (pt->type != NLA_UNSPEC)
+ minlen = nla_attr_minlen[pt->type];
+
+ if (attrlen < minlen)
+ return -ERANGE;
+ }
+
+ return 0;
+}
+
+/**
+ * nla_parse - Parse a stream of attributes into a tb buffer
+ * @tb: destination array with maxtype+1 elements
+ * @maxtype: maximum attribute type to be expected
+ * @head: head of attribute stream
+ * @len: length of attribute stream
+ * @policy: validation policy
+ *
+ * Parses a stream of attributes and stores a pointer to each attribute in
+ * the tb array accessible via the attribute type. Attributes with a type
+ * exceeding maxtype will be silently ignored for backwards compatibility
+ * reasons. policy may be set to NULL if no validation is required.
+ *
+ * Returns 0 on success or a negative error code.
+ */
+static int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
+ int len, const struct nla_policy *policy)
+{
+ const struct nlattr *nla;
+ int rem, err;
+
+ memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+
+ nla_for_each_attr(nla, head, len, rem) {
+ __u16 type = nla_type(nla);
+
+ if (type > 0 && type <= maxtype) {
+ if (policy) {
+ err = validate_nla(nla, maxtype, policy);
+ if (err < 0)
+ goto errout;
+ }
+
+ tb[type] = (struct nlattr *)nla;
+ }
+ }
+
+ err = 0;
+errout:
+ return err;
+}
+
+/* dump netlink extended ack error message */
+int nla_dump_errormsg(struct nlmsghdr *nlh)
+{
+ const struct nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
+ [NLMSGERR_ATTR_MSG] = { .type = NLA_STRING },
+ [NLMSGERR_ATTR_OFFS] = { .type = NLA_U32 },
+ };
+ struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr;
+ struct nlmsgerr *err;
+ char *errmsg = NULL;
+ int hlen, alen;
+
+ /* no TLVs, nothing to do here */
+ if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+ return 0;
+
+ err = (struct nlmsgerr *)NLMSG_DATA(nlh);
+ hlen = sizeof(*err);
+
+ /* if NLM_F_CAPPED is set then the inner err msg was capped */
+ if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+ hlen += nlmsg_len(&err->msg);
+
+ attr = (struct nlattr *) ((void *) err + hlen);
+ alen = nlh->nlmsg_len - hlen;
+
+ if (nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen, extack_policy) != 0) {
+ fprintf(stderr,
+ "Failed to parse extended error attributes\n");
+ return 0;
+ }
+
+ if (tb[NLMSGERR_ATTR_MSG])
+ errmsg = (char *) nla_data(tb[NLMSGERR_ATTR_MSG]);
+
+ fprintf(stderr, "Kernel error message: %s\n", errmsg);
+
+ return 0;
+}
diff --git a/tools/lib/bpf/nlattr.h b/tools/lib/bpf/nlattr.h
new file mode 100644
index 000000000000..b95f3e64c14d
--- /dev/null
+++ b/tools/lib/bpf/nlattr.h
@@ -0,0 +1,164 @@
+#ifndef __NLATTR_H
+#define __NLATTR_H
+
+#include <linux/netlink.h>
+
+/**
+ * Standard attribute types to specify validation policy
+ */
+enum {
+ NLA_UNSPEC,
+ NLA_U8,
+ NLA_U16,
+ NLA_U32,
+ NLA_U64,
+ NLA_STRING,
+ NLA_FLAG,
+ NLA_MSECS,
+ NLA_NESTED,
+ NLA_NESTED_COMPAT,
+ NLA_NUL_STRING,
+ NLA_BINARY,
+ NLA_S8,
+ NLA_S16,
+ NLA_S32,
+ NLA_S64,
+ __NLA_TYPE_MAX,
+};
+
+#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
+
+/**
+ * nla_type - attribute type
+ * @nla: netlink attribute
+ */
+static inline int nla_type(const struct nlattr *nla)
+{
+ return nla->nla_type & NLA_TYPE_MASK;
+}
+
+/**
+ * nla_len - length of payload
+ * @nla: netlink attribute
+ */
+static inline int nla_len(const struct nlattr *nla)
+{
+ return nla->nla_len - NLA_HDRLEN;
+}
+
+/**
+ * struct nla_policy - attribute validation policy
+ * @type: Type of attribute or NLA_UNSPEC
+ * @len: Type specific length of payload
+ *
+ * Policies are defined as arrays of this struct, the array must be
+ * accessible by attribute type up to the highest identifier to be expected.
+ *
+ * Meaning of `len' field:
+ * NLA_STRING Maximum length of string
+ * NLA_NUL_STRING Maximum length of string (excluding NUL)
+ * NLA_FLAG Unused
+ * NLA_BINARY Maximum length of attribute payload
+ * NLA_NESTED Don't use `len' field -- length verification is
+ * done by checking len of nested header (or empty)
+ * NLA_NESTED_COMPAT Minimum length of structure payload
+ * NLA_U8, NLA_U16,
+ * NLA_U32, NLA_U64,
+ * NLA_S8, NLA_S16,
+ * NLA_S32, NLA_S64,
+ * NLA_MSECS Leaving the length field zero will verify the
+ * given type fits, using it verifies minimum length
+ * just like "All other"
+ * All other Minimum length of attribute payload
+ *
+ * Example:
+ * static const struct nla_policy my_policy[ATTR_MAX+1] = {
+ * [ATTR_FOO] = { .type = NLA_U16 },
+ * [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
+ * [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
+ * };
+ */
+struct nla_policy {
+ __u16 type;
+ __u16 len;
+};
+
+/**
+ * nla_ok - check if the netlink attribute fits into the remaining bytes
+ * @nla: netlink attribute
+ * @remaining: number of bytes remaining in attribute stream
+ */
+static inline int nla_ok(const struct nlattr *nla, int remaining)
+{
+ return remaining >= (int) sizeof(*nla) &&
+ nla->nla_len >= sizeof(*nla) &&
+ nla->nla_len <= remaining;
+}
+
+/**
+ * nla_next - next netlink attribute in attribute stream
+ * @nla: netlink attribute
+ * @remaining: number of bytes remaining in attribute stream
+ *
+ * Returns the next netlink attribute in the attribute stream and
+ * decrements remaining by the size of the current attribute.
+ */
+static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
+{
+ unsigned int totlen = NLA_ALIGN(nla->nla_len);
+
+ *remaining -= totlen;
+ return (struct nlattr *) ((char *) nla + totlen);
+}
+
+/**
+ * nla_for_each_attr - iterate over a stream of attributes
+ * @pos: loop counter, set to current attribute
+ * @head: head of attribute stream
+ * @len: length of attribute stream
+ * @rem: initialized to len, holds bytes currently remaining in stream
+ */
+#define nla_for_each_attr(pos, head, len, rem) \
+ for (pos = head, rem = len; \
+ nla_ok(pos, rem); \
+ pos = nla_next(pos, &(rem)))
+
+/**
+ * nla_data - head of payload
+ * @nla: netlink attribute
+ */
+static inline void *nla_data(const struct nlattr *nla)
+{
+ return (char *) nla + NLA_HDRLEN;
+}
+
+/**
+ * nla_get_u32 - return payload of u32 attribute
+ * @nla: u32 netlink attribute
+ */
+static inline __u32 nla_get_u32(const struct nlattr *nla)
+{
+ return *(__u32 *) nla_data(nla);
+}
+
+/**
+ * nla_get_u16 - return payload of u16 attribute
+ * @nla: u16 netlink attribute
+ */
+static inline __u16 nla_get_u16(const struct nlattr *nla)
+{
+ return *(__u16 *) nla_data(nla);
+}
+
+/**
+ * nlmsg_len - length of message payload
+ * @nlh: netlink message header
+ */
+static inline int nlmsg_len(const struct nlmsghdr *nlh)
+{
+ return nlh->nlmsg_len - NLMSG_HDRLEN;
+}
+
+int nla_dump_errormsg(struct nlmsghdr *nlh);
+
+#endif /* __NLATTR_H */
--
2.15.1
next prev parent reply other threads:[~2017-12-25 22:13 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-25 22:13 [PATCH bpf-next 0/3] add XDP loading support to libbpf Eric Leblond
2017-12-25 22:13 ` [PATCH bpf-next 1/3] libbpf: add function to setup XDP Eric Leblond
2017-12-25 22:13 ` Eric Leblond [this message]
2017-12-27 2:27 ` [PATCH bpf-next 2/3] libbpf: add error reporting in XDP Alexei Starovoitov
2017-12-27 18:02 ` [PATCH bpf-next v2 0/4] libbpf: add function to setup XDP Eric Leblond
2017-12-27 18:02 ` [PATCH 1/4] " Eric Leblond
2017-12-27 18:57 ` Alexei Starovoitov
2017-12-28 0:59 ` Toshiaki Makita
2017-12-27 18:02 ` [PATCH 2/4] libbpf: add error reporting in XDP Eric Leblond
2017-12-27 18:57 ` Alexei Starovoitov
2017-12-27 18:02 ` [PATCH 3/4] libbpf: break loop earlier Eric Leblond
2017-12-27 19:00 ` Alexei Starovoitov
2017-12-27 20:30 ` Eric Leblond
2017-12-27 23:05 ` Daniel Borkmann
2017-12-28 8:04 ` [PATCH bpf-next v3 0/3] libbpf: add XDP setup support Eric Leblond
2017-12-28 8:04 ` [PATCH bpf-next v3 1/3] libbpf: add function to setup XDP Eric Leblond
2017-12-28 8:18 ` Toshiaki Makita
2017-12-30 20:41 ` [PATCH bpf-next v4 0/3] " Eric Leblond
2017-12-30 20:41 ` [PATCH bpf-next v4 1/3] " Eric Leblond
2018-01-03 23:59 ` Eric Leblond
2018-01-04 8:21 ` [PATCH bpf-next v5 1/4] " Eric Leblond
2018-01-04 8:21 ` [PATCH bpf-next v5 2/4] libbpf: add error reporting in XDP Eric Leblond
2018-01-06 21:16 ` Daniel Borkmann
2018-01-18 23:35 ` Eric Leblond
2018-01-18 23:43 ` [PATCH bpf-next 0/4] libbpf: add XDP binding support Eric Leblond
2018-01-18 23:43 ` [PATCH bpf-next v6 1/4] libbpf: add function to setup XDP Eric Leblond
2018-01-18 23:43 ` [PATCH bpf-next v6 2/4] libbpf: add error reporting in XDP Eric Leblond
2018-01-18 23:43 ` [PATCH bpf-next v6 3/4] libbpf: add missing SPDX-License-Identifier Eric Leblond
2018-01-18 23:43 ` [PATCH bpf-next v6 4/4] samples/bpf: use bpf_set_link_xdp_fd Eric Leblond
2018-01-20 2:00 ` [PATCH bpf-next 0/4] libbpf: add XDP binding support Daniel Borkmann
2018-01-20 2:27 ` Alexei Starovoitov
2018-01-20 8:21 ` Daniel Borkmann
2018-01-25 0:05 ` [PATCH bpf-next v7 0/5] libbpf: add XDP setup support Eric Leblond
2018-01-25 0:05 ` [PATCH bpf-next v7 1/5] tools: import netlink header in tools uapi Eric Leblond
2018-01-25 0:05 ` [PATCH bpf-next v7 2/5] libbpf: add function to setup XDP Eric Leblond
2018-01-27 1:23 ` Daniel Borkmann
2018-01-27 10:22 ` Eric Leblond
2018-01-25 0:05 ` [PATCH bpf-next v7 3/5] libbpf: add error reporting in XDP Eric Leblond
2018-01-27 1:28 ` Daniel Borkmann
2018-01-27 10:32 ` Eric Leblond
2018-01-30 10:58 ` Daniel Borkmann
2018-01-30 20:50 ` [PATCH bpf-next v8 0/5] libbpf: add XDP binding support Eric Leblond
2018-01-31 16:53 ` Daniel Borkmann
2018-02-03 2:01 ` Alexei Starovoitov
2018-01-30 20:55 ` [PATCH bpf-next v8 1/5] tools: add netlink.h and if_link.h in tools uapi Eric Leblond
2018-01-30 20:55 ` [PATCH bpf-next v8 2/5] libbpf: add function to setup XDP Eric Leblond
2018-01-30 20:55 ` [PATCH bpf-next v8 3/5] libbpf: add error reporting in XDP Eric Leblond
2018-01-30 20:55 ` [PATCH bpf-next v8 4/5] libbpf: add missing SPDX-License-Identifier Eric Leblond
2018-01-30 20:55 ` [PATCH bpf-next v8 5/5] samples/bpf: use bpf_set_link_xdp_fd Eric Leblond
2018-01-25 0:05 ` [PATCH bpf-next v7 4/5] libbpf: add missing SPDX-License-Identifier Eric Leblond
2018-01-25 0:05 ` [PATCH bpf-next v7 5/5] samples/bpf: use bpf_set_link_xdp_fd Eric Leblond
2018-01-04 8:21 ` [PATCH bpf-next v5 3/4] libbpf: add missing SPDX-License-Identifier Eric Leblond
2018-01-04 9:49 ` Philippe Ombredanne
2018-01-04 8:21 ` [PATCH bpf-next v5 4/4] samples/bpf: use bpf_set_link_xdp_fd Eric Leblond
2017-12-30 20:41 ` [PATCH bpf-next v4 2/3] libbpf: add error reporting in XDP Eric Leblond
2017-12-31 11:20 ` Philippe Ombredanne
2017-12-30 20:41 ` [PATCH bpf-next v4 3/3] libbpf: add missing SPDX-License-Identifier Eric Leblond
2017-12-28 8:04 ` [PATCH bpf-next v3 2/3] libbpf: add error reporting in XDP Eric Leblond
2017-12-28 8:04 ` [PATCH bpf-next v3 3/3] libbpf: add missing SPDX-License-Identifier Eric Leblond
2017-12-29 12:35 ` Philippe Ombredanne
2017-12-27 18:02 ` [PATCH 4/4] " Eric Leblond
2017-12-27 19:01 ` Alexei Starovoitov
2017-12-25 22:13 ` [PATCH bpf-next 3/3] libbpf: break loop earlier Eric Leblond
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