196 lines
4.9 KiB
C
196 lines
4.9 KiB
C
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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/*
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* NETLINK Netlink attributes
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*
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* Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
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*/
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#include <errno.h>
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#include <string.h>
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#include <stdio.h>
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#include <linux/rtnetlink.h>
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#include "nlattr.h"
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#include "libbpf_internal.h"
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static uint16_t nla_attr_minlen[LIBBPF_NLA_TYPE_MAX+1] = {
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[LIBBPF_NLA_U8] = sizeof(uint8_t),
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[LIBBPF_NLA_U16] = sizeof(uint16_t),
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[LIBBPF_NLA_U32] = sizeof(uint32_t),
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[LIBBPF_NLA_U64] = sizeof(uint64_t),
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[LIBBPF_NLA_STRING] = 1,
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[LIBBPF_NLA_FLAG] = 0,
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};
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static struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
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{
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int totlen = NLA_ALIGN(nla->nla_len);
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*remaining -= totlen;
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return (struct nlattr *)((void *)nla + totlen);
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}
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static int nla_ok(const struct nlattr *nla, int remaining)
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{
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return remaining >= sizeof(*nla) &&
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nla->nla_len >= sizeof(*nla) &&
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nla->nla_len <= remaining;
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}
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static int nla_type(const struct nlattr *nla)
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{
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return nla->nla_type & NLA_TYPE_MASK;
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}
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static int validate_nla(struct nlattr *nla, int maxtype,
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struct libbpf_nla_policy *policy)
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{
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struct libbpf_nla_policy *pt;
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unsigned int minlen = 0;
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int type = nla_type(nla);
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if (type < 0 || type > maxtype)
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return 0;
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pt = &policy[type];
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if (pt->type > LIBBPF_NLA_TYPE_MAX)
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return 0;
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if (pt->minlen)
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minlen = pt->minlen;
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else if (pt->type != LIBBPF_NLA_UNSPEC)
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minlen = nla_attr_minlen[pt->type];
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if (libbpf_nla_len(nla) < minlen)
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return -1;
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if (pt->maxlen && libbpf_nla_len(nla) > pt->maxlen)
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return -1;
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if (pt->type == LIBBPF_NLA_STRING) {
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char *data = libbpf_nla_data(nla);
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if (data[libbpf_nla_len(nla) - 1] != '\0')
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return -1;
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}
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return 0;
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}
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static inline int nlmsg_len(const struct nlmsghdr *nlh)
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{
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return nlh->nlmsg_len - NLMSG_HDRLEN;
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}
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/**
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* Create attribute index based on a stream of attributes.
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* @arg tb Index array to be filled (maxtype+1 elements).
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* @arg maxtype Maximum attribute type expected and accepted.
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* @arg head Head of attribute stream.
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* @arg len Length of attribute stream.
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* @arg policy Attribute validation policy.
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*
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* Iterates over the stream of attributes and stores a pointer to each
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* attribute in the index array using the attribute type as index to
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* the array. Attribute with a type greater than the maximum type
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* specified will be silently ignored in order to maintain backwards
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* compatibility. If \a policy is not NULL, the attribute will be
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* validated using the specified policy.
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*
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* @see nla_validate
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* @return 0 on success or a negative error code.
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*/
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int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
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int len, struct libbpf_nla_policy *policy)
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{
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struct nlattr *nla;
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int rem, err;
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memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
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libbpf_nla_for_each_attr(nla, head, len, rem) {
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int type = nla_type(nla);
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if (type > maxtype)
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continue;
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if (policy) {
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err = validate_nla(nla, maxtype, policy);
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if (err < 0)
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goto errout;
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}
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if (tb[type])
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pr_warn("Attribute of type %#x found multiple times in message, "
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"previous attribute is being ignored.\n", type);
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tb[type] = nla;
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}
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err = 0;
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errout:
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return err;
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}
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/**
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* Create attribute index based on nested attribute
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* @arg tb Index array to be filled (maxtype+1 elements).
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* @arg maxtype Maximum attribute type expected and accepted.
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* @arg nla Nested Attribute.
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* @arg policy Attribute validation policy.
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*
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* Feeds the stream of attributes nested into the specified attribute
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* to libbpf_nla_parse().
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*
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* @see libbpf_nla_parse
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* @return 0 on success or a negative error code.
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*/
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int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
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struct nlattr *nla,
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struct libbpf_nla_policy *policy)
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{
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return libbpf_nla_parse(tb, maxtype, libbpf_nla_data(nla),
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libbpf_nla_len(nla), policy);
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}
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/* dump netlink extended ack error message */
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int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh)
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{
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struct libbpf_nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
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[NLMSGERR_ATTR_MSG] = { .type = LIBBPF_NLA_STRING },
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[NLMSGERR_ATTR_OFFS] = { .type = LIBBPF_NLA_U32 },
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};
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struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr;
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struct nlmsgerr *err;
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char *errmsg = NULL;
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int hlen, alen;
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/* no TLVs, nothing to do here */
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if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
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return 0;
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err = (struct nlmsgerr *)NLMSG_DATA(nlh);
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hlen = sizeof(*err);
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/* if NLM_F_CAPPED is set then the inner err msg was capped */
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if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
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hlen += nlmsg_len(&err->msg);
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attr = (struct nlattr *) ((void *) err + hlen);
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alen = nlh->nlmsg_len - hlen;
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if (libbpf_nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen,
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extack_policy) != 0) {
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pr_warn("Failed to parse extended error attributes\n");
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return 0;
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}
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if (tb[NLMSGERR_ATTR_MSG])
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errmsg = (char *) libbpf_nla_data(tb[NLMSGERR_ATTR_MSG]);
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pr_warn("Kernel error message: %s\n", errmsg);
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return 0;
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}
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