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1bc38b8f | 1 | // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) |
bbf48c18 EL |
2 | |
3 | /* | |
4 | * NETLINK Netlink attributes | |
5 | * | |
bbf48c18 EL |
6 | * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch> |
7 | */ | |
8 | ||
9 | #include <errno.h> | |
bbf48c18 EL |
10 | #include <string.h> |
11 | #include <stdio.h> | |
85367030 AN |
12 | #include <linux/rtnetlink.h> |
13 | #include "nlattr.h" | |
14 | #include "libbpf_internal.h" | |
1d1a3bcf | 15 | |
f04bc8a4 AI |
16 | static uint16_t nla_attr_minlen[LIBBPF_NLA_TYPE_MAX+1] = { |
17 | [LIBBPF_NLA_U8] = sizeof(uint8_t), | |
18 | [LIBBPF_NLA_U16] = sizeof(uint16_t), | |
19 | [LIBBPF_NLA_U32] = sizeof(uint32_t), | |
20 | [LIBBPF_NLA_U64] = sizeof(uint64_t), | |
21 | [LIBBPF_NLA_STRING] = 1, | |
22 | [LIBBPF_NLA_FLAG] = 0, | |
bbf48c18 EL |
23 | }; |
24 | ||
bbf48c18 EL |
25 | static struct nlattr *nla_next(const struct nlattr *nla, int *remaining) |
26 | { | |
27 | int totlen = NLA_ALIGN(nla->nla_len); | |
28 | ||
29 | *remaining -= totlen; | |
ee62a5c6 | 30 | return (struct nlattr *)((void *)nla + totlen); |
bbf48c18 EL |
31 | } |
32 | ||
33 | static int nla_ok(const struct nlattr *nla, int remaining) | |
34 | { | |
51e05a8c | 35 | return remaining >= (int)sizeof(*nla) && |
bbf48c18 EL |
36 | nla->nla_len >= sizeof(*nla) && |
37 | nla->nla_len <= remaining; | |
38 | } | |
39 | ||
bbf48c18 EL |
40 | static int nla_type(const struct nlattr *nla) |
41 | { | |
42 | return nla->nla_type & NLA_TYPE_MASK; | |
43 | } | |
44 | ||
45 | static int validate_nla(struct nlattr *nla, int maxtype, | |
f04bc8a4 | 46 | struct libbpf_nla_policy *policy) |
bbf48c18 | 47 | { |
f04bc8a4 | 48 | struct libbpf_nla_policy *pt; |
bbf48c18 EL |
49 | unsigned int minlen = 0; |
50 | int type = nla_type(nla); | |
51 | ||
52 | if (type < 0 || type > maxtype) | |
53 | return 0; | |
54 | ||
55 | pt = &policy[type]; | |
56 | ||
f04bc8a4 | 57 | if (pt->type > LIBBPF_NLA_TYPE_MAX) |
bbf48c18 EL |
58 | return 0; |
59 | ||
60 | if (pt->minlen) | |
61 | minlen = pt->minlen; | |
f04bc8a4 | 62 | else if (pt->type != LIBBPF_NLA_UNSPEC) |
bbf48c18 EL |
63 | minlen = nla_attr_minlen[pt->type]; |
64 | ||
f04bc8a4 | 65 | if (libbpf_nla_len(nla) < minlen) |
bbf48c18 EL |
66 | return -1; |
67 | ||
f04bc8a4 | 68 | if (pt->maxlen && libbpf_nla_len(nla) > pt->maxlen) |
bbf48c18 EL |
69 | return -1; |
70 | ||
f04bc8a4 AI |
71 | if (pt->type == LIBBPF_NLA_STRING) { |
72 | char *data = libbpf_nla_data(nla); | |
73 | ||
74 | if (data[libbpf_nla_len(nla) - 1] != '\0') | |
bbf48c18 EL |
75 | return -1; |
76 | } | |
77 | ||
78 | return 0; | |
79 | } | |
80 | ||
81 | static inline int nlmsg_len(const struct nlmsghdr *nlh) | |
82 | { | |
83 | return nlh->nlmsg_len - NLMSG_HDRLEN; | |
84 | } | |
85 | ||
86 | /** | |
87 | * Create attribute index based on a stream of attributes. | |
88 | * @arg tb Index array to be filled (maxtype+1 elements). | |
89 | * @arg maxtype Maximum attribute type expected and accepted. | |
90 | * @arg head Head of attribute stream. | |
91 | * @arg len Length of attribute stream. | |
92 | * @arg policy Attribute validation policy. | |
93 | * | |
94 | * Iterates over the stream of attributes and stores a pointer to each | |
95 | * attribute in the index array using the attribute type as index to | |
96 | * the array. Attribute with a type greater than the maximum type | |
97 | * specified will be silently ignored in order to maintain backwards | |
98 | * compatibility. If \a policy is not NULL, the attribute will be | |
99 | * validated using the specified policy. | |
100 | * | |
101 | * @see nla_validate | |
102 | * @return 0 on success or a negative error code. | |
103 | */ | |
f04bc8a4 AI |
104 | int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, |
105 | int len, struct libbpf_nla_policy *policy) | |
bbf48c18 EL |
106 | { |
107 | struct nlattr *nla; | |
108 | int rem, err; | |
109 | ||
110 | memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); | |
111 | ||
f04bc8a4 | 112 | libbpf_nla_for_each_attr(nla, head, len, rem) { |
bbf48c18 EL |
113 | int type = nla_type(nla); |
114 | ||
115 | if (type > maxtype) | |
116 | continue; | |
117 | ||
118 | if (policy) { | |
119 | err = validate_nla(nla, maxtype, policy); | |
120 | if (err < 0) | |
121 | goto errout; | |
122 | } | |
123 | ||
124 | if (tb[type]) | |
b6e99b01 THJ |
125 | pr_warn("Attribute of type %#x found multiple times in message, " |
126 | "previous attribute is being ignored.\n", type); | |
bbf48c18 EL |
127 | |
128 | tb[type] = nla; | |
129 | } | |
130 | ||
131 | err = 0; | |
132 | errout: | |
133 | return err; | |
134 | } | |
135 | ||
36f1678d YS |
136 | /** |
137 | * Create attribute index based on nested attribute | |
138 | * @arg tb Index array to be filled (maxtype+1 elements). | |
139 | * @arg maxtype Maximum attribute type expected and accepted. | |
140 | * @arg nla Nested Attribute. | |
141 | * @arg policy Attribute validation policy. | |
142 | * | |
143 | * Feeds the stream of attributes nested into the specified attribute | |
f04bc8a4 | 144 | * to libbpf_nla_parse(). |
36f1678d | 145 | * |
f04bc8a4 | 146 | * @see libbpf_nla_parse |
36f1678d YS |
147 | * @return 0 on success or a negative error code. |
148 | */ | |
f04bc8a4 AI |
149 | int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype, |
150 | struct nlattr *nla, | |
151 | struct libbpf_nla_policy *policy) | |
36f1678d | 152 | { |
f04bc8a4 AI |
153 | return libbpf_nla_parse(tb, maxtype, libbpf_nla_data(nla), |
154 | libbpf_nla_len(nla), policy); | |
36f1678d YS |
155 | } |
156 | ||
bbf48c18 | 157 | /* dump netlink extended ack error message */ |
f04bc8a4 | 158 | int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh) |
bbf48c18 | 159 | { |
f04bc8a4 AI |
160 | struct libbpf_nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = { |
161 | [NLMSGERR_ATTR_MSG] = { .type = LIBBPF_NLA_STRING }, | |
162 | [NLMSGERR_ATTR_OFFS] = { .type = LIBBPF_NLA_U32 }, | |
bbf48c18 EL |
163 | }; |
164 | struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr; | |
165 | struct nlmsgerr *err; | |
166 | char *errmsg = NULL; | |
167 | int hlen, alen; | |
168 | ||
169 | /* no TLVs, nothing to do here */ | |
170 | if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS)) | |
171 | return 0; | |
172 | ||
173 | err = (struct nlmsgerr *)NLMSG_DATA(nlh); | |
174 | hlen = sizeof(*err); | |
175 | ||
176 | /* if NLM_F_CAPPED is set then the inner err msg was capped */ | |
177 | if (!(nlh->nlmsg_flags & NLM_F_CAPPED)) | |
178 | hlen += nlmsg_len(&err->msg); | |
179 | ||
180 | attr = (struct nlattr *) ((void *) err + hlen); | |
17bcd27a | 181 | alen = (void *)nlh + nlh->nlmsg_len - (void *)attr; |
bbf48c18 | 182 | |
f04bc8a4 AI |
183 | if (libbpf_nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen, |
184 | extack_policy) != 0) { | |
b6e99b01 | 185 | pr_warn("Failed to parse extended error attributes\n"); |
bbf48c18 EL |
186 | return 0; |
187 | } | |
188 | ||
189 | if (tb[NLMSGERR_ATTR_MSG]) | |
f04bc8a4 | 190 | errmsg = (char *) libbpf_nla_data(tb[NLMSGERR_ATTR_MSG]); |
bbf48c18 | 191 | |
b6e99b01 | 192 | pr_warn("Kernel error message: %s\n", errmsg); |
bbf48c18 EL |
193 | |
194 | return 0; | |
195 | } |