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