Move functions only needed by audiod from stat.c to audiod_command.c.
[paraslash.git] / acl.c
1 /*
2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file acl.c Access control lists for paraslash senders. */
8
9 #include <regex.h>
10
11 #include "para.h"
12 #include "error.h"
13 #include "string.h"
14 #include "list.h"
15 #include "net.h"
16
17 /**
18 * Describes one entry in the blacklist/whitelist of a paraslash sender.
19 */
20 struct access_info {
21 /** The address to be black/whitelisted. */
22 struct in_addr addr;
23 /** The netmask for this entry. */
24 unsigned netmask;
25 /** The position of this entry in the acl. */
26 struct list_head node;
27 };
28
29 /**
30 * Return true if addr_1 matches addr_2 in the first `netmask' bits.
31 */
32 static int v4_addr_match(uint32_t addr_1, uint32_t addr_2, uint8_t netmask)
33 {
34 uint32_t mask = ~0U;
35
36 if (netmask < 32)
37 mask <<= (32 - netmask);
38 return (htonl(addr_1) & mask) == (htonl(addr_2) & mask);
39 }
40
41 /**
42 * Find out whether the peer name of a given fd belongs to an acl.
43 *
44 * \param fd File descriptor.
45 * \param acl The access control list.
46 *
47 * \return One if \a fd belongs to \a acl, zero otherwise.
48 */
49 static int acl_lookup(int fd, struct list_head *acl)
50 {
51 struct access_info *ai, *tmp;
52 struct sockaddr_storage ss;
53 socklen_t sslen = sizeof(ss);
54 struct in_addr v4_addr;
55
56 if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
57 PARA_ERROR_LOG("Can not determine peer address: %s\n", strerror(errno));
58 goto no_match;
59 }
60 v4_addr = extract_v4_addr(&ss);
61 if (!v4_addr.s_addr)
62 goto no_match;
63
64 list_for_each_entry_safe(ai, tmp, acl, node)
65 if (v4_addr_match(v4_addr.s_addr, ai->addr.s_addr, ai->netmask))
66 return 1;
67 no_match:
68 return 0;
69 }
70
71 /**
72 * Add an entry to an access control list.
73 *
74 * \param acl The access control list.
75 * \param addr The address to add.
76 * \param netmask The netmask to use for this entry.
77 */
78 static void acl_add_entry(struct list_head *acl, char *addr, int netmask)
79 {
80 struct access_info *ai = para_malloc(sizeof(struct access_info));
81
82 inet_pton(AF_INET, addr, &ai->addr);
83 ai->netmask = netmask;
84 PARA_INFO_LOG("adding %s/%i to access list\n", addr, ai->netmask);
85 para_list_add(&ai->node, acl);
86 }
87
88 /**
89 * Delete an entry from an access control list.
90 *
91 * \param acl The access control list.
92 * \param addr The address to delete.
93 * \param netmask The netmask of the entry to be removed from the list.
94 */
95 static void acl_del_entry(struct list_head *acl, char *addr, unsigned netmask)
96 {
97 struct access_info *ai, *tmp;
98 struct in_addr to_delete;
99
100 inet_pton(AF_INET, addr, &to_delete);
101
102 list_for_each_entry_safe(ai, tmp, acl, node) {
103
104 if (v4_addr_match(to_delete.s_addr, ai->addr.s_addr,
105 PARA_MIN(netmask, ai->netmask))) {
106 PARA_NOTICE_LOG("removing %s/%i from access list\n",
107 addr, ai->netmask);
108 list_del(&ai->node);
109 free(ai);
110 }
111 }
112 }
113
114 /**
115 * Compute a string containing the contents of an acl.
116 *
117 * \param acl The access control list.
118 *
119 * \return A string containing the contents of \a acl, or \p NULL
120 * if \a acl is empty.
121 */
122 char *acl_get_contents(struct list_head *acl)
123 {
124 struct access_info *ai, *tmp_ai;
125 char *ret = NULL;
126
127 list_for_each_entry_safe(ai, tmp_ai, acl, node) {
128 char *tmp = make_message("%s%s/%d ", ret? ret : "",
129 inet_ntoa(ai->addr), ai->netmask);
130 free(ret);
131 ret = tmp;
132 }
133 return ret;
134 }
135
136 /**
137 * Initialize an access control list.
138 *
139 * \param acl The list to initialize.
140 * \param acl_info An array of strings of the form ip/netmask.
141 * \param num The number of strings in \a acl_info.
142 */
143 void acl_init(struct list_head *acl, char * const *acl_info, int num)
144 {
145 char addr[16];
146 int mask, i;
147
148 INIT_LIST_HEAD(acl);
149 for (i = 0; i < num; i++)
150 if (parse_cidr(acl_info[i], addr, sizeof(addr), &mask) == NULL)
151 PARA_CRIT_LOG("ACL syntax error: %s, ignoring\n",
152 acl_info[i]);
153 else
154 acl_add_entry(acl, addr, mask);
155 }
156
157 /**
158 * Check whether the peer name of a given fd is allowed by an acl.
159 *
160 * \param fd File descriptor.
161 * \param acl The access control list.
162 * \param default_deny Whether \a acl is a whitelist.
163 *
164 * \return Positive if the peer of \a fd is permitted by \a acl, \p -E_ACL_PERM
165 * otherwise.
166 */
167 int acl_check_access(int fd, struct list_head *acl, int default_deny)
168 {
169 int match = acl_lookup(fd, acl);
170
171 return (!match || default_deny) && (match || !default_deny)?
172 1 : -E_ACL_PERM;
173 }
174
175 /**
176 * Permit access for a range of IP addresses.
177 *
178 * \param addr The address to permit.
179 * \param netmask The netmask of the entry to be permitted.
180 * \param acl The access control list.
181 * \param default_deny Whether \a acl is a whitelist.
182 */
183 void acl_allow(char *addr, int netmask,
184 struct list_head *acl, int default_deny)
185 {
186 if (default_deny)
187 acl_add_entry(acl, addr, netmask);
188 else
189 acl_del_entry(acl, addr, netmask);
190 }
191
192 /**
193 * Deny access for a range of IP addresses.
194 *
195 * \param addr The address to deny.
196 * \param netmask The netmask of the entry to be denied.
197 * \param acl The access control list.
198 * \param default_deny Whether \a acl is a whitelist.
199 */
200 void acl_deny(char *addr, int netmask,
201 struct list_head *acl, int default_deny)
202 {
203 acl_allow(addr, netmask, acl, !default_deny);
204 }