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46 .Nd "library for handling application capabilities"
55 .Fn cap_wrap "int sock"
57 .Fn cap_unwrap "cap_channel_t *chan"
59 .Fn cap_sock "const cap_channel_t *chan"
61 .Fn cap_clone "const cap_channel_t *chan"
63 .Fn cap_close "cap_channel_t *chan"
65 .Fn cap_limit_get "const cap_channel_t *chan" "nvlist_t **limitsp"
67 .Fn cap_limit_set "const cap_channel_t *chan" "nvlist_t *limits"
69 .Fn cap_send_nvlist "const cap_channel_t *chan" "const nvlist_t *nvl"
71 .Fn cap_recv_nvlist "const cap_channel_t *chan" "int flags"
73 .Fn cap_xfer_nvlist "const cap_channel_t *chan" "nvlist_t *nvl" "int flags"
74 .In libcapsicum_service.h
76 .Fn cap_service_open "const cap_channel_t *chan" "const char *name"
80 library allows to manage application capabilities through the
84 The application capability (represented by the
86 type) is a communication channel between the caller and the
88 daemon or an instance of one of its services.
91 daemon obtained with the
93 function allows to create capabilities to casper's services via the
99 function opens capability to the
107 based on the given socket.
108 The function is used when capability is inherited through
112 domain socket as a regular file descriptor and has to be represented as
118 function is the opposite of the
123 structure and returns
125 domain socket associated with it.
129 function clones the given capability.
133 function closes the given capability.
139 domain socket descriptor associated with the given capability for use with
148 function stores current limits of the given capability in the
151 If the function return
157 it means there are no limits set.
161 function sets limits for the given capability.
162 The limits are provided as nvlist.
163 The exact format depends on the service the capability represents.
167 function sends the given nvlist over the given capability.
168 This is low level interface to communicate with casper services.
169 Most services should provide higher level API.
173 function receives the given nvlist over the given capability.
176 argument defines what type the top nvlist is expected to be.
177 If the nvlist flags do not match the flags passed to
178 .Fn cap_recv_nvlist ,
179 the nvlist will not be returned.
183 function sends the given nvlist, destroys it and receives new nvlist in
184 response over the given capability.
187 argument defines what type the top nvlist is expected to be.
188 If the nvlist flags do not match the flags passed to
189 .Fn cap_xfer_nvlist ,
190 the nvlist will not be returned.
191 It does not matter if the function succeeds or fails, the nvlist given
192 for sending will always be destroyed once the function returns.
196 function opens casper service of the given name through casper capability
200 The function returns capability that provides access to opened service.
205 .Fn cap_recv_nvlist ,
206 .Fn cap_service_open ,
232 functions always succeed.
234 The following example first opens capability to the
236 daemon, then using this capability creates new capability to the
238 casper service and uses the latter capability to resolve IP address.
240 cap_channel_t *capcas, *capdns;
242 const char *ipstr = "127.0.0.1";
246 /* Open capability to the Casper daemon. */
249 err(1, "Unable to contact Casper daemon");
251 /* Enter capability mode sandbox. */
252 if (cap_enter() < 0 && errno != ENOSYS)
253 err(1, "Unable to enter capability mode");
255 /* Use Casper capability to create capability to the system.dns service. */
256 capdns = cap_service_open(capcas, "system.dns");
258 err(1, "Unable to open system.dns service");
260 /* Close Casper capability, we don't need it anymore. */
263 /* Limit system.dns to reverse DNS lookups and IPv4 addresses. */
264 limits = nvlist_create(0);
265 nvlist_add_string(limits, "type", "ADDR");
266 nvlist_add_number(limits, "family", (uint64_t)AF_INET);
267 if (cap_limit_set(capdns, limits) < 0)
268 err(1, "Unable to limit access to the system.dns service");
270 /* Convert IP address in C-string to in_addr. */
271 if (!inet_aton(ipstr, &ip))
272 errx(1, "Unable to parse IP address %s.", ipstr);
274 /* Find hostname for the given IP address. */
275 hp = cap_gethostbyaddr(capdns, (const void *)&ip, sizeof(ip), AF_INET);
277 errx(1, "No name associated with %s.", ipstr);
279 printf("Name associated with %s is %s.\\n", ipstr, hp->h_name);
287 .Xr cap_gethostbyaddr 3 ,
289 .Xr gethostbyaddr 3 ,
298 library was implemented by
299 .An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net
300 under sponsorship from the FreeBSD Foundation.