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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"
75 .Fn cap_service_open "const cap_channel_t *chan" "const char *name"
79 library allows to manage application capabilities through the casper process.
81 The application capability (represented by the
83 type) is a communication channel between the caller and the casper process
84 daemon or an instance of one of its services.
85 A capability to the casper process obtained with the
87 function allows to create capabilities to casper's services via the
93 function opens capability to the casper process.
99 based on the given socket.
100 The function is used when capability is inherited through
104 domain socket as a regular file descriptor and has to be represented as
110 function is the opposite of the
115 structure and returns
117 domain socket associated with it.
121 function clones the given capability.
125 function closes the given capability.
131 domain socket descriptor associated with the given capability for use with
140 function stores current limits of the given capability in the
143 If the function return
149 it means there are no limits set.
153 function sets limits for the given capability.
154 The limits are provided as nvlist.
155 The exact format depends on the service the capability represents.
159 function sends the given nvlist over the given capability.
160 This is low level interface to communicate with casper services.
161 Most services should provide higher level API.
165 function receives the given nvlist over the given capability.
168 argument defines what type the top nvlist is expected to be.
169 If the nvlist flags do not match the flags passed to
170 .Fn cap_recv_nvlist ,
171 the nvlist will not be returned.
175 function sends the given nvlist, destroys it and receives new nvlist in
176 response over the given capability.
179 argument defines what type the top nvlist is expected to be.
180 If the nvlist flags do not match the flags passed to
181 .Fn cap_xfer_nvlist ,
182 the nvlist will not be returned.
183 It does not matter if the function succeeds or fails, the nvlist given
184 for sending will always be destroyed once the function returns.
188 function opens casper service of the given name through casper capability
192 The function returns capability that provides access to opened service.
193 Casper supports the following services in the base system:
194 .Bl -tag -width "system.random" -compact -offset indent
197 provides DNS libc compatible API
207 allows to obtain entropy from
221 .Fn cap_recv_nvlist ,
222 .Fn cap_service_open ,
248 functions always succeed.
250 The following example first opens capability to the casper then using this
251 capability creates new capability to the
253 casper service and uses the latter capability to resolve IP address.
255 cap_channel_t *capcas, *capdns;
257 const char *ipstr = "127.0.0.1";
261 /* Open capability to the Casper. */
264 err(1, "Unable to contact Casper");
266 /* Enter capability mode sandbox. */
267 if (cap_enter() < 0 && errno != ENOSYS)
268 err(1, "Unable to enter capability mode");
270 /* Use Casper capability to create capability to the system.dns service. */
271 capdns = cap_service_open(capcas, "system.dns");
273 err(1, "Unable to open system.dns service");
275 /* Close Casper capability, we don't need it anymore. */
278 /* Limit system.dns to reverse DNS lookups and IPv4 addresses. */
279 limits = nvlist_create(0);
280 nvlist_add_string(limits, "type", "ADDR");
281 nvlist_add_number(limits, "family", (uint64_t)AF_INET);
282 if (cap_limit_set(capdns, limits) < 0)
283 err(1, "Unable to limit access to the system.dns service");
285 /* Convert IP address in C-string to in_addr. */
286 if (!inet_aton(ipstr, &ip))
287 errx(1, "Unable to parse IP address %s.", ipstr);
289 /* Find hostname for the given IP address. */
290 hp = cap_gethostbyaddr(capdns, (const void *)&ip, sizeof(ip), AF_INET);
292 errx(1, "No name associated with %s.", ipstr);
294 printf("Name associated with %s is %s.\\n", ipstr, hp->h_name);
302 .Xr cap_gethostbyaddr 3 ,
304 .Xr gethostbyaddr 3 ,
312 library was implemented by
313 .An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net
314 under sponsorship from the FreeBSD Foundation.
317 new architecture was implemented by
318 .An Mariusz Zaborski Aq Mt oshogbo@FreeBSD.org