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46 .Nd "library for handling application capabilities"
50 .Fd #define WITH_CASPER
56 .Fn cap_wrap "int sock" "int flags"
58 .Fn cap_unwrap "cap_channel_t *chan" "int *flags"
60 .Fn cap_sock "const cap_channel_t *chan"
62 .Fn cap_clone "const cap_channel_t *chan"
64 .Fn cap_close "cap_channel_t *chan"
66 .Fn cap_limit_get "const cap_channel_t *chan" "nvlist_t **limitsp"
68 .Fn cap_limit_set "const cap_channel_t *chan" "nvlist_t *limits"
70 .Fn cap_send_nvlist "const cap_channel_t *chan" "const nvlist_t *nvl"
72 .Fn cap_recv_nvlist "const cap_channel_t *chan"
74 .Fn cap_xfer_nvlist "const cap_channel_t *chan" "nvlist_t *nvl"
76 .Fn cap_service_open "const cap_channel_t *chan" "const char *name"
80 library allows to manage application capabilities through the casper process.
82 The application capability (represented by the
84 type) is a communication channel between the caller and the casper process
85 daemon or an instance of one of its services.
86 A capability to the casper process obtained with the
88 function allows to create capabilities to casper's services via the
94 function opens capability to the casper process.
100 based on the given socket.
101 The function is used when capability is inherited through
105 domain socket as a regular file descriptor and has to be represented as
110 argument defines the channel behavior.
111 The supported flags are:
112 .Bl -ohang -offset indent
114 The communication between process and casper uses no unique version of nvlist.
119 function is the opposite of the
124 structure and returns
126 domain socket associated with it.
130 function clones the given capability.
134 function closes the given capability.
140 domain socket descriptor associated with the given capability for use with
149 function stores current limits of the given capability in the
152 If the function return
158 it means there are no limits set.
162 function sets limits for the given capability.
163 The limits are provided as
165 The exact format depends on the service the capability represents.
169 function sends the given
171 over the given capability.
172 This is low level interface to communicate with casper services.
173 Most services should provide higher level API.
177 function receives the given
179 over the given capability.
183 function sends the given
185 destroys it and receives new
187 in response over the given capability.
188 It does not matter if the function succeeds or fails, the
190 given for sending will always be destroyed once the function returns.
194 function opens casper service of the given name through casper capability
198 The function returns capability that provides access to opened service.
199 Casper supports the following services in the base system:
200 .Bl -tag -width "system.random" -compact -offset indent
203 provides DNS libc compatible API
213 allows to obtain entropy from
227 .Fn cap_recv_nvlist ,
228 .Fn cap_service_open ,
254 functions always succeed.
256 The following example first opens capability to the casper then using this
257 capability creates new capability to the
259 casper service and uses the latter capability to resolve IP address.
261 cap_channel_t *capcas, *capdns;
263 const char *ipstr = "127.0.0.1";
267 /* Open capability to the Casper. */
270 err(1, "Unable to contact Casper");
272 /* Enter capability mode sandbox. */
273 if (cap_enter() < 0 && errno != ENOSYS)
274 err(1, "Unable to enter capability mode");
276 /* Use Casper capability to create capability to the system.dns service. */
277 capdns = cap_service_open(capcas, "system.dns");
279 err(1, "Unable to open system.dns service");
281 /* Close Casper capability, we don't need it anymore. */
284 /* Limit system.dns to reverse DNS lookups and IPv4 addresses. */
285 limits = nvlist_create(0);
286 nvlist_add_string(limits, "type", "ADDR");
287 nvlist_add_number(limits, "family", (uint64_t)AF_INET);
288 if (cap_limit_set(capdns, limits) < 0)
289 err(1, "Unable to limit access to the system.dns service");
291 /* Convert IP address in C-string to in_addr. */
292 if (!inet_aton(ipstr, &ip))
293 errx(1, "Unable to parse IP address %s.", ipstr);
295 /* Find hostname for the given IP address. */
296 hp = cap_gethostbyaddr(capdns, (const void *)&ip, sizeof(ip), AF_INET);
298 errx(1, "No name associated with %s.", ipstr);
300 printf("Name associated with %s is %s.\\n", ipstr, hp->h_name);
308 .Xr cap_gethostbyaddr 3 ,
310 .Xr gethostbyaddr 3 ,
318 library was implemented by
319 .An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net
320 under sponsorship from the FreeBSD Foundation.
323 new architecture was implemented by
324 .An Mariusz Zaborski Aq Mt oshogbo@FreeBSD.org