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LIBCASPER(3) Library Functions Manual LIBCASPER(3) NAME cap_init, cap_wrap, cap_unwrap, cap_sock, cap_clone, cap_close, cap_limit_get, cap_limit_set, cap_send_nvlist, cap_recv_nvlist, cap_xfer_nvlist, cap_service_open -- library for handling application capabilities LIBRARY library "libcasper" SYNOPSIS #define WITH_CASPER #include <sys/nv.h> #include <libcasper.h> cap_channel_t * cap_init(void); cap_channel_t * cap_wrap(int sock, int flags); int cap_unwrap(cap_channel_t *chan, int *flags); int cap_sock(const cap_channel_t *chan); cap_channel_t * cap_clone(const cap_channel_t *chan); void cap_close(cap_channel_t *chan); int cap_limit_get(const cap_channel_t *chan, nvlist_t **limitsp); int cap_limit_set(const cap_channel_t *chan, nvlist_t *limits); int cap_send_nvlist(const cap_channel_t *chan, const nvlist_t *nvl); nvlist_t * cap_recv_nvlist(const cap_channel_t *chan); nvlist_t * cap_xfer_nvlist(const cap_channel_t *chan, nvlist_t *nvl); cap_channel_t * cap_service_open(const cap_channel_t *chan, const char *name); DESCRIPTION The libcasper library provides for the control of application capabili- ties through the casper process. An application capability, represented by the cap_channel_t type, is a communication channel between the caller and the casper daemon or an instance of one of the daemon's services. A capability to the casper process, obtained with the cap_init() function, allows a program to create capabilities to access the casper daemon's services via the cap_service_open() function. The cap_init() function instantiates a capability to allow a program to access the casper daemon. It must be called from a single-threaded context. The cap_wrap() function creates a cap_channel_t based on the socket supplied in the call. The function is used when a capability is inher- ited through the execve(2) system call, or sent over a unix(4) domain socket as a file descriptor, and has to be converted into a cap_channel_t. The flags argument defines the channel behavior. The supported flags are: CASPER_NO_UNIQ The communication between the process and the casper daemon uses no unique version of nvlist. The cap_unwrap() function returns the unix(4) domain socket used by the daemon service, and frees the cap_channel_t structure. The cap_clone() function returns a clone of the capability passed as its only argument. The cap_close() function closes, and frees, the given capability. The cap_sock() function returns the unix(4) domain socket descriptor associated with the given capability for use with system calls such as: kevent(2), poll(2), and select(2). The cap_limit_get() function stores the current limits of the given ca- pability in the limitsp argument. If the function returns 0 and NULL is stored in the limitsp argument, there are no limits set. The cap_limit_set() function sets limits for the given capability. The limits are provided as an nvlist(9). The exact format of the limits depends on the service that the capability represents. cap_limit_set() frees the limits passed to the call, whether or not the operation suc- ceeds or fails. The cap_send_nvlist() function sends the given nvlist(9) over the given capability. This is a low level interface to communicate with casper services. It is expected that most services will provide a higher level API. The cap_recv_nvlist() function receives the given nvlist(9) over the given capability. The cap_xfer_nvlist() function sends the given nvlist(9), destroys it, and receives a new nvlist(9) in response over the given capability. It does not matter if the function succeeds or fails, the nvlist(9) given for sending will always be destroyed before the function returns. The cap_service_open() function opens the casper service named in the call using the casper capability obtained via the cap_init() function. The cap_service_open() function returns a capability that provides ac- cess to the opened service. Casper supports the following services in the base system: system.dns provides libc compatible DNS API system.fileargs provides an API for opening files specified on a command line system.grp provides a getgrent(3) compatible API system.net provides a libc compatible network API system.netdb provides libc compatible network proto API system.pwd provides a getpwent(3) compatible API system.sysctl provides a sysctlbyname(3) compatible API system.syslog provides a syslog(3) compatible API RETURN VALUES The cap_clone(), cap_init(), cap_recv_nvlist(), cap_service_open(), cap_wrap() and cap_xfer_nvlist() functions return NULL and set the errno variable on failure. The cap_limit_get(), cap_limit_set() and cap_send_nvlist() functions return -1 and set the errno variable on failure. The cap_close(), cap_sock() and cap_unwrap() functions always succeed. SEE ALSO errno(2), execve(2), kevent(2), poll(2), select(2), cap_dns(3), cap_fileargs(3), cap_grp(3), cap_net(3), cap_netdb(3), cap_pwd(3), cap_sysctl(3), cap_syslog(3), libcasper_service(3), capsicum(4), unix(4), nv(9) HISTORY The libcasper library first appeared in FreeBSD 10.3. AUTHORS The libcasper library was implemented by Pawel Jakub Dawidek <pawel@dawidek.net> under sponsorship from the FreeBSD Foundation. The libcasper new architecture was implemented by Mariusz Zaborski <oshogbo@FreeBSD.org> FreeBSD 13.2 September 6, 2023 LIBCASPER(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | HISTORY | AUTHORS
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