CAPSICUM_HELPERS(3)

NAME
caph_limit_stream, caph_limit_stdin, caph_limit_stderr, caph_limit_stdout, caph_limit_stdio, caph_stream_rights, caph_cache_tzdata, caph_cache_catpages, caph_enter, caph_enter_casper, caph_rights_limit, caph_ioctls_limit, caph_fcntls_limit - set of the capsicum helpers, part of the libcapsicum

LIBRARY
libcapsicum

SYNOPSIS
#include <capsicum_helpers.h>
int
caph_enter(void);
int
caph_enter_casper(void);
int
caph_rights_limit(int fd, const cap_rights_t *rights);
int
caph_ioctls_limit(int fd, const unsigned long *cmds, size_t ncmds);
int
caph_fcntls_limit(int fd, uint32_t fcntlrights);
int
caph_limit_stream(int fd, int flags);
int
caph_limit_stdin(void);
int
caph_limit_stderr(void);
int
caph_limit_stdout(void);
int
caph_limit_stdio(void);
void
caph_stream_rights(cap_rights_t *, int flags);
void
caph_cache_tzdata(void);
void
caph_cache_catpages(void);

DESCRIPTION
The caph_enter, caph_rights_limit, caph_ioctls_limit and caph_fcntls_limit are respectively equivalent to cap_enter(2), cap_rights_limit(2), cap_ioctls_limit(2) and cap_fcntls_limit(2), it returns success when the kernel is built without support of the capability mode.

The caph_enter_casper is equivalent to the caph_enter it returns success when the system is built without Casper support.

The capsicum helpers are a set of a inline functions which simplify modifying programs to use Capsicum. The goal is to reduce duplicated code patterns. The capsicum helpers are part of libcapsicum but there is no need to link to the library.

caph_limit_stream() restricts capabilities on fd to only those needed by POSIX stream objects (that is, FILEs).

These flags can be provided:

CAPH_IGNORE_EBADF
    Do not return an error if file descriptor is invalid.
CAPH_READ
    Set CAP_READ on limited descriptor.
CAPH_WRITE
    Set CAP_WRITE on limited descriptor.

caph_limit_stdin(), caph_limit_stderr() and caph_limit_stdout() limit standard descriptors using the caph_limit_stream function.

caph_limit_stdio() limits stdin, stderr and stdout.

caph_stream_rights may be used to initialize rights with the same rights that a stream would be limited to, as if caph_limit_stream() had been invoked using the same flags.

caph_cache_tzdata() precaches all timezone data needed to use libc local time functions.

caph_cache_catpages() caches Native Language Support (NLS) data. NLS data is used for localized error printing by strerror(3) and err(3), among others.

RETURN VALUES
Upon successful completion, caph_enter(), caph_enter_casper(), caph_rights_limit(), caph_ioctls_limit(), caph_fcntls_limit(), caph_limit_stream(), caph_limit_stdin(), caph_limit_stderr(), caph_limit_stdout(), and caph_limit_stdio() return a value of 0. Otherwise, a value of -1 is returned and the global variable errno is set to indicate the error.

Functions caph_stream_rights(), caph_cache_tzdata(), and caph_cache_catpages() can not fail.

SEE ALSO
cap_enter(2), cap_rights_limit(2), rights(4)