NAME

     cap_ioctls_limit, cap_ioctls_get — manage allowed ioctl commands

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/capsicum.h>

     int
     cap_ioctls_limit(int fd, const unsigned long *cmds, size_t ncmds);

     ssize_t
     cap_ioctls_get(int fd, unsigned long *cmds, size_t maxcmds);

DESCRIPTION

     If a file descriptor is granted the CAP_IOCTL capability right, the list of allowed ioctl(2)
     commands can be selectively reduced (but never expanded) with the cap_ioctls_limit() system
     call.  The cmds argument is an array of ioctl(2) commands and the ncmds argument specifies
     the number of elements in the array.  There can be up to 256 elements in the array.
     Including an element that has been previously revoked will generate an error.  After a
     successful call only those listed in the array may be used.

     The list of allowed ioctl commands for a given file descriptor can be obtained with the
     cap_ioctls_get() system call.  The cmds argument points at memory that can hold up to
     maxcmds values.  The function populates the provided buffer with up to maxcmds elements, but
     always returns the total number of ioctl commands allowed for the given file descriptor.
     The total number of ioctls commands for the given file descriptor can be obtained by passing
     NULL as the cmds argument and 0 as the maxcmds argument.  If all ioctl commands are allowed
     (CAP_IOCTL capability right is assigned to the file descriptor and the cap_ioctls_limit()
     system call was never called for this file descriptor), the cap_ioctls_get() system call
     will return CAP_IOCTLS_ALL and will not modify the buffer pointed to by the cmds argument.

RETURN VALUES

     The cap_ioctls_limit() function returns the value 0 if successful; otherwise the value -1 is
     returned and the global variable errno is set to indicate the error.

     The cap_ioctls_get() function, if successful, returns the total number of allowed ioctl
     commands or the value CAP_IOCTLS_ALL if all ioctls commands are allowed.  On failure the
     value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

     cap_ioctls_limit() succeeds unless:

     [EBADF]            The fd argument is not a valid descriptor.

     [EFAULT]           The cmds argument points at an invalid address.

     [EINVAL]           The ncmds argument is greater than 256.

     [ENOTCAPABLE]      cmds would expand the list of allowed ioctl(2) commands.

     cap_ioctls_get() succeeds unless:

     [EBADF]            The fd argument is not a valid descriptor.

     [EFAULT]           The cmds argument points at invalid address.

SEE ALSO

     cap_fcntls_limit(2), cap_rights_limit(2), ioctl(2)

HISTORY

     Support for capabilities and capabilities mode was developed as part of the TrustedBSD
     Project.

AUTHORS

     This function was created by Pawel Jakub Dawidek <pawel@dawidek.net> under sponsorship of
     the FreeBSD Foundation.