CAP_IOCTLS_LIMIT(2)       FreeBSD System Calls Manual      CAP_IOCTLS_LIMIT(2)

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
     The cap_ioctls_get() and cap_ioctls_limit() system calls first appeared
     in FreeBSD 8.3.  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.

FreeBSD 13.1-RELEASE-p6           May 5, 2020          FreeBSD 13.1-RELEASE-p6