cap_fcntls_limit, cap_fcntls_get — manage allowed fcntl commands

This function was created by Pawel Jakub Dawidek <pawel@dawidek.net> under sponsorship of the FreeBSD Foundation. Debian May 5, 2020 CAP_FCNTLS_LIMIT(2)

If a file descriptor is granted the CAP_FCNTL capability right, the list of allowed fcntl(2) commands can be selectively reduced (but never expanded) with the cap_fcntls_limit() system call. A bitmask of allowed fcntls commands for a given file descriptor can be obtained with the cap_fcntls_get() system call.

cap_fcntls_limit() succeeds unless: [EBADF] The fd argument is not a valid descriptor. [EINVAL] An invalid flag has been passed in fcntlrights. [ENOTCAPABLE] fcntlrights would expand the list of allowed fcntl(2) commands. cap_fcntls_get() succeeds unless: [EBADF] The fd argument is not a valid descriptor. [EFAULT] The fcntlrightsp argument points at an invalid address.

The following flags may be specified in the fcntlrights argument or returned in the fcntlrightsp argument: CAP_FCNTL_GETFL Permit F_GETFL command. CAP_FCNTL_SETFL Permit F_SETFL command. CAP_FCNTL_GETOWN Permit F_GETOWN command. CAP_FCNTL_SETOWN Permit F_SETOWN command.

The cap_fcntls_get() and cap_fcntls_limit() system calls first appeared in FreeBSD 8.3. Support for capabilities and capabilities mode was developed as part of the TrustedBSD Project.

Standard C Library (libc, -lc)

cap_fcntls_limit, cap_fcntls_get — manage allowed fcntl commands

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

cap_ioctls_limit(2), cap_rights_limit(2), fcntl(2)

#include<sys/capsicum.h>intcap_fcntls_limit(intfd, uint32_tfcntlrights); intcap_fcntls_get(intfd, uint32_t*fcntlrightsp);