SIMPLE SOLUTIONS

CAP_RIGHTS_LIMIT(2FREEBSD) - Linux man page online | System calls

Limit capability rights.

Chapter
March 27, 2014
CAP_RIGHTS_LIMIT(2) BSD System Calls Manual CAP_RIGHTS_LIMIT(2)

NAME

cap_rights_limit — limit capability rights

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/capsicum.h> int cap_rights_limit(int fd, const cap_rights_t *rights);

DESCRIPTION

When a file descriptor is created by a function such as accept(2), accept4(2), fhopen(2), kqueue(2), mq_open(2), open(2), openat(2), pdfork(2), pipe(2), shm_open(2), socket(2) or socketpair(2), it is assigned all capability rights. Those rights can be reduced (but never expanded) by using the cap_rights_limit() system call. Once capability rights are reduced, operations on the file descriptor will be limited to those permitted by rights. The rights argument should be prepared using cap_rights_init(3) family of functions. Capability rights assigned to a file descriptor can be obtained with the cap_rights_get(3) function. The complete list of the capability rights can be found in the rights(4) manual page.

RETURN VALUES

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.

EXAMPLES

The following example demonstrates how to limit file descriptor capability rights to allow reading only. cap_rights_t setrights; char buf[1]; int fd; fd = open("/tmp/foo", O_RDWR); if (fd < 0) err(1, "open() failed"); if (cap_enter() < 0) err(1, "cap_enter() failed"); cap_rights_init(&setrights, CAP_READ); if (cap_rights_limit(fd, &setrights) < 0) err(1, "cap_rights_limit() failed"); buf[0] = 'X'; if (write(fd, buf, sizeof(buf)) > 0) errx(1, "write() succeeded!"); if (read(fd, buf, sizeof(buf)) < 0) err(1, "read() failed");

ERRORS

cap_rights_limit() succeeds unless: [EBADF] The fd argument is not a valid active descriptor. [EINVAL] An invalid right has been requested in rights. [ENOTCAPABLE] The rights argument contains capability rights not present for the given file descriptor. Capability rights list can only be reduced, never expanded.

SEE ALSO

accept(2), accept4(2), cap_enter(2), fhopen(2), kqueue(2), mq_open(2), open(2), openat(2), pdfork(2), pipe(2), read(2), shm_open(2), socket(2), socketpair(2), write(2), cap_rights_get(3), cap_rights_init(3), err(3), capsicum(4), rights(4)

HISTORY

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

AUTHORS

This function was created by Pawel Jakub Dawidek <@dawidek.net> under sponsorship of the FreeBSD Foundation.
BSD March 27, 2014 BSD
This manual Reference Other manuals
cap_rights_limit(2freebsd) referred by cap_enter(2freebsd) | cap_fcntls_get(2freebsd) | cap_fcntls_limit(2freebsd) | cap_getmode(2freebsd) | cap_ioctls_get(2freebsd) | cap_ioctls_limit(2freebsd) | capsicum(4freebsd) | rights(4freebsd)
refer to accept(2) | cap_enter(2freebsd) | capsicum(4freebsd) | err(3) | fhopen(2freebsd) | kqueue(2) | mq_open(2freebsd) | open(2) | pdfork(2freebsd) | pipe(2) | read(2) | rights(4freebsd) | shm_open(2freebsd) | socket(2) | socketpair(2) | write(2)
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