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cap_ioctls_limit(2) [freebsd man page]

CAP_IOCTLS_LIMIT(2)					      BSD 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. 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 won't 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. BSD
March 27, 2014 BSD

Check Out this Related Man Page

CAP_ENTER(2)						      BSD System Calls Manual						      CAP_ENTER(2)

NAME
cap_enter, cap_getmode -- Capability mode system calls LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/capsicum.h> int cap_enter(void); int cap_getmode(u_int *modep); DESCRIPTION
cap_enter() places the current process into capability mode, a mode of execution in which processes may only issue system calls operating on file descriptors or reading limited global system state. Access to global name spaces, such as file system or IPC name spaces, is prevented. If the process is already in a capability mode sandbox, the system call is a no-op. Future process descendants created with fork(2) or pdfork(2) will be placed in capability mode from inception. When combined with cap_rights_limit(2), cap_ioctls_limit(2), cap_fcntls_limit(2), cap_enter() may be used to create kernel-enforced sandboxes in which appropriately-crafted applications or application components may be run. cap_getmode() returns a flag indicating whether or not the process is in a capability mode sandbox. CAVEAT
Creating effective process sandboxes is a tricky process that involves identifying the least possible rights required by the process and then passing those rights into the process in a safe manner. Consumers of cap_enter() should also be aware of other inherited rights, such as access to VM resources, memory contents, and other process properties that should be considered. It is advisable to use fexecve(2) to create a runtime environment inside the sandbox that has as few implicitly acquired rights as possible. RETURN VALUES
The cap_enter() and cap_getmode() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS
The cap_enter() and cap_getmode() system calls will fail if: [ENOSYS] The kernel is compiled without: options CAPABILITY_MODE The cap_getmode() system call may also return the following error: [EFAULT] Pointer modep points outside the process's allocated address space. SEE ALSO
cap_fcntls_limit(2), cap_ioctls_limit(2), cap_rights_limit(2), fexecve(2), cap_sandboxed(3), capsicum(4) HISTORY
Support for capabilities and capabilities mode was developed as part of the TrustedBSD Project. AUTHORS
These functions and the capability facility were created by Robert N. M. Watson at the University of Cambridge Computer Laboratory with sup- port from a grant from Google, Inc. BSD
March 27, 2014 BSD
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