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cap_getmode(2) [freebsd man page]

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

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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CAPSICUM(4)						   BSD Kernel Interfaces Manual 					       CAPSICUM(4)

Capsicum -- lightweight OS capability and sandbox framework SYNOPSIS
Capsicum is a lightweight OS capability and sandbox framework implementing a hybrid capability system model. Capsicum can be used for appli- cation and library compartmentalisation, the decomposition of larger bodies of software into isolated (sandboxed) components in order to implement security policies and limit the impact of software vulnerabilities. Capsicum provides two core kernel primitives: capability mode A process mode, entered by invoking cap_enter(2), in which access to global OS namespaces (such as the file system and PID names- paces) is restricted; only explicitly delegated rights, referenced by memory mappings or file descriptors, may be used. Once set, the flag is inherited by future children processes, and may not be cleared. capabilities Limit operations that can be called on file descriptors. For example, a file descriptor returned by open(2) may be refined using cap_rights_limit(2) so that only read(2) and write(2) can be called, but not fchmod(2). The complete list of the capability rights can be found in the rights(4) manual page. In some cases, Capsicum requires use of alternatives to traditional POSIX APIs in order to name objects using capabilities rather than global namespaces: process descriptors File descriptors representing processes, allowing parent processes to manage child processes without requiring access to the PID namespace; described in greater detail in procdesc(4). anonymous shared memory An extension to the POSIX shared memory API to support anonymous swap objects associated with file descriptors; described in greater detail in shm_open(2). SEE ALSO
cap_enter(2), cap_fcntls_limit(2), cap_getmode(2), cap_ioctls_limit(2), cap_rights_limit(2), fchmod(2), open(2), pdfork(2), pdgetpid(2), pdkill(2), pdwait4(2), read(2), shm_open(2), write(2), cap_rights_get(3), libcapsicum(3), procdesc(4), casperd(8) HISTORY
Capsicum first appeared in FreeBSD 9.0, and was developed at the University of Cambridge. AUTHORS
Capsicum was developed by Robert Watson <> and Jonathan Anderson <> at the University of Cambridge, and Ben Laurie <> and Kris Kennaway <> at Google, Inc., and Pawel Jakub Dawidek <>. BUGS
Capsicum is considered experimental in FreeBSD. BSD
October 19, 2013 BSD
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