c1754372ea
intended declaration.
614 lines
14 KiB
C
614 lines
14 KiB
C
/*-
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* Copyright (c) 2008-2011 Robert N. M. Watson
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* Copyright (c) 2010-2011 Jonathan Anderson
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* Copyright (c) 2012 FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed at the University of Cambridge Computer
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* Laboratory with support from a grant from Google, Inc.
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*
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* Portions of this software were developed by Pawel Jakub Dawidek under
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* sponsorship from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* FreeBSD kernel capability facility.
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*
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* Two kernel features are implemented here: capability mode, a sandboxed mode
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* of execution for processes, and capabilities, a refinement on file
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* descriptors that allows fine-grained control over operations on the file
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* descriptor. Collectively, these allow processes to run in the style of a
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* historic "capability system" in which they can use only resources
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* explicitly delegated to them. This model is enforced by restricting access
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* to global namespaces in capability mode.
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*
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* Capabilities wrap other file descriptor types, binding them to a constant
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* rights mask set when the capability is created. New capabilities may be
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* derived from existing capabilities, but only if they have the same or a
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* strict subset of the rights on the original capability.
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*
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* System calls permitted in capability mode are defined in capabilities.conf;
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* calls must be carefully audited for safety to ensure that they don't allow
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* escape from a sandbox. Some calls permit only a subset of operations in
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* capability mode -- for example, shm_open(2) is limited to creating
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* anonymous, rather than named, POSIX shared memory objects.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_capsicum.h"
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/capability.h>
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#include <sys/file.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/limits.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/syscallsubr.h>
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#include <sys/sysproto.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <sys/ucred.h>
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#include <security/audit/audit.h>
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#include <vm/uma.h>
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#include <vm/vm.h>
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#ifdef CAPABILITY_MODE
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FEATURE(security_capability_mode, "Capsicum Capability Mode");
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/*
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* System call to enter capability mode for the process.
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*/
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int
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sys_cap_enter(struct thread *td, struct cap_enter_args *uap)
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{
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struct ucred *newcred, *oldcred;
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struct proc *p;
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if (IN_CAPABILITY_MODE(td))
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return (0);
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newcred = crget();
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p = td->td_proc;
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PROC_LOCK(p);
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oldcred = p->p_ucred;
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crcopy(newcred, oldcred);
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newcred->cr_flags |= CRED_FLAG_CAPMODE;
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p->p_ucred = newcred;
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PROC_UNLOCK(p);
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crfree(oldcred);
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return (0);
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}
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/*
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* System call to query whether the process is in capability mode.
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*/
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int
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sys_cap_getmode(struct thread *td, struct cap_getmode_args *uap)
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{
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u_int i;
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i = IN_CAPABILITY_MODE(td) ? 1 : 0;
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return (copyout(&i, uap->modep, sizeof(i)));
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}
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#else /* !CAPABILITY_MODE */
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int
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sys_cap_enter(struct thread *td, struct cap_enter_args *uap)
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{
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return (ENOSYS);
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}
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int
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sys_cap_getmode(struct thread *td, struct cap_getmode_args *uap)
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{
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return (ENOSYS);
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}
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#endif /* CAPABILITY_MODE */
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#ifdef CAPABILITIES
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FEATURE(security_capabilities, "Capsicum Capabilities");
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MALLOC_DECLARE(M_FILECAPS);
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static inline int
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_cap_check(const cap_rights_t *havep, const cap_rights_t *needp,
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enum ktr_cap_fail_type type)
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{
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int i;
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for (i = 0; i < nitems(havep->cr_rights); i++) {
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if (!cap_rights_contains(havep, needp)) {
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#ifdef KTRACE
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if (KTRPOINT(curthread, KTR_CAPFAIL))
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ktrcapfail(type, needp, havep);
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#endif
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return (ENOTCAPABLE);
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}
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}
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return (0);
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}
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/*
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* Test whether a capability grants the requested rights.
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*/
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int
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cap_check(const cap_rights_t *havep, const cap_rights_t *needp)
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{
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return (_cap_check(havep, needp, CAPFAIL_NOTCAPABLE));
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}
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/*
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* Convert capability rights into VM access flags.
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*/
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u_char
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cap_rights_to_vmprot(cap_rights_t *havep)
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{
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u_char maxprot;
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maxprot = VM_PROT_NONE;
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if (cap_rights_is_set(havep, CAP_MMAP_R))
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maxprot |= VM_PROT_READ;
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if (cap_rights_is_set(havep, CAP_MMAP_W))
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maxprot |= VM_PROT_WRITE;
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if (cap_rights_is_set(havep, CAP_MMAP_X))
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maxprot |= VM_PROT_EXECUTE;
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return (maxprot);
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}
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/*
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* Extract rights from a capability for monitoring purposes -- not for use in
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* any other way, as we want to keep all capability permission evaluation in
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* this one file.
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*/
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cap_rights_t *
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cap_rights(struct filedesc *fdp, int fd)
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{
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return (&fdp->fd_ofiles[fd].fde_rights);
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}
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/*
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* System call to limit rights of the given capability.
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*/
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int
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sys_cap_rights_limit(struct thread *td, struct cap_rights_limit_args *uap)
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{
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struct filedesc *fdp;
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cap_rights_t rights;
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int error, fd, version;
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cap_rights_init(&rights);
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error = copyin(uap->rightsp, &rights, sizeof(rights.cr_rights[0]));
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if (error != 0)
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return (error);
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version = CAPVER(&rights);
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if (version != CAP_RIGHTS_VERSION_00)
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return (EINVAL);
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error = copyin(uap->rightsp, &rights,
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sizeof(rights.cr_rights[0]) * CAPARSIZE(&rights));
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if (error != 0)
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return (error);
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/* Check for race. */
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if (CAPVER(&rights) != version)
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return (EINVAL);
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if (!cap_rights_is_valid(&rights))
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return (EINVAL);
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if (version != CAP_RIGHTS_VERSION) {
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rights.cr_rights[0] &= ~(0x3ULL << 62);
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rights.cr_rights[0] |= ((uint64_t)CAP_RIGHTS_VERSION << 62);
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}
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_STRUCT))
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ktrcaprights(&rights);
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#endif
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fd = uap->fd;
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AUDIT_ARG_FD(fd);
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AUDIT_ARG_RIGHTS(&rights);
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fdp = td->td_proc->p_fd;
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FILEDESC_XLOCK(fdp);
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if (fget_locked(fdp, fd) == NULL) {
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FILEDESC_XUNLOCK(fdp);
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return (EBADF);
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}
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error = _cap_check(cap_rights(fdp, fd), &rights, CAPFAIL_INCREASE);
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if (error == 0) {
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fdp->fd_ofiles[fd].fde_rights = rights;
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if (!cap_rights_is_set(&rights, CAP_IOCTL)) {
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free(fdp->fd_ofiles[fd].fde_ioctls, M_FILECAPS);
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fdp->fd_ofiles[fd].fde_ioctls = NULL;
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fdp->fd_ofiles[fd].fde_nioctls = 0;
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}
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if (!cap_rights_is_set(&rights, CAP_FCNTL))
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fdp->fd_ofiles[fd].fde_fcntls = 0;
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}
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FILEDESC_XUNLOCK(fdp);
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return (error);
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}
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/*
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* System call to query the rights mask associated with a capability.
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*/
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int
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sys___cap_rights_get(struct thread *td, struct __cap_rights_get_args *uap)
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{
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struct filedesc *fdp;
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cap_rights_t rights;
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int error, fd, i, n;
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if (uap->version != CAP_RIGHTS_VERSION_00)
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return (EINVAL);
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fd = uap->fd;
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AUDIT_ARG_FD(fd);
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fdp = td->td_proc->p_fd;
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FILEDESC_SLOCK(fdp);
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if (fget_locked(fdp, fd) == NULL) {
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FILEDESC_SUNLOCK(fdp);
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return (EBADF);
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}
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rights = *cap_rights(fdp, fd);
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FILEDESC_SUNLOCK(fdp);
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n = uap->version + 2;
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if (uap->version != CAPVER(&rights)) {
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/*
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* For older versions we need to check if the descriptor
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* doesn't contain rights not understood by the caller.
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* If it does, we have to return an error.
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*/
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for (i = n; i < CAPARSIZE(&rights); i++) {
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if ((rights.cr_rights[i] & ~(0x7FULL << 57)) != 0)
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return (EINVAL);
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}
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}
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error = copyout(&rights, uap->rightsp, sizeof(rights.cr_rights[0]) * n);
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#ifdef KTRACE
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if (error == 0 && KTRPOINT(td, KTR_STRUCT))
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ktrcaprights(&rights);
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#endif
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return (error);
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}
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/*
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* Test whether a capability grants the given ioctl command.
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* If descriptor doesn't have CAP_IOCTL, then ioctls list is empty and
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* ENOTCAPABLE will be returned.
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*/
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int
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cap_ioctl_check(struct filedesc *fdp, int fd, u_long cmd)
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{
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u_long *cmds;
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ssize_t ncmds;
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long i;
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FILEDESC_LOCK_ASSERT(fdp);
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KASSERT(fd >= 0 && fd < fdp->fd_nfiles,
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("%s: invalid fd=%d", __func__, fd));
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ncmds = fdp->fd_ofiles[fd].fde_nioctls;
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if (ncmds == -1)
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return (0);
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cmds = fdp->fd_ofiles[fd].fde_ioctls;
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for (i = 0; i < ncmds; i++) {
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if (cmds[i] == cmd)
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return (0);
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}
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return (ENOTCAPABLE);
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}
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/*
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* Check if the current ioctls list can be replaced by the new one.
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*/
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static int
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cap_ioctl_limit_check(struct filedesc *fdp, int fd, const u_long *cmds,
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size_t ncmds)
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{
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u_long *ocmds;
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ssize_t oncmds;
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u_long i;
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long j;
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oncmds = fdp->fd_ofiles[fd].fde_nioctls;
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if (oncmds == -1)
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return (0);
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if (oncmds < (ssize_t)ncmds)
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return (ENOTCAPABLE);
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ocmds = fdp->fd_ofiles[fd].fde_ioctls;
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for (i = 0; i < ncmds; i++) {
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for (j = 0; j < oncmds; j++) {
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if (cmds[i] == ocmds[j])
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break;
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}
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if (j == oncmds)
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return (ENOTCAPABLE);
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}
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return (0);
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}
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int
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kern_cap_ioctls_limit(struct thread *td, int fd, u_long *cmds, size_t ncmds)
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{
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struct filedesc *fdp;
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u_long *ocmds;
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int error;
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AUDIT_ARG_FD(fd);
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fdp = td->td_proc->p_fd;
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FILEDESC_XLOCK(fdp);
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if (fget_locked(fdp, fd) == NULL) {
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error = EBADF;
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goto out;
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}
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error = cap_ioctl_limit_check(fdp, fd, cmds, ncmds);
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if (error != 0)
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goto out;
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ocmds = fdp->fd_ofiles[fd].fde_ioctls;
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fdp->fd_ofiles[fd].fde_ioctls = cmds;
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fdp->fd_ofiles[fd].fde_nioctls = ncmds;
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cmds = ocmds;
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error = 0;
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out:
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FILEDESC_XUNLOCK(fdp);
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free(cmds, M_FILECAPS);
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return (error);
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}
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int
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sys_cap_ioctls_limit(struct thread *td, struct cap_ioctls_limit_args *uap)
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{
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u_long *cmds;
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size_t ncmds;
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int error;
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ncmds = uap->ncmds;
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if (ncmds > 256) /* XXX: Is 256 sane? */
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return (EINVAL);
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if (ncmds == 0) {
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cmds = NULL;
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} else {
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cmds = malloc(sizeof(cmds[0]) * ncmds, M_FILECAPS, M_WAITOK);
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error = copyin(uap->cmds, cmds, sizeof(cmds[0]) * ncmds);
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if (error != 0) {
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free(cmds, M_FILECAPS);
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return (error);
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}
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}
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return (kern_cap_ioctls_limit(td, uap->fd, cmds, ncmds));
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}
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int
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sys_cap_ioctls_get(struct thread *td, struct cap_ioctls_get_args *uap)
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{
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struct filedesc *fdp;
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struct filedescent *fdep;
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u_long *cmds;
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size_t maxcmds;
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int error, fd;
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fd = uap->fd;
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cmds = uap->cmds;
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maxcmds = uap->maxcmds;
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AUDIT_ARG_FD(fd);
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fdp = td->td_proc->p_fd;
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FILEDESC_SLOCK(fdp);
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if (fget_locked(fdp, fd) == NULL) {
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error = EBADF;
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goto out;
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}
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/*
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* If all ioctls are allowed (fde_nioctls == -1 && fde_ioctls == NULL)
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* the only sane thing we can do is to not populate the given array and
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* return CAP_IOCTLS_ALL.
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*/
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fdep = &fdp->fd_ofiles[fd];
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if (cmds != NULL && fdep->fde_ioctls != NULL) {
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error = copyout(fdep->fde_ioctls, cmds,
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sizeof(cmds[0]) * MIN(fdep->fde_nioctls, maxcmds));
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if (error != 0)
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goto out;
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}
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if (fdep->fde_nioctls == -1)
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td->td_retval[0] = CAP_IOCTLS_ALL;
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else
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td->td_retval[0] = fdep->fde_nioctls;
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error = 0;
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out:
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FILEDESC_SUNLOCK(fdp);
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return (error);
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}
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/*
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* Test whether a capability grants the given fcntl command.
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*/
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int
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cap_fcntl_check(struct filedesc *fdp, int fd, int cmd)
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{
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uint32_t fcntlcap;
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KASSERT(fd >= 0 && fd < fdp->fd_nfiles,
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("%s: invalid fd=%d", __func__, fd));
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fcntlcap = (1 << cmd);
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KASSERT((CAP_FCNTL_ALL & fcntlcap) != 0,
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("Unsupported fcntl=%d.", cmd));
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if ((fdp->fd_ofiles[fd].fde_fcntls & fcntlcap) != 0)
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return (0);
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return (ENOTCAPABLE);
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}
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int
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sys_cap_fcntls_limit(struct thread *td, struct cap_fcntls_limit_args *uap)
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{
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struct filedesc *fdp;
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uint32_t fcntlrights;
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int fd;
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fd = uap->fd;
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fcntlrights = uap->fcntlrights;
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AUDIT_ARG_FD(fd);
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AUDIT_ARG_FCNTL_RIGHTS(fcntlrights);
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if ((fcntlrights & ~CAP_FCNTL_ALL) != 0)
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return (EINVAL);
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fdp = td->td_proc->p_fd;
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FILEDESC_XLOCK(fdp);
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if (fget_locked(fdp, fd) == NULL) {
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FILEDESC_XUNLOCK(fdp);
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return (EBADF);
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}
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if ((fcntlrights & ~fdp->fd_ofiles[fd].fde_fcntls) != 0) {
|
|
FILEDESC_XUNLOCK(fdp);
|
|
return (ENOTCAPABLE);
|
|
}
|
|
|
|
fdp->fd_ofiles[fd].fde_fcntls = fcntlrights;
|
|
FILEDESC_XUNLOCK(fdp);
|
|
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
sys_cap_fcntls_get(struct thread *td, struct cap_fcntls_get_args *uap)
|
|
{
|
|
struct filedesc *fdp;
|
|
uint32_t rights;
|
|
int fd;
|
|
|
|
fd = uap->fd;
|
|
|
|
AUDIT_ARG_FD(fd);
|
|
|
|
fdp = td->td_proc->p_fd;
|
|
FILEDESC_SLOCK(fdp);
|
|
if (fget_locked(fdp, fd) == NULL) {
|
|
FILEDESC_SUNLOCK(fdp);
|
|
return (EBADF);
|
|
}
|
|
rights = fdp->fd_ofiles[fd].fde_fcntls;
|
|
FILEDESC_SUNLOCK(fdp);
|
|
|
|
return (copyout(&rights, uap->fcntlrightsp, sizeof(rights)));
|
|
}
|
|
|
|
#else /* !CAPABILITIES */
|
|
|
|
/*
|
|
* Stub Capability functions for when options CAPABILITIES isn't compiled
|
|
* into the kernel.
|
|
*/
|
|
|
|
int
|
|
sys_cap_rights_limit(struct thread *td, struct cap_rights_limit_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
int
|
|
sys___cap_rights_get(struct thread *td, struct __cap_rights_get_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
int
|
|
sys_cap_ioctls_limit(struct thread *td, struct cap_ioctls_limit_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
int
|
|
sys_cap_ioctls_get(struct thread *td, struct cap_ioctls_get_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
int
|
|
sys_cap_fcntls_limit(struct thread *td, struct cap_fcntls_limit_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
int
|
|
sys_cap_fcntls_get(struct thread *td, struct cap_fcntls_get_args *uap)
|
|
{
|
|
|
|
return (ENOSYS);
|
|
}
|
|
|
|
#endif /* CAPABILITIES */
|