Index: head/sys/kern/sys_capability.c =================================================================== --- head/sys/kern/sys_capability.c (revision 359131) +++ head/sys/kern/sys_capability.c (revision 359132) @@ -1,680 +1,689 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2008-2011 Robert N. M. Watson * Copyright (c) 2010-2011 Jonathan Anderson * Copyright (c) 2012 FreeBSD Foundation * All rights reserved. * * This software was developed at the University of Cambridge Computer * Laboratory with support from a grant from Google, Inc. * * Portions of this software were developed by Pawel Jakub Dawidek under * sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * FreeBSD kernel capability facility. * * Two kernel features are implemented here: capability mode, a sandboxed mode * of execution for processes, and capabilities, a refinement on file * descriptors that allows fine-grained control over operations on the file * descriptor. Collectively, these allow processes to run in the style of a * historic "capability system" in which they can use only resources * explicitly delegated to them. This model is enforced by restricting access * to global namespaces in capability mode. * * Capabilities wrap other file descriptor types, binding them to a constant * rights mask set when the capability is created. New capabilities may be * derived from existing capabilities, but only if they have the same or a * strict subset of the rights on the original capability. * * System calls permitted in capability mode are defined in capabilities.conf; * calls must be carefully audited for safety to ensure that they don't allow * escape from a sandbox. Some calls permit only a subset of operations in * capability mode -- for example, shm_open(2) is limited to creating * anonymous, rather than named, POSIX shared memory objects. */ #include __FBSDID("$FreeBSD$"); #include "opt_capsicum.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include bool __read_frequently trap_enotcap; SYSCTL_BOOL(_kern, OID_AUTO, trap_enotcap, CTLFLAG_RWTUN, &trap_enotcap, 0, "Deliver SIGTRAP on ENOTCAPABLE"); #ifdef CAPABILITY_MODE #define IOCTLS_MAX_COUNT 256 /* XXX: Is 256 sane? */ FEATURE(security_capability_mode, "Capsicum Capability Mode"); /* * System call to enter capability mode for the process. */ int sys_cap_enter(struct thread *td, struct cap_enter_args *uap) { struct ucred *newcred, *oldcred; struct proc *p; if (IN_CAPABILITY_MODE(td)) return (0); newcred = crget(); p = td->td_proc; PROC_LOCK(p); oldcred = crcopysafe(p, newcred); newcred->cr_flags |= CRED_FLAG_CAPMODE; proc_set_cred(p, newcred); PROC_UNLOCK(p); crfree(oldcred); return (0); } /* * System call to query whether the process is in capability mode. */ int sys_cap_getmode(struct thread *td, struct cap_getmode_args *uap) { u_int i; i = IN_CAPABILITY_MODE(td) ? 1 : 0; return (copyout(&i, uap->modep, sizeof(i))); } #else /* !CAPABILITY_MODE */ int sys_cap_enter(struct thread *td, struct cap_enter_args *uap) { return (ENOSYS); } int sys_cap_getmode(struct thread *td, struct cap_getmode_args *uap) { return (ENOSYS); } #endif /* CAPABILITY_MODE */ #ifdef CAPABILITIES FEATURE(security_capabilities, "Capsicum Capabilities"); MALLOC_DECLARE(M_FILECAPS); static inline int _cap_check(const cap_rights_t *havep, const cap_rights_t *needp, enum ktr_cap_fail_type type) { if (!cap_rights_contains(havep, needp)) { #ifdef KTRACE if (KTRPOINT(curthread, KTR_CAPFAIL)) ktrcapfail(type, needp, havep); #endif return (ENOTCAPABLE); } return (0); } /* * Test whether a capability grants the requested rights. */ int cap_check(const cap_rights_t *havep, const cap_rights_t *needp) { return (_cap_check(havep, needp, CAPFAIL_NOTCAPABLE)); } int cap_check_failed_notcapable(const cap_rights_t *havep, const cap_rights_t *needp) { #ifdef KTRACE if (KTRPOINT(curthread, KTR_CAPFAIL)) ktrcapfail(CAPFAIL_NOTCAPABLE, needp, havep); #endif return (ENOTCAPABLE); } /* * Convert capability rights into VM access flags. */ vm_prot_t cap_rights_to_vmprot(const cap_rights_t *havep) { vm_prot_t maxprot; maxprot = VM_PROT_NONE; if (cap_rights_is_set(havep, CAP_MMAP_R)) maxprot |= VM_PROT_READ; if (cap_rights_is_set(havep, CAP_MMAP_W)) maxprot |= VM_PROT_WRITE; if (cap_rights_is_set(havep, CAP_MMAP_X)) maxprot |= VM_PROT_EXECUTE; return (maxprot); } /* * Extract rights from a capability for monitoring purposes -- not for use in * any other way, as we want to keep all capability permission evaluation in * this one file. */ const cap_rights_t * cap_rights_fde(const struct filedescent *fdep) { return (cap_rights_fde_inline(fdep)); } const cap_rights_t * cap_rights(struct filedesc *fdp, int fd) { return (cap_rights_fde(&fdp->fd_ofiles[fd])); } int kern_cap_rights_limit(struct thread *td, int fd, cap_rights_t *rights) { struct filedesc *fdp; struct filedescent *fdep; + u_long *ioctls; int error; fdp = td->td_proc->p_fd; FILEDESC_XLOCK(fdp); fdep = fdeget_locked(fdp, fd); if (fdep == NULL) { FILEDESC_XUNLOCK(fdp); return (EBADF); } + ioctls = NULL; error = _cap_check(cap_rights(fdp, fd), rights, CAPFAIL_INCREASE); if (error == 0) { + seqc_write_begin(&fdep->fde_seqc); fdep->fde_rights = *rights; if (!cap_rights_is_set(rights, CAP_IOCTL)) { - free(fdep->fde_ioctls, M_FILECAPS); + ioctls = fdep->fde_ioctls; fdep->fde_ioctls = NULL; fdep->fde_nioctls = 0; } if (!cap_rights_is_set(rights, CAP_FCNTL)) fdep->fde_fcntls = 0; + seqc_write_end(&fdep->fde_seqc); } FILEDESC_XUNLOCK(fdp); + free(ioctls, M_FILECAPS); return (error); } /* * System call to limit rights of the given capability. */ int sys_cap_rights_limit(struct thread *td, struct cap_rights_limit_args *uap) { cap_rights_t rights; int error, version; cap_rights_init_zero(&rights); error = copyin(uap->rightsp, &rights, sizeof(rights.cr_rights[0])); if (error != 0) return (error); version = CAPVER(&rights); if (version != CAP_RIGHTS_VERSION_00) return (EINVAL); error = copyin(uap->rightsp, &rights, sizeof(rights.cr_rights[0]) * CAPARSIZE(&rights)); if (error != 0) return (error); /* Check for race. */ if (CAPVER(&rights) != version) return (EINVAL); if (!cap_rights_is_valid(&rights)) return (EINVAL); if (version != CAP_RIGHTS_VERSION) { rights.cr_rights[0] &= ~(0x3ULL << 62); rights.cr_rights[0] |= ((uint64_t)CAP_RIGHTS_VERSION << 62); } #ifdef KTRACE if (KTRPOINT(td, KTR_STRUCT)) ktrcaprights(&rights); #endif AUDIT_ARG_FD(uap->fd); AUDIT_ARG_RIGHTS(&rights); return (kern_cap_rights_limit(td, uap->fd, &rights)); } /* * System call to query the rights mask associated with a capability. */ int sys___cap_rights_get(struct thread *td, struct __cap_rights_get_args *uap) { struct filedesc *fdp; cap_rights_t rights; int error, fd, i, n; if (uap->version != CAP_RIGHTS_VERSION_00) return (EINVAL); 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 = *cap_rights(fdp, fd); FILEDESC_SUNLOCK(fdp); n = uap->version + 2; if (uap->version != CAPVER(&rights)) { /* * For older versions we need to check if the descriptor * doesn't contain rights not understood by the caller. * If it does, we have to return an error. */ for (i = n; i < CAPARSIZE(&rights); i++) { if ((rights.cr_rights[i] & ~(0x7FULL << 57)) != 0) return (EINVAL); } } error = copyout(&rights, uap->rightsp, sizeof(rights.cr_rights[0]) * n); #ifdef KTRACE if (error == 0 && KTRPOINT(td, KTR_STRUCT)) ktrcaprights(&rights); #endif return (error); } /* * Test whether a capability grants the given ioctl command. * If descriptor doesn't have CAP_IOCTL, then ioctls list is empty and * ENOTCAPABLE will be returned. */ int cap_ioctl_check(struct filedesc *fdp, int fd, u_long cmd) { struct filedescent *fdep; u_long *cmds; ssize_t ncmds; long i; KASSERT(fd >= 0 && fd < fdp->fd_nfiles, ("%s: invalid fd=%d", __func__, fd)); fdep = fdeget_locked(fdp, fd); KASSERT(fdep != NULL, ("%s: invalid fd=%d", __func__, fd)); ncmds = fdep->fde_nioctls; if (ncmds == -1) return (0); cmds = fdep->fde_ioctls; for (i = 0; i < ncmds; i++) { if (cmds[i] == cmd) return (0); } return (ENOTCAPABLE); } /* * Check if the current ioctls list can be replaced by the new one. */ static int cap_ioctl_limit_check(struct filedescent *fdep, const u_long *cmds, size_t ncmds) { u_long *ocmds; ssize_t oncmds; u_long i; long j; oncmds = fdep->fde_nioctls; if (oncmds == -1) return (0); if (oncmds < (ssize_t)ncmds) return (ENOTCAPABLE); ocmds = fdep->fde_ioctls; for (i = 0; i < ncmds; i++) { for (j = 0; j < oncmds; j++) { if (cmds[i] == ocmds[j]) break; } if (j == oncmds) return (ENOTCAPABLE); } return (0); } int kern_cap_ioctls_limit(struct thread *td, int fd, u_long *cmds, size_t ncmds) { struct filedesc *fdp; struct filedescent *fdep; u_long *ocmds; int error; AUDIT_ARG_FD(fd); if (ncmds > IOCTLS_MAX_COUNT) { error = EINVAL; goto out_free; } fdp = td->td_proc->p_fd; FILEDESC_XLOCK(fdp); fdep = fdeget_locked(fdp, fd); if (fdep == NULL) { error = EBADF; goto out; } error = cap_ioctl_limit_check(fdep, cmds, ncmds); if (error != 0) goto out; ocmds = fdep->fde_ioctls; + seqc_write_begin(&fdep->fde_seqc); fdep->fde_ioctls = cmds; fdep->fde_nioctls = ncmds; + seqc_write_end(&fdep->fde_seqc); cmds = ocmds; error = 0; out: FILEDESC_XUNLOCK(fdp); out_free: free(cmds, M_FILECAPS); return (error); } int sys_cap_ioctls_limit(struct thread *td, struct cap_ioctls_limit_args *uap) { u_long *cmds; size_t ncmds; int error; ncmds = uap->ncmds; if (ncmds > IOCTLS_MAX_COUNT) return (EINVAL); if (ncmds == 0) { cmds = NULL; } else { cmds = malloc(sizeof(cmds[0]) * ncmds, M_FILECAPS, M_WAITOK); error = copyin(uap->cmds, cmds, sizeof(cmds[0]) * ncmds); if (error != 0) { free(cmds, M_FILECAPS); return (error); } } return (kern_cap_ioctls_limit(td, uap->fd, cmds, ncmds)); } int sys_cap_ioctls_get(struct thread *td, struct cap_ioctls_get_args *uap) { struct filedesc *fdp; struct filedescent *fdep; u_long *cmdsp, *dstcmds; size_t maxcmds, ncmds; int16_t count; int error, fd; fd = uap->fd; dstcmds = uap->cmds; maxcmds = uap->maxcmds; AUDIT_ARG_FD(fd); fdp = td->td_proc->p_fd; cmdsp = NULL; if (dstcmds != NULL) { cmdsp = malloc(sizeof(cmdsp[0]) * IOCTLS_MAX_COUNT, M_FILECAPS, M_WAITOK | M_ZERO); } FILEDESC_SLOCK(fdp); fdep = fdeget_locked(fdp, fd); if (fdep == NULL) { error = EBADF; FILEDESC_SUNLOCK(fdp); goto out; } count = fdep->fde_nioctls; if (count != -1 && cmdsp != NULL) { ncmds = MIN(count, maxcmds); memcpy(cmdsp, fdep->fde_ioctls, sizeof(cmdsp[0]) * ncmds); } FILEDESC_SUNLOCK(fdp); /* * If all ioctls are allowed (fde_nioctls == -1 && fde_ioctls == NULL) * the only sane thing we can do is to not populate the given array and * return CAP_IOCTLS_ALL. */ if (count != -1) { if (cmdsp != NULL) { error = copyout(cmdsp, dstcmds, sizeof(cmdsp[0]) * ncmds); if (error != 0) goto out; } td->td_retval[0] = count; } else { td->td_retval[0] = CAP_IOCTLS_ALL; } error = 0; out: free(cmdsp, M_FILECAPS); return (error); } /* * Test whether a capability grants the given fcntl command. */ int cap_fcntl_check_fde(struct filedescent *fdep, int cmd) { uint32_t fcntlcap; fcntlcap = (1 << cmd); KASSERT((CAP_FCNTL_ALL & fcntlcap) != 0, ("Unsupported fcntl=%d.", cmd)); if ((fdep->fde_fcntls & fcntlcap) != 0) return (0); return (ENOTCAPABLE); } int cap_fcntl_check(struct filedesc *fdp, int fd, int cmd) { KASSERT(fd >= 0 && fd < fdp->fd_nfiles, ("%s: invalid fd=%d", __func__, fd)); return (cap_fcntl_check_fde(&fdp->fd_ofiles[fd], cmd)); } int sys_cap_fcntls_limit(struct thread *td, struct cap_fcntls_limit_args *uap) { struct filedesc *fdp; struct filedescent *fdep; uint32_t fcntlrights; int fd; fd = uap->fd; fcntlrights = uap->fcntlrights; AUDIT_ARG_FD(fd); AUDIT_ARG_FCNTL_RIGHTS(fcntlrights); if ((fcntlrights & ~CAP_FCNTL_ALL) != 0) return (EINVAL); fdp = td->td_proc->p_fd; FILEDESC_XLOCK(fdp); fdep = fdeget_locked(fdp, fd); if (fdep == NULL) { FILEDESC_XUNLOCK(fdp); return (EBADF); } if ((fcntlrights & ~fdep->fde_fcntls) != 0) { FILEDESC_XUNLOCK(fdp); return (ENOTCAPABLE); } + seqc_write_begin(&fdep->fde_seqc); fdep->fde_fcntls = fcntlrights; + seqc_write_end(&fdep->fde_seqc); FILEDESC_XUNLOCK(fdp); return (0); } int sys_cap_fcntls_get(struct thread *td, struct cap_fcntls_get_args *uap) { struct filedesc *fdp; struct filedescent *fdep; uint32_t rights; int fd; fd = uap->fd; AUDIT_ARG_FD(fd); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); fdep = fdeget_locked(fdp, fd); if (fdep == NULL) { FILEDESC_SUNLOCK(fdp); return (EBADF); } rights = fdep->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 */