diff options
Diffstat (limited to 'freebsd/sys/kern/kern_prot.c')
| -rw-r--r-- | freebsd/sys/kern/kern_prot.c | 2247 |
1 files changed, 2247 insertions, 0 deletions
diff --git a/freebsd/sys/kern/kern_prot.c b/freebsd/sys/kern/kern_prot.c new file mode 100644 index 00000000..a62b6f76 --- /dev/null +++ b/freebsd/sys/kern/kern_prot.c @@ -0,0 +1,2247 @@ +/*- + * SPDX-License-Identifier: BSD-3-Clause + * + * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 + * The Regents of the University of California. + * (c) UNIX System Laboratories, Inc. + * Copyright (c) 2000-2001 Robert N. M. Watson. + * All rights reserved. + * + * All or some portions of this file are derived from material licensed + * to the University of California by American Telephone and Telegraph + * Co. or Unix System Laboratories, Inc. and are reproduced herein with + * the permission of UNIX System Laboratories, Inc. + * + * 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. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. + * + * @(#)kern_prot.c 8.6 (Berkeley) 1/21/94 + */ + +/* + * System calls related to processes and protection + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_inet.h" +#include "opt_inet6.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/acct.h> +#include <sys/kdb.h> +#include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/loginclass.h> +#include <sys/malloc.h> +#include <sys/mutex.h> +#include <sys/refcount.h> +#include <sys/sx.h> +#include <sys/priv.h> +#include <sys/proc.h> +#include <sys/sysent.h> +#include <sys/sysproto.h> +#include <sys/jail.h> +#include <sys/pioctl.h> +#include <sys/racct.h> +#include <sys/rctl.h> +#include <sys/resourcevar.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/syscallsubr.h> +#include <sys/sysctl.h> + +#ifdef REGRESSION +FEATURE(regression, + "Kernel support for interfaces necessary for regression testing (SECURITY RISK!)"); +#endif + +#include <security/audit/audit.h> +#include <security/mac/mac_framework.h> + +static MALLOC_DEFINE(M_CRED, "cred", "credentials"); + +SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW, 0, "BSD security policy"); + +static void crsetgroups_locked(struct ucred *cr, int ngrp, + gid_t *groups); + +#ifndef _SYS_SYSPROTO_H_ +struct getpid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_getpid(struct thread *td, struct getpid_args *uap) +{ + struct proc *p = td->td_proc; + + td->td_retval[0] = p->p_pid; +#if defined(COMPAT_43) + if (SV_PROC_FLAG(p, SV_AOUT)) + td->td_retval[1] = kern_getppid(td); +#endif + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getppid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_getppid(struct thread *td, struct getppid_args *uap) +{ + + td->td_retval[0] = kern_getppid(td); + return (0); +} + +int +kern_getppid(struct thread *td) +{ + struct proc *p = td->td_proc; + + return (p->p_oppid); +} + +/* + * Get process group ID; note that POSIX getpgrp takes no parameter. + */ +#ifndef _SYS_SYSPROTO_H_ +struct getpgrp_args { + int dummy; +}; +#endif +int +sys_getpgrp(struct thread *td, struct getpgrp_args *uap) +{ + struct proc *p = td->td_proc; + + PROC_LOCK(p); + td->td_retval[0] = p->p_pgrp->pg_id; + PROC_UNLOCK(p); + return (0); +} + +/* Get an arbitrary pid's process group id */ +#ifndef _SYS_SYSPROTO_H_ +struct getpgid_args { + pid_t pid; +}; +#endif +int +sys_getpgid(struct thread *td, struct getpgid_args *uap) +{ + struct proc *p; + int error; + + if (uap->pid == 0) { + p = td->td_proc; + PROC_LOCK(p); + } else { + p = pfind(uap->pid); + if (p == NULL) + return (ESRCH); + error = p_cansee(td, p); + if (error) { + PROC_UNLOCK(p); + return (error); + } + } + td->td_retval[0] = p->p_pgrp->pg_id; + PROC_UNLOCK(p); + return (0); +} + +/* + * Get an arbitrary pid's session id. + */ +#ifndef _SYS_SYSPROTO_H_ +struct getsid_args { + pid_t pid; +}; +#endif +int +sys_getsid(struct thread *td, struct getsid_args *uap) +{ + struct proc *p; + int error; + + if (uap->pid == 0) { + p = td->td_proc; + PROC_LOCK(p); + } else { + p = pfind(uap->pid); + if (p == NULL) + return (ESRCH); + error = p_cansee(td, p); + if (error) { + PROC_UNLOCK(p); + return (error); + } + } + td->td_retval[0] = p->p_session->s_sid; + PROC_UNLOCK(p); + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getuid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_getuid(struct thread *td, struct getuid_args *uap) +{ + + td->td_retval[0] = td->td_ucred->cr_ruid; +#if defined(COMPAT_43) + td->td_retval[1] = td->td_ucred->cr_uid; +#endif + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct geteuid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_geteuid(struct thread *td, struct geteuid_args *uap) +{ + + td->td_retval[0] = td->td_ucred->cr_uid; + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getgid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_getgid(struct thread *td, struct getgid_args *uap) +{ + + td->td_retval[0] = td->td_ucred->cr_rgid; +#if defined(COMPAT_43) + td->td_retval[1] = td->td_ucred->cr_groups[0]; +#endif + return (0); +} + +/* + * Get effective group ID. The "egid" is groups[0], and could be obtained + * via getgroups. This syscall exists because it is somewhat painful to do + * correctly in a library function. + */ +#ifndef _SYS_SYSPROTO_H_ +struct getegid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_getegid(struct thread *td, struct getegid_args *uap) +{ + + td->td_retval[0] = td->td_ucred->cr_groups[0]; + return (0); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getgroups_args { + u_int gidsetsize; + gid_t *gidset; +}; +#endif +int +sys_getgroups(struct thread *td, struct getgroups_args *uap) +{ + struct ucred *cred; + u_int ngrp; + int error; + + cred = td->td_ucred; + ngrp = cred->cr_ngroups; + + if (uap->gidsetsize == 0) { + error = 0; + goto out; + } + if (uap->gidsetsize < ngrp) + return (EINVAL); + + error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t)); +out: + td->td_retval[0] = ngrp; + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setsid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_setsid(struct thread *td, struct setsid_args *uap) +{ + struct pgrp *pgrp; + int error; + struct proc *p = td->td_proc; + struct pgrp *newpgrp; + struct session *newsess; + + error = 0; + pgrp = NULL; + + newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); + newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); + + sx_xlock(&proctree_lock); + + if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { + if (pgrp != NULL) + PGRP_UNLOCK(pgrp); + error = EPERM; + } else { + (void)enterpgrp(p, p->p_pid, newpgrp, newsess); + td->td_retval[0] = p->p_pid; + newpgrp = NULL; + newsess = NULL; + } + + sx_xunlock(&proctree_lock); + + if (newpgrp != NULL) + free(newpgrp, M_PGRP); + if (newsess != NULL) + free(newsess, M_SESSION); + + return (error); +} + +/* + * set process group (setpgid/old setpgrp) + * + * caller does setpgid(targpid, targpgid) + * + * pid must be caller or child of caller (ESRCH) + * if a child + * pid must be in same session (EPERM) + * pid can't have done an exec (EACCES) + * if pgid != pid + * there must exist some pid in same session having pgid (EPERM) + * pid must not be session leader (EPERM) + */ +#ifndef _SYS_SYSPROTO_H_ +struct setpgid_args { + int pid; /* target process id */ + int pgid; /* target pgrp id */ +}; +#endif +/* ARGSUSED */ +int +sys_setpgid(struct thread *td, struct setpgid_args *uap) +{ + struct proc *curp = td->td_proc; + struct proc *targp; /* target process */ + struct pgrp *pgrp; /* target pgrp */ + int error; + struct pgrp *newpgrp; + + if (uap->pgid < 0) + return (EINVAL); + + error = 0; + + newpgrp = malloc(sizeof(struct pgrp), M_PGRP, M_WAITOK | M_ZERO); + + sx_xlock(&proctree_lock); + if (uap->pid != 0 && uap->pid != curp->p_pid) { + if ((targp = pfind(uap->pid)) == NULL) { + error = ESRCH; + goto done; + } + if (!inferior(targp)) { + PROC_UNLOCK(targp); + error = ESRCH; + goto done; + } + if ((error = p_cansee(td, targp))) { + PROC_UNLOCK(targp); + goto done; + } + if (targp->p_pgrp == NULL || + targp->p_session != curp->p_session) { + PROC_UNLOCK(targp); + error = EPERM; + goto done; + } + if (targp->p_flag & P_EXEC) { + PROC_UNLOCK(targp); + error = EACCES; + goto done; + } + PROC_UNLOCK(targp); + } else + targp = curp; + if (SESS_LEADER(targp)) { + error = EPERM; + goto done; + } + if (uap->pgid == 0) + uap->pgid = targp->p_pid; + if ((pgrp = pgfind(uap->pgid)) == NULL) { + if (uap->pgid == targp->p_pid) { + error = enterpgrp(targp, uap->pgid, newpgrp, + NULL); + if (error == 0) + newpgrp = NULL; + } else + error = EPERM; + } else { + if (pgrp == targp->p_pgrp) { + PGRP_UNLOCK(pgrp); + goto done; + } + if (pgrp->pg_id != targp->p_pid && + pgrp->pg_session != curp->p_session) { + PGRP_UNLOCK(pgrp); + error = EPERM; + goto done; + } + PGRP_UNLOCK(pgrp); + error = enterthispgrp(targp, pgrp); + } +done: + sx_xunlock(&proctree_lock); + KASSERT((error == 0) || (newpgrp != NULL), + ("setpgid failed and newpgrp is NULL")); + if (newpgrp != NULL) + free(newpgrp, M_PGRP); + return (error); +} + +/* + * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD + * compatible. It says that setting the uid/gid to euid/egid is a special + * case of "appropriate privilege". Once the rules are expanded out, this + * basically means that setuid(nnn) sets all three id's, in all permitted + * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) + * does not set the saved id - this is dangerous for traditional BSD + * programs. For this reason, we *really* do not want to set + * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. + */ +#define POSIX_APPENDIX_B_4_2_2 + +#ifndef _SYS_SYSPROTO_H_ +struct setuid_args { + uid_t uid; +}; +#endif +/* ARGSUSED */ +int +sys_setuid(struct thread *td, struct setuid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + uid_t uid; + struct uidinfo *uip; + int error; + + uid = uap->uid; + AUDIT_ARG_UID(uid); + newcred = crget(); + uip = uifind(uid); + PROC_LOCK(p); + /* + * Copy credentials so other references do not see our changes. + */ + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setuid(oldcred, uid); + if (error) + goto fail; +#endif + + /* + * See if we have "permission" by POSIX 1003.1 rules. + * + * Note that setuid(geteuid()) is a special case of + * "appropriate privileges" in appendix B.4.2.2. We need + * to use this clause to be compatible with traditional BSD + * semantics. Basically, it means that "setuid(xx)" sets all + * three id's (assuming you have privs). + * + * Notes on the logic. We do things in three steps. + * 1: We determine if the euid is going to change, and do EPERM + * right away. We unconditionally change the euid later if this + * test is satisfied, simplifying that part of the logic. + * 2: We determine if the real and/or saved uids are going to + * change. Determined by compile options. + * 3: Change euid last. (after tests in #2 for "appropriate privs") + */ + if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ +#ifdef _POSIX_SAVED_IDS + uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ +#endif +#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ + uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ +#endif + (error = priv_check_cred(oldcred, PRIV_CRED_SETUID, 0)) != 0) + goto fail; + +#ifdef _POSIX_SAVED_IDS + /* + * Do we have "appropriate privileges" (are we root or uid == euid) + * If so, we are changing the real uid and/or saved uid. + */ + if ( +#ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ + uid == oldcred->cr_uid || +#endif + /* We are using privs. */ + priv_check_cred(oldcred, PRIV_CRED_SETUID, 0) == 0) +#endif + { + /* + * Set the real uid and transfer proc count to new user. + */ + if (uid != oldcred->cr_ruid) { + change_ruid(newcred, uip); + setsugid(p); + } + /* + * Set saved uid + * + * XXX always set saved uid even if not _POSIX_SAVED_IDS, as + * the security of seteuid() depends on it. B.4.2.2 says it + * is important that we should do this. + */ + if (uid != oldcred->cr_svuid) { + change_svuid(newcred, uid); + setsugid(p); + } + } + + /* + * In all permitted cases, we are changing the euid. + */ + if (uid != oldcred->cr_uid) { + change_euid(newcred, uip); + setsugid(p); + } + proc_set_cred(p, newcred); +#ifdef RACCT + racct_proc_ucred_changed(p, oldcred, newcred); + crhold(newcred); +#endif + PROC_UNLOCK(p); +#ifdef RCTL + rctl_proc_ucred_changed(p, newcred); + crfree(newcred); +#endif + uifree(uip); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + uifree(uip); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct seteuid_args { + uid_t euid; +}; +#endif +/* ARGSUSED */ +int +sys_seteuid(struct thread *td, struct seteuid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + uid_t euid; + struct uidinfo *euip; + int error; + + euid = uap->euid; + AUDIT_ARG_EUID(euid); + newcred = crget(); + euip = uifind(euid); + PROC_LOCK(p); + /* + * Copy credentials so other references do not see our changes. + */ + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_seteuid(oldcred, euid); + if (error) + goto fail; +#endif + + if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ + euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ + (error = priv_check_cred(oldcred, PRIV_CRED_SETEUID, 0)) != 0) + goto fail; + + /* + * Everything's okay, do it. + */ + if (oldcred->cr_uid != euid) { + change_euid(newcred, euip); + setsugid(p); + } + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + uifree(euip); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + uifree(euip); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setgid_args { + gid_t gid; +}; +#endif +/* ARGSUSED */ +int +sys_setgid(struct thread *td, struct setgid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + gid_t gid; + int error; + + gid = uap->gid; + AUDIT_ARG_GID(gid); + newcred = crget(); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setgid(oldcred, gid); + if (error) + goto fail; +#endif + + /* + * See if we have "permission" by POSIX 1003.1 rules. + * + * Note that setgid(getegid()) is a special case of + * "appropriate privileges" in appendix B.4.2.2. We need + * to use this clause to be compatible with traditional BSD + * semantics. Basically, it means that "setgid(xx)" sets all + * three id's (assuming you have privs). + * + * For notes on the logic here, see setuid() above. + */ + if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ +#ifdef _POSIX_SAVED_IDS + gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ +#endif +#ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ + gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ +#endif + (error = priv_check_cred(oldcred, PRIV_CRED_SETGID, 0)) != 0) + goto fail; + +#ifdef _POSIX_SAVED_IDS + /* + * Do we have "appropriate privileges" (are we root or gid == egid) + * If so, we are changing the real uid and saved gid. + */ + if ( +#ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ + gid == oldcred->cr_groups[0] || +#endif + /* We are using privs. */ + priv_check_cred(oldcred, PRIV_CRED_SETGID, 0) == 0) +#endif + { + /* + * Set real gid + */ + if (oldcred->cr_rgid != gid) { + change_rgid(newcred, gid); + setsugid(p); + } + /* + * Set saved gid + * + * XXX always set saved gid even if not _POSIX_SAVED_IDS, as + * the security of setegid() depends on it. B.4.2.2 says it + * is important that we should do this. + */ + if (oldcred->cr_svgid != gid) { + change_svgid(newcred, gid); + setsugid(p); + } + } + /* + * In all cases permitted cases, we are changing the egid. + * Copy credentials so other references do not see our changes. + */ + if (oldcred->cr_groups[0] != gid) { + change_egid(newcred, gid); + setsugid(p); + } + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setegid_args { + gid_t egid; +}; +#endif +/* ARGSUSED */ +int +sys_setegid(struct thread *td, struct setegid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + gid_t egid; + int error; + + egid = uap->egid; + AUDIT_ARG_EGID(egid); + newcred = crget(); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setegid(oldcred, egid); + if (error) + goto fail; +#endif + + if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ + egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ + (error = priv_check_cred(oldcred, PRIV_CRED_SETEGID, 0)) != 0) + goto fail; + + if (oldcred->cr_groups[0] != egid) { + change_egid(newcred, egid); + setsugid(p); + } + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setgroups_args { + u_int gidsetsize; + gid_t *gidset; +}; +#endif +/* ARGSUSED */ +int +sys_setgroups(struct thread *td, struct setgroups_args *uap) +{ + gid_t smallgroups[XU_NGROUPS]; + gid_t *groups; + u_int gidsetsize; + int error; + + gidsetsize = uap->gidsetsize; + if (gidsetsize > ngroups_max + 1) + return (EINVAL); + + if (gidsetsize > XU_NGROUPS) + groups = malloc(gidsetsize * sizeof(gid_t), M_TEMP, M_WAITOK); + else + groups = smallgroups; + + error = copyin(uap->gidset, groups, gidsetsize * sizeof(gid_t)); + if (error == 0) + error = kern_setgroups(td, gidsetsize, groups); + + if (gidsetsize > XU_NGROUPS) + free(groups, M_TEMP); + return (error); +} + +int +kern_setgroups(struct thread *td, u_int ngrp, gid_t *groups) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + int error; + + MPASS(ngrp <= ngroups_max + 1); + AUDIT_ARG_GROUPSET(groups, ngrp); + newcred = crget(); + crextend(newcred, ngrp); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setgroups(oldcred, ngrp, groups); + if (error) + goto fail; +#endif + + error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS, 0); + if (error) + goto fail; + + if (ngrp == 0) { + /* + * setgroups(0, NULL) is a legitimate way of clearing the + * groups vector on non-BSD systems (which generally do not + * have the egid in the groups[0]). We risk security holes + * when running non-BSD software if we do not do the same. + */ + newcred->cr_ngroups = 1; + } else { + crsetgroups_locked(newcred, ngrp, groups); + } + setsugid(p); + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setreuid_args { + uid_t ruid; + uid_t euid; +}; +#endif +/* ARGSUSED */ +int +sys_setreuid(struct thread *td, struct setreuid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + uid_t euid, ruid; + struct uidinfo *euip, *ruip; + int error; + + euid = uap->euid; + ruid = uap->ruid; + AUDIT_ARG_EUID(euid); + AUDIT_ARG_RUID(ruid); + newcred = crget(); + euip = uifind(euid); + ruip = uifind(ruid); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setreuid(oldcred, ruid, euid); + if (error) + goto fail; +#endif + + if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && + ruid != oldcred->cr_svuid) || + (euid != (uid_t)-1 && euid != oldcred->cr_uid && + euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && + (error = priv_check_cred(oldcred, PRIV_CRED_SETREUID, 0)) != 0) + goto fail; + + if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { + change_euid(newcred, euip); + setsugid(p); + } + if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { + change_ruid(newcred, ruip); + setsugid(p); + } + if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && + newcred->cr_svuid != newcred->cr_uid) { + change_svuid(newcred, newcred->cr_uid); + setsugid(p); + } + proc_set_cred(p, newcred); +#ifdef RACCT + racct_proc_ucred_changed(p, oldcred, newcred); + crhold(newcred); +#endif + PROC_UNLOCK(p); +#ifdef RCTL + rctl_proc_ucred_changed(p, newcred); + crfree(newcred); +#endif + uifree(ruip); + uifree(euip); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + uifree(ruip); + uifree(euip); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct setregid_args { + gid_t rgid; + gid_t egid; +}; +#endif +/* ARGSUSED */ +int +sys_setregid(struct thread *td, struct setregid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + gid_t egid, rgid; + int error; + + egid = uap->egid; + rgid = uap->rgid; + AUDIT_ARG_EGID(egid); + AUDIT_ARG_RGID(rgid); + newcred = crget(); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setregid(oldcred, rgid, egid); + if (error) + goto fail; +#endif + + if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && + rgid != oldcred->cr_svgid) || + (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && + egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && + (error = priv_check_cred(oldcred, PRIV_CRED_SETREGID, 0)) != 0) + goto fail; + + if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { + change_egid(newcred, egid); + setsugid(p); + } + if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { + change_rgid(newcred, rgid); + setsugid(p); + } + if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && + newcred->cr_svgid != newcred->cr_groups[0]) { + change_svgid(newcred, newcred->cr_groups[0]); + setsugid(p); + } + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + crfree(newcred); + return (error); +} + +/* + * setresuid(ruid, euid, suid) is like setreuid except control over the saved + * uid is explicit. + */ +#ifndef _SYS_SYSPROTO_H_ +struct setresuid_args { + uid_t ruid; + uid_t euid; + uid_t suid; +}; +#endif +/* ARGSUSED */ +int +sys_setresuid(struct thread *td, struct setresuid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + uid_t euid, ruid, suid; + struct uidinfo *euip, *ruip; + int error; + + euid = uap->euid; + ruid = uap->ruid; + suid = uap->suid; + AUDIT_ARG_EUID(euid); + AUDIT_ARG_RUID(ruid); + AUDIT_ARG_SUID(suid); + newcred = crget(); + euip = uifind(euid); + ruip = uifind(ruid); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setresuid(oldcred, ruid, euid, suid); + if (error) + goto fail; +#endif + + if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && + ruid != oldcred->cr_svuid && + ruid != oldcred->cr_uid) || + (euid != (uid_t)-1 && euid != oldcred->cr_ruid && + euid != oldcred->cr_svuid && + euid != oldcred->cr_uid) || + (suid != (uid_t)-1 && suid != oldcred->cr_ruid && + suid != oldcred->cr_svuid && + suid != oldcred->cr_uid)) && + (error = priv_check_cred(oldcred, PRIV_CRED_SETRESUID, 0)) != 0) + goto fail; + + if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { + change_euid(newcred, euip); + setsugid(p); + } + if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { + change_ruid(newcred, ruip); + setsugid(p); + } + if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { + change_svuid(newcred, suid); + setsugid(p); + } + proc_set_cred(p, newcred); +#ifdef RACCT + racct_proc_ucred_changed(p, oldcred, newcred); + crhold(newcred); +#endif + PROC_UNLOCK(p); +#ifdef RCTL + rctl_proc_ucred_changed(p, newcred); + crfree(newcred); +#endif + uifree(ruip); + uifree(euip); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + uifree(ruip); + uifree(euip); + crfree(newcred); + return (error); + +} + +/* + * setresgid(rgid, egid, sgid) is like setregid except control over the saved + * gid is explicit. + */ +#ifndef _SYS_SYSPROTO_H_ +struct setresgid_args { + gid_t rgid; + gid_t egid; + gid_t sgid; +}; +#endif +/* ARGSUSED */ +int +sys_setresgid(struct thread *td, struct setresgid_args *uap) +{ + struct proc *p = td->td_proc; + struct ucred *newcred, *oldcred; + gid_t egid, rgid, sgid; + int error; + + egid = uap->egid; + rgid = uap->rgid; + sgid = uap->sgid; + AUDIT_ARG_EGID(egid); + AUDIT_ARG_RGID(rgid); + AUDIT_ARG_SGID(sgid); + newcred = crget(); + PROC_LOCK(p); + oldcred = crcopysafe(p, newcred); + +#ifdef MAC + error = mac_cred_check_setresgid(oldcred, rgid, egid, sgid); + if (error) + goto fail; +#endif + + if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && + rgid != oldcred->cr_svgid && + rgid != oldcred->cr_groups[0]) || + (egid != (gid_t)-1 && egid != oldcred->cr_rgid && + egid != oldcred->cr_svgid && + egid != oldcred->cr_groups[0]) || + (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && + sgid != oldcred->cr_svgid && + sgid != oldcred->cr_groups[0])) && + (error = priv_check_cred(oldcred, PRIV_CRED_SETRESGID, 0)) != 0) + goto fail; + + if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { + change_egid(newcred, egid); + setsugid(p); + } + if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { + change_rgid(newcred, rgid); + setsugid(p); + } + if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { + change_svgid(newcred, sgid); + setsugid(p); + } + proc_set_cred(p, newcred); + PROC_UNLOCK(p); + crfree(oldcred); + return (0); + +fail: + PROC_UNLOCK(p); + crfree(newcred); + return (error); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getresuid_args { + uid_t *ruid; + uid_t *euid; + uid_t *suid; +}; +#endif +/* ARGSUSED */ +int +sys_getresuid(struct thread *td, struct getresuid_args *uap) +{ + struct ucred *cred; + int error1 = 0, error2 = 0, error3 = 0; + + cred = td->td_ucred; + if (uap->ruid) + error1 = copyout(&cred->cr_ruid, + uap->ruid, sizeof(cred->cr_ruid)); + if (uap->euid) + error2 = copyout(&cred->cr_uid, + uap->euid, sizeof(cred->cr_uid)); + if (uap->suid) + error3 = copyout(&cred->cr_svuid, + uap->suid, sizeof(cred->cr_svuid)); + return (error1 ? error1 : error2 ? error2 : error3); +} + +#ifndef _SYS_SYSPROTO_H_ +struct getresgid_args { + gid_t *rgid; + gid_t *egid; + gid_t *sgid; +}; +#endif +/* ARGSUSED */ +int +sys_getresgid(struct thread *td, struct getresgid_args *uap) +{ + struct ucred *cred; + int error1 = 0, error2 = 0, error3 = 0; + + cred = td->td_ucred; + if (uap->rgid) + error1 = copyout(&cred->cr_rgid, + uap->rgid, sizeof(cred->cr_rgid)); + if (uap->egid) + error2 = copyout(&cred->cr_groups[0], + uap->egid, sizeof(cred->cr_groups[0])); + if (uap->sgid) + error3 = copyout(&cred->cr_svgid, + uap->sgid, sizeof(cred->cr_svgid)); + return (error1 ? error1 : error2 ? error2 : error3); +} + +#ifndef _SYS_SYSPROTO_H_ +struct issetugid_args { + int dummy; +}; +#endif +/* ARGSUSED */ +int +sys_issetugid(struct thread *td, struct issetugid_args *uap) +{ + struct proc *p = td->td_proc; + + /* + * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, + * we use P_SUGID because we consider changing the owners as + * "tainting" as well. + * This is significant for procs that start as root and "become" + * a user without an exec - programs cannot know *everything* + * that libc *might* have put in their data segment. + */ + td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; + return (0); +} + +int +sys___setugid(struct thread *td, struct __setugid_args *uap) +{ +#ifdef REGRESSION + struct proc *p; + + p = td->td_proc; + switch (uap->flag) { + case 0: + PROC_LOCK(p); + p->p_flag &= ~P_SUGID; + PROC_UNLOCK(p); + return (0); + case 1: + PROC_LOCK(p); + p->p_flag |= P_SUGID; + PROC_UNLOCK(p); + return (0); + default: + return (EINVAL); + } +#else /* !REGRESSION */ + + return (ENOSYS); +#endif /* REGRESSION */ +} + +/* + * Check if gid is a member of the group set. + */ +int +groupmember(gid_t gid, struct ucred *cred) +{ + int l; + int h; + int m; + + if (cred->cr_groups[0] == gid) + return(1); + + /* + * If gid was not our primary group, perform a binary search + * of the supplemental groups. This is possible because we + * sort the groups in crsetgroups(). + */ + l = 1; + h = cred->cr_ngroups; + while (l < h) { + m = l + ((h - l) / 2); + if (cred->cr_groups[m] < gid) + l = m + 1; + else + h = m; + } + if ((l < cred->cr_ngroups) && (cred->cr_groups[l] == gid)) + return (1); + + return (0); +} + +/* + * Test the active securelevel against a given level. securelevel_gt() + * implements (securelevel > level). securelevel_ge() implements + * (securelevel >= level). Note that the logic is inverted -- these + * functions return EPERM on "success" and 0 on "failure". + * + * Due to care taken when setting the securelevel, we know that no jail will + * be less secure that its parent (or the physical system), so it is sufficient + * to test the current jail only. + * + * XXXRW: Possibly since this has to do with privilege, it should move to + * kern_priv.c. + */ +int +securelevel_gt(struct ucred *cr, int level) +{ + + return (cr->cr_prison->pr_securelevel > level ? EPERM : 0); +} + +int +securelevel_ge(struct ucred *cr, int level) +{ + + return (cr->cr_prison->pr_securelevel >= level ? EPERM : 0); +} + +/* + * 'see_other_uids' determines whether or not visibility of processes + * and sockets with credentials holding different real uids is possible + * using a variety of system MIBs. + * XXX: data declarations should be together near the beginning of the file. + */ +static int see_other_uids = 1; +SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, + &see_other_uids, 0, + "Unprivileged processes may see subjects/objects with different real uid"); + +/*- + * Determine if u1 "can see" the subject specified by u2, according to the + * 'see_other_uids' policy. + * Returns: 0 for permitted, ESRCH otherwise + * Locks: none + * References: *u1 and *u2 must not change during the call + * u1 may equal u2, in which case only one reference is required + */ +int +cr_canseeotheruids(struct ucred *u1, struct ucred *u2) +{ + + if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { + if (priv_check_cred(u1, PRIV_SEEOTHERUIDS, 0) != 0) + return (ESRCH); + } + return (0); +} + +/* + * 'see_other_gids' determines whether or not visibility of processes + * and sockets with credentials holding different real gids is possible + * using a variety of system MIBs. + * XXX: data declarations should be together near the beginning of the file. + */ +static int see_other_gids = 1; +SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW, + &see_other_gids, 0, + "Unprivileged processes may see subjects/objects with different real gid"); + +/* + * Determine if u1 can "see" the subject specified by u2, according to the + * 'see_other_gids' policy. + * Returns: 0 for permitted, ESRCH otherwise + * Locks: none + * References: *u1 and *u2 must not change during the call + * u1 may equal u2, in which case only one reference is required + */ +int +cr_canseeothergids(struct ucred *u1, struct ucred *u2) +{ + int i, match; + + if (!see_other_gids) { + match = 0; + for (i = 0; i < u1->cr_ngroups; i++) { + if (groupmember(u1->cr_groups[i], u2)) + match = 1; + if (match) + break; + } + if (!match) { + if (priv_check_cred(u1, PRIV_SEEOTHERGIDS, 0) != 0) + return (ESRCH); + } + } + return (0); +} + +/* + * 'see_jail_proc' determines whether or not visibility of processes and + * sockets with credentials holding different jail ids is possible using a + * variety of system MIBs. + * + * XXX: data declarations should be together near the beginning of the file. + */ + +static int see_jail_proc = 1; +SYSCTL_INT(_security_bsd, OID_AUTO, see_jail_proc, CTLFLAG_RW, + &see_jail_proc, 0, + "Unprivileged processes may see subjects/objects with different jail ids"); + +/*- + * Determine if u1 "can see" the subject specified by u2, according to the + * 'see_jail_proc' policy. + * Returns: 0 for permitted, ESRCH otherwise + * Locks: none + * References: *u1 and *u2 must not change during the call + * u1 may equal u2, in which case only one reference is required + */ +int +cr_canseejailproc(struct ucred *u1, struct ucred *u2) +{ + if (u1->cr_uid == 0) + return (0); + return (!see_jail_proc && u1->cr_prison != u2->cr_prison ? ESRCH : 0); +} + +/*- + * Determine if u1 "can see" the subject specified by u2. + * Returns: 0 for permitted, an errno value otherwise + * Locks: none + * References: *u1 and *u2 must not change during the call + * u1 may equal u2, in which case only one reference is required + */ +int +cr_cansee(struct ucred *u1, struct ucred *u2) +{ + int error; + + if ((error = prison_check(u1, u2))) + return (error); +#ifdef MAC + if ((error = mac_cred_check_visible(u1, u2))) + return (error); +#endif + if ((error = cr_canseeotheruids(u1, u2))) + return (error); + if ((error = cr_canseeothergids(u1, u2))) + return (error); + if ((error = cr_canseejailproc(u1, u2))) + return (error); + return (0); +} + +/*- + * Determine if td "can see" the subject specified by p. + * Returns: 0 for permitted, an errno value otherwise + * Locks: Sufficient locks to protect p->p_ucred must be held. td really + * should be curthread. + * References: td and p must be valid for the lifetime of the call + */ +int +p_cansee(struct thread *td, struct proc *p) +{ + + /* Wrap cr_cansee() for all functionality. */ + KASSERT(td == curthread, ("%s: td not curthread", __func__)); + PROC_LOCK_ASSERT(p, MA_OWNED); + return (cr_cansee(td->td_ucred, p->p_ucred)); +} + +/* + * 'conservative_signals' prevents the delivery of a broad class of + * signals by unprivileged processes to processes that have changed their + * credentials since the last invocation of execve(). This can prevent + * the leakage of cached information or retained privileges as a result + * of a common class of signal-related vulnerabilities. However, this + * may interfere with some applications that expect to be able to + * deliver these signals to peer processes after having given up + * privilege. + */ +static int conservative_signals = 1; +SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW, + &conservative_signals, 0, "Unprivileged processes prevented from " + "sending certain signals to processes whose credentials have changed"); +/*- + * Determine whether cred may deliver the specified signal to proc. + * Returns: 0 for permitted, an errno value otherwise. + * Locks: A lock must be held for proc. + * References: cred and proc must be valid for the lifetime of the call. + */ +int +cr_cansignal(struct ucred *cred, struct proc *proc, int signum) +{ + int error; + + PROC_LOCK_ASSERT(proc, MA_OWNED); + /* + * Jail semantics limit the scope of signalling to proc in the + * same jail as cred, if cred is in jail. + */ + error = prison_check(cred, proc->p_ucred); + if (error) + return (error); +#ifdef MAC + if ((error = mac_proc_check_signal(cred, proc, signum))) + return (error); +#endif + if ((error = cr_canseeotheruids(cred, proc->p_ucred))) + return (error); + if ((error = cr_canseeothergids(cred, proc->p_ucred))) + return (error); + + /* + * UNIX signal semantics depend on the status of the P_SUGID + * bit on the target process. If the bit is set, then additional + * restrictions are placed on the set of available signals. + */ + if (conservative_signals && (proc->p_flag & P_SUGID)) { + switch (signum) { + case 0: + case SIGKILL: + case SIGINT: + case SIGTERM: + case SIGALRM: + case SIGSTOP: + case SIGTTIN: + case SIGTTOU: + case SIGTSTP: + case SIGHUP: + case SIGUSR1: + case SIGUSR2: + /* + * Generally, permit job and terminal control + * signals. + */ + break; + default: + /* Not permitted without privilege. */ + error = priv_check_cred(cred, PRIV_SIGNAL_SUGID, 0); + if (error) + return (error); + } + } + + /* + * Generally, the target credential's ruid or svuid must match the + * subject credential's ruid or euid. + */ + if (cred->cr_ruid != proc->p_ucred->cr_ruid && + cred->cr_ruid != proc->p_ucred->cr_svuid && + cred->cr_uid != proc->p_ucred->cr_ruid && + cred->cr_uid != proc->p_ucred->cr_svuid) { + error = priv_check_cred(cred, PRIV_SIGNAL_DIFFCRED, 0); + if (error) + return (error); + } + + return (0); +} + +/*- + * Determine whether td may deliver the specified signal to p. + * Returns: 0 for permitted, an errno value otherwise + * Locks: Sufficient locks to protect various components of td and p + * must be held. td must be curthread, and a lock must be + * held for p. + * References: td and p must be valid for the lifetime of the call + */ +int +p_cansignal(struct thread *td, struct proc *p, int signum) +{ + + KASSERT(td == curthread, ("%s: td not curthread", __func__)); + PROC_LOCK_ASSERT(p, MA_OWNED); + if (td->td_proc == p) + return (0); + + /* + * UNIX signalling semantics require that processes in the same + * session always be able to deliver SIGCONT to one another, + * overriding the remaining protections. + */ + /* XXX: This will require an additional lock of some sort. */ + if (signum == SIGCONT && td->td_proc->p_session == p->p_session) + return (0); + /* + * Some compat layers use SIGTHR and higher signals for + * communication between different kernel threads of the same + * process, so that they expect that it's always possible to + * deliver them, even for suid applications where cr_cansignal() can + * deny such ability for security consideration. It should be + * pretty safe to do since the only way to create two processes + * with the same p_leader is via rfork(2). + */ + if (td->td_proc->p_leader != NULL && signum >= SIGTHR && + signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader) + return (0); + + return (cr_cansignal(td->td_ucred, p, signum)); +} + +/*- + * Determine whether td may reschedule p. + * Returns: 0 for permitted, an errno value otherwise + * Locks: Sufficient locks to protect various components of td and p + * must be held. td must be curthread, and a lock must + * be held for p. + * References: td and p must be valid for the lifetime of the call + */ +int +p_cansched(struct thread *td, struct proc *p) +{ + int error; + + KASSERT(td == curthread, ("%s: td not curthread", __func__)); + PROC_LOCK_ASSERT(p, MA_OWNED); + if (td->td_proc == p) + return (0); + if ((error = prison_check(td->td_ucred, p->p_ucred))) + return (error); +#ifdef MAC + if ((error = mac_proc_check_sched(td->td_ucred, p))) + return (error); +#endif + if ((error = cr_canseeotheruids(td->td_ucred, p->p_ucred))) + return (error); + if ((error = cr_canseeothergids(td->td_ucred, p->p_ucred))) + return (error); + if (td->td_ucred->cr_ruid != p->p_ucred->cr_ruid && + td->td_ucred->cr_uid != p->p_ucred->cr_ruid) { + error = priv_check(td, PRIV_SCHED_DIFFCRED); + if (error) + return (error); + } + return (0); +} + +/* + * The 'unprivileged_proc_debug' flag may be used to disable a variety of + * unprivileged inter-process debugging services, including some procfs + * functionality, ptrace(), and ktrace(). In the past, inter-process + * debugging has been involved in a variety of security problems, and sites + * not requiring the service might choose to disable it when hardening + * systems. + * + * XXX: Should modifying and reading this variable require locking? + * XXX: data declarations should be together near the beginning of the file. + */ +static int unprivileged_proc_debug = 1; +SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLFLAG_RW, + &unprivileged_proc_debug, 0, + "Unprivileged processes may use process debugging facilities"); + +/*- + * Determine whether td may debug p. + * Returns: 0 for permitted, an errno value otherwise + * Locks: Sufficient locks to protect various components of td and p + * must be held. td must be curthread, and a lock must + * be held for p. + * References: td and p must be valid for the lifetime of the call + */ +int +p_candebug(struct thread *td, struct proc *p) +{ + int credentialchanged, error, grpsubset, i, uidsubset; + + KASSERT(td == curthread, ("%s: td not curthread", __func__)); + PROC_LOCK_ASSERT(p, MA_OWNED); + if (!unprivileged_proc_debug) { + error = priv_check(td, PRIV_DEBUG_UNPRIV); + if (error) + return (error); + } + if (td->td_proc == p) + return (0); + if ((error = prison_check(td->td_ucred, p->p_ucred))) + return (error); +#ifdef MAC + if ((error = mac_proc_check_debug(td->td_ucred, p))) + return (error); +#endif + if ((error = cr_canseeotheruids(td->td_ucred, p->p_ucred))) + return (error); + if ((error = cr_canseeothergids(td->td_ucred, p->p_ucred))) + return (error); + + /* + * Is p's group set a subset of td's effective group set? This + * includes p's egid, group access list, rgid, and svgid. + */ + grpsubset = 1; + for (i = 0; i < p->p_ucred->cr_ngroups; i++) { + if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { + grpsubset = 0; + break; + } + } + grpsubset = grpsubset && + groupmember(p->p_ucred->cr_rgid, td->td_ucred) && + groupmember(p->p_ucred->cr_svgid, td->td_ucred); + + /* + * Are the uids present in p's credential equal to td's + * effective uid? This includes p's euid, svuid, and ruid. + */ + uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && + td->td_ucred->cr_uid == p->p_ucred->cr_svuid && + td->td_ucred->cr_uid == p->p_ucred->cr_ruid); + + /* + * Has the credential of the process changed since the last exec()? + */ + credentialchanged = (p->p_flag & P_SUGID); + + /* + * If p's gids aren't a subset, or the uids aren't a subset, + * or the credential has changed, require appropriate privilege + * for td to debug p. + */ + if (!grpsubset || !uidsubset) { + error = priv_check(td, PRIV_DEBUG_DIFFCRED); + if (error) + return (error); + } + + if (credentialchanged) { + error = priv_check(td, PRIV_DEBUG_SUGID); + if (error) + return (error); + } + + /* Can't trace init when securelevel > 0. */ + if (p == initproc) { + error = securelevel_gt(td->td_ucred, 0); + if (error) + return (error); + } + + /* + * Can't trace a process that's currently exec'ing. + * + * XXX: Note, this is not a security policy decision, it's a + * basic correctness/functionality decision. Therefore, this check + * should be moved to the caller's of p_candebug(). + */ + if ((p->p_flag & P_INEXEC) != 0) + return (EBUSY); + + /* Denied explicitely */ + if ((p->p_flag2 & P2_NOTRACE) != 0) { + error = priv_check(td, PRIV_DEBUG_DENIED); + if (error != 0) + return (error); + } + + return (0); +} + +/*- + * Determine whether the subject represented by cred can "see" a socket. + * Returns: 0 for permitted, ENOENT otherwise. + */ +int +cr_canseesocket(struct ucred *cred, struct socket *so) +{ + int error; + + error = prison_check(cred, so->so_cred); + if (error) + return (ENOENT); +#ifdef MAC + error = mac_socket_check_visible(cred, so); + if (error) + return (error); +#endif + if (cr_canseeotheruids(cred, so->so_cred)) + return (ENOENT); + if (cr_canseeothergids(cred, so->so_cred)) + return (ENOENT); + + return (0); +} + +/*- + * Determine whether td can wait for the exit of p. + * Returns: 0 for permitted, an errno value otherwise + * Locks: Sufficient locks to protect various components of td and p + * must be held. td must be curthread, and a lock must + * be held for p. + * References: td and p must be valid for the lifetime of the call + + */ +int +p_canwait(struct thread *td, struct proc *p) +{ + int error; + + KASSERT(td == curthread, ("%s: td not curthread", __func__)); + PROC_LOCK_ASSERT(p, MA_OWNED); + if ((error = prison_check(td->td_ucred, p->p_ucred))) + return (error); +#ifdef MAC + if ((error = mac_proc_check_wait(td->td_ucred, p))) + return (error); +#endif +#if 0 + /* XXXMAC: This could have odd effects on some shells. */ + if ((error = cr_canseeotheruids(td->td_ucred, p->p_ucred))) + return (error); +#endif + + return (0); +} + +/* + * Allocate a zeroed cred structure. + */ +struct ucred * +crget(void) +{ + struct ucred *cr; + + cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); + refcount_init(&cr->cr_ref, 1); +#ifdef AUDIT + audit_cred_init(cr); +#endif +#ifdef MAC + mac_cred_init(cr); +#endif + cr->cr_groups = cr->cr_smallgroups; + cr->cr_agroups = + sizeof(cr->cr_smallgroups) / sizeof(cr->cr_smallgroups[0]); + return (cr); +} + +/* + * Claim another reference to a ucred structure. + */ +struct ucred * +crhold(struct ucred *cr) +{ + + refcount_acquire(&cr->cr_ref); + return (cr); +} + +/* + * Free a cred structure. Throws away space when ref count gets to 0. + */ +void +crfree(struct ucred *cr) +{ + + KASSERT(cr->cr_ref > 0, ("bad ucred refcount: %d", cr->cr_ref)); + KASSERT(cr->cr_ref != 0xdeadc0de, ("dangling reference to ucred")); + if (refcount_release(&cr->cr_ref)) { + /* + * Some callers of crget(), such as nfs_statfs(), + * allocate a temporary credential, but don't + * allocate a uidinfo structure. + */ + if (cr->cr_uidinfo != NULL) + uifree(cr->cr_uidinfo); + if (cr->cr_ruidinfo != NULL) + uifree(cr->cr_ruidinfo); + /* + * Free a prison, if any. + */ + if (cr->cr_prison != NULL) + prison_free(cr->cr_prison); + if (cr->cr_loginclass != NULL) + loginclass_free(cr->cr_loginclass); +#ifdef AUDIT + audit_cred_destroy(cr); +#endif +#ifdef MAC + mac_cred_destroy(cr); +#endif + if (cr->cr_groups != cr->cr_smallgroups) + free(cr->cr_groups, M_CRED); + free(cr, M_CRED); + } +} + +/* + * Copy a ucred's contents from a template. Does not block. + */ +void +crcopy(struct ucred *dest, struct ucred *src) +{ + + KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred")); + bcopy(&src->cr_startcopy, &dest->cr_startcopy, + (unsigned)((caddr_t)&src->cr_endcopy - + (caddr_t)&src->cr_startcopy)); + crsetgroups(dest, src->cr_ngroups, src->cr_groups); + uihold(dest->cr_uidinfo); + uihold(dest->cr_ruidinfo); + prison_hold(dest->cr_prison); + loginclass_hold(dest->cr_loginclass); +#ifdef AUDIT + audit_cred_copy(src, dest); +#endif +#ifdef MAC + mac_cred_copy(src, dest); +#endif +} + +/* + * Dup cred struct to a new held one. + */ +struct ucred * +crdup(struct ucred *cr) +{ + struct ucred *newcr; + + newcr = crget(); + crcopy(newcr, cr); + return (newcr); +} + +/* + * Fill in a struct xucred based on a struct ucred. + */ +void +cru2x(struct ucred *cr, struct xucred *xcr) +{ + int ngroups; + + bzero(xcr, sizeof(*xcr)); + xcr->cr_version = XUCRED_VERSION; + xcr->cr_uid = cr->cr_uid; + + ngroups = MIN(cr->cr_ngroups, XU_NGROUPS); + xcr->cr_ngroups = ngroups; + bcopy(cr->cr_groups, xcr->cr_groups, + ngroups * sizeof(*cr->cr_groups)); +} + +/* + * Set initial process credentials. + * Callers are responsible for providing the reference for provided credentials. + */ +void +proc_set_cred_init(struct proc *p, struct ucred *newcred) +{ + + p->p_ucred = newcred; +} + +/* + * Change process credentials. + * Callers are responsible for providing the reference for passed credentials + * and for freeing old ones. + * + * Process has to be locked except when it does not have credentials (as it + * should not be visible just yet) or when newcred is NULL (as this can be + * only used when the process is about to be freed, at which point it should + * not be visible anymore). + */ +struct ucred * +proc_set_cred(struct proc *p, struct ucred *newcred) +{ + struct ucred *oldcred; + + MPASS(p->p_ucred != NULL); + if (newcred == NULL) + MPASS(p->p_state == PRS_ZOMBIE); + else + PROC_LOCK_ASSERT(p, MA_OWNED); + + oldcred = p->p_ucred; + p->p_ucred = newcred; + if (newcred != NULL) + PROC_UPDATE_COW(p); + return (oldcred); +} + +struct ucred * +crcopysafe(struct proc *p, struct ucred *cr) +{ + struct ucred *oldcred; + int groups; + + PROC_LOCK_ASSERT(p, MA_OWNED); + + oldcred = p->p_ucred; + while (cr->cr_agroups < oldcred->cr_agroups) { + groups = oldcred->cr_agroups; + PROC_UNLOCK(p); + crextend(cr, groups); + PROC_LOCK(p); + oldcred = p->p_ucred; + } + crcopy(cr, oldcred); + + return (oldcred); +} + +/* + * Extend the passed in credential to hold n items. + */ +void +crextend(struct ucred *cr, int n) +{ + int cnt; + + /* Truncate? */ + if (n <= cr->cr_agroups) + return; + + /* + * We extend by 2 each time since we're using a power of two + * allocator until we need enough groups to fill a page. + * Once we're allocating multiple pages, only allocate as many + * as we actually need. The case of processes needing a + * non-power of two number of pages seems more likely than + * a real world process that adds thousands of groups one at a + * time. + */ + if ( n < PAGE_SIZE / sizeof(gid_t) ) { + if (cr->cr_agroups == 0) + cnt = MINALLOCSIZE / sizeof(gid_t); + else + cnt = cr->cr_agroups * 2; + + while (cnt < n) + cnt *= 2; + } else + cnt = roundup2(n, PAGE_SIZE / sizeof(gid_t)); + + /* Free the old array. */ + if (cr->cr_groups != cr->cr_smallgroups) + free(cr->cr_groups, M_CRED); + + cr->cr_groups = malloc(cnt * sizeof(gid_t), M_CRED, M_WAITOK | M_ZERO); + cr->cr_agroups = cnt; +} + +/* + * Copy groups in to a credential, preserving any necessary invariants. + * Currently this includes the sorting of all supplemental gids. + * crextend() must have been called before hand to ensure sufficient + * space is available. + */ +static void +crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups) +{ + int i; + int j; + gid_t g; + + KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small")); + + bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t)); + cr->cr_ngroups = ngrp; + + /* + * Sort all groups except cr_groups[0] to allow groupmember to + * perform a binary search. + * + * XXX: If large numbers of groups become common this should + * be replaced with shell sort like linux uses or possibly + * heap sort. + */ + for (i = 2; i < ngrp; i++) { + g = cr->cr_groups[i]; + for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--) + cr->cr_groups[j + 1] = cr->cr_groups[j]; + cr->cr_groups[j + 1] = g; + } +} + +/* + * Copy groups in to a credential after expanding it if required. + * Truncate the list to (ngroups_max + 1) if it is too large. + */ +void +crsetgroups(struct ucred *cr, int ngrp, gid_t *groups) +{ + + if (ngrp > ngroups_max + 1) + ngrp = ngroups_max + 1; + + crextend(cr, ngrp); + crsetgroups_locked(cr, ngrp, groups); +} + +/* + * Get login name, if available. + */ +#ifndef _SYS_SYSPROTO_H_ +struct getlogin_args { + char *namebuf; + u_int namelen; +}; +#endif +/* ARGSUSED */ +int +sys_getlogin(struct thread *td, struct getlogin_args *uap) +{ + char login[MAXLOGNAME]; + struct proc *p = td->td_proc; + size_t len; + + if (uap->namelen > MAXLOGNAME) + uap->namelen = MAXLOGNAME; + PROC_LOCK(p); + SESS_LOCK(p->p_session); + len = strlcpy(login, p->p_session->s_login, uap->namelen) + 1; + SESS_UNLOCK(p->p_session); + PROC_UNLOCK(p); + if (len > uap->namelen) + return (ERANGE); + return (copyout(login, uap->namebuf, len)); +} + +/* + * Set login name. + */ +#ifndef _SYS_SYSPROTO_H_ +struct setlogin_args { + char *namebuf; +}; +#endif +/* ARGSUSED */ +int +sys_setlogin(struct thread *td, struct setlogin_args *uap) +{ + struct proc *p = td->td_proc; + int error; + char logintmp[MAXLOGNAME]; + + CTASSERT(sizeof(p->p_session->s_login) >= sizeof(logintmp)); + + error = priv_check(td, PRIV_PROC_SETLOGIN); + if (error) + return (error); + error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); + if (error != 0) { + if (error == ENAMETOOLONG) + error = EINVAL; + return (error); + } + AUDIT_ARG_LOGIN(logintmp); + PROC_LOCK(p); + SESS_LOCK(p->p_session); + strcpy(p->p_session->s_login, logintmp); + SESS_UNLOCK(p->p_session); + PROC_UNLOCK(p); + return (0); +} + +void +setsugid(struct proc *p) +{ + + PROC_LOCK_ASSERT(p, MA_OWNED); + p->p_flag |= P_SUGID; + if (!(p->p_pfsflags & PF_ISUGID)) + p->p_stops = 0; +} + +/*- + * Change a process's effective uid. + * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_euid(struct ucred *newcred, struct uidinfo *euip) +{ + + newcred->cr_uid = euip->ui_uid; + uihold(euip); + uifree(newcred->cr_uidinfo); + newcred->cr_uidinfo = euip; +} + +/*- + * Change a process's effective gid. + * Side effects: newcred->cr_gid will be modified. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_egid(struct ucred *newcred, gid_t egid) +{ + + newcred->cr_groups[0] = egid; +} + +/*- + * Change a process's real uid. + * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo + * will be updated, and the old and new cr_ruidinfo proc + * counts will be updated. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_ruid(struct ucred *newcred, struct uidinfo *ruip) +{ + + (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); + newcred->cr_ruid = ruip->ui_uid; + uihold(ruip); + uifree(newcred->cr_ruidinfo); + newcred->cr_ruidinfo = ruip; + (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); +} + +/*- + * Change a process's real gid. + * Side effects: newcred->cr_rgid will be updated. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_rgid(struct ucred *newcred, gid_t rgid) +{ + + newcred->cr_rgid = rgid; +} + +/*- + * Change a process's saved uid. + * Side effects: newcred->cr_svuid will be updated. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_svuid(struct ucred *newcred, uid_t svuid) +{ + + newcred->cr_svuid = svuid; +} + +/*- + * Change a process's saved gid. + * Side effects: newcred->cr_svgid will be updated. + * References: newcred must be an exclusive credential reference for the + * duration of the call. + */ +void +change_svgid(struct ucred *newcred, gid_t svgid) +{ + + newcred->cr_svgid = svgid; +} |