/* * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * 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 * $FreeBSD: src/sys/kern/kern_prot.c,v 1.53.2.9 2002/03/09 05:20:26 dd Exp $ */ /* * System calls related to processes and protection */ #include "opt_compat.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_CRED, "cred", "credentials"); int sys_getpid(struct getpid_args *uap) { struct proc *p = curproc; uap->sysmsg_fds[0] = p->p_pid; #if defined(COMPAT_43) lwkt_gettoken_shared(&p->p_token); uap->sysmsg_fds[1] = p->p_pptr->p_pid; lwkt_reltoken(&p->p_token); #endif return (0); } int sys_getppid(struct getppid_args *uap) { struct proc *p = curproc; lwkt_gettoken_shared(&p->p_token); uap->sysmsg_result = p->p_pptr->p_pid; lwkt_reltoken(&p->p_token); return (0); } int sys_lwp_gettid(struct lwp_gettid_args *uap) { struct lwp *lp = curthread->td_lwp; uap->sysmsg_result = lp->lwp_tid; return (0); } /* * Get process group ID; note that POSIX getpgrp takes no parameter */ int sys_getpgrp(struct getpgrp_args *uap) { struct proc *p = curproc; lwkt_gettoken_shared(&p->p_token); uap->sysmsg_result = p->p_pgrp->pg_id; lwkt_reltoken(&p->p_token); return (0); } /* * Get an arbitrary pid's process group id */ int sys_getpgid(struct getpgid_args *uap) { struct proc *p = curproc; struct proc *pt; int error; error = 0; if (uap->pid == 0) { pt = p; PHOLD(pt); } else { pt = pfind(uap->pid); if (pt == NULL) error = ESRCH; } if (error == 0) { lwkt_gettoken_shared(&pt->p_token); uap->sysmsg_result = pt->p_pgrp->pg_id; lwkt_reltoken(&pt->p_token); } if (pt) PRELE(pt); return (error); } /* * Get an arbitrary pid's session id. */ int sys_getsid(struct getsid_args *uap) { struct proc *p = curproc; struct proc *pt; int error; error = 0; if (uap->pid == 0) { pt = p; PHOLD(pt); } else { pt = pfind(uap->pid); if (pt == NULL) error = ESRCH; } if (error == 0) uap->sysmsg_result = pt->p_session->s_sid; if (pt) PRELE(pt); return (error); } /* * getuid() */ int sys_getuid(struct getuid_args *uap) { struct ucred *cred = curthread->td_ucred; uap->sysmsg_fds[0] = cred->cr_ruid; #if defined(COMPAT_43) uap->sysmsg_fds[1] = cred->cr_uid; #endif return (0); } /* * geteuid() */ int sys_geteuid(struct geteuid_args *uap) { struct ucred *cred = curthread->td_ucred; uap->sysmsg_result = cred->cr_uid; return (0); } /* * getgid() */ int sys_getgid(struct getgid_args *uap) { struct ucred *cred = curthread->td_ucred; uap->sysmsg_fds[0] = cred->cr_rgid; #if defined(COMPAT_43) uap->sysmsg_fds[1] = cred->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. */ int sys_getegid(struct getegid_args *uap) { struct ucred *cred = curthread->td_ucred; uap->sysmsg_result = cred->cr_groups[0]; return (0); } int sys_getgroups(struct getgroups_args *uap) { struct ucred *cr; u_int ngrp; int error; cr = curthread->td_ucred; if ((ngrp = uap->gidsetsize) == 0) { uap->sysmsg_result = cr->cr_ngroups; return (0); } if (ngrp < cr->cr_ngroups) return (EINVAL); ngrp = cr->cr_ngroups; error = copyout((caddr_t)cr->cr_groups, (caddr_t)uap->gidset, ngrp * sizeof(gid_t)); if (error == 0) uap->sysmsg_result = ngrp; return (error); } int sys_setsid(struct setsid_args *uap) { struct proc *p = curproc; struct pgrp *pg = NULL; int error; lwkt_gettoken(&p->p_token); if (p->p_pgid == p->p_pid || (pg = pgfind(p->p_pid)) != NULL) { error = EPERM; if (pg) pgrel(pg); } else { enterpgrp(p, p->p_pid, 1); uap->sysmsg_result = p->p_pid; error = 0; } lwkt_reltoken(&p->p_token); 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) */ int sys_setpgid(struct setpgid_args *uap) { struct proc *curp = curproc; struct proc *targp; /* target process */ struct pgrp *pgrp = NULL; /* target pgrp */ int error; if (uap->pgid < 0) return (EINVAL); if (uap->pid != 0 && uap->pid != curp->p_pid) { if ((targp = pfind(uap->pid)) == NULL || !inferior(targp)) { if (targp) PRELE(targp); error = ESRCH; targp = NULL; goto done; } lwkt_gettoken(&targp->p_token); /* targp now referenced and its token is held */ if (targp->p_pgrp == NULL || targp->p_session != curp->p_session) { error = EPERM; goto done; } if (targp->p_flags & P_EXEC) { error = EACCES; goto done; } } else { targp = curp; PHOLD(targp); lwkt_gettoken(&targp->p_token); } if (SESS_LEADER(targp)) { error = EPERM; goto done; } if (uap->pgid == 0) { uap->pgid = targp->p_pid; } else if (uap->pgid != targp->p_pid) { if ((pgrp = pgfind(uap->pgid)) == NULL || pgrp->pg_session != curp->p_session) { error = EPERM; goto done; } } error = enterpgrp(targp, uap->pgid, 0); done: if (pgrp) pgrel(pgrp); if (targp) { lwkt_reltoken(&targp->p_token); PRELE(targp); } 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 int sys_setuid(struct setuid_args *uap) { struct proc *p = curproc; struct ucred *cr; uid_t uid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; /* * 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 uid's are going to * change. Determined by compile options. * 3: Change euid last. (after tests in #2 for "appropriate privs") */ uid = uap->uid; if (uid != cr->cr_ruid && /* allow setuid(getuid()) */ #ifdef _POSIX_SAVED_IDS uid != crc->cr_svuid && /* allow setuid(saved gid) */ #endif #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ uid != cr->cr_uid && /* allow setuid(geteuid()) */ #endif (error = priv_check_cred(cr, PRIV_CRED_SETUID, 0))) goto done; #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 == cr->cr_uid || #endif priv_check_cred(cr, PRIV_CRED_SETUID, 0) == 0) /* we are using privs */ #endif { /* * Set the real uid and transfer proc count to new user. */ if (uid != cr->cr_ruid) { cr = change_ruid(uid); setsugid(); } /* * 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 (cr->cr_svuid != uid) { cr = cratom(&p->p_ucred); cr->cr_svuid = uid; setsugid(); } } /* * In all permitted cases, we are changing the euid. * Copy credentials so other references do not see our changes. */ if (cr->cr_uid != uid) { change_euid(uid); setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_seteuid(struct seteuid_args *uap) { struct proc *p = curproc; struct ucred *cr; uid_t euid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; euid = uap->euid; if (euid != cr->cr_ruid && /* allow seteuid(getuid()) */ euid != cr->cr_svuid && /* allow seteuid(saved uid) */ (error = priv_check_cred(cr, PRIV_CRED_SETEUID, 0))) { lwkt_reltoken(&p->p_token); return (error); } /* * Everything's okay, do it. Copy credentials so other references do * not see our changes. */ if (cr->cr_uid != euid) { change_euid(euid); setsugid(); } lwkt_reltoken(&p->p_token); return (0); } int sys_setgid(struct setgid_args *uap) { struct proc *p = curproc; struct ucred *cr; gid_t gid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; /* * 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. */ gid = uap->gid; if (gid != cr->cr_rgid && /* allow setgid(getgid()) */ #ifdef _POSIX_SAVED_IDS gid != cr->cr_svgid && /* allow setgid(saved gid) */ #endif #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ gid != cr->cr_groups[0] && /* allow setgid(getegid()) */ #endif (error = priv_check_cred(cr, PRIV_CRED_SETGID, 0))) { goto done; } #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 == cr->cr_groups[0] || #endif priv_check_cred(cr, PRIV_CRED_SETGID, 0) == 0) /* we are using privs */ #endif { /* * Set real gid */ if (cr->cr_rgid != gid) { cr = cratom(&p->p_ucred); cr->cr_rgid = gid; setsugid(); } /* * 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 (cr->cr_svgid != gid) { cr = cratom(&p->p_ucred); cr->cr_svgid = gid; setsugid(); } } /* * In all cases permitted cases, we are changing the egid. * Copy credentials so other references do not see our changes. */ if (cr->cr_groups[0] != gid) { cr = cratom(&p->p_ucred); cr->cr_groups[0] = gid; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_setegid(struct setegid_args *uap) { struct proc *p = curproc; struct ucred *cr; gid_t egid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; egid = uap->egid; if (egid != cr->cr_rgid && /* allow setegid(getgid()) */ egid != cr->cr_svgid && /* allow setegid(saved gid) */ (error = priv_check_cred(cr, PRIV_CRED_SETEGID, 0))) { goto done; } if (cr->cr_groups[0] != egid) { cr = cratom(&p->p_ucred); cr->cr_groups[0] = egid; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_setgroups(struct setgroups_args *uap) { struct proc *p = curproc; struct ucred *cr; u_int ngrp; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; if ((error = priv_check_cred(cr, PRIV_CRED_SETGROUPS, 0))) goto done; ngrp = uap->gidsetsize; if (ngrp > NGROUPS) { error = EINVAL; goto done; } /* * XXX A little bit lazy here. We could test if anything has * changed before cratom() and setting P_SUGID. */ cr = cratom(&p->p_ucred); if (ngrp < 1) { /* * 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. */ cr->cr_ngroups = 1; } else { error = copyin(uap->gidset, cr->cr_groups, ngrp * sizeof(gid_t)); if (error) goto done; cr->cr_ngroups = ngrp; } setsugid(); error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_setreuid(struct setreuid_args *uap) { struct proc *p = curproc; struct ucred *cr; uid_t ruid, euid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; ruid = uap->ruid; euid = uap->euid; if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && ruid != cr->cr_svuid) || (euid != (uid_t)-1 && euid != cr->cr_uid && euid != cr->cr_ruid && euid != cr->cr_svuid)) && (error = priv_check_cred(cr, PRIV_CRED_SETREUID, 0)) != 0) { goto done; } if (euid != (uid_t)-1 && cr->cr_uid != euid) { cr = change_euid(euid); setsugid(); } if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { cr = change_ruid(ruid); setsugid(); } if ((ruid != (uid_t)-1 || cr->cr_uid != cr->cr_ruid) && cr->cr_svuid != cr->cr_uid) { cr = cratom(&p->p_ucred); cr->cr_svuid = cr->cr_uid; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_setregid(struct setregid_args *uap) { struct proc *p = curproc; struct ucred *cr; gid_t rgid, egid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; rgid = uap->rgid; egid = uap->egid; if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && rgid != cr->cr_svgid) || (egid != (gid_t)-1 && egid != cr->cr_groups[0] && egid != cr->cr_rgid && egid != cr->cr_svgid)) && (error = priv_check_cred(cr, PRIV_CRED_SETREGID, 0)) != 0) { goto done; } if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { cr = cratom(&p->p_ucred); cr->cr_groups[0] = egid; setsugid(); } if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { cr = cratom(&p->p_ucred); cr->cr_rgid = rgid; setsugid(); } if ((rgid != (gid_t)-1 || cr->cr_groups[0] != cr->cr_rgid) && cr->cr_svgid != cr->cr_groups[0]) { cr = cratom(&p->p_ucred); cr->cr_svgid = cr->cr_groups[0]; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } /* * setresuid(ruid, euid, suid) is like setreuid except control over the * saved uid is explicit. */ int sys_setresuid(struct setresuid_args *uap) { struct proc *p = curproc; struct ucred *cr; uid_t ruid, euid, suid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; ruid = uap->ruid; euid = uap->euid; suid = uap->suid; if (((ruid != (uid_t)-1 && ruid != cr->cr_ruid && ruid != cr->cr_svuid && ruid != cr->cr_uid) || (euid != (uid_t)-1 && euid != cr->cr_ruid && euid != cr->cr_svuid && euid != cr->cr_uid) || (suid != (uid_t)-1 && suid != cr->cr_ruid && suid != cr->cr_svuid && suid != cr->cr_uid)) && (error = priv_check_cred(cr, PRIV_CRED_SETRESUID, 0)) != 0) { goto done; } if (euid != (uid_t)-1 && cr->cr_uid != euid) { cr = change_euid(euid); setsugid(); } if (ruid != (uid_t)-1 && cr->cr_ruid != ruid) { cr = change_ruid(ruid); setsugid(); } if (suid != (uid_t)-1 && cr->cr_svuid != suid) { cr = cratom(&p->p_ucred); cr->cr_svuid = suid; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } /* * setresgid(rgid, egid, sgid) is like setregid except control over the * saved gid is explicit. */ int sys_setresgid(struct setresgid_args *uap) { struct proc *p = curproc; struct ucred *cr; gid_t rgid, egid, sgid; int error; lwkt_gettoken(&p->p_token); cr = p->p_ucred; rgid = uap->rgid; egid = uap->egid; sgid = uap->sgid; if (((rgid != (gid_t)-1 && rgid != cr->cr_rgid && rgid != cr->cr_svgid && rgid != cr->cr_groups[0]) || (egid != (gid_t)-1 && egid != cr->cr_rgid && egid != cr->cr_svgid && egid != cr->cr_groups[0]) || (sgid != (gid_t)-1 && sgid != cr->cr_rgid && sgid != cr->cr_svgid && sgid != cr->cr_groups[0])) && (error = priv_check_cred(cr, PRIV_CRED_SETRESGID, 0)) != 0) { goto done; } if (egid != (gid_t)-1 && cr->cr_groups[0] != egid) { cr = cratom(&p->p_ucred); cr->cr_groups[0] = egid; setsugid(); } if (rgid != (gid_t)-1 && cr->cr_rgid != rgid) { cr = cratom(&p->p_ucred); cr->cr_rgid = rgid; setsugid(); } if (sgid != (gid_t)-1 && cr->cr_svgid != sgid) { cr = cratom(&p->p_ucred); cr->cr_svgid = sgid; setsugid(); } error = 0; done: lwkt_reltoken(&p->p_token); return (error); } int sys_getresuid(struct getresuid_args *uap) { struct ucred *cr; int error1 = 0, error2 = 0, error3 = 0; /* * copyout's can fault synchronously so we cannot use a shared * token here. */ cr = curthread->td_ucred; if (uap->ruid) error1 = copyout((caddr_t)&cr->cr_ruid, (caddr_t)uap->ruid, sizeof(cr->cr_ruid)); if (uap->euid) error2 = copyout((caddr_t)&cr->cr_uid, (caddr_t)uap->euid, sizeof(cr->cr_uid)); if (uap->suid) error3 = copyout((caddr_t)&cr->cr_svuid, (caddr_t)uap->suid, sizeof(cr->cr_svuid)); return error1 ? error1 : (error2 ? error2 : error3); } int sys_getresgid(struct getresgid_args *uap) { struct ucred *cr; int error1 = 0, error2 = 0, error3 = 0; cr = curthread->td_ucred; if (uap->rgid) error1 = copyout(&cr->cr_rgid, uap->rgid, sizeof(cr->cr_rgid)); if (uap->egid) error2 = copyout(&cr->cr_groups[0], uap->egid, sizeof(cr->cr_groups[0])); if (uap->sgid) error3 = copyout(&cr->cr_svgid, uap->sgid, sizeof(cr->cr_svgid)); return error1 ? error1 : (error2 ? error2 : error3); } /* * 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. */ int sys_issetugid(struct issetugid_args *uap) { uap->sysmsg_result = (curproc->p_flags & P_SUGID) ? 1 : 0; return (0); } /* * Check if gid is a member of the group set. */ int groupmember(gid_t gid, struct ucred *cred) { gid_t *gp; gid_t *egp; egp = &(cred->cr_groups[cred->cr_ngroups]); for (gp = cred->cr_groups; gp < egp; gp++) { if (*gp == gid) return (1); } return (0); } /* * Test whether the specified credentials have the privilege * in question. * * A kernel thread without a process context is assumed to have * the privilege in question. In situations where the caller always * expect a cred to exist, the cred should be passed separately and * priv_check_cred() should be used instead of priv_check(). * * Returns 0 or error. */ int priv_check(struct thread *td, int priv) { if (td->td_lwp != NULL) return priv_check_cred(td->td_ucred, priv, 0); return (0); } /* * Check a credential for privilege. * * A non-null credential is expected unless NULL_CRED_OKAY is set. */ int priv_check_cred(struct ucred *cred, int priv, int flags) { int error; KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege")); KASSERT(cred != NULL || (flags & NULL_CRED_OKAY), ("priv_check_cred: NULL cred!")); if (cred == NULL) { if (flags & NULL_CRED_OKAY) return (0); else return (EPERM); } if (cred->cr_uid != 0) return (EPERM); error = prison_priv_check(cred, priv); if (error) return (error); /* NOTE: accounting for suser access (p_acflag/ASU) removed */ return (0); } /* * Return zero if p1 can fondle p2, return errno (EPERM/ESRCH) otherwise. */ int p_trespass(struct ucred *cr1, struct ucred *cr2) { if (cr1 == cr2) return (0); if (!PRISON_CHECK(cr1, cr2)) return (ESRCH); if (cr1->cr_ruid == cr2->cr_ruid) return (0); if (cr1->cr_uid == cr2->cr_ruid) return (0); if (cr1->cr_ruid == cr2->cr_uid) return (0); if (cr1->cr_uid == cr2->cr_uid) return (0); if (priv_check_cred(cr1, PRIV_PROC_TRESPASS, 0) == 0) return (0); return (EPERM); } static __inline void _crinit(struct ucred *cr) { cr->cr_ref = 1; } void crinit(struct ucred *cr) { bzero(cr, sizeof(*cr)); _crinit(cr); } /* * Allocate a zeroed cred structure. */ struct ucred * crget(void) { struct ucred *cr; cr = kmalloc(sizeof(*cr), M_CRED, M_WAITOK|M_ZERO); _crinit(cr); return (cr); } /* * Claim another reference to a ucred structure. Can be used with special * creds. * * It must be possible to call this routine with spinlocks held, meaning * that this routine itself cannot obtain a spinlock. */ struct ucred * crhold(struct ucred *cr) { if (cr != NOCRED && cr != FSCRED) atomic_add_int(&cr->cr_ref, 1); return(cr); } /* * Drop a reference from the cred structure, free it if the reference count * reaches 0. * * NOTE: because we used atomic_add_int() above, without a spinlock, we * must also use atomic_subtract_int() below. A spinlock is required * in crfree() to handle multiple callers racing the refcount to 0. */ void crfree(struct ucred *cr) { if (cr->cr_ref <= 0) panic("Freeing already free credential! %p", cr); if (atomic_fetchadd_int(&cr->cr_ref, -1) == 1) { /* * Some callers of crget(), such as nfs_statfs(), * allocate a temporary credential, but don't * allocate a uidinfo structure. */ if (cr->cr_uidinfo != NULL) { uidrop(cr->cr_uidinfo); cr->cr_uidinfo = NULL; } if (cr->cr_ruidinfo != NULL) { uidrop(cr->cr_ruidinfo); cr->cr_ruidinfo = NULL; } /* * Destroy empty prisons */ if (jailed(cr)) prison_free(cr->cr_prison); cr->cr_prison = NULL; /* safety */ kfree((caddr_t)cr, M_CRED); } } /* * Atomize a cred structure so it can be modified without polluting * other references to it. * * MPSAFE (however, *pcr must be stable) */ struct ucred * cratom(struct ucred **pcr) { struct ucred *oldcr; struct ucred *newcr; oldcr = *pcr; if (oldcr->cr_ref == 1) return (oldcr); newcr = crget(); *newcr = *oldcr; if (newcr->cr_uidinfo) uihold(newcr->cr_uidinfo); if (newcr->cr_ruidinfo) uihold(newcr->cr_ruidinfo); if (jailed(newcr)) prison_hold(newcr->cr_prison); newcr->cr_ref = 1; crfree(oldcr); *pcr = newcr; return (newcr); } /* * Dup cred struct to a new held one. */ struct ucred * crdup(struct ucred *cr) { struct ucred *newcr; newcr = crget(); *newcr = *cr; if (newcr->cr_uidinfo) uihold(newcr->cr_uidinfo); if (newcr->cr_ruidinfo) uihold(newcr->cr_ruidinfo); if (jailed(newcr)) prison_hold(newcr->cr_prison); newcr->cr_ref = 1; return (newcr); } /* * Fill in a struct xucred based on a struct ucred. */ void cru2x(struct ucred *cr, struct xucred *xcr) { bzero(xcr, sizeof(*xcr)); xcr->cr_version = XUCRED_VERSION; xcr->cr_uid = cr->cr_uid; xcr->cr_ngroups = cr->cr_ngroups; bcopy(cr->cr_groups, xcr->cr_groups, sizeof(cr->cr_groups)); } /* * Get login name, if available. */ int sys_getlogin(struct getlogin_args *uap) { struct proc *p = curproc; char buf[MAXLOGNAME]; int error; if (uap->namelen > MAXLOGNAME) /* namelen is unsigned */ uap->namelen = MAXLOGNAME; bzero(buf, sizeof(buf)); lwkt_gettoken_shared(&p->p_token); bcopy(p->p_pgrp->pg_session->s_login, buf, uap->namelen); lwkt_reltoken(&p->p_token); error = copyout(buf, uap->namebuf, uap->namelen); return (error); } /* * Set login name. */ int sys_setlogin(struct setlogin_args *uap) { struct thread *td = curthread; struct proc *p; struct ucred *cred; char buf[MAXLOGNAME]; int error; cred = td->td_ucred; p = td->td_proc; if ((error = priv_check_cred(cred, PRIV_PROC_SETLOGIN, 0))) return (error); bzero(buf, sizeof(buf)); error = copyinstr(uap->namebuf, buf, sizeof(buf), NULL); if (error == ENAMETOOLONG) error = EINVAL; if (error == 0) { lwkt_gettoken_shared(&p->p_token); memcpy(p->p_pgrp->pg_session->s_login, buf, sizeof(buf)); lwkt_reltoken(&p->p_token); } return (error); } void setsugid(void) { struct proc *p = curproc; KKASSERT(p != NULL); lwkt_gettoken(&p->p_token); p->p_flags |= P_SUGID; if (!(p->p_pfsflags & PF_ISUGID)) p->p_stops = 0; lwkt_reltoken(&p->p_token); } /* * Helper function to change the effective uid of a process */ struct ucred * change_euid(uid_t euid) { struct proc *p = curproc; struct ucred *cr; KKASSERT(p != NULL); lf_count_adjust(p, 0); cr = cratom(&p->p_ucred); cr->cr_uid = euid; uireplace(&cr->cr_uidinfo, uifind(euid)); lf_count_adjust(p, 1); return (cr); } /* * Helper function to change the real uid of a process * * The per-uid process count for this process is transfered from * the old uid to the new uid. */ struct ucred * change_ruid(uid_t ruid) { struct proc *p = curproc; struct ucred *cr; KKASSERT(p != NULL); cr = cratom(&p->p_ucred); chgproccnt(cr->cr_ruidinfo, -1, 0); cr->cr_ruid = ruid; uireplace(&cr->cr_ruidinfo, uifind(ruid)); chgproccnt(cr->cr_ruidinfo, 1, 0); return (cr); }