/*- * 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. * Copyright (c) 2024-2025 The FreeBSD Foundation * * Portions of this software were developed by Olivier Certner * at Kumacom SARL under sponsorship from the FreeBSD * Foundation. * * 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. */ /* * System calls related to processes and protection */ #include #include "opt_inet.h" #include "opt_inet6.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef COMPAT_43 #include #endif #include #include #include #include #include #include #include #include #include #ifdef MAC #include #endif #include #ifdef REGRESSION FEATURE(regression, "Kernel support for interfaces necessary for regression testing (SECURITY RISK!)"); #endif #include #include static MALLOC_DEFINE(M_CRED, "cred", "credentials"); SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "BSD security policy"); static void crfree_final(struct ucred *cr); static inline void groups_check_positive_len(int ngrp) { MPASS2(ngrp >= 0, "negative number of groups"); } static inline void groups_check_max_len(int ngrp) { MPASS2(ngrp <= ngroups_max, "too many supplementary groups"); } static void groups_normalize(int *ngrp, gid_t *groups); static void crsetgroups_internal(struct ucred *cr, int ngrp, const gid_t *groups); static int cr_canseeotheruids(struct ucred *u1, struct ucred *u2); static int cr_canseeothergids(struct ucred *u1, struct ucred *u2); static int cr_canseejailproc(struct ucred *u1, struct ucred *u2); #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) { return (kern_getsid(td, uap->pid)); } int kern_getsid(struct thread *td, pid_t pid) { struct proc *p; int error; if (pid == 0) { p = td->td_proc; PROC_LOCK(p); } else { p = pfind(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_gid; #endif return (0); } #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_gid; return (0); } #ifdef COMPAT_FREEBSD14 int freebsd14_getgroups(struct thread *td, struct freebsd14_getgroups_args *uap) { struct ucred *cred; int ngrp, error; cred = td->td_ucred; /* * For FreeBSD < 15.0, we account for the egid being placed at the * beginning of the group list prior to all supplementary groups. */ ngrp = cred->cr_ngroups + 1; if (uap->gidsetsize == 0) { error = 0; goto out; } else if (uap->gidsetsize < ngrp) { return (EINVAL); } error = copyout(&cred->cr_gid, uap->gidset, sizeof(gid_t)); if (error == 0) error = copyout(cred->cr_groups, uap->gidset + 1, (ngrp - 1) * sizeof(gid_t)); out: td->td_retval[0] = ngrp; return (error); } #endif /* COMPAT_FREEBSD14 */ #ifndef _SYS_SYSPROTO_H_ struct getgroups_args { int gidsetsize; gid_t *gidset; }; #endif int sys_getgroups(struct thread *td, struct getgroups_args *uap) { struct ucred *cred; int ngrp, 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; pgrp = NULL; newpgrp = uma_zalloc(pgrp_zone, M_WAITOK); newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); again: error = 0; 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 { error = enterpgrp(p, p->p_pid, newpgrp, newsess); if (error == ERESTART) goto again; MPASS(error == 0); td->td_retval[0] = p->p_pid; newpgrp = NULL; newsess = NULL; } sx_xunlock(&proctree_lock); uma_zfree(pgrp_zone, newpgrp); 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); newpgrp = uma_zalloc(pgrp_zone, M_WAITOK); again: error = 0; 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: KASSERT(error == 0 || newpgrp != NULL, ("setpgid failed and newpgrp is NULL")); if (error == ERESTART) goto again; sx_xunlock(&proctree_lock); uma_zfree(pgrp_zone, newpgrp); return (error); } static int gidp_cmp(const void *p1, const void *p2) { const gid_t g1 = *(const gid_t *)p1; const gid_t g2 = *(const gid_t *)p2; return ((g1 > g2) - (g1 < g2)); } /* * 'smallgroups' must be an (uninitialized) array of length CRED_SMALLGROUPS_NB. * Always sets 'sc_supp_groups', either to a valid kernel-space groups array * (which may or may not be 'smallgroups'), or NULL if SETCREDF_SUPP_GROUPS was * not specified or there are too many groups, or a buffer containing garbage on * copyin() failure. In the last two cases, 'sc_supp_groups_nb' is additionally * set to 0 as a security measure. 'sc_supp_groups' must be freed (M_TEMP) if * not equal to 'smallgroups' even on failure. */ static int user_setcred_copyin_supp_groups(struct setcred *const wcred, const u_int flags, gid_t *const smallgroups) { gid_t *groups; int error; if ((flags & SETCREDF_SUPP_GROUPS) == 0) { error = 0; goto reset_groups_exit; } /* * Check the number of groups' limit right now in order to limit the * amount of bytes to copy. */ if (wcred->sc_supp_groups_nb > ngroups_max) { error = EINVAL; goto reset_groups_exit; } groups = wcred->sc_supp_groups_nb <= CRED_SMALLGROUPS_NB ? smallgroups : malloc(wcred->sc_supp_groups_nb * sizeof(gid_t), M_TEMP, M_WAITOK); error = copyin(wcred->sc_supp_groups, groups, wcred->sc_supp_groups_nb * sizeof(gid_t)); wcred->sc_supp_groups = groups; if (error != 0) { wcred->sc_supp_groups_nb = 0; /* * 'sc_supp_groups' must be freed by caller if not * 'smallgroups'. */ return (error); } return (0); reset_groups_exit: wcred->sc_supp_groups_nb = 0; wcred->sc_supp_groups = NULL; return (error); } int user_setcred(struct thread *td, const u_int flags, struct setcred *const wcred) { #ifdef MAC struct mac mac; /* Pointer to 'struct mac' or 'struct mac32'. */ void *umac; #endif gid_t smallgroups[CRED_SMALLGROUPS_NB]; int error; /* * As the only point of this wrapper function is to copyin() from * userland, we only interpret the data pieces we need to perform this * operation and defer further sanity checks to kern_setcred(), except * that we redundantly check here that no unknown flags have been * passed. */ if ((flags & ~SETCREDF_MASK) != 0) return (EINVAL); #ifdef MAC umac = wcred->sc_label; #endif /* Also done on !MAC as a defensive measure. */ wcred->sc_label = NULL; /* * Copy supplementary groups as needed. There is no specific * alternative for 32-bit compatibility as 'gid_t' has the same size * everywhere. */ error = user_setcred_copyin_supp_groups(wcred, flags, smallgroups); if (error != 0) goto free_groups; #ifdef MAC if ((flags & SETCREDF_MAC_LABEL) != 0) { error = mac_label_copyin(umac, &mac, NULL); if (error != 0) goto free_groups; wcred->sc_label = &mac; } #endif error = kern_setcred(td, flags, wcred); #ifdef MAC if (wcred->sc_label != NULL) free_copied_label(wcred->sc_label); #endif free_groups: if (wcred->sc_supp_groups != smallgroups) free(wcred->sc_supp_groups, M_TEMP); return (error); } #ifndef _SYS_SYSPROTO_H_ struct setcred_args { u_int flags; /* Flags. */ const struct setcred *wcred; size_t size; /* Passed 'setcred' structure length. */ }; #endif /* ARGSUSED */ int sys_setcred(struct thread *td, struct setcred_args *uap) { struct setcred wcred; int error; if (uap->size != sizeof(wcred)) return (EINVAL); error = copyin(uap->wcred, &wcred, sizeof(wcred)); if (error != 0) return (error); return (user_setcred(td, uap->flags, &wcred)); } /* * CAUTION: This function normalizes groups in 'wcred'. */ int kern_setcred(struct thread *const td, const u_int flags, struct setcred *const wcred) { struct proc *const p = td->td_proc; struct ucred *new_cred, *old_cred, *to_free_cred = NULL; struct uidinfo *uip = NULL, *ruip = NULL; #ifdef MAC void *mac_set_proc_data = NULL; bool proc_label_set = false; #endif int error; bool cred_set = false; /* Bail out on unrecognized flags. */ if (flags & ~SETCREDF_MASK) return (EINVAL); /* * Part 1: We allocate and perform preparatory operations with no locks. */ if ((flags & SETCREDF_SUPP_GROUPS) != 0 && wcred->sc_supp_groups_nb > ngroups_max) return (EINVAL); if (flags & SETCREDF_MAC_LABEL) { #ifdef MAC error = mac_set_proc_prepare(td, wcred->sc_label, &mac_set_proc_data); if (error != 0) return (error); #else return (ENOTSUP); #endif } if (flags & SETCREDF_UID) { AUDIT_ARG_EUID(wcred->sc_uid); uip = uifind(wcred->sc_uid); } if (flags & SETCREDF_RUID) { AUDIT_ARG_RUID(wcred->sc_ruid); ruip = uifind(wcred->sc_ruid); } if (flags & SETCREDF_SVUID) AUDIT_ARG_SUID(wcred->sc_svuid); if (flags & SETCREDF_GID) AUDIT_ARG_EGID(wcred->sc_gid); if (flags & SETCREDF_RGID) AUDIT_ARG_RGID(wcred->sc_rgid); if (flags & SETCREDF_SVGID) AUDIT_ARG_SGID(wcred->sc_svgid); if (flags & SETCREDF_SUPP_GROUPS) { /* * Output the raw supplementary groups array for better * traceability. */ AUDIT_ARG_GROUPSET(wcred->sc_supp_groups, wcred->sc_supp_groups_nb); groups_normalize(&wcred->sc_supp_groups_nb, wcred->sc_supp_groups); } /* * We first completely build the new credentials and only then pass them * to MAC along with the old ones so that modules can check whether the * requested transition is allowed. */ new_cred = crget(); to_free_cred = new_cred; if (flags & SETCREDF_SUPP_GROUPS) crextend(new_cred, wcred->sc_supp_groups_nb); #ifdef MAC mac_cred_setcred_enter(); #endif /* * Part 2: We grab the process lock as to have a stable view of its * current credentials, and prepare a copy of them with the requested * changes applied under that lock. */ PROC_LOCK(p); old_cred = crcopysafe(p, new_cred); /* * Change user IDs. */ if (flags & SETCREDF_UID) change_euid(new_cred, uip); if (flags & SETCREDF_RUID) change_ruid(new_cred, ruip); if (flags & SETCREDF_SVUID) change_svuid(new_cred, wcred->sc_svuid); /* * Change groups. */ if (flags & SETCREDF_SUPP_GROUPS) crsetgroups_internal(new_cred, wcred->sc_supp_groups_nb, wcred->sc_supp_groups); if (flags & SETCREDF_GID) change_egid(new_cred, wcred->sc_gid); if (flags & SETCREDF_RGID) change_rgid(new_cred, wcred->sc_rgid); if (flags & SETCREDF_SVGID) change_svgid(new_cred, wcred->sc_svgid); #ifdef MAC /* * Change the MAC label. */ if (flags & SETCREDF_MAC_LABEL) { error = mac_set_proc_core(td, new_cred, mac_set_proc_data); if (error != 0) goto unlock_finish; proc_label_set = true; } /* * MAC security modules checks. */ error = mac_cred_check_setcred(flags, old_cred, new_cred); if (error != 0) goto unlock_finish; #endif /* * Privilege check. */ error = priv_check_cred(old_cred, PRIV_CRED_SETCRED); if (error != 0) goto unlock_finish; #ifdef RACCT /* * Hold a reference to 'new_cred', as we need to call some functions on * it after proc_set_cred_enforce_proc_lim(). */ crhold(new_cred); #endif /* Set the new credentials. */ cred_set = proc_set_cred_enforce_proc_lim(p, new_cred); if (cred_set) { setsugid(p); #ifdef RACCT /* Adjust RACCT counters. */ racct_proc_ucred_changed(p, old_cred, new_cred); #endif to_free_cred = old_cred; MPASS(error == 0); } else { #ifdef RACCT /* Matches the crhold() just before the containing 'if'. */ crfree(new_cred); #endif error = EAGAIN; } unlock_finish: PROC_UNLOCK(p); /* * Part 3: After releasing the process lock, we perform cleanups and * finishing operations. */ #ifdef RACCT if (cred_set) { #ifdef RCTL rctl_proc_ucred_changed(p, new_cred); #endif /* Paired with the crhold() above. */ crfree(new_cred); } #endif #ifdef MAC if (mac_set_proc_data != NULL) mac_set_proc_finish(td, proc_label_set, mac_set_proc_data); mac_cred_setcred_exit(); #endif crfree(to_free_cred); if (uip != NULL) uifree(uip); if (ruip != NULL) uifree(ruip); 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) 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) #endif { /* * Set the real uid. */ 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); } #ifdef RACCT racct_proc_ucred_changed(p, oldcred, newcred); #endif #ifdef RCTL crhold(newcred); #endif /* * Takes over 'newcred''s reference, so 'newcred' must not be used * besides this point except on RCTL where we took an additional * reference above. */ proc_set_cred(p, newcred); 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) 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_gid && /* allow setgid(getegid()) */ #endif (error = priv_check_cred(oldcred, PRIV_CRED_SETGID)) != 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_gid || #endif /* We are using privs. */ priv_check_cred(oldcred, PRIV_CRED_SETGID) == 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_gid != 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) goto fail; if (oldcred->cr_gid != 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); } #ifdef COMPAT_FREEBSD14 int freebsd14_setgroups(struct thread *td, struct freebsd14_setgroups_args *uap) { gid_t smallgroups[CRED_SMALLGROUPS_NB]; gid_t *groups; int gidsetsize, error; /* * Before FreeBSD 15.0, we allow one more group to be supplied to * account for the egid appearing before the supplementary groups. This * may technically allow one more supplementary group for systems that * did use the default NGROUPS_MAX if we round it back up to 1024. */ gidsetsize = uap->gidsetsize; if (gidsetsize > ngroups_max + 1 || gidsetsize < 0) return (EINVAL); if (gidsetsize > CRED_SMALLGROUPS_NB) 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) { int ngroups = gidsetsize > 0 ? gidsetsize - 1 /* egid */ : 0; error = kern_setgroups(td, &ngroups, groups + 1); if (error == 0 && gidsetsize > 0) td->td_proc->p_ucred->cr_gid = groups[0]; } if (groups != smallgroups) free(groups, M_TEMP); return (error); } #endif /* COMPAT_FREEBSD14 */ #ifndef _SYS_SYSPROTO_H_ struct setgroups_args { int gidsetsize; gid_t *gidset; }; #endif /* ARGSUSED */ int sys_setgroups(struct thread *td, struct setgroups_args *uap) { gid_t smallgroups[CRED_SMALLGROUPS_NB]; gid_t *groups; int gidsetsize, error; /* * Sanity check size now to avoid passing too big a value to copyin(), * even if kern_setgroups() will do it again. * * Ideally, the 'gidsetsize' argument should have been a 'u_int' (and it * was, in this implementation, for a long time), but POSIX standardized * getgroups() to take an 'int' and it would be quite entrapping to have * setgroups() differ. */ gidsetsize = uap->gidsetsize; if (gidsetsize > ngroups_max || gidsetsize < 0) return (EINVAL); if (gidsetsize > CRED_SMALLGROUPS_NB) 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 (groups != smallgroups) free(groups, M_TEMP); return (error); } /* * CAUTION: This function normalizes 'groups', possibly also changing the value * of '*ngrpp' as a consequence. */ int kern_setgroups(struct thread *td, int *ngrpp, gid_t *groups) { struct proc *p = td->td_proc; struct ucred *newcred, *oldcred; int ngrp, error; ngrp = *ngrpp; /* Sanity check size. */ if (ngrp < 0 || ngrp > ngroups_max) return (EINVAL); AUDIT_ARG_GROUPSET(groups, ngrp); groups_normalize(&ngrp, groups); *ngrpp = ngrp; newcred = crget(); crextend(newcred, ngrp); PROC_LOCK(p); oldcred = crcopysafe(p, newcred); #ifdef MAC /* * We pass NULL here explicitly if we don't have any supplementary * groups mostly for the sake of normalization, but also to avoid/detect * a situation where a MAC module has some assumption about the layout * of `groups` matching historical behavior. */ error = mac_cred_check_setgroups(oldcred, ngrp, ngrp == 0 ? NULL : groups); if (error) goto fail; #endif error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS); if (error) goto fail; crsetgroups_internal(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) 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); } #ifdef RACCT racct_proc_ucred_changed(p, oldcred, newcred); #endif #ifdef RCTL crhold(newcred); #endif /* * Takes over 'newcred''s reference, so 'newcred' must not be used * besides this point except on RCTL where we took an additional * reference above. */ proc_set_cred(p, newcred); 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_gid && egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && (error = priv_check_cred(oldcred, PRIV_CRED_SETREGID)) != 0) goto fail; if (egid != (gid_t)-1 && oldcred->cr_gid != 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_gid != newcred->cr_rgid) && newcred->cr_svgid != newcred->cr_gid) { change_svgid(newcred, newcred->cr_gid); 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) 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); } #ifdef RACCT racct_proc_ucred_changed(p, oldcred, newcred); #endif #ifdef RCTL crhold(newcred); #endif /* * Takes over 'newcred''s reference, so 'newcred' must not be used * besides this point except on RCTL where we took an additional * reference above. */ proc_set_cred(p, newcred); 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_gid) || (egid != (gid_t)-1 && egid != oldcred->cr_rgid && egid != oldcred->cr_svgid && egid != oldcred->cr_gid) || (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && sgid != oldcred->cr_svgid && sgid != oldcred->cr_gid)) && (error = priv_check_cred(oldcred, PRIV_CRED_SETRESGID)) != 0) goto fail; if (egid != (gid_t)-1 && oldcred->cr_gid != 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_gid, uap->egid, sizeof(cred->cr_gid)); 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 */ } #ifdef INVARIANTS static void groups_check_normalized(int ngrp, const gid_t *groups) { gid_t prev_g; groups_check_positive_len(ngrp); groups_check_max_len(ngrp); if (ngrp <= 1) return; prev_g = groups[0]; for (int i = 1; i < ngrp; ++i) { const gid_t g = groups[i]; if (prev_g >= g) panic("%s: groups[%d] (%u) >= groups[%d] (%u)", __func__, i - 1, prev_g, i, g); prev_g = g; } } #else #define groups_check_normalized(...) #endif /* * Returns whether gid designates a supplementary group in cred. */ bool group_is_supplementary(const gid_t gid, const struct ucred *const cred) { groups_check_normalized(cred->cr_ngroups, cred->cr_groups); /* * Perform a binary search of the supplementary groups. This is * possible because we sort the groups in crsetgroups(). */ return (bsearch(&gid, cred->cr_groups, cred->cr_ngroups, sizeof(gid), gidp_cmp) != NULL); } /* * Check if gid is a member of the (effective) group set (i.e., effective and * supplementary groups). */ bool groupmember(gid_t gid, const struct ucred *cred) { groups_check_positive_len(cred->cr_ngroups); if (gid == cred->cr_gid) return (true); return (group_is_supplementary(gid, cred)); } /* * Check if gid is a member of the real group set (i.e., real and supplementary * groups). */ bool realgroupmember(gid_t gid, const struct ucred *cred) { groups_check_positive_len(cred->cr_ngroups); if (gid == cred->cr_rgid) return (true); return (group_is_supplementary(gid, cred)); } /* * 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 */ static 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) 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 */ static int cr_canseeothergids(struct ucred *u1, struct ucred *u2) { if (see_other_gids) return (0); /* Restriction in force. */ if (realgroupmember(u1->cr_rgid, u2)) return (0); for (int i = 0; i < u1->cr_ngroups; i++) if (realgroupmember(u1->cr_groups[i], u2)) return (0); if (priv_check_cred(u1, PRIV_SEEOTHERGIDS) == 0) return (0); return (ESRCH); } /* * '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 */ static int cr_canseejailproc(struct ucred *u1, struct ucred *u2) { if (see_jail_proc || /* Policy deactivated. */ u1->cr_prison == u2->cr_prison || /* Same jail. */ priv_check_cred(u1, PRIV_SEEJAILPROC) == 0) /* Privileged. */ return (0); return (ESRCH); } /* * Determine if u1 can tamper with the subject specified by u2, if they are in * different jails and 'unprivileged_parent_tampering' jail policy allows it. * * May be called if u1 and u2 are in the same jail, but it is expected that the * caller has already done a prison_check() prior to calling it. * * Returns: 0 for permitted, EPERM otherwise */ static int cr_can_tamper_with_subjail(struct ucred *u1, struct ucred *u2, int priv) { MPASS(prison_check(u1, u2) == 0); if (u1->cr_prison == u2->cr_prison) return (0); if (priv_check_cred(u1, priv) == 0) return (0); /* * Jails do not maintain a distinct UID space, so process visibility is * all that would control an unprivileged process' ability to tamper * with a process in a subjail by default if we did not have the * allow.unprivileged_parent_tampering knob to restrict it by default. */ if (prison_allow(u2, PR_ALLOW_UNPRIV_PARENT_TAMPER)) return (0); return (EPERM); } /* * Helper for cr_cansee*() functions to abide by system-wide security.bsd.see_* * policies. Determines if u1 "can see" u2 according to these policies. * Returns: 0 for permitted, ESRCH otherwise */ int cr_bsd_visible(struct ucred *u1, struct ucred *u2) { int error; error = cr_canseeotheruids(u1, u2); if (error != 0) return (error); error = cr_canseeothergids(u1, u2); if (error != 0) return (error); error = cr_canseejailproc(u1, u2); if (error != 0) return (error); return (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_bsd_visible(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); if (td->td_proc == p) return (0); 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_bsd_visible(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); 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); if (error) return (error); } /* * At this point, the target may be in a different jail than the * subject -- the subject must be in a parent jail to the target, * whether it is prison0 or a subordinate of prison0 that has * children. Additional privileges are required to allow this, as * whether the creds are truly equivalent or not must be determined on * a case-by-case basis. */ error = cr_can_tamper_with_subjail(cred, proc->p_ucred, PRIV_SIGNAL_DIFFJAIL); 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_bsd_visible(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); } error = cr_can_tamper_with_subjail(td->td_ucred, p->p_ucred, PRIV_SCHED_DIFFJAIL); if (error) return (error); return (0); } /* * Handle getting or setting the prison's unprivileged_proc_debug * value. */ static int sysctl_unprivileged_proc_debug(SYSCTL_HANDLER_ARGS) { int error, val; val = prison_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG); error = sysctl_handle_int(oidp, &val, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (val != 0 && val != 1) return (EINVAL); prison_set_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG, val); 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. */ SYSCTL_PROC(_security_bsd, OID_AUTO, unprivileged_proc_debug, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_SECURE | CTLFLAG_MPSAFE, 0, 0, sysctl_unprivileged_proc_debug, "I", "Unprivileged processes may use process debugging facilities"); /* * Return true if the object owner/group ids are subset of the active * credentials. */ bool cr_xids_subset(struct ucred *active_cred, struct ucred *obj_cred) { int i; bool grpsubset, uidsubset; /* * 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 = true; for (i = 0; i < obj_cred->cr_ngroups; i++) { if (!groupmember(obj_cred->cr_groups[i], active_cred)) { grpsubset = false; break; } } grpsubset = grpsubset && groupmember(obj_cred->cr_gid, active_cred) && groupmember(obj_cred->cr_rgid, active_cred) && groupmember(obj_cred->cr_svgid, active_cred); /* * Are the uids present in obj_cred's credential equal to * active_cred's effective uid? This includes obj_cred's * euid, svuid, and ruid. */ uidsubset = (active_cred->cr_uid == obj_cred->cr_uid && active_cred->cr_uid == obj_cred->cr_svuid && active_cred->cr_uid == obj_cred->cr_ruid); return (uidsubset && grpsubset); } /*- * 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 error; KASSERT(td == curthread, ("%s: td not curthread", __func__)); PROC_LOCK_ASSERT(p, MA_OWNED); if (td->td_proc == p) return (0); if ((error = priv_check(td, PRIV_DEBUG_UNPRIV))) return (error); 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_bsd_visible(td->td_ucred, p->p_ucred))) return (error); /* * 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 (!cr_xids_subset(td->td_ucred, p->p_ucred)) { error = priv_check(td, PRIV_DEBUG_DIFFCRED); if (error) return (error); } /* * Has the credential of the process changed since the last exec()? */ if ((p->p_flag & P_SUGID) != 0) { error = priv_check(td, PRIV_DEBUG_SUGID); if (error) return (error); } error = cr_can_tamper_with_subjail(td->td_ucred, p->p_ucred, PRIV_DEBUG_DIFFJAIL); 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 explicitly */ 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_bsd_visible(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_bsd_visible(td->td_ucred, p->p_ucred))) return (error); #endif return (0); } /* * Credential management. * * struct ucred objects are rarely allocated but gain and lose references all * the time (e.g., on struct file alloc/dealloc) turning refcount updates into * a significant source of cache-line ping ponging. Common cases are worked * around by modifying thread-local counter instead if the cred to operate on * matches td_realucred. * * The counter is split into 2 parts: * - cr_users -- total count of all struct proc and struct thread objects * which have given cred in p_ucred and td_ucred respectively * - cr_ref -- the actual ref count, only valid if cr_users == 0 * * If users == 0 then cr_ref behaves similarly to refcount(9), in particular if * the count reaches 0 the object is freeable. * If users > 0 and curthread->td_realucred == cred, then updates are performed * against td_ucredref. * In other cases updates are performed against cr_ref. * * Changing td_realucred into something else decrements cr_users and transfers * accumulated updates. */ struct ucred * crcowget(struct ucred *cr) { mtx_lock(&cr->cr_mtx); KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); cr->cr_users++; cr->cr_ref++; mtx_unlock(&cr->cr_mtx); return (cr); } static struct ucred * crunuse(struct thread *td) { struct ucred *cr, *crold; MPASS(td->td_realucred == td->td_ucred); cr = td->td_realucred; mtx_lock(&cr->cr_mtx); cr->cr_ref += td->td_ucredref; td->td_ucredref = 0; KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); cr->cr_users--; if (cr->cr_users == 0) { KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p", __func__, cr->cr_ref, cr)); crold = cr; } else { cr->cr_ref--; crold = NULL; } mtx_unlock(&cr->cr_mtx); td->td_realucred = NULL; return (crold); } static void crunusebatch(struct ucred *cr, u_int users, long ref) { KASSERT(users > 0, ("%s: passed users %d not > 0 ; cred %p", __func__, users, cr)); mtx_lock(&cr->cr_mtx); KASSERT(cr->cr_users >= users, ("%s: users %d not > %d on cred %p", __func__, cr->cr_users, users, cr)); cr->cr_users -= users; cr->cr_ref += ref; cr->cr_ref -= users; if (cr->cr_users > 0) { mtx_unlock(&cr->cr_mtx); return; } KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p", __func__, cr->cr_ref, cr)); if (cr->cr_ref > 0) { mtx_unlock(&cr->cr_mtx); return; } crfree_final(cr); } void crcowfree(struct thread *td) { struct ucred *cr; cr = crunuse(td); if (cr != NULL) crfree(cr); } struct ucred * crcowsync(void) { struct thread *td; struct proc *p; struct ucred *crnew, *crold; td = curthread; p = td->td_proc; PROC_LOCK_ASSERT(p, MA_OWNED); MPASS(td->td_realucred == td->td_ucred); if (td->td_realucred == p->p_ucred) return (NULL); crnew = crcowget(p->p_ucred); crold = crunuse(td); td->td_realucred = crnew; td->td_ucred = td->td_realucred; return (crold); } /* * Batching. */ void credbatch_add(struct credbatch *crb, struct thread *td) { struct ucred *cr; MPASS(td->td_realucred != NULL); MPASS(td->td_realucred == td->td_ucred); MPASS(TD_GET_STATE(td) == TDS_INACTIVE); cr = td->td_realucred; KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); if (crb->cred != cr) { if (crb->users > 0) { MPASS(crb->cred != NULL); crunusebatch(crb->cred, crb->users, crb->ref); crb->users = 0; crb->ref = 0; } } crb->cred = cr; crb->users++; crb->ref += td->td_ucredref; td->td_ucredref = 0; td->td_realucred = NULL; } void credbatch_final(struct credbatch *crb) { MPASS(crb->cred != NULL); MPASS(crb->users > 0); crunusebatch(crb->cred, crb->users, crb->ref); } /* * Allocate a zeroed cred structure. */ struct ucred * crget(void) { struct ucred *cr; cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); mtx_init(&cr->cr_mtx, "cred", NULL, MTX_DEF); 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 = nitems(cr->cr_smallgroups); return (cr); } /* * Claim another reference to a ucred structure. */ struct ucred * crhold(struct ucred *cr) { struct thread *td; td = curthread; if (__predict_true(td->td_realucred == cr)) { KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); td->td_ucredref++; return (cr); } mtx_lock(&cr->cr_mtx); cr->cr_ref++; mtx_unlock(&cr->cr_mtx); return (cr); } /* * Free a cred structure. Throws away space when ref count gets to 0. */ void crfree(struct ucred *cr) { struct thread *td; td = curthread; if (__predict_true(td->td_realucred == cr)) { KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); td->td_ucredref--; return; } mtx_lock(&cr->cr_mtx); KASSERT(cr->cr_users >= 0, ("%s: users %d not >= 0 on cred %p", __func__, cr->cr_users, cr)); cr->cr_ref--; if (cr->cr_users > 0) { mtx_unlock(&cr->cr_mtx); return; } KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p", __func__, cr->cr_ref, cr)); if (cr->cr_ref > 0) { mtx_unlock(&cr->cr_mtx); return; } crfree_final(cr); } static void crfree_final(struct ucred *cr) { KASSERT(cr->cr_users == 0, ("%s: users %d not == 0 on cred %p", __func__, cr->cr_users, cr)); KASSERT(cr->cr_ref == 0, ("%s: ref %ld not == 0 on cred %p", __func__, cr->cr_ref, cr)); /* * 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); 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 mtx_destroy(&cr->cr_mtx); 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) { bcopy(&src->cr_startcopy, &dest->cr_startcopy, (unsigned)((caddr_t)&src->cr_endcopy - (caddr_t)&src->cr_startcopy)); dest->cr_flags = src->cr_flags; 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; xcr->cr_gid = cr->cr_gid; /* * We use a union to alias cr_gid to cr_groups[0] in the xucred, so * this is kind of ugly; cr_ngroups still includes the egid for our * purposes to avoid bumping the xucred version. */ ngroups = MIN(cr->cr_ngroups + 1, nitems(xcr->cr_groups)); xcr->cr_ngroups = ngroups; bcopy(cr->cr_groups, xcr->cr_sgroups, (ngroups - 1) * sizeof(*cr->cr_groups)); } void cru2xt(struct thread *td, struct xucred *xcr) { cru2x(td->td_ucred, xcr); xcr->cr_pid = td->td_proc->p_pid; } /* * Change process credentials. * * Callers are responsible for providing the reference for passed credentials * and for freeing old ones. Calls chgproccnt() to correctly account the * current process to the proper real UID, if the latter has changed. Returns * whether the operation was successful. Failure can happen only on * 'enforce_proc_lim' being true and if no new process can be accounted to the * new real UID because of the current limit (see the inner comment for more * details) and the caller does not have privilege (PRIV_PROC_LIMIT) to override * that. In this case, the reference to 'newcred' is not taken over. */ static bool _proc_set_cred(struct proc *p, struct ucred *newcred, bool enforce_proc_lim) { struct ucred *const oldcred = p->p_ucred; MPASS(oldcred != NULL); PROC_LOCK_ASSERT(p, MA_OWNED); if (newcred->cr_ruidinfo != oldcred->cr_ruidinfo) { /* * XXXOC: This check is flawed but nonetheless the best we can * currently do as we don't really track limits per UID contrary * to what we pretend in setrlimit(2). Until this is reworked, * we just check here that the number of processes for our new * real UID doesn't exceed this process' process number limit * (which is meant to be associated with the current real UID). */ const int proccnt_changed = chgproccnt(newcred->cr_ruidinfo, 1, enforce_proc_lim ? lim_cur_proc(p, RLIMIT_NPROC) : 0); if (!proccnt_changed) { if (priv_check_cred(oldcred, PRIV_PROC_LIMIT) != 0) return (false); (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); } } mtx_lock(&oldcred->cr_mtx); KASSERT(oldcred->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, oldcred->cr_users, oldcred)); oldcred->cr_users--; mtx_unlock(&oldcred->cr_mtx); mtx_lock(&newcred->cr_mtx); newcred->cr_users++; mtx_unlock(&newcred->cr_mtx); p->p_ucred = newcred; PROC_UPDATE_COW(p); if (newcred->cr_ruidinfo != oldcred->cr_ruidinfo) (void)chgproccnt(oldcred->cr_ruidinfo, -1, 0); return (true); } void proc_set_cred(struct proc *p, struct ucred *newcred) { bool success __diagused = _proc_set_cred(p, newcred, false); MPASS(success); } bool proc_set_cred_enforce_proc_lim(struct proc *p, struct ucred *newcred) { return (_proc_set_cred(p, newcred, true)); } void proc_unset_cred(struct proc *p, bool decrement_proc_count) { struct ucred *cr; MPASS(p->p_state == PRS_ZOMBIE || p->p_state == PRS_NEW); cr = p->p_ucred; p->p_ucred = NULL; KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", __func__, cr->cr_users, cr)); mtx_lock(&cr->cr_mtx); cr->cr_users--; if (cr->cr_users == 0) KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p", __func__, cr->cr_ref, cr)); mtx_unlock(&cr->cr_mtx); if (decrement_proc_count) (void)chgproccnt(cr->cr_ruidinfo, -1, 0); crfree(cr); } 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_ngroups) { groups = oldcred->cr_ngroups; PROC_UNLOCK(p); crextend(cr, groups); PROC_LOCK(p); oldcred = p->p_ucred; } crcopy(cr, oldcred); return (oldcred); } /* * Extend the passed-in credentials to hold n groups. * * Must not be called after groups have been set. */ void crextend(struct ucred *cr, int n) { size_t nbytes; MPASS2(cr->cr_ref == 1, "'cr_ref' must be 1 (referenced, unshared)"); MPASS2((cr->cr_flags & CRED_FLAG_GROUPSET) == 0, "groups on 'cr' already set!"); groups_check_positive_len(n); groups_check_max_len(n); if (n <= cr->cr_agroups) return; nbytes = n * sizeof(gid_t); if (nbytes < n) panic("Too many groups (memory size overflow)! " "Computation of 'kern.ngroups' should have prevented this, " "please fix it. In the meantime, reduce 'kern.ngroups'."); /* * We allocate a power of 2 larger than 'nbytes', except when that * exceeds PAGE_SIZE, in which case we allocate the right multiple of * pages. We assume PAGE_SIZE is a power of 2 (the call to roundup2() * below) but do not need to for sizeof(gid_t). */ if (nbytes < PAGE_SIZE) { if (!powerof2(nbytes)) /* fls*() return a bit index starting at 1. */ nbytes = 1 << flsl(nbytes); } else nbytes = roundup2(nbytes, PAGE_SIZE); /* Free the old array. */ if (cr->cr_groups != cr->cr_smallgroups) free(cr->cr_groups, M_CRED); cr->cr_groups = malloc(nbytes, M_CRED, M_WAITOK | M_ZERO); cr->cr_agroups = nbytes / sizeof(gid_t); } /* * Normalizes a set of groups to be applied to a 'struct ucred'. * * Normalization ensures that the supplementary groups are sorted in ascending * order and do not contain duplicates. This allows group_is_supplementary() to * do a binary search. */ static void groups_normalize(int *ngrp, gid_t *groups) { gid_t prev_g; int ins_idx; groups_check_positive_len(*ngrp); groups_check_max_len(*ngrp); if (*ngrp <= 1) return; qsort(groups, *ngrp, sizeof(*groups), gidp_cmp); /* Remove duplicates. */ prev_g = groups[0]; ins_idx = 1; for (int i = ins_idx; i < *ngrp; ++i) { const gid_t g = groups[i]; if (g != prev_g) { if (i != ins_idx) groups[ins_idx] = g; ++ins_idx; prev_g = g; } } *ngrp = ins_idx; groups_check_normalized(*ngrp, groups); } /* * Internal function copying groups into a credential. * * 'ngrp' must be strictly positive. Either the passed 'groups' array must have * been normalized in advance (see groups_normalize()), else it must be so * before the structure is to be used again. * * This function is suitable to be used under any lock (it doesn't take any lock * itself nor sleep, and in particular doesn't allocate memory). crextend() * must have been called beforehand to ensure sufficient space is available. * See also crsetgroups(), which handles that. */ static void crsetgroups_internal(struct ucred *cr, int ngrp, const gid_t *groups) { MPASS2(cr->cr_ref == 1, "'cr_ref' must be 1 (referenced, unshared)"); MPASS2(cr->cr_agroups >= ngrp, "'cr_agroups' too small"); groups_check_positive_len(ngrp); bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t)); cr->cr_ngroups = ngrp; cr->cr_flags |= CRED_FLAG_GROUPSET; } /* * Copy groups in to a credential after expanding it if required. * * May sleep in order to allocate memory (except if, e.g., crextend() was called * before with 'ngrp' or greater). Truncates the list to 'ngroups_max' if * it is too large. Array 'groups' doesn't need to be sorted. 'ngrp' must be * positive. */ void crsetgroups(struct ucred *cr, int ngrp, const gid_t *groups) { if (ngrp > ngroups_max) ngrp = ngroups_max; cr->cr_ngroups = 0; if (ngrp == 0) { cr->cr_flags |= CRED_FLAG_GROUPSET; return; } /* * crextend() asserts that groups are not set, as it may allocate a new * backing storage without copying the content of the old one. Since we * are going to install a completely new set anyway, signal that we * consider the old ones thrown away. */ cr->cr_flags &= ~CRED_FLAG_GROUPSET; crextend(cr, ngrp); crsetgroups_internal(cr, ngrp, groups); groups_normalize(&cr->cr_ngroups, cr->cr_groups); } /* * Same as crsetgroups() but sets the effective GID as well. * * This function ensures that an effective GID is always present in credentials. * An empty array will only set the effective GID to 'default_egid', while * a non-empty array will peel off groups[0] to set as the effective GID and use * the remainder, if any, as supplementary groups. */ void crsetgroups_and_egid(struct ucred *cr, int ngrp, const gid_t *groups, const gid_t default_egid) { if (ngrp == 0) { cr->cr_gid = default_egid; cr->cr_ngroups = 0; cr->cr_flags |= CRED_FLAG_GROUPSET; return; } crsetgroups(cr, ngrp - 1, groups + 1); cr->cr_gid = groups[0]; } /* * 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; } /*- * 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_gid = egid; } /*- * Change a process's real uid. * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo * 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) { newcred->cr_ruid = ruip->ui_uid; uihold(ruip); uifree(newcred->cr_ruidinfo); newcred->cr_ruidinfo = ruip; } /*- * 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; } bool allow_ptrace = true; SYSCTL_BOOL(_security_bsd, OID_AUTO, allow_ptrace, CTLFLAG_RWTUN, &allow_ptrace, 0, "Deny ptrace(2) use by returning ENOSYS");