FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_prot.c

     /*      $NetBSD: kern_prot.c,v 1.84 2004/05/04 21:27:28 pk Exp $        */
     
     /*
      * 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 8.9 (Berkeley) 2/14/95
     */
    
    /*
     * System calls related to processes and protection
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: kern_prot.c,v 1.84 2004/05/04 21:27:28 pk Exp $");
    
    #include "opt_compat_43.h"
    
    #include <sys/param.h>
    #include <sys/acct.h>
    #include <sys/systm.h>
    #include <sys/ucred.h>
    #include <sys/proc.h>
    #include <sys/timeb.h>
    #include <sys/times.h>
    #include <sys/pool.h>
    #include <sys/syslog.h>
    #include <sys/resourcevar.h>
    
    #include <sys/mount.h>
    #include <sys/sa.h>
    #include <sys/syscallargs.h>
    
    POOL_INIT(cred_pool, sizeof(struct ucred), 0, 0, 0, "credpl",
        &pool_allocator_nointr);
    
    int     sys_getpid(struct lwp *, void *, register_t *);
    int     sys_getpid_with_ppid(struct lwp *, void *, register_t *);
    int     sys_getuid(struct lwp *, void *, register_t *);
    int     sys_getuid_with_euid(struct lwp *, void *, register_t *);
    int     sys_getgid(struct lwp *, void *, register_t *);
    int     sys_getgid_with_egid(struct lwp *, void *, register_t *);
    
    /* ARGSUSED */
    int
    sys_getpid(struct lwp *l, void *v, register_t *retval)
    {
            struct proc *p = l->l_proc;
    
            *retval = p->p_pid;
            return (0);
    }
    
    /* ARGSUSED */
    int
    sys_getpid_with_ppid(struct lwp *l, void *v, register_t *retval)
    {
            struct proc *p = l->l_proc;
    
            retval[0] = p->p_pid;
            retval[1] = p->p_pptr->p_pid;
            return (0);
    }
    
    /* ARGSUSED */
    int
    sys_getppid(struct lwp *l, void *v, register_t *retval)
    {
            struct proc *p = l->l_proc;
    
           *retval = p->p_pptr->p_pid;
           return (0);
   }
   
   /* Get process group ID; note that POSIX getpgrp takes no parameter */
   int
   sys_getpgrp(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           *retval = p->p_pgrp->pg_id;
           return (0);
   }
   
   /*
    * Return the process group ID of the session leader (session ID)
    * for the specified process.
    */
   int
   sys_getsid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_getsid_args /* {
                   syscalldarg(pid_t) pid;
           } */ *uap = v;
           struct proc *p = l->l_proc;
   
           if (SCARG(uap, pid) == 0)
                   goto found;
           if ((p = pfind(SCARG(uap, pid))) == 0)
                   return (ESRCH);
   found:
           *retval = p->p_session->s_sid;
           return (0);
   }
   
   int
   sys_getpgid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_getpgid_args /* {
                   syscallarg(pid_t) pid;
           } */ *uap = v;
           struct proc *p = l->l_proc;
   
           if (SCARG(uap, pid) == 0)
                   goto found;
           if ((p = pfind(SCARG(uap, pid))) == 0)
                   return (ESRCH);
   found:
           *retval = p->p_pgid;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_getuid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           *retval = p->p_cred->p_ruid;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_getuid_with_euid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           retval[0] = p->p_cred->p_ruid;
           retval[1] = p->p_ucred->cr_uid;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_geteuid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           *retval = p->p_ucred->cr_uid;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_getgid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           *retval = p->p_cred->p_rgid;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_getgid_with_egid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           retval[0] = p->p_cred->p_rgid;
           retval[1] = p->p_ucred->cr_gid;
           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.
    */
   /* ARGSUSED */
   int
   sys_getegid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           *retval = p->p_ucred->cr_gid;
           return (0);
   }
   
   int
   sys_getgroups(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_getgroups_args /* {
                   syscallarg(int) gidsetsize;
                   syscallarg(gid_t *) gidset;
           } */ *uap = v;
           struct proc *p = l->l_proc;
           struct pcred *pc = p->p_cred;
           u_int ngrp;
           int error;
   
           if (SCARG(uap, gidsetsize) == 0) {
                   *retval = pc->pc_ucred->cr_ngroups;
                   return (0);
           } else if (SCARG(uap, gidsetsize) < 0)
                   return (EINVAL);
           ngrp = SCARG(uap, gidsetsize);
           if (ngrp < pc->pc_ucred->cr_ngroups)
                   return (EINVAL);
           ngrp = pc->pc_ucred->cr_ngroups;
           error = copyout((caddr_t)pc->pc_ucred->cr_groups,
               (caddr_t)SCARG(uap, gidset), ngrp * sizeof(gid_t));
           if (error)
                   return (error);
           *retval = ngrp;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_setsid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_proc;
   
           if (p->p_pgid == p->p_pid || pgfind(p->p_pid)) {
                   return (EPERM);
           } else {
                   (void)enterpgrp(p, p->p_pid, 1);
                   *retval = p->p_pid;
                   return (0);
           }
   }
   
   /*
    * set process group (setpgid/old setpgrp)
    *
    * caller does setpgid(targpid, targpgid)
    *
    * pgid must be in valid range (EINVAL)
    * 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)
    *
    * Permission checks now in enterpgrp()
    */
   /* ARGSUSED */
   int
   sys_setpgid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setpgid_args /* {
                   syscallarg(int) pid;
                   syscallarg(int) pgid;
           } */ *uap = v;
           struct proc *curp = l->l_proc;
           struct proc *targp;                     /* target process */
   
           if (SCARG(uap, pgid) < 0)
                   return EINVAL;
   
           /* XXX MP - there is a horrid race here with targp exiting! */
           if (SCARG(uap, pid) != 0 && SCARG(uap, pid) != curp->p_pid) {
                   targp = pfind(SCARG(uap, pid));
                   if (targp == NULL)
                           return ESRCH;
           } else
                   targp = curp;
   
           if (SCARG(uap, pgid) == 0)
                   SCARG(uap, pgid) = targp->p_pid;
           return enterpgrp(targp, SCARG(uap, pgid), 0);
   }
   
   /*
    * Set real, effective and saved uids to the requested values.
    * non-root callers can only ever change uids to values that match
    * one of the processes current uid values.
    * This is further restricted by the flags argument.
    */
   
   int
   do_setresuid(struct lwp *l, uid_t r, uid_t e, uid_t sv, u_int flags)
   {
           int error;
           struct proc *p = l->l_proc;
           struct pcred *pcred = p->p_cred;
           struct ucred *cred = pcred->pc_ucred;
   
           /* Superuser can do anything it wants to.... */
           error = suser(cred, &p->p_acflag);
           if (error) {
                   /* Otherwise check new value is one of the allowed
                      existing values. */
                   if (r != -1 && !((flags & ID_R_EQ_R) && r == pcred->p_ruid)
                               && !((flags & ID_R_EQ_E) && r == cred->cr_uid)
                               && !((flags & ID_R_EQ_S) && r == pcred->p_svuid))
                           return error;
                   if (e != -1 && !((flags & ID_E_EQ_R) && e == pcred->p_ruid)
                               && !((flags & ID_E_EQ_E) && e == cred->cr_uid)
                               && !((flags & ID_E_EQ_S) && e == pcred->p_svuid))
                           return error;
                   if (sv != -1 && !((flags & ID_S_EQ_R) && sv == pcred->p_ruid)
                               && !((flags & ID_S_EQ_E) && sv == cred->cr_uid)
                               && !((flags & ID_S_EQ_S) && sv == pcred->p_svuid))
                           return error;
           }
   
           /* If nothing has changed, short circuit the request */
           if ((r == -1 || r == pcred->p_ruid)
               && (e == -1 || e == cred->cr_uid)
               && (sv == -1 || sv == pcred->p_svuid))
                   /* nothing to do */
                   return 0;
   
           /* The pcred structure is not actually shared... */
           if (r != -1 && r != pcred->p_ruid) {
                   /* Update count of processes for this user */
                   (void)chgproccnt(pcred->p_ruid, -1);
                   (void)chgproccnt(r, 1);
                   pcred->p_ruid = r;
           }
           if (sv != -1)
                   pcred->p_svuid = sv;
           if (e != -1 && e != cred->cr_uid) {
                   /* Update a clone of the current credentials */
                   pcred->pc_ucred = cred = crcopy(cred);
                   cred->cr_uid = e;
           }
   
           /* Mark process as having changed credentials, stops tracing etc */
           p_sugid(p);
           return 0;
   }
   
   /*
    * Set real, effective and saved gids to the requested values.
    * non-root callers can only ever change gids to values that match
    * one of the processes current gid values.
    * This is further restricted by the flags argument.
    */
   
   int
   do_setresgid(struct lwp *l, gid_t r, gid_t e, gid_t sv, u_int flags)
   {
           int error;
           struct proc *p = l->l_proc;
           struct pcred *pcred = p->p_cred;
           struct ucred *cred = pcred->pc_ucred;
   
           /* Superuser can do anything it wants to.... */
           error = suser(cred, &p->p_acflag);
           if (error) {
                   /* Otherwise check new value is one of the allowed
                      existing values. */
                   if (r != -1 && !((flags & ID_R_EQ_R) && r == pcred->p_rgid)
                               && !((flags & ID_R_EQ_E) && r == cred->cr_gid)
                               && !((flags & ID_R_EQ_S) && r == pcred->p_svgid))
                           return error;
                   if (e != -1 && !((flags & ID_E_EQ_R) && e == pcred->p_rgid)
                               && !((flags & ID_E_EQ_E) && e == cred->cr_gid)
                               && !((flags & ID_E_EQ_S) && e == pcred->p_svgid))
                           return error;
                   if (sv != -1 && !((flags & ID_S_EQ_R) && sv == pcred->p_rgid)
                               && !((flags & ID_S_EQ_E) && sv == cred->cr_gid)
                               && !((flags & ID_S_EQ_S) && sv == pcred->p_svgid))
                           return error;
           }
   
           /* If nothing has changed, short circuit the request */
           if ((r == -1 || r == pcred->p_rgid)
               && (e == -1 || e == cred->cr_gid)
               && (sv == -1 || sv == pcred->p_svgid))
                   /* nothing to do */
                   return 0;
   
           /* The pcred structure is not actually shared... */
           if (r != -1)
                   pcred->p_rgid = r;
           if (sv != -1)
                   pcred->p_svgid = sv;
           if (e != -1 && e != cred->cr_gid) {
                   /* Update a clone of the current credentials */
                   pcred->pc_ucred = cred = crcopy(cred);
                   cred->cr_gid = e;
           }
   
           /* Mark process as having changed credentials, stops tracing etc */
           p_sugid(p);
           return 0;
   }
   
   /* ARGSUSED */
   int
   sys_setuid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setuid_args /* {
                   syscallarg(uid_t) uid;
           } */ *uap = v;
           uid_t uid = SCARG(uap, uid);
   
           return do_setresuid(l, uid, uid, uid,
                               ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
   }
   
   /* ARGSUSED */
   int
   sys_seteuid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_seteuid_args /* {
                   syscallarg(uid_t) euid;
           } */ *uap = v;
   
           return do_setresuid(l, -1, SCARG(uap, euid), -1, ID_E_EQ_R | ID_E_EQ_S);
   }
   
   int
   sys_setreuid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setreuid_args /* {
                   syscallarg(uid_t) ruid;
                   syscallarg(uid_t) euid;
           } */ *uap = v;
           struct proc *p = l->l_proc;
           uid_t ruid, euid, svuid;
   
           ruid = SCARG(uap, ruid);
           euid = SCARG(uap, euid);
           if (ruid == -1)
                   ruid = p->p_cred->p_ruid;
           if (euid == -1)
                   euid = p->p_ucred->cr_uid;
           /* Saved uid is set to the new euid if the ruid changed */
           svuid = (ruid == p->p_cred->p_ruid) ? -1 : euid;
   
           return do_setresuid(l, ruid, euid, svuid,
                               ID_R_EQ_R | ID_R_EQ_E |
                               ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
                               ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
   }
   
   /* ARGSUSED */
   int
   sys_setgid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setgid_args /* {
                   syscallarg(gid_t) gid;
           } */ *uap = v;
           gid_t gid = SCARG(uap, gid);
   
           return do_setresgid(l, gid, gid, gid,
                               ID_R_EQ_R | ID_E_EQ_R | ID_S_EQ_R);
   }
   
   /* ARGSUSED */
   int
   sys_setegid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setegid_args /* {
                   syscallarg(gid_t) egid;
           } */ *uap = v;
   
           return do_setresgid(l, -1, SCARG(uap, egid), -1, ID_E_EQ_R | ID_E_EQ_S);
   }
   
   int
   sys_setregid(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setregid_args /* {
                   syscallarg(gid_t) rgid;
                   syscallarg(gid_t) egid;
           } */ *uap = v;
           struct proc *p = l->l_proc;
           gid_t rgid, egid, svgid;
   
           rgid = SCARG(uap, rgid);
           egid = SCARG(uap, egid);
           if (rgid == -1)
                   rgid = p->p_cred->p_rgid;
           if (egid == -1)
                   egid = p->p_ucred->cr_gid;
           /* Saved gid is set to the new egid if the rgid changed */
           svgid = rgid == p->p_cred->p_rgid ? -1 : egid;
   
           return do_setresgid(l, rgid, egid, svgid,
                           ID_R_EQ_R | ID_R_EQ_E |
                           ID_E_EQ_R | ID_E_EQ_E | ID_E_EQ_S |
                           ID_S_EQ_R | ID_S_EQ_E | ID_S_EQ_S);
   }
   
   int
   sys_issetugid(struct lwp *l, void *v, register_t *retval)
   {
           struct proc *p = l->l_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.
            */
           *retval = (p->p_flag & P_SUGID) != 0;
           return (0);
   }
   
   /* ARGSUSED */
   int
   sys_setgroups(struct lwp *l, void *v, register_t *retval)
   {
           struct sys_setgroups_args /* {
                   syscallarg(int) gidsetsize;
                   syscallarg(const gid_t *) gidset;
           } */ *uap = v;
           struct proc *p = l->l_proc;
           struct pcred *pc = p->p_cred;
           int ngrp;
           int error;
           gid_t grp[NGROUPS];
           size_t grsize;
   
           if ((error = suser(pc->pc_ucred, &p->p_acflag)) != 0)
                   return (error);
   
           ngrp = SCARG(uap, gidsetsize);
           if ((u_int)ngrp > NGROUPS)
                   return (EINVAL);
   
           grsize = ngrp * sizeof(gid_t);
           error = copyin(SCARG(uap, gidset), grp, grsize);
           if (error)
                   return (error);
           /*
            * Check if this is a no-op.
            */
           if (pc->pc_ucred->cr_ngroups == (u_int) ngrp &&
               memcmp(grp, pc->pc_ucred->cr_groups, grsize) == 0)
                   return (0);
   
           pc->pc_ucred = crcopy(pc->pc_ucred);
           (void)memcpy(pc->pc_ucred->cr_groups, grp, grsize);
           pc->pc_ucred->cr_ngroups = ngrp;
           p_sugid(p);
           return (0);
   }
   
   /*
    * Check if gid is a member of the group set.
    */
   int
   groupmember(gid_t gid, const struct ucred *cred)
   {
           const gid_t *gp;
           const 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 imply "super-user"
    * privilege; if so, and we have accounting info, set the flag
    * indicating use of super-powers.
    * Returns 0 or error.
    */
   int
   suser(const struct ucred *cred, u_short *acflag)
   {
   
           if (cred->cr_uid == 0) {
                   if (acflag)
                           *acflag |= ASU;
                   return (0);
           }
           return (EPERM);
   }
   
   /*
    * Allocate a zeroed cred structure.
    */
   struct ucred *
   crget(void)
   {
           struct ucred *cr;
   
           cr = pool_get(&cred_pool, PR_WAITOK);
           memset(cr, 0, sizeof(*cr));
           simple_lock_init(&cr->cr_lock);
           cr->cr_ref = 1;
           return (cr);
   }
   
   /*
    * Free a cred structure.
    * Throws away space when ref count gets to 0.
    */
   void
   crfree(struct ucred *cr)
   {
           int n;
   
           simple_lock(&cr->cr_lock);
           n = --cr->cr_ref;
           simple_unlock(&cr->cr_lock);
           if (n == 0)
                   pool_put(&cred_pool, cr);
   }
   
   /*
    * Compare cred structures and return 0 if they match
    */
   int
   crcmp(const struct ucred *cr1, const struct uucred *cr2)
   {
           return cr1->cr_uid != cr2->cr_uid ||
               cr1->cr_gid != cr2->cr_gid ||
               cr1->cr_ngroups != (uint32_t)cr2->cr_ngroups ||
               memcmp(cr1->cr_groups, cr2->cr_groups, cr1->cr_ngroups);
   }
   
   /*
    * Copy cred structure to a new one and free the old one.
    */
   struct ucred *
   crcopy(struct ucred *cr)
   {
           struct ucred *newcr;
   
           if (cr->cr_ref == 1)
                   return (cr);
   
           newcr = crget();
           memcpy(&newcr->cr_startcopy, &cr->cr_startcopy,
                   sizeof(struct ucred) - offsetof(struct ucred, cr_startcopy));
           crfree(cr);
           return (newcr);
   }
   
   /*
    * Dup cred struct to a new held one.
    */
   struct ucred *
   crdup(const struct ucred *cr)
   {
           struct ucred *newcr;
   
           newcr = crget();
           memcpy(&newcr->cr_startcopy, &cr->cr_startcopy,
                   sizeof(struct ucred) - offsetof(struct ucred, cr_startcopy));
           return (newcr);
   }
   
   /*
    * convert from userland credentials to kernel one
    */
   void
   crcvt(struct ucred *uc, const struct uucred *uuc)
   {
   
           uc->cr_ref = 0;
           uc->cr_uid = uuc->cr_uid;
           uc->cr_gid = uuc->cr_gid;
           uc->cr_ngroups = uuc->cr_ngroups;
           (void)memcpy(uc->cr_groups, uuc->cr_groups, sizeof(uuc->cr_groups));
   }
   
   /*
    * Get login name, if available.
    */
   /* ARGSUSED */
   int
   sys___getlogin(struct lwp *l, void *v, register_t *retval)
   {
           struct sys___getlogin_args /* {
                   syscallarg(char *) namebuf;
                   syscallarg(size_t) namelen;
           } */ *uap = v;
           struct proc *p = l->l_proc;
   
           if (SCARG(uap, namelen) > sizeof(p->p_pgrp->pg_session->s_login))
                   SCARG(uap, namelen) = sizeof(p->p_pgrp->pg_session->s_login);
           return (copyout((caddr_t) p->p_pgrp->pg_session->s_login,
               (caddr_t) SCARG(uap, namebuf), SCARG(uap, namelen)));
   }
   
   /*
    * Set login name.
    */
   /* ARGSUSED */
   int
   sys___setlogin(struct lwp *l, void *v, register_t *retval)
   {
           struct sys___setlogin_args /* {
                   syscallarg(const char *) namebuf;
           } */ *uap = v;
           struct proc *p = l->l_proc;
           struct session *s = p->p_pgrp->pg_session;
           char newname[sizeof s->s_login + 1];
           int error;
   
           if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
                   return (error);
           error = copyinstr(SCARG(uap, namebuf), &newname, sizeof newname, NULL);
           if (error != 0)
                   return (error == ENAMETOOLONG ? EINVAL : error);
   
           if (s->s_flags & S_LOGIN_SET && p->p_pid != s->s_sid &&
               strncmp(newname, s->s_login, sizeof s->s_login) != 0)
                   log(LOG_WARNING, "%s (pid %d) changing logname from "
                       "%.*s to %s\n", p->p_comm, p->p_pid,
                       (int)sizeof s->s_login, s->s_login, newname);
           s->s_flags |= S_LOGIN_SET;
           strncpy(s->s_login, newname, sizeof s->s_login);
           return (0);
   }

Cache object: 89e211355545752150245f0296b8fcc1