The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2014 John Baldwin
    3  * Copyright (c) 2014 The FreeBSD Foundation
    4  *
    5  * Portions of this software were developed by Konstantin Belousov
    6  * under sponsorship from the FreeBSD Foundation.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_procctl.c 286975 2015-08-20 22:44:26Z kib $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/capsicum.h>
   36 #include <sys/lock.h>
   37 #include <sys/mutex.h>
   38 #include <sys/priv.h>
   39 #include <sys/proc.h>
   40 #include <sys/procctl.h>
   41 #include <sys/sx.h>
   42 #include <sys/syscallsubr.h>
   43 #include <sys/sysproto.h>
   44 #include <sys/wait.h>
   45 
   46 static int
   47 protect_setchild(struct thread *td, struct proc *p, int flags)
   48 {
   49 
   50         PROC_LOCK_ASSERT(p, MA_OWNED);
   51         if (p->p_flag & P_SYSTEM || p_cansched(td, p) != 0)
   52                 return (0);
   53         if (flags & PPROT_SET) {
   54                 p->p_flag |= P_PROTECTED;
   55                 if (flags & PPROT_INHERIT)
   56                         p->p_flag2 |= P2_INHERIT_PROTECTED;
   57         } else {
   58                 p->p_flag &= ~P_PROTECTED;
   59                 p->p_flag2 &= ~P2_INHERIT_PROTECTED;
   60         }
   61         return (1);
   62 }
   63 
   64 static int
   65 protect_setchildren(struct thread *td, struct proc *top, int flags)
   66 {
   67         struct proc *p;
   68         int ret;
   69 
   70         p = top;
   71         ret = 0;
   72         sx_assert(&proctree_lock, SX_LOCKED);
   73         for (;;) {
   74                 ret |= protect_setchild(td, p, flags);
   75                 PROC_UNLOCK(p);
   76                 /*
   77                  * If this process has children, descend to them next,
   78                  * otherwise do any siblings, and if done with this level,
   79                  * follow back up the tree (but not past top).
   80                  */
   81                 if (!LIST_EMPTY(&p->p_children))
   82                         p = LIST_FIRST(&p->p_children);
   83                 else for (;;) {
   84                         if (p == top) {
   85                                 PROC_LOCK(p);
   86                                 return (ret);
   87                         }
   88                         if (LIST_NEXT(p, p_sibling)) {
   89                                 p = LIST_NEXT(p, p_sibling);
   90                                 break;
   91                         }
   92                         p = p->p_pptr;
   93                 }
   94                 PROC_LOCK(p);
   95         }
   96 }
   97 
   98 static int
   99 protect_set(struct thread *td, struct proc *p, int flags)
  100 {
  101         int error, ret;
  102 
  103         switch (PPROT_OP(flags)) {
  104         case PPROT_SET:
  105         case PPROT_CLEAR:
  106                 break;
  107         default:
  108                 return (EINVAL);
  109         }
  110 
  111         if ((PPROT_FLAGS(flags) & ~(PPROT_DESCEND | PPROT_INHERIT)) != 0)
  112                 return (EINVAL);
  113 
  114         error = priv_check(td, PRIV_VM_MADV_PROTECT);
  115         if (error)
  116                 return (error);
  117 
  118         if (flags & PPROT_DESCEND)
  119                 ret = protect_setchildren(td, p, flags);
  120         else
  121                 ret = protect_setchild(td, p, flags);
  122         if (ret == 0)
  123                 return (EPERM);
  124         return (0);
  125 }
  126 
  127 static int
  128 reap_acquire(struct thread *td, struct proc *p)
  129 {
  130 
  131         sx_assert(&proctree_lock, SX_XLOCKED);
  132         if (p != curproc)
  133                 return (EPERM);
  134         if ((p->p_treeflag & P_TREE_REAPER) != 0)
  135                 return (EBUSY);
  136         p->p_treeflag |= P_TREE_REAPER;
  137         /*
  138          * We do not reattach existing children and the whole tree
  139          * under them to us, since p->p_reaper already seen them.
  140          */
  141         return (0);
  142 }
  143 
  144 static int
  145 reap_release(struct thread *td, struct proc *p)
  146 {
  147 
  148         sx_assert(&proctree_lock, SX_XLOCKED);
  149         if (p != curproc)
  150                 return (EPERM);
  151         if (p == initproc)
  152                 return (EINVAL);
  153         if ((p->p_treeflag & P_TREE_REAPER) == 0)
  154                 return (EINVAL);
  155         reaper_abandon_children(p, false);
  156         return (0);
  157 }
  158 
  159 static int
  160 reap_status(struct thread *td, struct proc *p,
  161     struct procctl_reaper_status *rs)
  162 {
  163         struct proc *reap, *p2, *first_p;
  164 
  165         sx_assert(&proctree_lock, SX_LOCKED);
  166         bzero(rs, sizeof(*rs));
  167         if ((p->p_treeflag & P_TREE_REAPER) == 0) {
  168                 reap = p->p_reaper;
  169         } else {
  170                 reap = p;
  171                 rs->rs_flags |= REAPER_STATUS_OWNED;
  172         }
  173         if (reap == initproc)
  174                 rs->rs_flags |= REAPER_STATUS_REALINIT;
  175         rs->rs_reaper = reap->p_pid;
  176         rs->rs_descendants = 0;
  177         rs->rs_children = 0;
  178         if (!LIST_EMPTY(&reap->p_reaplist)) {
  179                 first_p = LIST_FIRST(&reap->p_children);
  180                 if (first_p == NULL)
  181                         first_p = LIST_FIRST(&reap->p_reaplist);
  182                 rs->rs_pid = first_p->p_pid;
  183                 LIST_FOREACH(p2, &reap->p_reaplist, p_reapsibling) {
  184                         if (proc_realparent(p2) == reap)
  185                                 rs->rs_children++;
  186                         rs->rs_descendants++;
  187                 }
  188         } else {
  189                 rs->rs_pid = -1;
  190         }
  191         return (0);
  192 }
  193 
  194 static int
  195 reap_getpids(struct thread *td, struct proc *p, struct procctl_reaper_pids *rp)
  196 {
  197         struct proc *reap, *p2;
  198         struct procctl_reaper_pidinfo *pi, *pip;
  199         u_int i, n;
  200         int error;
  201 
  202         sx_assert(&proctree_lock, SX_LOCKED);
  203         PROC_UNLOCK(p);
  204         reap = (p->p_treeflag & P_TREE_REAPER) == 0 ? p->p_reaper : p;
  205         n = i = 0;
  206         error = 0;
  207         LIST_FOREACH(p2, &reap->p_reaplist, p_reapsibling)
  208                 n++;
  209         sx_unlock(&proctree_lock);
  210         if (rp->rp_count < n)
  211                 n = rp->rp_count;
  212         pi = malloc(n * sizeof(*pi), M_TEMP, M_WAITOK);
  213         sx_slock(&proctree_lock);
  214         LIST_FOREACH(p2, &reap->p_reaplist, p_reapsibling) {
  215                 if (i == n)
  216                         break;
  217                 pip = &pi[i];
  218                 bzero(pip, sizeof(*pip));
  219                 pip->pi_pid = p2->p_pid;
  220                 pip->pi_subtree = p2->p_reapsubtree;
  221                 pip->pi_flags = REAPER_PIDINFO_VALID;
  222                 if (proc_realparent(p2) == reap)
  223                         pip->pi_flags |= REAPER_PIDINFO_CHILD;
  224                 i++;
  225         }
  226         sx_sunlock(&proctree_lock);
  227         error = copyout(pi, rp->rp_pids, i * sizeof(*pi));
  228         free(pi, M_TEMP);
  229         sx_slock(&proctree_lock);
  230         PROC_LOCK(p);
  231         return (error);
  232 }
  233 
  234 static int
  235 reap_kill(struct thread *td, struct proc *p, struct procctl_reaper_kill *rk)
  236 {
  237         struct proc *reap, *p2;
  238         ksiginfo_t ksi;
  239         int error, error1;
  240 
  241         sx_assert(&proctree_lock, SX_LOCKED);
  242         if (IN_CAPABILITY_MODE(td))
  243                 return (ECAPMODE);
  244         if (rk->rk_sig <= 0 || rk->rk_sig > _SIG_MAXSIG)
  245                 return (EINVAL);
  246         if ((rk->rk_flags & ~REAPER_KILL_CHILDREN) != 0)
  247                 return (EINVAL);
  248         PROC_UNLOCK(p);
  249         reap = (p->p_treeflag & P_TREE_REAPER) == 0 ? p->p_reaper : p;
  250         ksiginfo_init(&ksi);
  251         ksi.ksi_signo = rk->rk_sig;
  252         ksi.ksi_code = SI_USER;
  253         ksi.ksi_pid = td->td_proc->p_pid;
  254         ksi.ksi_uid = td->td_ucred->cr_ruid;
  255         error = ESRCH;
  256         rk->rk_killed = 0;
  257         rk->rk_fpid = -1;
  258         for (p2 = (rk->rk_flags & REAPER_KILL_CHILDREN) != 0 ?
  259             LIST_FIRST(&reap->p_children) : LIST_FIRST(&reap->p_reaplist);
  260             p2 != NULL;
  261             p2 = (rk->rk_flags & REAPER_KILL_CHILDREN) != 0 ?
  262             LIST_NEXT(p2, p_sibling) : LIST_NEXT(p2, p_reapsibling)) {
  263                 if ((rk->rk_flags & REAPER_KILL_SUBTREE) != 0 &&
  264                     p2->p_reapsubtree != rk->rk_subtree)
  265                         continue;
  266                 PROC_LOCK(p2);
  267                 error1 = p_cansignal(td, p2, rk->rk_sig);
  268                 if (error1 == 0) {
  269                         pksignal(p2, rk->rk_sig, &ksi);
  270                         rk->rk_killed++;
  271                         error = error1;
  272                 } else if (error == ESRCH) {
  273                         error = error1;
  274                         rk->rk_fpid = p2->p_pid;
  275                 }
  276                 PROC_UNLOCK(p2);
  277                 /* Do not end the loop on error, signal everything we can. */
  278         }
  279         PROC_LOCK(p);
  280         return (error);
  281 }
  282 
  283 static int
  284 trace_ctl(struct thread *td, struct proc *p, int state)
  285 {
  286 
  287         PROC_LOCK_ASSERT(p, MA_OWNED);
  288 
  289         /*
  290          * Ktrace changes p_traceflag from or to zero under the
  291          * process lock, so the test does not need to acquire ktrace
  292          * mutex.
  293          */
  294         if ((p->p_flag & P_TRACED) != 0 || p->p_traceflag != 0)
  295                 return (EBUSY);
  296 
  297         switch (state) {
  298         case PROC_TRACE_CTL_ENABLE:
  299                 if (td->td_proc != p)
  300                         return (EPERM);
  301                 p->p_flag2 &= ~(P2_NOTRACE | P2_NOTRACE_EXEC);
  302                 break;
  303         case PROC_TRACE_CTL_DISABLE_EXEC:
  304                 p->p_flag2 |= P2_NOTRACE_EXEC | P2_NOTRACE;
  305                 break;
  306         case PROC_TRACE_CTL_DISABLE:
  307                 if ((p->p_flag2 & P2_NOTRACE_EXEC) != 0) {
  308                         KASSERT((p->p_flag2 & P2_NOTRACE) != 0,
  309                             ("dandling P2_NOTRACE_EXEC"));
  310                         if (td->td_proc != p)
  311                                 return (EPERM);
  312                         p->p_flag2 &= ~P2_NOTRACE_EXEC;
  313                 } else {
  314                         p->p_flag2 |= P2_NOTRACE;
  315                 }
  316                 break;
  317         default:
  318                 return (EINVAL);
  319         }
  320         return (0);
  321 }
  322 
  323 static int
  324 trace_status(struct thread *td, struct proc *p, int *data)
  325 {
  326 
  327         if ((p->p_flag2 & P2_NOTRACE) != 0) {
  328                 KASSERT((p->p_flag & P_TRACED) == 0,
  329                     ("%d traced but tracing disabled", p->p_pid));
  330                 *data = -1;
  331         } else if ((p->p_flag & P_TRACED) != 0) {
  332                 *data = p->p_pptr->p_pid;
  333         } else {
  334                 *data = 0;
  335         }
  336         return (0);
  337 }
  338 
  339 #ifndef _SYS_SYSPROTO_H_
  340 struct procctl_args {
  341         idtype_t idtype;
  342         id_t    id;
  343         int     com;
  344         void    *data;
  345 };
  346 #endif
  347 /* ARGSUSED */
  348 int
  349 sys_procctl(struct thread *td, struct procctl_args *uap)
  350 {
  351         void *data;
  352         union {
  353                 struct procctl_reaper_status rs;
  354                 struct procctl_reaper_pids rp;
  355                 struct procctl_reaper_kill rk;
  356         } x;
  357         int error, error1, flags;
  358 
  359         switch (uap->com) {
  360         case PROC_SPROTECT:
  361         case PROC_TRACE_CTL:
  362                 error = copyin(uap->data, &flags, sizeof(flags));
  363                 if (error != 0)
  364                         return (error);
  365                 data = &flags;
  366                 break;
  367         case PROC_REAP_ACQUIRE:
  368         case PROC_REAP_RELEASE:
  369                 if (uap->data != NULL)
  370                         return (EINVAL);
  371                 data = NULL;
  372                 break;
  373         case PROC_REAP_STATUS:
  374                 data = &x.rs;
  375                 break;
  376         case PROC_REAP_GETPIDS:
  377                 error = copyin(uap->data, &x.rp, sizeof(x.rp));
  378                 if (error != 0)
  379                         return (error);
  380                 data = &x.rp;
  381                 break;
  382         case PROC_REAP_KILL:
  383                 error = copyin(uap->data, &x.rk, sizeof(x.rk));
  384                 if (error != 0)
  385                         return (error);
  386                 data = &x.rk;
  387                 break;
  388         case PROC_TRACE_STATUS:
  389                 data = &flags;
  390                 break;
  391         default:
  392                 return (EINVAL);
  393         }
  394         error = kern_procctl(td, uap->idtype, uap->id, uap->com, data);
  395         switch (uap->com) {
  396         case PROC_REAP_STATUS:
  397                 if (error == 0)
  398                         error = copyout(&x.rs, uap->data, sizeof(x.rs));
  399                 break;
  400         case PROC_REAP_KILL:
  401                 error1 = copyout(&x.rk, uap->data, sizeof(x.rk));
  402                 if (error == 0)
  403                         error = error1;
  404                 break;
  405         case PROC_TRACE_STATUS:
  406                 if (error == 0)
  407                         error = copyout(&flags, uap->data, sizeof(flags));
  408                 break;
  409         }
  410         return (error);
  411 }
  412 
  413 static int
  414 kern_procctl_single(struct thread *td, struct proc *p, int com, void *data)
  415 {
  416 
  417         PROC_LOCK_ASSERT(p, MA_OWNED);
  418         switch (com) {
  419         case PROC_SPROTECT:
  420                 return (protect_set(td, p, *(int *)data));
  421         case PROC_REAP_ACQUIRE:
  422                 return (reap_acquire(td, p));
  423         case PROC_REAP_RELEASE:
  424                 return (reap_release(td, p));
  425         case PROC_REAP_STATUS:
  426                 return (reap_status(td, p, data));
  427         case PROC_REAP_GETPIDS:
  428                 return (reap_getpids(td, p, data));
  429         case PROC_REAP_KILL:
  430                 return (reap_kill(td, p, data));
  431         case PROC_TRACE_CTL:
  432                 return (trace_ctl(td, p, *(int *)data));
  433         case PROC_TRACE_STATUS:
  434                 return (trace_status(td, p, data));
  435         default:
  436                 return (EINVAL);
  437         }
  438 }
  439 
  440 int
  441 kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data)
  442 {
  443         struct pgrp *pg;
  444         struct proc *p;
  445         int error, first_error, ok;
  446         bool tree_locked;
  447 
  448         switch (com) {
  449         case PROC_REAP_ACQUIRE:
  450         case PROC_REAP_RELEASE:
  451         case PROC_REAP_STATUS:
  452         case PROC_REAP_GETPIDS:
  453         case PROC_REAP_KILL:
  454         case PROC_TRACE_STATUS:
  455                 if (idtype != P_PID)
  456                         return (EINVAL);
  457         }
  458 
  459         switch (com) {
  460         case PROC_SPROTECT:
  461         case PROC_REAP_STATUS:
  462         case PROC_REAP_GETPIDS:
  463         case PROC_REAP_KILL:
  464         case PROC_TRACE_CTL:
  465                 sx_slock(&proctree_lock);
  466                 tree_locked = true;
  467                 break;
  468         case PROC_REAP_ACQUIRE:
  469         case PROC_REAP_RELEASE:
  470                 sx_xlock(&proctree_lock);
  471                 tree_locked = true;
  472                 break;
  473         case PROC_TRACE_STATUS:
  474                 tree_locked = false;
  475                 break;
  476         default:
  477                 return (EINVAL);
  478         }
  479 
  480         switch (idtype) {
  481         case P_PID:
  482                 p = pfind(id);
  483                 if (p == NULL) {
  484                         error = ESRCH;
  485                         break;
  486                 }
  487                 error = p_cansee(td, p);
  488                 if (error == 0)
  489                         error = kern_procctl_single(td, p, com, data);
  490                 PROC_UNLOCK(p);
  491                 break;
  492         case P_PGID:
  493                 /*
  494                  * Attempt to apply the operation to all members of the
  495                  * group.  Ignore processes in the group that can't be
  496                  * seen.  Ignore errors so long as at least one process is
  497                  * able to complete the request successfully.
  498                  */
  499                 pg = pgfind(id);
  500                 if (pg == NULL) {
  501                         error = ESRCH;
  502                         break;
  503                 }
  504                 PGRP_UNLOCK(pg);
  505                 ok = 0;
  506                 first_error = 0;
  507                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  508                         PROC_LOCK(p);
  509                         if (p->p_state == PRS_NEW || p_cansee(td, p) != 0) {
  510                                 PROC_UNLOCK(p);
  511                                 continue;
  512                         }
  513                         error = kern_procctl_single(td, p, com, data);
  514                         PROC_UNLOCK(p);
  515                         if (error == 0)
  516                                 ok = 1;
  517                         else if (first_error == 0)
  518                                 first_error = error;
  519                 }
  520                 if (ok)
  521                         error = 0;
  522                 else if (first_error != 0)
  523                         error = first_error;
  524                 else
  525                         /*
  526                          * Was not able to see any processes in the
  527                          * process group.
  528                          */
  529                         error = ESRCH;
  530                 break;
  531         default:
  532                 error = EINVAL;
  533                 break;
  534         }
  535         if (tree_locked)
  536                 sx_unlock(&proctree_lock);
  537         return (error);
  538 }

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