1/*
2 * Copyright (c) 1982, 1986, 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/map.h>
44#include <sys/filedesc.h>
45#include <sys/kernel.h>
46#include <sys/malloc.h>
47#include <sys/proc.h>
48#include <sys/resourcevar.h>
49#include <sys/vnode.h>
50#include <sys/file.h>
51#include <sys/acct.h>
52#include <sys/ktrace.h>
53
54struct fork_args {
55 int dummy;
56};
57/* ARGSUSED */
| 1/*
2 * Copyright (c) 1982, 1986, 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/map.h>
44#include <sys/filedesc.h>
45#include <sys/kernel.h>
46#include <sys/malloc.h>
47#include <sys/proc.h>
48#include <sys/resourcevar.h>
49#include <sys/vnode.h>
50#include <sys/file.h>
51#include <sys/acct.h>
52#include <sys/ktrace.h>
53
54struct fork_args {
55 int dummy;
56};
57/* ARGSUSED */
|
| 58int
|
58fork(p, uap, retval)
59 struct proc *p;
60 struct fork_args *uap;
61 int retval[];
62{
63
64 return (fork1(p, 0, retval));
65}
66
67/* ARGSUSED */
| 59fork(p, uap, retval)
60 struct proc *p;
61 struct fork_args *uap;
62 int retval[];
63{
64
65 return (fork1(p, 0, retval));
66}
67
68/* ARGSUSED */
|
| 69int
|
68vfork(p, uap, retval)
69 struct proc *p;
70 struct fork_args *uap;
71 int retval[];
72{
73
74 return (fork1(p, 1, retval));
75}
76
77int nprocs = 1; /* process 0 */
78
| 70vfork(p, uap, retval)
71 struct proc *p;
72 struct fork_args *uap;
73 int retval[];
74{
75
76 return (fork1(p, 1, retval));
77}
78
79int nprocs = 1; /* process 0 */
80
|
| 81int
|
79fork1(p1, isvfork, retval)
80 register struct proc *p1;
81 int isvfork, retval[];
82{
83 register struct proc *p2;
84 register uid_t uid;
85 struct proc *newproc;
86 struct proc **hash;
87 int count;
88 static int nextpid, pidchecked = 0;
89
90 /*
91 * Although process entries are dynamically created, we still keep
92 * a global limit on the maximum number we will create. Don't allow
93 * a nonprivileged user to use the last process; don't let root
94 * exceed the limit. The variable nprocs is the current number of
95 * processes, maxproc is the limit.
96 */
97 uid = p1->p_cred->p_ruid;
98 if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
99 tablefull("proc");
100 return (EAGAIN);
101 }
102 /*
103 * Increment the count of procs running with this uid. Don't allow
104 * a nonprivileged user to exceed their current limit.
105 */
106 count = chgproccnt(uid, 1);
107 if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {
108 (void)chgproccnt(uid, -1);
109 return (EAGAIN);
110 }
111
112 /* Allocate new proc. */
113 MALLOC(newproc, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
114
115 /*
116 * Find an unused process ID. We remember a range of unused IDs
117 * ready to use (from nextpid+1 through pidchecked-1).
118 */
119 nextpid++;
120retry:
121 /*
122 * If the process ID prototype has wrapped around,
123 * restart somewhat above 0, as the low-numbered procs
124 * tend to include daemons that don't exit.
125 */
126 if (nextpid >= PID_MAX) {
127 nextpid = 100;
128 pidchecked = 0;
129 }
130 if (nextpid >= pidchecked) {
131 int doingzomb = 0;
132
133 pidchecked = PID_MAX;
134 /*
135 * Scan the active and zombie procs to check whether this pid
136 * is in use. Remember the lowest pid that's greater
137 * than nextpid, so we can avoid checking for a while.
138 */
139 p2 = (struct proc *)allproc;
140again:
141 for (; p2 != NULL; p2 = p2->p_next) {
142 while (p2->p_pid == nextpid ||
143 p2->p_pgrp->pg_id == nextpid) {
144 nextpid++;
145 if (nextpid >= pidchecked)
146 goto retry;
147 }
148 if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
149 pidchecked = p2->p_pid;
150 if (p2->p_pgrp->pg_id > nextpid &&
151 pidchecked > p2->p_pgrp->pg_id)
152 pidchecked = p2->p_pgrp->pg_id;
153 }
154 if (!doingzomb) {
155 doingzomb = 1;
156 p2 = zombproc;
157 goto again;
158 }
159 }
160
161
162 /*
163 * Link onto allproc (this should probably be delayed).
164 * Heavy use of volatile here to prevent the compiler from
165 * rearranging code. Yes, it *is* terribly ugly, but at least
166 * it works.
167 */
168 nprocs++;
169 p2 = newproc;
170#define Vp2 ((volatile struct proc *)p2)
171 Vp2->p_stat = SIDL; /* protect against others */
172 Vp2->p_pid = nextpid;
173 /*
174 * This is really:
175 * p2->p_next = allproc;
176 * allproc->p_prev = &p2->p_next;
177 * p2->p_prev = &allproc;
178 * allproc = p2;
179 * The assignment via allproc is legal since it is never NULL.
180 */
181 *(volatile struct proc **)&Vp2->p_next = allproc;
182 *(volatile struct proc ***)&allproc->p_prev =
183 (volatile struct proc **)&Vp2->p_next;
184 *(volatile struct proc ***)&Vp2->p_prev = &allproc;
185 allproc = Vp2;
186#undef Vp2
187 p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
188
189 /* Insert on the hash chain. */
190 hash = &pidhash[PIDHASH(p2->p_pid)];
191 p2->p_hash = *hash;
192 *hash = p2;
193
194 /*
195 * Make a proc table entry for the new process.
196 * Start by zeroing the section of proc that is zero-initialized,
197 * then copy the section that is copied directly from the parent.
198 */
199 bzero(&p2->p_startzero,
200 (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
201 bcopy(&p1->p_startcopy, &p2->p_startcopy,
202 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
203
204 /*
205 * Duplicate sub-structures as needed.
206 * Increase reference counts on shared objects.
207 * The p_stats and p_sigacts substructs are set in vm_fork.
208 */
209 p2->p_flag = P_INMEM;
210 if (p1->p_flag & P_PROFIL)
211 startprofclock(p2);
212 MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
213 M_SUBPROC, M_WAITOK);
214 bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
215 p2->p_cred->p_refcnt = 1;
216 crhold(p1->p_ucred);
217
218 /* bump references to the text vnode (for procfs) */
219 p2->p_textvp = p1->p_textvp;
220 if (p2->p_textvp)
221 VREF(p2->p_textvp);
222
223 p2->p_fd = fdcopy(p1);
224 /*
225 * If p_limit is still copy-on-write, bump refcnt,
226 * otherwise get a copy that won't be modified.
227 * (If PL_SHAREMOD is clear, the structure is shared
228 * copy-on-write.)
229 */
230 if (p1->p_limit->p_lflags & PL_SHAREMOD)
231 p2->p_limit = limcopy(p1->p_limit);
232 else {
233 p2->p_limit = p1->p_limit;
234 p2->p_limit->p_refcnt++;
235 }
236
237 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
238 p2->p_flag |= P_CONTROLT;
239 if (isvfork)
240 p2->p_flag |= P_PPWAIT;
241 p2->p_pgrpnxt = p1->p_pgrpnxt;
242 p1->p_pgrpnxt = p2;
243 p2->p_pptr = p1;
244 p2->p_osptr = p1->p_cptr;
245 if (p1->p_cptr)
246 p1->p_cptr->p_ysptr = p2;
247 p1->p_cptr = p2;
248#ifdef KTRACE
249 /*
250 * Copy traceflag and tracefile if enabled.
251 * If not inherited, these were zeroed above.
252 */
253 if (p1->p_traceflag&KTRFAC_INHERIT) {
254 p2->p_traceflag = p1->p_traceflag;
255 if ((p2->p_tracep = p1->p_tracep) != NULL)
256 VREF(p2->p_tracep);
257 }
258#endif
259
260 /*
261 * This begins the section where we must prevent the parent
262 * from being swapped.
263 */
264 p1->p_flag |= P_NOSWAP;
265 /*
266 * Set return values for child before vm_fork,
267 * so they can be copied to child stack.
268 * We return parent pid, and mark as child in retval[1].
269 * NOTE: the kernel stack may be at a different location in the child
270 * process, and thus addresses of automatic variables (including retval)
271 * may be invalid after vm_fork returns in the child process.
272 */
273 retval[0] = p1->p_pid;
274 retval[1] = 1;
275 if (vm_fork(p1, p2, isvfork)) {
276 /*
277 * Child process. Set start time and get to work.
278 */
279 (void) splclock();
280 p2->p_stats->p_start = time;
281 (void) spl0();
282 p2->p_acflag = AFORK;
283 return (0);
284 }
285
286 /*
287 * Make child runnable and add to run queue.
288 */
289 (void) splhigh();
290 p2->p_stat = SRUN;
291 setrunqueue(p2);
292 (void) spl0();
293
294 /*
295 * Now can be swapped.
296 */
297 p1->p_flag &= ~P_NOSWAP;
298
299 /*
300 * Preserve synchronization semantics of vfork. If waiting for
301 * child to exec or exit, set P_PPWAIT on child, and sleep on our
302 * proc (in case of exit).
303 */
304 if (isvfork)
305 while (p2->p_flag & P_PPWAIT)
306 tsleep(p1, PWAIT, "ppwait", 0);
307
308 /*
309 * Return child pid to parent process,
310 * marking us as parent via retval[1].
311 */
312 retval[0] = p2->p_pid;
313 retval[1] = 0;
314 return (0);
315}
| 82fork1(p1, isvfork, retval)
83 register struct proc *p1;
84 int isvfork, retval[];
85{
86 register struct proc *p2;
87 register uid_t uid;
88 struct proc *newproc;
89 struct proc **hash;
90 int count;
91 static int nextpid, pidchecked = 0;
92
93 /*
94 * Although process entries are dynamically created, we still keep
95 * a global limit on the maximum number we will create. Don't allow
96 * a nonprivileged user to use the last process; don't let root
97 * exceed the limit. The variable nprocs is the current number of
98 * processes, maxproc is the limit.
99 */
100 uid = p1->p_cred->p_ruid;
101 if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
102 tablefull("proc");
103 return (EAGAIN);
104 }
105 /*
106 * Increment the count of procs running with this uid. Don't allow
107 * a nonprivileged user to exceed their current limit.
108 */
109 count = chgproccnt(uid, 1);
110 if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {
111 (void)chgproccnt(uid, -1);
112 return (EAGAIN);
113 }
114
115 /* Allocate new proc. */
116 MALLOC(newproc, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
117
118 /*
119 * Find an unused process ID. We remember a range of unused IDs
120 * ready to use (from nextpid+1 through pidchecked-1).
121 */
122 nextpid++;
123retry:
124 /*
125 * If the process ID prototype has wrapped around,
126 * restart somewhat above 0, as the low-numbered procs
127 * tend to include daemons that don't exit.
128 */
129 if (nextpid >= PID_MAX) {
130 nextpid = 100;
131 pidchecked = 0;
132 }
133 if (nextpid >= pidchecked) {
134 int doingzomb = 0;
135
136 pidchecked = PID_MAX;
137 /*
138 * Scan the active and zombie procs to check whether this pid
139 * is in use. Remember the lowest pid that's greater
140 * than nextpid, so we can avoid checking for a while.
141 */
142 p2 = (struct proc *)allproc;
143again:
144 for (; p2 != NULL; p2 = p2->p_next) {
145 while (p2->p_pid == nextpid ||
146 p2->p_pgrp->pg_id == nextpid) {
147 nextpid++;
148 if (nextpid >= pidchecked)
149 goto retry;
150 }
151 if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
152 pidchecked = p2->p_pid;
153 if (p2->p_pgrp->pg_id > nextpid &&
154 pidchecked > p2->p_pgrp->pg_id)
155 pidchecked = p2->p_pgrp->pg_id;
156 }
157 if (!doingzomb) {
158 doingzomb = 1;
159 p2 = zombproc;
160 goto again;
161 }
162 }
163
164
165 /*
166 * Link onto allproc (this should probably be delayed).
167 * Heavy use of volatile here to prevent the compiler from
168 * rearranging code. Yes, it *is* terribly ugly, but at least
169 * it works.
170 */
171 nprocs++;
172 p2 = newproc;
173#define Vp2 ((volatile struct proc *)p2)
174 Vp2->p_stat = SIDL; /* protect against others */
175 Vp2->p_pid = nextpid;
176 /*
177 * This is really:
178 * p2->p_next = allproc;
179 * allproc->p_prev = &p2->p_next;
180 * p2->p_prev = &allproc;
181 * allproc = p2;
182 * The assignment via allproc is legal since it is never NULL.
183 */
184 *(volatile struct proc **)&Vp2->p_next = allproc;
185 *(volatile struct proc ***)&allproc->p_prev =
186 (volatile struct proc **)&Vp2->p_next;
187 *(volatile struct proc ***)&Vp2->p_prev = &allproc;
188 allproc = Vp2;
189#undef Vp2
190 p2->p_forw = p2->p_back = NULL; /* shouldn't be necessary */
191
192 /* Insert on the hash chain. */
193 hash = &pidhash[PIDHASH(p2->p_pid)];
194 p2->p_hash = *hash;
195 *hash = p2;
196
197 /*
198 * Make a proc table entry for the new process.
199 * Start by zeroing the section of proc that is zero-initialized,
200 * then copy the section that is copied directly from the parent.
201 */
202 bzero(&p2->p_startzero,
203 (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
204 bcopy(&p1->p_startcopy, &p2->p_startcopy,
205 (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
206
207 /*
208 * Duplicate sub-structures as needed.
209 * Increase reference counts on shared objects.
210 * The p_stats and p_sigacts substructs are set in vm_fork.
211 */
212 p2->p_flag = P_INMEM;
213 if (p1->p_flag & P_PROFIL)
214 startprofclock(p2);
215 MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
216 M_SUBPROC, M_WAITOK);
217 bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
218 p2->p_cred->p_refcnt = 1;
219 crhold(p1->p_ucred);
220
221 /* bump references to the text vnode (for procfs) */
222 p2->p_textvp = p1->p_textvp;
223 if (p2->p_textvp)
224 VREF(p2->p_textvp);
225
226 p2->p_fd = fdcopy(p1);
227 /*
228 * If p_limit is still copy-on-write, bump refcnt,
229 * otherwise get a copy that won't be modified.
230 * (If PL_SHAREMOD is clear, the structure is shared
231 * copy-on-write.)
232 */
233 if (p1->p_limit->p_lflags & PL_SHAREMOD)
234 p2->p_limit = limcopy(p1->p_limit);
235 else {
236 p2->p_limit = p1->p_limit;
237 p2->p_limit->p_refcnt++;
238 }
239
240 if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
241 p2->p_flag |= P_CONTROLT;
242 if (isvfork)
243 p2->p_flag |= P_PPWAIT;
244 p2->p_pgrpnxt = p1->p_pgrpnxt;
245 p1->p_pgrpnxt = p2;
246 p2->p_pptr = p1;
247 p2->p_osptr = p1->p_cptr;
248 if (p1->p_cptr)
249 p1->p_cptr->p_ysptr = p2;
250 p1->p_cptr = p2;
251#ifdef KTRACE
252 /*
253 * Copy traceflag and tracefile if enabled.
254 * If not inherited, these were zeroed above.
255 */
256 if (p1->p_traceflag&KTRFAC_INHERIT) {
257 p2->p_traceflag = p1->p_traceflag;
258 if ((p2->p_tracep = p1->p_tracep) != NULL)
259 VREF(p2->p_tracep);
260 }
261#endif
262
263 /*
264 * This begins the section where we must prevent the parent
265 * from being swapped.
266 */
267 p1->p_flag |= P_NOSWAP;
268 /*
269 * Set return values for child before vm_fork,
270 * so they can be copied to child stack.
271 * We return parent pid, and mark as child in retval[1].
272 * NOTE: the kernel stack may be at a different location in the child
273 * process, and thus addresses of automatic variables (including retval)
274 * may be invalid after vm_fork returns in the child process.
275 */
276 retval[0] = p1->p_pid;
277 retval[1] = 1;
278 if (vm_fork(p1, p2, isvfork)) {
279 /*
280 * Child process. Set start time and get to work.
281 */
282 (void) splclock();
283 p2->p_stats->p_start = time;
284 (void) spl0();
285 p2->p_acflag = AFORK;
286 return (0);
287 }
288
289 /*
290 * Make child runnable and add to run queue.
291 */
292 (void) splhigh();
293 p2->p_stat = SRUN;
294 setrunqueue(p2);
295 (void) spl0();
296
297 /*
298 * Now can be swapped.
299 */
300 p1->p_flag &= ~P_NOSWAP;
301
302 /*
303 * Preserve synchronization semantics of vfork. If waiting for
304 * child to exec or exit, set P_PPWAIT on child, and sleep on our
305 * proc (in case of exit).
306 */
307 if (isvfork)
308 while (p2->p_flag & P_PPWAIT)
309 tsleep(p1, PWAIT, "ppwait", 0);
310
311 /*
312 * Return child pid to parent process,
313 * marking us as parent via retval[1].
314 */
315 retval[0] = p2->p_pid;
316 retval[1] = 0;
317 return (0);
318}
|