FreeBSD/Linux Kernel Cross Reference
sys/kern/exec_subr.c
1 /* $NetBSD: exec_subr.c,v 1.61.8.2 2010/08/31 10:55:00 bouyer Exp $ */
2
3 /*
4 * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by Christopher G. Demetriou.
18 * 4. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <sys/cdefs.h>
34 __KERNEL_RCSID(0, "$NetBSD: exec_subr.c,v 1.61.8.2 2010/08/31 10:55:00 bouyer Exp $");
35
36 #include "opt_pax.h"
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/proc.h>
41 #include <sys/kmem.h>
42 #include <sys/vnode.h>
43 #include <sys/filedesc.h>
44 #include <sys/exec.h>
45 #include <sys/mman.h>
46 #include <sys/resourcevar.h>
47 #include <sys/device.h>
48
49 #ifdef PAX_MPROTECT
50 #include <sys/pax.h>
51 #endif /* PAX_MPROTECT */
52
53 #include <uvm/uvm.h>
54
55 #define VMCMD_EVCNT_DECL(name) \
56 static struct evcnt vmcmd_ev_##name = \
57 EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "vmcmd", #name); \
58 EVCNT_ATTACH_STATIC(vmcmd_ev_##name)
59
60 #define VMCMD_EVCNT_INCR(name) \
61 vmcmd_ev_##name.ev_count++
62
63 VMCMD_EVCNT_DECL(calls);
64 VMCMD_EVCNT_DECL(extends);
65 VMCMD_EVCNT_DECL(kills);
66
67 /*
68 * new_vmcmd():
69 * create a new vmcmd structure and fill in its fields based
70 * on function call arguments. make sure objects ref'd by
71 * the vmcmd are 'held'.
72 */
73
74 void
75 new_vmcmd(struct exec_vmcmd_set *evsp,
76 int (*proc)(struct lwp * l, struct exec_vmcmd *),
77 u_long len, u_long addr, struct vnode *vp, u_long offset,
78 u_int prot, int flags)
79 {
80 struct exec_vmcmd *vcp;
81
82 VMCMD_EVCNT_INCR(calls);
83
84 if (evsp->evs_used >= evsp->evs_cnt)
85 vmcmdset_extend(evsp);
86 vcp = &evsp->evs_cmds[evsp->evs_used++];
87 vcp->ev_proc = proc;
88 vcp->ev_len = len;
89 vcp->ev_addr = addr;
90 if ((vcp->ev_vp = vp) != NULL)
91 vref(vp);
92 vcp->ev_offset = offset;
93 vcp->ev_prot = prot;
94 vcp->ev_flags = flags;
95 }
96
97 void
98 vmcmdset_extend(struct exec_vmcmd_set *evsp)
99 {
100 struct exec_vmcmd *nvcp;
101 u_int ocnt;
102
103 #ifdef DIAGNOSTIC
104 if (evsp->evs_used < evsp->evs_cnt)
105 panic("vmcmdset_extend: not necessary");
106 #endif
107
108 /* figure out number of entries in new set */
109 if ((ocnt = evsp->evs_cnt) != 0) {
110 evsp->evs_cnt += ocnt;
111 VMCMD_EVCNT_INCR(extends);
112 } else
113 evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE;
114
115 /* allocate it */
116 nvcp = kmem_alloc(evsp->evs_cnt * sizeof(struct exec_vmcmd), KM_SLEEP);
117
118 /* free the old struct, if there was one, and record the new one */
119 if (ocnt) {
120 memcpy(nvcp, evsp->evs_cmds,
121 (ocnt * sizeof(struct exec_vmcmd)));
122 kmem_free(evsp->evs_cmds, ocnt * sizeof(struct exec_vmcmd));
123 }
124 evsp->evs_cmds = nvcp;
125 }
126
127 void
128 kill_vmcmds(struct exec_vmcmd_set *evsp)
129 {
130 struct exec_vmcmd *vcp;
131 u_int i;
132
133 VMCMD_EVCNT_INCR(kills);
134
135 if (evsp->evs_cnt == 0)
136 return;
137
138 for (i = 0; i < evsp->evs_used; i++) {
139 vcp = &evsp->evs_cmds[i];
140 if (vcp->ev_vp != NULL)
141 vrele(vcp->ev_vp);
142 }
143 kmem_free(evsp->evs_cmds, evsp->evs_cnt * sizeof(struct exec_vmcmd));
144 evsp->evs_used = evsp->evs_cnt = 0;
145 }
146
147 /*
148 * vmcmd_map_pagedvn():
149 * handle vmcmd which specifies that a vnode should be mmap'd.
150 * appropriate for handling demand-paged text and data segments.
151 */
152
153 int
154 vmcmd_map_pagedvn(struct lwp *l, struct exec_vmcmd *cmd)
155 {
156 struct uvm_object *uobj;
157 struct vnode *vp = cmd->ev_vp;
158 struct proc *p = l->l_proc;
159 int error;
160 vm_prot_t prot, maxprot;
161
162 KASSERT(vp->v_iflag & VI_TEXT);
163
164 /*
165 * map the vnode in using uvm_map.
166 */
167
168 if (cmd->ev_len == 0)
169 return(0);
170 if (cmd->ev_offset & PAGE_MASK)
171 return(EINVAL);
172 if (cmd->ev_addr & PAGE_MASK)
173 return(EINVAL);
174 if (cmd->ev_len & PAGE_MASK)
175 return(EINVAL);
176
177 prot = cmd->ev_prot;
178 maxprot = UVM_PROT_ALL;
179 #ifdef PAX_MPROTECT
180 pax_mprotect(l, &prot, &maxprot);
181 #endif /* PAX_MPROTECT */
182
183 /*
184 * check the file system's opinion about mmapping the file
185 */
186
187 error = VOP_MMAP(vp, prot, l->l_cred);
188 if (error)
189 return error;
190
191 if ((vp->v_vflag & VV_MAPPED) == 0) {
192 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
193 vp->v_vflag |= VV_MAPPED;
194 VOP_UNLOCK(vp, 0);
195 }
196
197 /*
198 * do the map, reference the object for this map entry
199 */
200 uobj = &vp->v_uobj;
201 vref(vp);
202
203 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len,
204 uobj, cmd->ev_offset, 0,
205 UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
206 UVM_ADV_NORMAL, UVM_FLAG_COPYONW|UVM_FLAG_FIXED));
207 if (error) {
208 uobj->pgops->pgo_detach(uobj);
209 }
210 return error;
211 }
212
213 /*
214 * vmcmd_map_readvn():
215 * handle vmcmd which specifies that a vnode should be read from.
216 * appropriate for non-demand-paged text/data segments, i.e. impure
217 * objects (a la OMAGIC and NMAGIC).
218 */
219 int
220 vmcmd_map_readvn(struct lwp *l, struct exec_vmcmd *cmd)
221 {
222 struct proc *p = l->l_proc;
223 int error;
224 long diff;
225
226 if (cmd->ev_len == 0)
227 return 0;
228
229 diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
230 cmd->ev_addr -= diff; /* required by uvm_map */
231 cmd->ev_offset -= diff;
232 cmd->ev_len += diff;
233
234 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
235 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
236 UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_COPY,
237 UVM_ADV_NORMAL,
238 UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW));
239
240 if (error)
241 return error;
242
243 return vmcmd_readvn(l, cmd);
244 }
245
246 int
247 vmcmd_readvn(struct lwp *l, struct exec_vmcmd *cmd)
248 {
249 struct proc *p = l->l_proc;
250 int error;
251 vm_prot_t prot, maxprot;
252
253 error = vn_rdwr(UIO_READ, cmd->ev_vp, (void *)cmd->ev_addr,
254 cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT,
255 l->l_cred, NULL, l);
256 if (error)
257 return error;
258
259 prot = cmd->ev_prot;
260 maxprot = VM_PROT_ALL;
261 #ifdef PAX_MPROTECT
262 pax_mprotect(l, &prot, &maxprot);
263 #endif /* PAX_MPROTECT */
264
265 #ifdef PMAP_NEED_PROCWR
266 /*
267 * we had to write the process, make sure the pages are synched
268 * with the instruction cache.
269 */
270 if (prot & VM_PROT_EXECUTE)
271 pmap_procwr(p, cmd->ev_addr, cmd->ev_len);
272 #endif
273
274 /*
275 * we had to map in the area at PROT_ALL so that vn_rdwr()
276 * could write to it. however, the caller seems to want
277 * it mapped read-only, so now we are going to have to call
278 * uvm_map_protect() to fix up the protection. ICK.
279 */
280 if (maxprot != VM_PROT_ALL) {
281 error = uvm_map_protect(&p->p_vmspace->vm_map,
282 trunc_page(cmd->ev_addr),
283 round_page(cmd->ev_addr + cmd->ev_len),
284 maxprot, true);
285 if (error)
286 return (error);
287 }
288
289 if (prot != maxprot) {
290 error = uvm_map_protect(&p->p_vmspace->vm_map,
291 trunc_page(cmd->ev_addr),
292 round_page(cmd->ev_addr + cmd->ev_len),
293 prot, false);
294 if (error)
295 return (error);
296 }
297
298 return 0;
299 }
300
301 /*
302 * vmcmd_map_zero():
303 * handle vmcmd which specifies a zero-filled address space region. The
304 * address range must be first allocated, then protected appropriately.
305 */
306
307 int
308 vmcmd_map_zero(struct lwp *l, struct exec_vmcmd *cmd)
309 {
310 struct proc *p = l->l_proc;
311 int error;
312 long diff;
313 vm_prot_t prot, maxprot;
314
315 diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
316 cmd->ev_addr -= diff; /* required by uvm_map */
317 cmd->ev_len += diff;
318
319 prot = cmd->ev_prot;
320 maxprot = UVM_PROT_ALL;
321 #ifdef PAX_MPROTECT
322 pax_mprotect(l, &prot, &maxprot);
323 #endif /* PAX_MPROTECT */
324
325 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
326 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
327 UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
328 UVM_ADV_NORMAL,
329 UVM_FLAG_FIXED|UVM_FLAG_COPYONW));
330 if (cmd->ev_flags & VMCMD_STACK)
331 curproc->p_vmspace->vm_issize += atop(round_page(cmd->ev_len));
332 return error;
333 }
334
335 /*
336 * exec_read_from():
337 *
338 * Read from vnode into buffer at offset.
339 */
340 int
341 exec_read_from(struct lwp *l, struct vnode *vp, u_long off, void *bf,
342 size_t size)
343 {
344 int error;
345 size_t resid;
346
347 if ((error = vn_rdwr(UIO_READ, vp, bf, size, off, UIO_SYSSPACE,
348 0, l->l_cred, &resid, NULL)) != 0)
349 return error;
350 /*
351 * See if we got all of it
352 */
353 if (resid != 0)
354 return ENOEXEC;
355 return 0;
356 }
357
358 /*
359 * exec_setup_stack(): Set up the stack segment for an elf
360 * executable.
361 *
362 * Note that the ep_ssize parameter must be set to be the current stack
363 * limit; this is adjusted in the body of execve() to yield the
364 * appropriate stack segment usage once the argument length is
365 * calculated.
366 *
367 * This function returns an int for uniformity with other (future) formats'
368 * stack setup functions. They might have errors to return.
369 */
370
371 int
372 exec_setup_stack(struct lwp *l, struct exec_package *epp)
373 {
374 u_long max_stack_size;
375 u_long access_linear_min, access_size;
376 u_long noaccess_linear_min, noaccess_size;
377
378 #ifndef USRSTACK32
379 #define USRSTACK32 (0x00000000ffffffffL&~PGOFSET)
380 #endif
381
382 if (epp->ep_flags & EXEC_32) {
383 epp->ep_minsaddr = USRSTACK32;
384 max_stack_size = MAXSSIZ;
385 } else {
386 epp->ep_minsaddr = USRSTACK;
387 max_stack_size = MAXSSIZ;
388 }
389 epp->ep_ssize = l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur;
390
391 #ifdef PAX_ASLR
392 pax_aslr_stack(l, epp, &max_stack_size);
393 #endif /* PAX_ASLR */
394
395 l->l_proc->p_stackbase = epp->ep_minsaddr;
396
397 epp->ep_maxsaddr = (u_long)STACK_GROW(epp->ep_minsaddr,
398 max_stack_size);
399
400 /*
401 * set up commands for stack. note that this takes *two*, one to
402 * map the part of the stack which we can access, and one to map
403 * the part which we can't.
404 *
405 * arguably, it could be made into one, but that would require the
406 * addition of another mapping proc, which is unnecessary
407 */
408 access_size = epp->ep_ssize;
409 access_linear_min = (u_long)STACK_ALLOC(epp->ep_minsaddr, access_size);
410 noaccess_size = max_stack_size - access_size;
411 noaccess_linear_min = (u_long)STACK_ALLOC(STACK_GROW(epp->ep_minsaddr,
412 access_size), noaccess_size);
413 if (noaccess_size > 0 && noaccess_size <= MAXSSIZ) {
414 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, noaccess_size,
415 noaccess_linear_min, NULL, 0, VM_PROT_NONE, VMCMD_STACK);
416 }
417 KASSERT(access_size > 0 && access_size <= MAXSSIZ);
418 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, access_size,
419 access_linear_min, NULL, 0, VM_PROT_READ | VM_PROT_WRITE,
420 VMCMD_STACK);
421
422 return 0;
423 }
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