1 /*-
2 * ----------------------------------------------------------------------------
3 * "THE BEER-WARE LICENSE" (Revision 42):
4 * <phk@FreeBSD.org> wrote this file. As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you think
6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
7 * ----------------------------------------------------------------------------
8 */
9
10 /*
11 * This module handles execution of a.out files which have been run through
12 * "gzip". This saves diskspace, but wastes cpu-cycles and VM.
13 *
14 * TODO:
15 * text-segments should be made R/O after being filled
16 * is the vm-stuff safe ?
17 * should handle the entire header of gzip'ed stuff.
18 * inflate isn't quite reentrant yet...
19 * error-handling is a mess...
20 * so is the rest...
21 * tidy up unnecesary includes
22 */
23
24 #include <sys/cdefs.h>
25 __FBSDID("$FreeBSD$");
26
27 #include <sys/param.h>
28 #include <sys/exec.h>
29 #include <sys/imgact.h>
30 #include <sys/imgact_aout.h>
31 #include <sys/kernel.h>
32 #include <sys/lock.h>
33 #include <sys/mman.h>
34 #include <sys/mutex.h>
35 #include <sys/proc.h>
36 #include <sys/resourcevar.h>
37 #include <sys/sysent.h>
38 #include <sys/systm.h>
39 #include <sys/vnode.h>
40 #include <sys/inflate.h>
41
42 #include <vm/vm.h>
43 #include <vm/vm_param.h>
44 #include <vm/pmap.h>
45 #include <vm/vm_map.h>
46 #include <vm/vm_kern.h>
47 #include <vm/vm_extern.h>
48
49 struct imgact_gzip {
50 struct image_params *ip;
51 struct exec a_out;
52 int error;
53 int gotheader;
54 int where;
55 u_char *inbuf;
56 u_long offset;
57 u_long output;
58 u_long len;
59 int idx;
60 u_long virtual_offset, file_offset, file_end, bss_size;
61 };
62
63 static int exec_gzip_imgact(struct image_params *imgp);
64 static int NextByte(void *vp);
65 static int do_aout_hdr(struct imgact_gzip *);
66 static int Flush(void *vp, u_char *, u_long siz);
67
68 static int
69 exec_gzip_imgact(imgp)
70 struct image_params *imgp;
71 {
72 int error, error2 = 0;
73 const u_char *p = (const u_char *) imgp->image_header;
74 struct imgact_gzip igz;
75 struct inflate infl;
76 struct vmspace *vmspace;
77
78 /* If these four are not OK, it isn't a gzip file */
79 if (p[0] != 0x1f)
80 return -1; /* 0 Simply magic */
81 if (p[1] != 0x8b)
82 return -1; /* 1 Simply magic */
83 if (p[2] != 0x08)
84 return -1; /* 2 Compression method */
85 if (p[9] != 0x03)
86 return -1; /* 9 OS compressed on */
87
88 /*
89 * If this one contains anything but a comment or a filename marker,
90 * we don't want to chew on it
91 */
92 if (p[3] & ~(0x18))
93 return ENOEXEC; /* 3 Flags */
94
95 /* These are of no use to us */
96 /* 4-7 Timestamp */
97 /* 8 Extra flags */
98
99 bzero(&igz, sizeof igz);
100 bzero(&infl, sizeof infl);
101 infl.gz_private = (void *) &igz;
102 infl.gz_input = NextByte;
103 infl.gz_output = Flush;
104
105 igz.ip = imgp;
106 igz.idx = 10;
107
108 if (p[3] & 0x08) { /* skip a filename */
109 while (p[igz.idx++])
110 if (igz.idx >= PAGE_SIZE)
111 return ENOEXEC;
112 }
113 if (p[3] & 0x10) { /* skip a comment */
114 while (p[igz.idx++])
115 if (igz.idx >= PAGE_SIZE)
116 return ENOEXEC;
117 }
118 igz.len = imgp->attr->va_size;
119
120 error = inflate(&infl);
121
122 /*
123 * The unzipped file may not even have been long enough to contain
124 * a header giving Flush() a chance to return error. Check for this.
125 */
126 if ( !igz.gotheader )
127 return ENOEXEC;
128
129 if ( !error ) {
130 vmspace = imgp->proc->p_vmspace;
131 error = vm_map_protect(&vmspace->vm_map,
132 (vm_offset_t) vmspace->vm_taddr,
133 (vm_offset_t) (vmspace->vm_taddr +
134 (vmspace->vm_tsize << PAGE_SHIFT)) ,
135 VM_PROT_READ|VM_PROT_EXECUTE,0);
136 }
137
138 if (igz.inbuf) {
139 error2 =
140 vm_map_remove(kernel_map, (vm_offset_t) igz.inbuf,
141 (vm_offset_t) igz.inbuf + PAGE_SIZE);
142 }
143 if (igz.error || error || error2) {
144 printf("Output=%lu ", igz.output);
145 printf("Inflate_error=%d igz.error=%d error2=%d where=%d\n",
146 error, igz.error, error2, igz.where);
147 }
148 if (igz.error)
149 return igz.error;
150 if (error)
151 return ENOEXEC;
152 if (error2)
153 return error2;
154 return 0;
155 }
156
157 static int
158 do_aout_hdr(struct imgact_gzip * gz)
159 {
160 int error;
161 struct thread *td = curthread;
162 struct vmspace *vmspace;
163 vm_offset_t vmaddr;
164
165 /*
166 * Set file/virtual offset based on a.out variant. We do two cases:
167 * host byte order and network byte order (for NetBSD compatibility)
168 */
169 switch ((int) (gz->a_out.a_magic & 0xffff)) {
170 case ZMAGIC:
171 gz->virtual_offset = 0;
172 if (gz->a_out.a_text) {
173 gz->file_offset = PAGE_SIZE;
174 } else {
175 /* Bill's "screwball mode" */
176 gz->file_offset = 0;
177 }
178 break;
179 case QMAGIC:
180 gz->virtual_offset = PAGE_SIZE;
181 gz->file_offset = 0;
182 break;
183 default:
184 /* NetBSD compatibility */
185 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) {
186 case ZMAGIC:
187 case QMAGIC:
188 gz->virtual_offset = PAGE_SIZE;
189 gz->file_offset = 0;
190 break;
191 default:
192 gz->where = __LINE__;
193 return (-1);
194 }
195 }
196
197 gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE);
198
199 /*
200 * Check various fields in header for validity/bounds.
201 */
202 if ( /* entry point must lay with text region */
203 gz->a_out.a_entry < gz->virtual_offset ||
204 gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||
205
206 /* text and data size must each be page rounded */
207 gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) {
208 gz->where = __LINE__;
209 return (-1);
210 }
211 /*
212 * text/data/bss must not exceed limits
213 */
214 PROC_LOCK(gz->ip->proc);
215 if ( /* text can't exceed maximum text size */
216 gz->a_out.a_text > maxtsiz ||
217
218 /* data + bss can't exceed rlimit */
219 gz->a_out.a_data + gz->bss_size >
220 lim_cur(gz->ip->proc, RLIMIT_DATA)) {
221 PROC_UNLOCK(gz->ip->proc);
222 gz->where = __LINE__;
223 return (ENOMEM);
224 }
225 PROC_UNLOCK(gz->ip->proc);
226 /* Find out how far we should go */
227 gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;
228
229 /*
230 * Avoid a possible deadlock if the current address space is destroyed
231 * and that address space maps the locked vnode. In the common case,
232 * the locked vnode's v_usecount is decremented but remains greater
233 * than zero. Consequently, the vnode lock is not needed by vrele().
234 * However, in cases where the vnode lock is external, such as nullfs,
235 * v_usecount may become zero.
236 */
237 VOP_UNLOCK(gz->ip->vp, 0, td);
238
239 /*
240 * Destroy old process VM and create a new one (with a new stack)
241 */
242 error = exec_new_vmspace(gz->ip, &aout_sysvec);
243
244 vn_lock(gz->ip->vp, LK_EXCLUSIVE | LK_RETRY, td);
245 if (error) {
246 gz->where = __LINE__;
247 return (error);
248 }
249
250 vmspace = gz->ip->proc->p_vmspace;
251
252 vmaddr = gz->virtual_offset;
253
254 error = vm_mmap(&vmspace->vm_map,
255 &vmaddr,
256 gz->a_out.a_text + gz->a_out.a_data,
257 VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
258 OBJT_DEFAULT,
259 NULL,
260 0);
261
262 if (error) {
263 gz->where = __LINE__;
264 return (error);
265 }
266
267 if (gz->bss_size != 0) {
268 /*
269 * Allocate demand-zeroed area for uninitialized data.
270 * "bss" = 'block started by symbol' - named after the
271 * IBM 7090 instruction of the same name.
272 */
273 vmaddr = gz->virtual_offset + gz->a_out.a_text +
274 gz->a_out.a_data;
275 error = vm_map_find(&vmspace->vm_map,
276 NULL,
277 0,
278 &vmaddr,
279 gz->bss_size,
280 FALSE, VM_PROT_ALL, VM_PROT_ALL, 0);
281 if (error) {
282 gz->where = __LINE__;
283 return (error);
284 }
285 }
286 /* Fill in process VM information */
287 vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
288 vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
289 vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
290 vmspace->vm_daddr = (caddr_t) (uintptr_t)
291 (gz->virtual_offset + gz->a_out.a_text);
292
293 /* Fill in image_params */
294 gz->ip->interpreted = 0;
295 gz->ip->entry_addr = gz->a_out.a_entry;
296
297 gz->ip->proc->p_sysent = &aout_sysvec;
298
299 return 0;
300 }
301
302 static int
303 NextByte(void *vp)
304 {
305 int error;
306 struct imgact_gzip *igz = (struct imgact_gzip *) vp;
307
308 if (igz->idx >= igz->len) {
309 igz->where = __LINE__;
310 return GZ_EOF;
311 }
312 if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
313 return igz->inbuf[(igz->idx++) - igz->offset];
314 }
315 if (igz->inbuf) {
316 error = vm_map_remove(kernel_map, (vm_offset_t) igz->inbuf,
317 (vm_offset_t) igz->inbuf + PAGE_SIZE);
318 if (error) {
319 igz->where = __LINE__;
320 igz->error = error;
321 return GZ_EOF;
322 }
323 }
324 igz->offset = igz->idx & ~PAGE_MASK;
325
326 error = vm_mmap(kernel_map, /* map */
327 (vm_offset_t *) & igz->inbuf, /* address */
328 PAGE_SIZE, /* size */
329 VM_PROT_READ, /* protection */
330 VM_PROT_READ, /* max protection */
331 0, /* flags */
332 OBJT_VNODE, /* handle type */
333 igz->ip->vp, /* vnode */
334 igz->offset); /* offset */
335 if (error) {
336 igz->where = __LINE__;
337 igz->error = error;
338 return GZ_EOF;
339 }
340 return igz->inbuf[(igz->idx++) - igz->offset];
341 }
342
343 static int
344 Flush(void *vp, u_char * ptr, u_long siz)
345 {
346 struct imgact_gzip *gz = (struct imgact_gzip *) vp;
347 u_char *p = ptr, *q;
348 int i;
349
350 /* First, find an a.out-header. */
351 if (gz->output < sizeof gz->a_out) {
352 q = (u_char *) & gz->a_out;
353 i = min(siz, sizeof gz->a_out - gz->output);
354 bcopy(p, q + gz->output, i);
355 gz->output += i;
356 p += i;
357 siz -= i;
358 if (gz->output == sizeof gz->a_out) {
359 gz->gotheader = 1;
360 i = do_aout_hdr(gz);
361 if (i == -1) {
362 if (!gz->where)
363 gz->where = __LINE__;
364 gz->error = ENOEXEC;
365 return ENOEXEC;
366 } else if (i) {
367 gz->where = __LINE__;
368 gz->error = i;
369 return ENOEXEC;
370 }
371 if (gz->file_offset == 0) {
372 q = (u_char *) (uintptr_t) gz->virtual_offset;
373 copyout(&gz->a_out, q, sizeof gz->a_out);
374 }
375 }
376 }
377 /* Skip over zero-padded first PAGE if needed */
378 if (gz->output < gz->file_offset &&
379 gz->output + siz > gz->file_offset) {
380 i = min(siz, gz->file_offset - gz->output);
381 gz->output += i;
382 p += i;
383 siz -= i;
384 }
385 if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
386 i = min(siz, gz->file_end - gz->output);
387 q = (u_char *) (uintptr_t)
388 (gz->virtual_offset + gz->output - gz->file_offset);
389 copyout(p, q, i);
390 gz->output += i;
391 p += i;
392 siz -= i;
393 }
394 gz->output += siz;
395 return 0;
396 }
397
398
399 /*
400 * Tell kern_execve.c about it, with a little help from the linker.
401 */
402 static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"};
403 EXEC_SET(execgzip, gzip_execsw);
Cache object: 956eff06296e7dc82d56953d5fc9f72f
|