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: releng/9.2/sys/kern/imgact_gzip.c 232387 2012-03-02 11:32:47Z kib $");
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/racct.h>
37 #include <sys/resourcevar.h>
38 #include <sys/sysent.h>
39 #include <sys/systm.h>
40 #include <sys/vnode.h>
41 #include <sys/inflate.h>
42
43 #include <vm/vm.h>
44 #include <vm/vm_param.h>
45 #include <vm/pmap.h>
46 #include <vm/vm_map.h>
47 #include <vm/vm_kern.h>
48 #include <vm/vm_extern.h>
49
50 struct imgact_gzip {
51 struct image_params *ip;
52 struct exec a_out;
53 int error;
54 int gotheader;
55 int where;
56 u_char *inbuf;
57 u_long offset;
58 u_long output;
59 u_long len;
60 int idx;
61 u_long virtual_offset, file_offset, file_end, bss_size;
62 };
63
64 static int exec_gzip_imgact(struct image_params *imgp);
65 static int NextByte(void *vp);
66 static int do_aout_hdr(struct imgact_gzip *);
67 static int Flush(void *vp, u_char *, u_long siz);
68
69 static int
70 exec_gzip_imgact(imgp)
71 struct image_params *imgp;
72 {
73 int error;
74 const u_char *p = (const u_char *) imgp->image_header;
75 struct imgact_gzip igz;
76 struct inflate infl;
77 struct vmspace *vmspace;
78
79 /* If these four are not OK, it isn't a gzip file */
80 if (p[0] != 0x1f)
81 return -1; /* 0 Simply magic */
82 if (p[1] != 0x8b)
83 return -1; /* 1 Simply magic */
84 if (p[2] != 0x08)
85 return -1; /* 2 Compression method */
86 if (p[9] != 0x03)
87 return -1; /* 9 OS compressed on */
88
89 /*
90 * If this one contains anything but a comment or a filename marker,
91 * we don't want to chew on it
92 */
93 if (p[3] & ~(0x18))
94 return ENOEXEC; /* 3 Flags */
95
96 /* These are of no use to us */
97 /* 4-7 Timestamp */
98 /* 8 Extra flags */
99
100 bzero(&igz, sizeof igz);
101 bzero(&infl, sizeof infl);
102 infl.gz_private = (void *) &igz;
103 infl.gz_input = NextByte;
104 infl.gz_output = Flush;
105
106 igz.ip = imgp;
107 igz.idx = 10;
108
109 if (p[3] & 0x08) { /* skip a filename */
110 while (p[igz.idx++])
111 if (igz.idx >= PAGE_SIZE)
112 return ENOEXEC;
113 }
114 if (p[3] & 0x10) { /* skip a comment */
115 while (p[igz.idx++])
116 if (igz.idx >= PAGE_SIZE)
117 return ENOEXEC;
118 }
119 igz.len = imgp->attr->va_size;
120
121 error = inflate(&infl);
122
123 /*
124 * The unzipped file may not even have been long enough to contain
125 * a header giving Flush() a chance to return error. Check for this.
126 */
127 if ( !igz.gotheader )
128 return ENOEXEC;
129
130 if ( !error ) {
131 vmspace = imgp->proc->p_vmspace;
132 error = vm_map_protect(&vmspace->vm_map,
133 (vm_offset_t) vmspace->vm_taddr,
134 (vm_offset_t) (vmspace->vm_taddr +
135 (vmspace->vm_tsize << PAGE_SHIFT)) ,
136 VM_PROT_READ|VM_PROT_EXECUTE,0);
137 }
138
139 if (igz.inbuf)
140 kmem_free_wakeup(exec_map, (vm_offset_t)igz.inbuf, PAGE_SIZE);
141 if (igz.error || error) {
142 printf("Output=%lu ", igz.output);
143 printf("Inflate_error=%d igz.error=%d where=%d\n",
144 error, igz.error, igz.where);
145 }
146 if (igz.error)
147 return igz.error;
148 if (error)
149 return ENOEXEC;
150 return 0;
151 }
152
153 static int
154 do_aout_hdr(struct imgact_gzip * gz)
155 {
156 int error;
157 struct vmspace *vmspace;
158 vm_offset_t vmaddr;
159
160 /*
161 * Set file/virtual offset based on a.out variant. We do two cases:
162 * host byte order and network byte order (for NetBSD compatibility)
163 */
164 switch ((int) (gz->a_out.a_magic & 0xffff)) {
165 case ZMAGIC:
166 gz->virtual_offset = 0;
167 if (gz->a_out.a_text) {
168 gz->file_offset = PAGE_SIZE;
169 } else {
170 /* Bill's "screwball mode" */
171 gz->file_offset = 0;
172 }
173 break;
174 case QMAGIC:
175 gz->virtual_offset = PAGE_SIZE;
176 gz->file_offset = 0;
177 break;
178 default:
179 /* NetBSD compatibility */
180 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) {
181 case ZMAGIC:
182 case QMAGIC:
183 gz->virtual_offset = PAGE_SIZE;
184 gz->file_offset = 0;
185 break;
186 default:
187 gz->where = __LINE__;
188 return (-1);
189 }
190 }
191
192 gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE);
193
194 /*
195 * Check various fields in header for validity/bounds.
196 */
197 if ( /* entry point must lay with text region */
198 gz->a_out.a_entry < gz->virtual_offset ||
199 gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||
200
201 /* text and data size must each be page rounded */
202 gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) {
203 gz->where = __LINE__;
204 return (-1);
205 }
206 /*
207 * text/data/bss must not exceed limits
208 */
209 PROC_LOCK(gz->ip->proc);
210 if ( /* text can't exceed maximum text size */
211 gz->a_out.a_text > maxtsiz ||
212
213 /* data + bss can't exceed rlimit */
214 gz->a_out.a_data + gz->bss_size >
215 lim_cur(gz->ip->proc, RLIMIT_DATA) ||
216 racct_set(gz->ip->proc, RACCT_DATA,
217 gz->a_out.a_data + gz->bss_size) != 0) {
218 PROC_UNLOCK(gz->ip->proc);
219 gz->where = __LINE__;
220 return (ENOMEM);
221 }
222 PROC_UNLOCK(gz->ip->proc);
223 /* Find out how far we should go */
224 gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;
225
226 /*
227 * Avoid a possible deadlock if the current address space is destroyed
228 * and that address space maps the locked vnode. In the common case,
229 * the locked vnode's v_usecount is decremented but remains greater
230 * than zero. Consequently, the vnode lock is not needed by vrele().
231 * However, in cases where the vnode lock is external, such as nullfs,
232 * v_usecount may become zero.
233 */
234 VOP_UNLOCK(gz->ip->vp, 0);
235
236 /*
237 * Destroy old process VM and create a new one (with a new stack)
238 */
239 error = exec_new_vmspace(gz->ip, &aout_sysvec);
240
241 vn_lock(gz->ip->vp, LK_EXCLUSIVE | LK_RETRY);
242 if (error) {
243 gz->where = __LINE__;
244 return (error);
245 }
246
247 vmspace = gz->ip->proc->p_vmspace;
248
249 vmaddr = gz->virtual_offset;
250
251 error = vm_mmap(&vmspace->vm_map,
252 &vmaddr,
253 gz->a_out.a_text + gz->a_out.a_data,
254 VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
255 OBJT_DEFAULT,
256 NULL,
257 0);
258
259 if (error) {
260 gz->where = __LINE__;
261 return (error);
262 }
263
264 if (gz->bss_size != 0) {
265 /*
266 * Allocate demand-zeroed area for uninitialized data.
267 * "bss" = 'block started by symbol' - named after the
268 * IBM 7090 instruction of the same name.
269 */
270 vmaddr = gz->virtual_offset + gz->a_out.a_text +
271 gz->a_out.a_data;
272 error = vm_map_find(&vmspace->vm_map,
273 NULL,
274 0,
275 &vmaddr,
276 gz->bss_size,
277 FALSE, VM_PROT_ALL, VM_PROT_ALL, 0);
278 if (error) {
279 gz->where = __LINE__;
280 return (error);
281 }
282 }
283 /* Fill in process VM information */
284 vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
285 vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
286 vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
287 vmspace->vm_daddr = (caddr_t) (uintptr_t)
288 (gz->virtual_offset + gz->a_out.a_text);
289
290 /* Fill in image_params */
291 gz->ip->interpreted = 0;
292 gz->ip->entry_addr = gz->a_out.a_entry;
293
294 gz->ip->proc->p_sysent = &aout_sysvec;
295
296 return 0;
297 }
298
299 static int
300 NextByte(void *vp)
301 {
302 int error;
303 struct imgact_gzip *igz = (struct imgact_gzip *) vp;
304
305 if (igz->idx >= igz->len) {
306 igz->where = __LINE__;
307 return GZ_EOF;
308 }
309 if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
310 return igz->inbuf[(igz->idx++) - igz->offset];
311 }
312 if (igz->inbuf)
313 kmem_free_wakeup(exec_map, (vm_offset_t)igz->inbuf, PAGE_SIZE);
314 igz->offset = igz->idx & ~PAGE_MASK;
315
316 error = vm_mmap(exec_map, /* map */
317 (vm_offset_t *) & igz->inbuf, /* address */
318 PAGE_SIZE, /* size */
319 VM_PROT_READ, /* protection */
320 VM_PROT_READ, /* max protection */
321 0, /* flags */
322 OBJT_VNODE, /* handle type */
323 igz->ip->vp, /* vnode */
324 igz->offset); /* offset */
325 if (error) {
326 igz->where = __LINE__;
327 igz->error = error;
328 return GZ_EOF;
329 }
330 return igz->inbuf[(igz->idx++) - igz->offset];
331 }
332
333 static int
334 Flush(void *vp, u_char * ptr, u_long siz)
335 {
336 struct imgact_gzip *gz = (struct imgact_gzip *) vp;
337 u_char *p = ptr, *q;
338 int i;
339
340 /* First, find an a.out-header. */
341 if (gz->output < sizeof gz->a_out) {
342 q = (u_char *) & gz->a_out;
343 i = min(siz, sizeof gz->a_out - gz->output);
344 bcopy(p, q + gz->output, i);
345 gz->output += i;
346 p += i;
347 siz -= i;
348 if (gz->output == sizeof gz->a_out) {
349 gz->gotheader = 1;
350 i = do_aout_hdr(gz);
351 if (i == -1) {
352 if (!gz->where)
353 gz->where = __LINE__;
354 gz->error = ENOEXEC;
355 return ENOEXEC;
356 } else if (i) {
357 gz->where = __LINE__;
358 gz->error = i;
359 return ENOEXEC;
360 }
361 if (gz->file_offset == 0) {
362 q = (u_char *) (uintptr_t) gz->virtual_offset;
363 copyout(&gz->a_out, q, sizeof gz->a_out);
364 }
365 }
366 }
367 /* Skip over zero-padded first PAGE if needed */
368 if (gz->output < gz->file_offset &&
369 gz->output + siz > gz->file_offset) {
370 i = min(siz, gz->file_offset - gz->output);
371 gz->output += i;
372 p += i;
373 siz -= i;
374 }
375 if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
376 i = min(siz, gz->file_end - gz->output);
377 q = (u_char *) (uintptr_t)
378 (gz->virtual_offset + gz->output - gz->file_offset);
379 copyout(p, q, i);
380 gz->output += i;
381 p += i;
382 siz -= i;
383 }
384 gz->output += siz;
385 return 0;
386 }
387
388
389 /*
390 * Tell kern_execve.c about it, with a little help from the linker.
391 */
392 static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"};
393 EXEC_SET(execgzip, gzip_execsw);
Cache object: 9b1d68540ec949a3a13f9f376cc7125b
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