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1.1.1.2 root 1: /*
2: * linux/fs/exec.c
3: *
4: * (C) 1991 Linus Torvalds
5: */
6:
1.1.1.3 root 7: /*
8: * #!-checking implemented by tytso.
9: */
10:
11: /*
12: * Demand-loading implemented 01.12.91 - no need to read anything but
13: * the header into memory. The inode of the executable is put into
14: * "current->executable", and page faults do the actual loading. Clean.
15: *
16: * Once more I can proudly say that linux stood up to being changed: it
17: * was less than 2 hours work to get demand-loading completely implemented.
18: */
19:
1.1.1.4 root 20: #include <signal.h>
1.1 root 21: #include <errno.h>
1.1.1.8 root 22: #include <sys/ptrace.h>
1.1 root 23: #include <a.out.h>
24:
1.1.1.9 ! root 25: #include <linux/string.h>
! 26: #include <linux/stat.h>
! 27: #include <linux/fcntl.h>
1.1 root 28: #include <linux/fs.h>
29: #include <linux/sched.h>
30: #include <linux/kernel.h>
31: #include <linux/mm.h>
32: #include <asm/segment.h>
1.1.1.8 root 33: #include <sys/user.h>
1.1 root 34:
35: extern int sys_exit(int exit_code);
36: extern int sys_close(int fd);
37:
38: /*
39: * MAX_ARG_PAGES defines the number of pages allocated for arguments
40: * and envelope for the new program. 32 should suffice, this gives
41: * a maximum env+arg of 128kB !
42: */
43: #define MAX_ARG_PAGES 32
44:
1.1.1.7 root 45: /*
1.1.1.8 root 46: * These are the only things you should do on a core-file: use only these
47: * macros to write out all the necessary info.
48: */
49: #define DUMP_WRITE(addr,nr) \
50: while (file.f_op->write(inode,&file,(char *)(addr),(nr)) != (nr)) goto close_coredump
51:
52: #define DUMP_SEEK(offset) \
53: if (file.f_op->lseek) { \
54: if (file.f_op->lseek(inode,&file,(offset),0) != (offset)) \
55: goto close_coredump; \
56: } else file.f_pos = (offset)
57:
58: /*
59: * Routine writes a core dump image in the current directory.
60: * Currently only a stub-function.
61: *
62: * Note that setuid/setgid files won't make a core-dump if the uid/gid
63: * changed due to the set[u|g]id. It's enforced by the "current->dumpable"
64: * field, which also makes sure the core-dumps won't be recursive if the
65: * dumping of the process results in another error..
66: */
67: int core_dump(long signr, struct pt_regs * regs)
68: {
69: struct inode * inode = NULL;
70: struct file file;
71: unsigned short fs;
72: int has_dumped = 0;
73: register int dump_start, dump_size;
74: struct user dump;
75:
76: if (!current->dumpable)
77: return 0;
78: current->dumpable = 0;
79: /* See if we have enough room to write the upage. */
80: if(current->rlim[RLIMIT_CORE].rlim_cur < PAGE_SIZE/1024) return 0;
81: __asm__("mov %%fs,%0":"=r" (fs));
82: __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x10));
83: if (open_namei("core",O_CREAT | O_WRONLY | O_TRUNC,0600,&inode))
84: goto end_coredump;
85: if (!S_ISREG(inode->i_mode))
86: goto end_coredump;
87: if (!inode->i_op || !inode->i_op->default_file_ops)
88: goto end_coredump;
89: file.f_mode = 3;
90: file.f_flags = 0;
91: file.f_count = 1;
92: file.f_inode = inode;
93: file.f_pos = 0;
94: file.f_reada = 0;
95: file.f_op = inode->i_op->default_file_ops;
96: if (file.f_op->open)
97: if (file.f_op->open(inode,&file))
98: goto end_coredump;
99: if (!file.f_op->write)
100: goto close_coredump;
101: has_dumped = 1;
102: /* write and seek example: from kernel space */
103: __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x10));
104: dump.u_tsize = current->end_code / PAGE_SIZE;
105: dump.u_dsize = (current->brk - current->end_code) / PAGE_SIZE;
106: dump.u_ssize =((current->start_stack +(PAGE_SIZE-1)) / PAGE_SIZE) -
107: (regs->esp/ PAGE_SIZE);
108: /* If the size of the dump file exceeds the rlimit, then see what would happen
109: if we wrote the stack, but not the data area. */
110: if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE/1024 >
111: current->rlim[RLIMIT_CORE].rlim_cur)
112: dump.u_dsize = 0;
113: /* Make sure we have enough room to write the stack and data areas. */
114: if ((dump.u_ssize+1) * PAGE_SIZE / 1024 >
115: current->rlim[RLIMIT_CORE].rlim_cur)
116: dump.u_ssize = 0;
117: dump.u_comm = 0;
118: dump.u_ar0 = (struct pt_regs *)(((int)(&dump.regs)) -((int)(&dump)));
119: dump.signal = signr;
120: dump.regs = *regs;
121: dump.start_code = 0;
122: dump.start_stack = regs->esp & ~(PAGE_SIZE - 1);
123: /* Flag indicating the math stuff is valid. */
124: if (dump.u_fpvalid = current->used_math) {
125: if (last_task_used_math == current)
126: __asm__("clts ; fnsave %0"::"m" (dump.i387));
127: else
128: memcpy(&dump.i387,¤t->tss.i387,sizeof(dump.i387));
129: };
130: DUMP_WRITE(&dump,sizeof(dump));
131: DUMP_SEEK(sizeof(dump));
132: /* Dump the task struct. Not be used by gdb, but could be useful */
133: DUMP_WRITE(current,sizeof(*current));
134: /* Now dump all of the user data. Include malloced stuff as well */
135: DUMP_SEEK(PAGE_SIZE);
136: /* now we start writing out the user space info */
137: __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x17));
138: /* Dump the data area */
139: if (dump.u_dsize != 0) {
140: dump_start = current->end_code;
141: dump_size = current->brk - current->end_code;
142: DUMP_WRITE(dump_start,dump_size);
143: };
144: /* Now prepare to dump the stack area */
145: if (dump.u_ssize != 0) {
146: dump_start = regs->esp & ~(PAGE_SIZE - 1);
147: dump_size = dump.u_ssize * PAGE_SIZE;
148: DUMP_WRITE(dump_start,dump_size);
149: };
150: close_coredump:
151: if (file.f_op->release)
152: file.f_op->release(inode,&file);
153: end_coredump:
154: __asm__("mov %0,%%fs"::"r" (fs));
155: iput(inode);
156: return has_dumped;
157: }
158:
159: /*
1.1.1.7 root 160: * Note that a shared library must be both readable and executable due to
161: * security reasons.
162: *
163: * Also note that we take the address to load from from the file itself.
164: */
1.1.1.4 root 165: int sys_uselib(const char * library)
166: {
1.1.1.7 root 167: #define libnum (current->numlibraries)
1.1.1.5 root 168: struct inode * inode;
1.1.1.7 root 169: struct buffer_head * bh;
170: struct exec ex;
1.1.1.4 root 171:
172: if (get_limit(0x17) != TASK_SIZE)
173: return -EINVAL;
1.1.1.7 root 174: if ((libnum >= MAX_SHARED_LIBS) || (libnum < 0))
175: return -EINVAL;
176: if (library)
177: inode = namei(library);
178: else
1.1.1.4 root 179: inode = NULL;
1.1.1.7 root 180: if (!inode)
181: return -ENOENT;
182: if (!S_ISREG(inode->i_mode) || !permission(inode,MAY_READ)) {
183: iput(inode);
184: return -EACCES;
185: }
186: if (!(bh = bread(inode->i_dev,inode->i_data[0]))) {
187: iput(inode);
188: return -EACCES;
189: }
190: ex = *(struct exec *) bh->b_data;
191: brelse(bh);
192: if (N_MAGIC(ex) != ZMAGIC || ex.a_trsize || ex.a_drsize ||
193: ex.a_text+ex.a_data+ex.a_bss>0x3000000 ||
194: inode->i_size < ex.a_text+ex.a_data+ex.a_syms+N_TXTOFF(ex)) {
195: iput(inode);
196: return -ENOEXEC;
197: }
198: current->libraries[libnum].library = inode;
199: current->libraries[libnum].start = ex.a_entry;
200: current->libraries[libnum].length = (ex.a_data+ex.a_text+0xfff) & 0xfffff000;
201: #if 0
202: printk("Loaded library %d at %08x, length %08x\n",
203: libnum,
204: current->libraries[libnum].start,
205: current->libraries[libnum].length);
206: #endif
207: libnum++;
1.1.1.4 root 208: return 0;
1.1.1.7 root 209: #undef libnum
1.1.1.4 root 210: }
211:
1.1 root 212: /*
213: * create_tables() parses the env- and arg-strings in new user
214: * memory and creates the pointer tables from them, and puts their
215: * addresses on the "stack", returning the new stack pointer value.
216: */
217: static unsigned long * create_tables(char * p,int argc,int envc)
218: {
219: unsigned long *argv,*envp;
220: unsigned long * sp;
221:
222: sp = (unsigned long *) (0xfffffffc & (unsigned long) p);
223: sp -= envc+1;
224: envp = sp;
225: sp -= argc+1;
226: argv = sp;
227: put_fs_long((unsigned long)envp,--sp);
228: put_fs_long((unsigned long)argv,--sp);
229: put_fs_long((unsigned long)argc,--sp);
230: while (argc-->0) {
231: put_fs_long((unsigned long) p,argv++);
232: while (get_fs_byte(p++)) /* nothing */ ;
233: }
234: put_fs_long(0,argv);
235: while (envc-->0) {
236: put_fs_long((unsigned long) p,envp++);
237: while (get_fs_byte(p++)) /* nothing */ ;
238: }
239: put_fs_long(0,envp);
240: return sp;
241: }
242:
243: /*
244: * count() counts the number of arguments/envelopes
245: */
246: static int count(char ** argv)
247: {
248: int i=0;
249: char ** tmp;
250:
251: if (tmp = argv)
252: while (get_fs_long((unsigned long *) (tmp++)))
253: i++;
254:
255: return i;
256: }
257:
258: /*
259: * 'copy_string()' copies argument/envelope strings from user
260: * memory to free pages in kernel mem. These are in a format ready
261: * to be put directly into the top of new user memory.
1.1.1.2 root 262: *
263: * Modified by TYT, 11/24/91 to add the from_kmem argument, which specifies
264: * whether the string and the string array are from user or kernel segments:
265: *
266: * from_kmem argv * argv **
267: * 0 user space user space
268: * 1 kernel space user space
269: * 2 kernel space kernel space
270: *
271: * We do this by playing games with the fs segment register. Since it
272: * it is expensive to load a segment register, we try to avoid calling
273: * set_fs() unless we absolutely have to.
1.1 root 274: */
275: static unsigned long copy_strings(int argc,char ** argv,unsigned long *page,
1.1.1.2 root 276: unsigned long p, int from_kmem)
1.1 root 277: {
1.1.1.9 ! root 278: char *tmp, *pag = NULL;
1.1.1.2 root 279: int len, offset = 0;
280: unsigned long old_fs, new_fs;
281:
282: if (!p)
283: return 0; /* bullet-proofing */
284: new_fs = get_ds();
285: old_fs = get_fs();
286: if (from_kmem==2)
287: set_fs(new_fs);
1.1 root 288: while (argc-- > 0) {
1.1.1.2 root 289: if (from_kmem == 1)
290: set_fs(new_fs);
291: if (!(tmp = (char *)get_fs_long(((unsigned long *)argv)+argc)))
1.1 root 292: panic("argc is wrong");
1.1.1.2 root 293: if (from_kmem == 1)
294: set_fs(old_fs);
1.1 root 295: len=0; /* remember zero-padding */
296: do {
297: len++;
298: } while (get_fs_byte(tmp++));
1.1.1.5 root 299: if (p < len) { /* this shouldn't happen - 128kB */
1.1.1.2 root 300: set_fs(old_fs);
1.1 root 301: return 0;
302: }
1.1.1.2 root 303: while (len) {
304: --p; --tmp; --len;
305: if (--offset < 0) {
306: offset = p % PAGE_SIZE;
307: if (from_kmem==2)
308: set_fs(old_fs);
309: if (!(pag = (char *) page[p/PAGE_SIZE]) &&
310: !(pag = (char *) page[p/PAGE_SIZE] =
311: (unsigned long *) get_free_page()))
312: return 0;
313: if (from_kmem==2)
314: set_fs(new_fs);
315:
316: }
317: *(pag + offset) = get_fs_byte(tmp);
318: }
1.1 root 319: }
1.1.1.2 root 320: if (from_kmem==2)
321: set_fs(old_fs);
1.1 root 322: return p;
323: }
324:
325: static unsigned long change_ldt(unsigned long text_size,unsigned long * page)
326: {
327: unsigned long code_limit,data_limit,code_base,data_base;
328: int i;
329:
1.1.1.4 root 330: code_limit = TASK_SIZE;
331: data_limit = TASK_SIZE;
1.1 root 332: code_base = get_base(current->ldt[1]);
333: data_base = code_base;
334: set_base(current->ldt[1],code_base);
335: set_limit(current->ldt[1],code_limit);
336: set_base(current->ldt[2],data_base);
337: set_limit(current->ldt[2],data_limit);
338: /* make sure fs points to the NEW data segment */
339: __asm__("pushl $0x17\n\tpop %%fs"::);
1.1.1.4 root 340: data_base += data_limit - LIBRARY_SIZE;
1.1 root 341: for (i=MAX_ARG_PAGES-1 ; i>=0 ; i--) {
342: data_base -= PAGE_SIZE;
343: if (page[i])
1.1.1.4 root 344: put_dirty_page(page[i],data_base);
1.1 root 345: }
346: return data_limit;
347: }
348:
1.1.1.7 root 349: static void read_omagic(struct inode *inode, int bytes)
350: {
351: struct buffer_head *bh;
352: int n, blkno, blk = 0;
353: char *dest = (char *) 0;
354:
355: while (bytes > 0) {
356: if (!(blkno = bmap(inode, blk)))
357: sys_exit(-1);
358: if (!(bh = bread(inode->i_dev, blkno)))
359: sys_exit(-1);
360: n = (blk ? BLOCK_SIZE : BLOCK_SIZE - sizeof(struct exec));
361: if (bytes < n)
362: n = bytes;
363:
364: memcpy_tofs(dest, (blk ? bh->b_data :
365: bh->b_data + sizeof(struct exec)), n);
366: brelse(bh);
367: ++blk;
368: dest += n;
369: bytes -= n;
370: }
371: iput(inode);
372: current->executable = NULL;
373: }
374:
1.1 root 375: /*
376: * 'do_execve()' executes a new program.
1.1.1.4 root 377: *
378: * NOTE! We leave 4MB free at the top of the data-area for a loadable
379: * library.
1.1 root 380: */
381: int do_execve(unsigned long * eip,long tmp,char * filename,
382: char ** argv, char ** envp)
383: {
1.1.1.5 root 384: struct inode * inode;
1.1 root 385: struct buffer_head * bh;
386: struct exec ex;
387: unsigned long page[MAX_ARG_PAGES];
388: int i,argc,envc;
1.1.1.2 root 389: int e_uid, e_gid;
390: int retval;
391: int sh_bang = 0;
392: unsigned long p=PAGE_SIZE*MAX_ARG_PAGES-4;
1.1.1.6 root 393: int ch;
1.1 root 394:
395: if ((0xffff & eip[1]) != 0x000f)
396: panic("execve called from supervisor mode");
397: for (i=0 ; i<MAX_ARG_PAGES ; i++) /* clear page-table */
398: page[i]=0;
399: if (!(inode=namei(filename))) /* get executables inode */
400: return -ENOENT;
1.1.1.2 root 401: argc = count(argv);
402: envc = count(envp);
403:
404: restart_interp:
1.1 root 405: if (!S_ISREG(inode->i_mode)) { /* must be regular file */
1.1.1.2 root 406: retval = -EACCES;
407: goto exec_error2;
1.1 root 408: }
409: i = inode->i_mode;
1.1.1.5 root 410: /* make sure we don't let suid, sgid files be ptraced. */
411: if (current->flags & PF_PTRACED) {
412: e_uid = current->euid;
413: e_gid = current->egid;
414: } else {
415: e_uid = (i & S_ISUID) ? inode->i_uid : current->euid;
416: e_gid = (i & S_ISGID) ? inode->i_gid : current->egid;
417: }
1.1.1.2 root 418: if (current->euid == inode->i_uid)
419: i >>= 6;
1.1.1.4 root 420: else if (in_group_p(inode->i_gid))
1.1.1.2 root 421: i >>= 3;
422: if (!(i & 1) &&
423: !((inode->i_mode & 0111) && suser())) {
1.1.1.5 root 424: retval = -EACCES;
1.1.1.2 root 425: goto exec_error2;
1.1 root 426: }
1.1.1.5 root 427: if (!(bh = bread(inode->i_dev,inode->i_data[0]))) {
1.1.1.2 root 428: retval = -EACCES;
429: goto exec_error2;
1.1 root 430: }
431: ex = *((struct exec *) bh->b_data); /* read exec-header */
1.1.1.2 root 432: if ((bh->b_data[0] == '#') && (bh->b_data[1] == '!') && (!sh_bang)) {
433: /*
434: * This section does the #! interpretation.
435: * Sorta complicated, but hopefully it will work. -TYT
436: */
437:
1.1.1.4 root 438: char buf[128], *cp, *interp, *i_name, *i_arg;
1.1.1.2 root 439: unsigned long old_fs;
440:
1.1.1.4 root 441: strncpy(buf, bh->b_data+2, 127);
1.1.1.2 root 442: brelse(bh);
443: iput(inode);
1.1.1.4 root 444: buf[127] = '\0';
1.1.1.2 root 445: if (cp = strchr(buf, '\n')) {
446: *cp = '\0';
447: for (cp = buf; (*cp == ' ') || (*cp == '\t'); cp++);
448: }
449: if (!cp || *cp == '\0') {
450: retval = -ENOEXEC; /* No interpreter name found */
451: goto exec_error1;
452: }
453: interp = i_name = cp;
454: i_arg = 0;
455: for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) {
456: if (*cp == '/')
457: i_name = cp+1;
458: }
459: if (*cp) {
460: *cp++ = '\0';
461: i_arg = cp;
462: }
463: /*
464: * OK, we've parsed out the interpreter name and
465: * (optional) argument.
466: */
467: if (sh_bang++ == 0) {
468: p = copy_strings(envc, envp, page, p, 0);
469: p = copy_strings(--argc, argv+1, page, p, 0);
470: }
471: /*
472: * Splice in (1) the interpreter's name for argv[0]
473: * (2) (optional) argument to interpreter
474: * (3) filename of shell script
475: *
476: * This is done in reverse order, because of how the
477: * user environment and arguments are stored.
478: */
479: p = copy_strings(1, &filename, page, p, 1);
480: argc++;
481: if (i_arg) {
482: p = copy_strings(1, &i_arg, page, p, 2);
483: argc++;
484: }
485: p = copy_strings(1, &i_name, page, p, 2);
486: argc++;
487: if (!p) {
488: retval = -ENOMEM;
489: goto exec_error1;
490: }
491: /*
492: * OK, now restart the process with the interpreter's inode.
493: */
494: old_fs = get_fs();
495: set_fs(get_ds());
496: if (!(inode=namei(interp))) { /* get executables inode */
497: set_fs(old_fs);
498: retval = -ENOENT;
499: goto exec_error1;
500: }
501: set_fs(old_fs);
502: goto restart_interp;
503: }
1.1 root 504: brelse(bh);
1.1.1.7 root 505: if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC) ||
506: ex.a_trsize || ex.a_drsize ||
1.1 root 507: ex.a_text+ex.a_data+ex.a_bss>0x3000000 ||
508: inode->i_size < ex.a_text+ex.a_data+ex.a_syms+N_TXTOFF(ex)) {
1.1.1.2 root 509: retval = -ENOEXEC;
510: goto exec_error2;
1.1 root 511: }
1.1.1.7 root 512: if (N_TXTOFF(ex) != BLOCK_SIZE && N_MAGIC(ex) != OMAGIC) {
1.1.1.2 root 513: printk("%s: N_TXTOFF != BLOCK_SIZE. See a.out.h.", filename);
514: retval = -ENOEXEC;
515: goto exec_error2;
516: }
517: if (!sh_bang) {
518: p = copy_strings(envc,envp,page,p,0);
519: p = copy_strings(argc,argv,page,p,0);
520: if (!p) {
521: retval = -ENOMEM;
522: goto exec_error2;
523: }
1.1 root 524: }
525: /* OK, This is the point of no return */
1.1.1.8 root 526: current->dumpable = 1;
1.1.1.6 root 527: for (i=0; (ch = get_fs_byte(filename++)) != '\0';)
528: if (ch == '/')
529: i = 0;
530: else
531: if (i < 8)
532: current->comm[i++] = ch;
533: if (i < 8)
534: current->comm[i] = '\0';
1.1.1.3 root 535: if (current->executable)
536: iput(current->executable);
1.1.1.7 root 537: i = current->numlibraries;
538: while (i-- > 0) {
539: iput(current->libraries[i].library);
540: current->libraries[i].library = NULL;
541: }
1.1.1.8 root 542: if (e_uid != current->euid || e_gid != current->egid ||
543: !permission(inode,MAY_READ))
544: current->dumpable = 0;
1.1.1.7 root 545: current->numlibraries = 0;
1.1.1.3 root 546: current->executable = inode;
1.1.1.4 root 547: current->signal = 0;
548: for (i=0 ; i<32 ; i++) {
549: current->sigaction[i].sa_mask = 0;
550: current->sigaction[i].sa_flags = 0;
551: if (current->sigaction[i].sa_handler != SIG_IGN)
552: current->sigaction[i].sa_handler = NULL;
553: }
1.1 root 554: for (i=0 ; i<NR_OPEN ; i++)
555: if ((current->close_on_exec>>i)&1)
556: sys_close(i);
557: current->close_on_exec = 0;
558: free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
559: free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
560: if (last_task_used_math == current)
561: last_task_used_math = NULL;
562: current->used_math = 0;
1.1.1.4 root 563: p += change_ldt(ex.a_text,page);
564: p -= LIBRARY_SIZE + MAX_ARG_PAGES*PAGE_SIZE;
1.1 root 565: p = (unsigned long) create_tables((char *)p,argc,envc);
566: current->brk = ex.a_bss +
567: (current->end_data = ex.a_data +
568: (current->end_code = ex.a_text));
1.1.1.5 root 569: current->start_stack = p;
1.1.1.6 root 570: current->rss = (LIBRARY_OFFSET - p + PAGE_SIZE-1) / PAGE_SIZE;
1.1.1.4 root 571: current->suid = current->euid = e_uid;
572: current->sgid = current->egid = e_gid;
1.1.1.7 root 573: if (N_MAGIC(ex) == OMAGIC)
574: read_omagic(inode, ex.a_text+ex.a_data);
1.1 root 575: eip[0] = ex.a_entry; /* eip, magic happens :-) */
576: eip[3] = p; /* stack pointer */
1.1.1.5 root 577: if (current->flags & PF_PTRACED)
1.1.1.8 root 578: send_sig(SIGTRAP, current, 0);
1.1 root 579: return 0;
1.1.1.2 root 580: exec_error2:
581: iput(inode);
582: exec_error1:
583: for (i=0 ; i<MAX_ARG_PAGES ; i++)
584: free_page(page[i]);
585: return(retval);
1.1 root 586: }
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.