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1  // SPDX-License-Identifier: GPL-2.0
2  /****************************************************************************/
3  /*
4   *  linux/fs/binfmt_flat.c
5   *
6   *	Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
7   *	Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
8   *	Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
9   *	Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
10   *  based heavily on:
11   *
12   *  linux/fs/binfmt_aout.c:
13   *      Copyright (C) 1991, 1992, 1996  Linus Torvalds
14   *  linux/fs/binfmt_flat.c for 2.0 kernel
15   *	    Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>
16   *	JAN/99 -- coded full program relocation (gerg@snapgear.com)
17   */
18  
19  #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
20  
21  #include <linux/kernel.h>
22  #include <linux/sched.h>
23  #include <linux/sched/task_stack.h>
24  #include <linux/mm.h>
25  #include <linux/mman.h>
26  #include <linux/errno.h>
27  #include <linux/signal.h>
28  #include <linux/string.h>
29  #include <linux/fs.h>
30  #include <linux/file.h>
31  #include <linux/ptrace.h>
32  #include <linux/user.h>
33  #include <linux/slab.h>
34  #include <linux/binfmts.h>
35  #include <linux/personality.h>
36  #include <linux/init.h>
37  #include <linux/flat.h>
38  #include <linux/uaccess.h>
39  #include <linux/vmalloc.h>
40  
41  #include <asm/byteorder.h>
42  #include <asm/unaligned.h>
43  #include <asm/cacheflush.h>
44  #include <asm/page.h>
45  #include <asm/flat.h>
46  
47  #ifndef flat_get_relocate_addr
48  #define flat_get_relocate_addr(rel)	(rel)
49  #endif
50  
51  /****************************************************************************/
52  
53  /*
54   * User data (data section and bss) needs to be aligned.
55   * We pick 0x20 here because it is the max value elf2flt has always
56   * used in producing FLAT files, and because it seems to be large
57   * enough to make all the gcc alignment related tests happy.
58   */
59  #define FLAT_DATA_ALIGN	(0x20)
60  
61  /*
62   * User data (stack) also needs to be aligned.
63   * Here we can be a bit looser than the data sections since this
64   * needs to only meet arch ABI requirements.
65   */
66  #define FLAT_STACK_ALIGN	max_t(unsigned long, sizeof(void *), ARCH_SLAB_MINALIGN)
67  
68  #define RELOC_FAILED 0xff00ff01		/* Relocation incorrect somewhere */
69  #define UNLOADED_LIB 0x7ff000ff		/* Placeholder for unused library */
70  
71  #define MAX_SHARED_LIBS			(1)
72  
73  #ifdef CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
74  #define DATA_START_OFFSET_WORDS		(0)
75  #else
76  #define DATA_START_OFFSET_WORDS		(MAX_SHARED_LIBS)
77  #endif
78  
79  struct lib_info {
80  	struct {
81  		unsigned long start_code;		/* Start of text segment */
82  		unsigned long start_data;		/* Start of data segment */
83  		unsigned long start_brk;		/* End of data segment */
84  		unsigned long text_len;			/* Length of text segment */
85  		unsigned long entry;			/* Start address for this module */
86  		unsigned long build_date;		/* When this one was compiled */
87  		bool loaded;				/* Has this library been loaded? */
88  	} lib_list[MAX_SHARED_LIBS];
89  };
90  
91  static int load_flat_binary(struct linux_binprm *);
92  
93  static struct linux_binfmt flat_format = {
94  	.module		= THIS_MODULE,
95  	.load_binary	= load_flat_binary,
96  };
97  
98  
99  /****************************************************************************/
100  /*
101   * create_flat_tables() parses the env- and arg-strings in new user
102   * memory and creates the pointer tables from them, and puts their
103   * addresses on the "stack", recording the new stack pointer value.
104   */
105  
create_flat_tables(struct linux_binprm * bprm,unsigned long arg_start)106  static int create_flat_tables(struct linux_binprm *bprm, unsigned long arg_start)
107  {
108  	char __user *p;
109  	unsigned long __user *sp;
110  	long i, len;
111  
112  	p = (char __user *)arg_start;
113  	sp = (unsigned long __user *)current->mm->start_stack;
114  
115  	sp -= bprm->envc + 1;
116  	sp -= bprm->argc + 1;
117  	if (IS_ENABLED(CONFIG_BINFMT_FLAT_ARGVP_ENVP_ON_STACK))
118  		sp -= 2; /* argvp + envp */
119  	sp -= 1;  /* &argc */
120  
121  	current->mm->start_stack = (unsigned long)sp & -FLAT_STACK_ALIGN;
122  	sp = (unsigned long __user *)current->mm->start_stack;
123  
124  	if (put_user(bprm->argc, sp++))
125  		return -EFAULT;
126  	if (IS_ENABLED(CONFIG_BINFMT_FLAT_ARGVP_ENVP_ON_STACK)) {
127  		unsigned long argv, envp;
128  		argv = (unsigned long)(sp + 2);
129  		envp = (unsigned long)(sp + 2 + bprm->argc + 1);
130  		if (put_user(argv, sp++) || put_user(envp, sp++))
131  			return -EFAULT;
132  	}
133  
134  	current->mm->arg_start = (unsigned long)p;
135  	for (i = bprm->argc; i > 0; i--) {
136  		if (put_user((unsigned long)p, sp++))
137  			return -EFAULT;
138  		len = strnlen_user(p, MAX_ARG_STRLEN);
139  		if (!len || len > MAX_ARG_STRLEN)
140  			return -EINVAL;
141  		p += len;
142  	}
143  	if (put_user(0, sp++))
144  		return -EFAULT;
145  	current->mm->arg_end = (unsigned long)p;
146  
147  	current->mm->env_start = (unsigned long) p;
148  	for (i = bprm->envc; i > 0; i--) {
149  		if (put_user((unsigned long)p, sp++))
150  			return -EFAULT;
151  		len = strnlen_user(p, MAX_ARG_STRLEN);
152  		if (!len || len > MAX_ARG_STRLEN)
153  			return -EINVAL;
154  		p += len;
155  	}
156  	if (put_user(0, sp++))
157  		return -EFAULT;
158  	current->mm->env_end = (unsigned long)p;
159  
160  	return 0;
161  }
162  
163  /****************************************************************************/
164  
165  #ifdef CONFIG_BINFMT_ZFLAT
166  
167  #include <linux/zlib.h>
168  
169  #define LBUFSIZE	4000
170  
171  /* gzip flag byte */
172  #define ASCII_FLAG   0x01 /* bit 0 set: file probably ASCII text */
173  #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
174  #define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
175  #define ORIG_NAME    0x08 /* bit 3 set: original file name present */
176  #define COMMENT      0x10 /* bit 4 set: file comment present */
177  #define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
178  #define RESERVED     0xC0 /* bit 6,7:   reserved */
179  
decompress_exec(struct linux_binprm * bprm,loff_t fpos,char * dst,long len,int fd)180  static int decompress_exec(struct linux_binprm *bprm, loff_t fpos, char *dst,
181  		long len, int fd)
182  {
183  	unsigned char *buf;
184  	z_stream strm;
185  	int ret, retval;
186  
187  	pr_debug("decompress_exec(offset=%llx,buf=%p,len=%lx)\n", fpos, dst, len);
188  
189  	memset(&strm, 0, sizeof(strm));
190  	strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
191  	if (!strm.workspace)
192  		return -ENOMEM;
193  
194  	buf = kmalloc(LBUFSIZE, GFP_KERNEL);
195  	if (!buf) {
196  		retval = -ENOMEM;
197  		goto out_free;
198  	}
199  
200  	/* Read in first chunk of data and parse gzip header. */
201  	ret = kernel_read(bprm->file, buf, LBUFSIZE, &fpos);
202  
203  	strm.next_in = buf;
204  	strm.avail_in = ret;
205  	strm.total_in = 0;
206  
207  	retval = -ENOEXEC;
208  
209  	/* Check minimum size -- gzip header */
210  	if (ret < 10) {
211  		pr_debug("file too small?\n");
212  		goto out_free_buf;
213  	}
214  
215  	/* Check gzip magic number */
216  	if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
217  		pr_debug("unknown compression magic?\n");
218  		goto out_free_buf;
219  	}
220  
221  	/* Check gzip method */
222  	if (buf[2] != 8) {
223  		pr_debug("unknown compression method?\n");
224  		goto out_free_buf;
225  	}
226  	/* Check gzip flags */
227  	if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
228  	    (buf[3] & RESERVED)) {
229  		pr_debug("unknown flags?\n");
230  		goto out_free_buf;
231  	}
232  
233  	ret = 10;
234  	if (buf[3] & EXTRA_FIELD) {
235  		ret += 2 + buf[10] + (buf[11] << 8);
236  		if (unlikely(ret >= LBUFSIZE)) {
237  			pr_debug("buffer overflow (EXTRA)?\n");
238  			goto out_free_buf;
239  		}
240  	}
241  	if (buf[3] & ORIG_NAME) {
242  		while (ret < LBUFSIZE && buf[ret++] != 0)
243  			;
244  		if (unlikely(ret == LBUFSIZE)) {
245  			pr_debug("buffer overflow (ORIG_NAME)?\n");
246  			goto out_free_buf;
247  		}
248  	}
249  	if (buf[3] & COMMENT) {
250  		while (ret < LBUFSIZE && buf[ret++] != 0)
251  			;
252  		if (unlikely(ret == LBUFSIZE)) {
253  			pr_debug("buffer overflow (COMMENT)?\n");
254  			goto out_free_buf;
255  		}
256  	}
257  
258  	strm.next_in += ret;
259  	strm.avail_in -= ret;
260  
261  	strm.next_out = dst;
262  	strm.avail_out = len;
263  	strm.total_out = 0;
264  
265  	if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
266  		pr_debug("zlib init failed?\n");
267  		goto out_free_buf;
268  	}
269  
270  	while ((ret = zlib_inflate(&strm, Z_NO_FLUSH)) == Z_OK) {
271  		ret = kernel_read(bprm->file, buf, LBUFSIZE, &fpos);
272  		if (ret <= 0)
273  			break;
274  		len -= ret;
275  
276  		strm.next_in = buf;
277  		strm.avail_in = ret;
278  		strm.total_in = 0;
279  	}
280  
281  	if (ret < 0) {
282  		pr_debug("decompression failed (%d), %s\n",
283  			ret, strm.msg);
284  		goto out_zlib;
285  	}
286  
287  	retval = 0;
288  out_zlib:
289  	zlib_inflateEnd(&strm);
290  out_free_buf:
291  	kfree(buf);
292  out_free:
293  	kfree(strm.workspace);
294  	return retval;
295  }
296  
297  #endif /* CONFIG_BINFMT_ZFLAT */
298  
299  /****************************************************************************/
300  
301  static unsigned long
calc_reloc(unsigned long r,struct lib_info * p)302  calc_reloc(unsigned long r, struct lib_info *p)
303  {
304  	unsigned long addr;
305  	unsigned long start_brk;
306  	unsigned long start_data;
307  	unsigned long text_len;
308  	unsigned long start_code;
309  
310  	start_brk = p->lib_list[0].start_brk;
311  	start_data = p->lib_list[0].start_data;
312  	start_code = p->lib_list[0].start_code;
313  	text_len = p->lib_list[0].text_len;
314  
315  	if (r > start_brk - start_data + text_len) {
316  		pr_err("reloc outside program 0x%lx (0 - 0x%lx/0x%lx)",
317  		       r, start_brk-start_data+text_len, text_len);
318  		goto failed;
319  	}
320  
321  	if (r < text_len)			/* In text segment */
322  		addr = r + start_code;
323  	else					/* In data segment */
324  		addr = r - text_len + start_data;
325  
326  	/* Range checked already above so doing the range tests is redundant...*/
327  	return addr;
328  
329  failed:
330  	pr_cont(", killing %s!\n", current->comm);
331  	send_sig(SIGSEGV, current, 0);
332  
333  	return RELOC_FAILED;
334  }
335  
336  /****************************************************************************/
337  
338  #ifdef CONFIG_BINFMT_FLAT_OLD
old_reloc(unsigned long rl)339  static void old_reloc(unsigned long rl)
340  {
341  	static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
342  	flat_v2_reloc_t	r;
343  	unsigned long __user *ptr;
344  	unsigned long val;
345  
346  	r.value = rl;
347  #if defined(CONFIG_COLDFIRE)
348  	ptr = (unsigned long __user *)(current->mm->start_code + r.reloc.offset);
349  #else
350  	ptr = (unsigned long __user *)(current->mm->start_data + r.reloc.offset);
351  #endif
352  	get_user(val, ptr);
353  
354  	pr_debug("Relocation of variable at DATASEG+%x "
355  		 "(address %p, currently %lx) into segment %s\n",
356  		 r.reloc.offset, ptr, val, segment[r.reloc.type]);
357  
358  	switch (r.reloc.type) {
359  	case OLD_FLAT_RELOC_TYPE_TEXT:
360  		val += current->mm->start_code;
361  		break;
362  	case OLD_FLAT_RELOC_TYPE_DATA:
363  		val += current->mm->start_data;
364  		break;
365  	case OLD_FLAT_RELOC_TYPE_BSS:
366  		val += current->mm->end_data;
367  		break;
368  	default:
369  		pr_err("Unknown relocation type=%x\n", r.reloc.type);
370  		break;
371  	}
372  	put_user(val, ptr);
373  
374  	pr_debug("Relocation became %lx\n", val);
375  }
376  #endif /* CONFIG_BINFMT_FLAT_OLD */
377  
378  /****************************************************************************/
379  
skip_got_header(u32 __user * rp)380  static inline u32 __user *skip_got_header(u32 __user *rp)
381  {
382  	if (IS_ENABLED(CONFIG_RISCV)) {
383  		/*
384  		 * RISC-V has a 16 byte GOT PLT header for elf64-riscv
385  		 * and 8 byte GOT PLT header for elf32-riscv.
386  		 * Skip the whole GOT PLT header, since it is reserved
387  		 * for the dynamic linker (ld.so).
388  		 */
389  		u32 rp_val0, rp_val1;
390  
391  		if (get_user(rp_val0, rp))
392  			return rp;
393  		if (get_user(rp_val1, rp + 1))
394  			return rp;
395  
396  		if (rp_val0 == 0xffffffff && rp_val1 == 0xffffffff)
397  			rp += 4;
398  		else if (rp_val0 == 0xffffffff)
399  			rp += 2;
400  	}
401  	return rp;
402  }
403  
load_flat_file(struct linux_binprm * bprm,struct lib_info * libinfo,unsigned long * extra_stack)404  static int load_flat_file(struct linux_binprm *bprm,
405  		struct lib_info *libinfo, unsigned long *extra_stack)
406  {
407  	struct flat_hdr *hdr;
408  	unsigned long textpos, datapos, realdatastart;
409  	u32 text_len, data_len, bss_len, stack_len, full_data, flags;
410  	unsigned long len, memp, memp_size, extra, rlim;
411  	__be32 __user *reloc;
412  	u32 __user *rp;
413  	int i, rev, relocs;
414  	loff_t fpos;
415  	unsigned long start_code, end_code;
416  	ssize_t result;
417  	int ret;
418  
419  	hdr = ((struct flat_hdr *) bprm->buf);		/* exec-header */
420  
421  	text_len  = ntohl(hdr->data_start);
422  	data_len  = ntohl(hdr->data_end) - ntohl(hdr->data_start);
423  	bss_len   = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
424  	stack_len = ntohl(hdr->stack_size);
425  	if (extra_stack) {
426  		stack_len += *extra_stack;
427  		*extra_stack = stack_len;
428  	}
429  	relocs    = ntohl(hdr->reloc_count);
430  	flags     = ntohl(hdr->flags);
431  	rev       = ntohl(hdr->rev);
432  	full_data = data_len + relocs * sizeof(unsigned long);
433  
434  	if (strncmp(hdr->magic, "bFLT", 4)) {
435  		/*
436  		 * Previously, here was a printk to tell people
437  		 *   "BINFMT_FLAT: bad header magic".
438  		 * But for the kernel which also use ELF FD-PIC format, this
439  		 * error message is confusing.
440  		 * because a lot of people do not manage to produce good
441  		 */
442  		ret = -ENOEXEC;
443  		goto err;
444  	}
445  
446  	if (flags & FLAT_FLAG_KTRACE)
447  		pr_info("Loading file: %s\n", bprm->filename);
448  
449  #ifdef CONFIG_BINFMT_FLAT_OLD
450  	if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
451  		pr_err("bad flat file version 0x%x (supported 0x%lx and 0x%lx)\n",
452  		       rev, FLAT_VERSION, OLD_FLAT_VERSION);
453  		ret = -ENOEXEC;
454  		goto err;
455  	}
456  
457  	/*
458  	 * fix up the flags for the older format,  there were all kinds
459  	 * of endian hacks,  this only works for the simple cases
460  	 */
461  	if (rev == OLD_FLAT_VERSION &&
462  	   (flags || IS_ENABLED(CONFIG_BINFMT_FLAT_OLD_ALWAYS_RAM)))
463  		flags = FLAT_FLAG_RAM;
464  
465  #else /* CONFIG_BINFMT_FLAT_OLD */
466  	if (rev != FLAT_VERSION) {
467  		pr_err("bad flat file version 0x%x (supported 0x%lx)\n",
468  		       rev, FLAT_VERSION);
469  		ret = -ENOEXEC;
470  		goto err;
471  	}
472  #endif /* !CONFIG_BINFMT_FLAT_OLD */
473  
474  	/*
475  	 * Make sure the header params are sane.
476  	 * 28 bits (256 MB) is way more than reasonable in this case.
477  	 * If some top bits are set we have probable binary corruption.
478  	*/
479  	if ((text_len | data_len | bss_len | stack_len | full_data) >> 28) {
480  		pr_err("bad header\n");
481  		ret = -ENOEXEC;
482  		goto err;
483  	}
484  
485  #ifndef CONFIG_BINFMT_ZFLAT
486  	if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
487  		pr_err("Support for ZFLAT executables is not enabled.\n");
488  		ret = -ENOEXEC;
489  		goto err;
490  	}
491  #endif
492  
493  	/*
494  	 * Check initial limits. This avoids letting people circumvent
495  	 * size limits imposed on them by creating programs with large
496  	 * arrays in the data or bss.
497  	 */
498  	rlim = rlimit(RLIMIT_DATA);
499  	if (rlim >= RLIM_INFINITY)
500  		rlim = ~0;
501  	if (data_len + bss_len > rlim) {
502  		ret = -ENOMEM;
503  		goto err;
504  	}
505  
506  	/* Flush all traces of the currently running executable */
507  	ret = begin_new_exec(bprm);
508  	if (ret)
509  		goto err;
510  
511  	/* OK, This is the point of no return */
512  	set_personality(PER_LINUX_32BIT);
513  	setup_new_exec(bprm);
514  
515  	/*
516  	 * calculate the extra space we need to map in
517  	 */
518  	extra = max_t(unsigned long, bss_len + stack_len,
519  			relocs * sizeof(unsigned long));
520  
521  	/*
522  	 * there are a couple of cases here,  the separate code/data
523  	 * case,  and then the fully copied to RAM case which lumps
524  	 * it all together.
525  	 */
526  	if (!IS_ENABLED(CONFIG_MMU) && !(flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP))) {
527  		/*
528  		 * this should give us a ROM ptr,  but if it doesn't we don't
529  		 * really care
530  		 */
531  		pr_debug("ROM mapping of file (we hope)\n");
532  
533  		textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
534  				  MAP_PRIVATE, 0);
535  		if (!textpos || IS_ERR_VALUE(textpos)) {
536  			ret = textpos;
537  			if (!textpos)
538  				ret = -ENOMEM;
539  			pr_err("Unable to mmap process text, errno %d\n", ret);
540  			goto err;
541  		}
542  
543  		len = data_len + extra +
544  			DATA_START_OFFSET_WORDS * sizeof(unsigned long);
545  		len = PAGE_ALIGN(len);
546  		realdatastart = vm_mmap(NULL, 0, len,
547  			PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
548  
549  		if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
550  			ret = realdatastart;
551  			if (!realdatastart)
552  				ret = -ENOMEM;
553  			pr_err("Unable to allocate RAM for process data, "
554  			       "errno %d\n", ret);
555  			vm_munmap(textpos, text_len);
556  			goto err;
557  		}
558  		datapos = ALIGN(realdatastart +
559  				DATA_START_OFFSET_WORDS * sizeof(unsigned long),
560  				FLAT_DATA_ALIGN);
561  
562  		pr_debug("Allocated data+bss+stack (%u bytes): %lx\n",
563  			 data_len + bss_len + stack_len, datapos);
564  
565  		fpos = ntohl(hdr->data_start);
566  #ifdef CONFIG_BINFMT_ZFLAT
567  		if (flags & FLAT_FLAG_GZDATA) {
568  			result = decompress_exec(bprm, fpos, (char *)datapos,
569  						 full_data, 0);
570  		} else
571  #endif
572  		{
573  			result = read_code(bprm->file, datapos, fpos,
574  					full_data);
575  		}
576  		if (IS_ERR_VALUE(result)) {
577  			ret = result;
578  			pr_err("Unable to read data+bss, errno %d\n", ret);
579  			vm_munmap(textpos, text_len);
580  			vm_munmap(realdatastart, len);
581  			goto err;
582  		}
583  
584  		reloc = (__be32 __user *)
585  			(datapos + (ntohl(hdr->reloc_start) - text_len));
586  		memp = realdatastart;
587  		memp_size = len;
588  	} else {
589  
590  		len = text_len + data_len + extra +
591  			DATA_START_OFFSET_WORDS * sizeof(u32);
592  		len = PAGE_ALIGN(len);
593  		textpos = vm_mmap(NULL, 0, len,
594  			PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
595  
596  		if (!textpos || IS_ERR_VALUE(textpos)) {
597  			ret = textpos;
598  			if (!textpos)
599  				ret = -ENOMEM;
600  			pr_err("Unable to allocate RAM for process text/data, "
601  			       "errno %d\n", ret);
602  			goto err;
603  		}
604  
605  		realdatastart = textpos + ntohl(hdr->data_start);
606  		datapos = ALIGN(realdatastart +
607  				DATA_START_OFFSET_WORDS * sizeof(u32),
608  				FLAT_DATA_ALIGN);
609  
610  		reloc = (__be32 __user *)
611  			(datapos + (ntohl(hdr->reloc_start) - text_len));
612  		memp = textpos;
613  		memp_size = len;
614  #ifdef CONFIG_BINFMT_ZFLAT
615  		/*
616  		 * load it all in and treat it like a RAM load from now on
617  		 */
618  		if (flags & FLAT_FLAG_GZIP) {
619  #ifndef CONFIG_MMU
620  			result = decompress_exec(bprm, sizeof(struct flat_hdr),
621  					 (((char *)textpos) + sizeof(struct flat_hdr)),
622  					 (text_len + full_data
623  						  - sizeof(struct flat_hdr)),
624  					 0);
625  			memmove((void *) datapos, (void *) realdatastart,
626  					full_data);
627  #else
628  			/*
629  			 * This is used on MMU systems mainly for testing.
630  			 * Let's use a kernel buffer to simplify things.
631  			 */
632  			long unz_text_len = text_len - sizeof(struct flat_hdr);
633  			long unz_len = unz_text_len + full_data;
634  			char *unz_data = vmalloc(unz_len);
635  			if (!unz_data) {
636  				result = -ENOMEM;
637  			} else {
638  				result = decompress_exec(bprm, sizeof(struct flat_hdr),
639  							 unz_data, unz_len, 0);
640  				if (result == 0 &&
641  				    (copy_to_user((void __user *)textpos + sizeof(struct flat_hdr),
642  						  unz_data, unz_text_len) ||
643  				     copy_to_user((void __user *)datapos,
644  						  unz_data + unz_text_len, full_data)))
645  					result = -EFAULT;
646  				vfree(unz_data);
647  			}
648  #endif
649  		} else if (flags & FLAT_FLAG_GZDATA) {
650  			result = read_code(bprm->file, textpos, 0, text_len);
651  			if (!IS_ERR_VALUE(result)) {
652  #ifndef CONFIG_MMU
653  				result = decompress_exec(bprm, text_len, (char *) datapos,
654  						 full_data, 0);
655  #else
656  				char *unz_data = vmalloc(full_data);
657  				if (!unz_data) {
658  					result = -ENOMEM;
659  				} else {
660  					result = decompress_exec(bprm, text_len,
661  						       unz_data, full_data, 0);
662  					if (result == 0 &&
663  					    copy_to_user((void __user *)datapos,
664  							 unz_data, full_data))
665  						result = -EFAULT;
666  					vfree(unz_data);
667  				}
668  #endif
669  			}
670  		} else
671  #endif /* CONFIG_BINFMT_ZFLAT */
672  		{
673  			result = read_code(bprm->file, textpos, 0, text_len);
674  			if (!IS_ERR_VALUE(result))
675  				result = read_code(bprm->file, datapos,
676  						   ntohl(hdr->data_start),
677  						   full_data);
678  		}
679  		if (IS_ERR_VALUE(result)) {
680  			ret = result;
681  			pr_err("Unable to read code+data+bss, errno %d\n", ret);
682  			vm_munmap(textpos, text_len + data_len + extra +
683  				  DATA_START_OFFSET_WORDS * sizeof(u32));
684  			goto err;
685  		}
686  	}
687  
688  	start_code = textpos + sizeof(struct flat_hdr);
689  	end_code = textpos + text_len;
690  	text_len -= sizeof(struct flat_hdr); /* the real code len */
691  
692  	/* The main program needs a little extra setup in the task structure */
693  	current->mm->start_code = start_code;
694  	current->mm->end_code = end_code;
695  	current->mm->start_data = datapos;
696  	current->mm->end_data = datapos + data_len;
697  	/*
698  	 * set up the brk stuff, uses any slack left in data/bss/stack
699  	 * allocation.  We put the brk after the bss (between the bss
700  	 * and stack) like other platforms.
701  	 * Userspace code relies on the stack pointer starting out at
702  	 * an address right at the end of a page.
703  	 */
704  	current->mm->start_brk = datapos + data_len + bss_len;
705  	current->mm->brk = (current->mm->start_brk + 3) & ~3;
706  #ifndef CONFIG_MMU
707  	current->mm->context.end_brk = memp + memp_size - stack_len;
708  #endif
709  
710  	if (flags & FLAT_FLAG_KTRACE) {
711  		pr_info("Mapping is %lx, Entry point is %x, data_start is %x\n",
712  			textpos, 0x00ffffff&ntohl(hdr->entry), ntohl(hdr->data_start));
713  		pr_info("%s %s: TEXT=%lx-%lx DATA=%lx-%lx BSS=%lx-%lx\n",
714  			"Load", bprm->filename,
715  			start_code, end_code, datapos, datapos + data_len,
716  			datapos + data_len, (datapos + data_len + bss_len + 3) & ~3);
717  	}
718  
719  	/* Store the current module values into the global library structure */
720  	libinfo->lib_list[0].start_code = start_code;
721  	libinfo->lib_list[0].start_data = datapos;
722  	libinfo->lib_list[0].start_brk = datapos + data_len + bss_len;
723  	libinfo->lib_list[0].text_len = text_len;
724  	libinfo->lib_list[0].loaded = 1;
725  	libinfo->lib_list[0].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
726  	libinfo->lib_list[0].build_date = ntohl(hdr->build_date);
727  
728  	/*
729  	 * We just load the allocations into some temporary memory to
730  	 * help simplify all this mumbo jumbo
731  	 *
732  	 * We've got two different sections of relocation entries.
733  	 * The first is the GOT which resides at the beginning of the data segment
734  	 * and is terminated with a -1.  This one can be relocated in place.
735  	 * The second is the extra relocation entries tacked after the image's
736  	 * data segment. These require a little more processing as the entry is
737  	 * really an offset into the image which contains an offset into the
738  	 * image.
739  	 */
740  	if (flags & FLAT_FLAG_GOTPIC) {
741  		rp = skip_got_header((u32 __user *) datapos);
742  		for (; ; rp++) {
743  			u32 addr, rp_val;
744  			if (get_user(rp_val, rp))
745  				return -EFAULT;
746  			if (rp_val == 0xffffffff)
747  				break;
748  			if (rp_val) {
749  				addr = calc_reloc(rp_val, libinfo);
750  				if (addr == RELOC_FAILED) {
751  					ret = -ENOEXEC;
752  					goto err;
753  				}
754  				if (put_user(addr, rp))
755  					return -EFAULT;
756  			}
757  		}
758  	}
759  
760  	/*
761  	 * Now run through the relocation entries.
762  	 * We've got to be careful here as C++ produces relocatable zero
763  	 * entries in the constructor and destructor tables which are then
764  	 * tested for being not zero (which will always occur unless we're
765  	 * based from address zero).  This causes an endless loop as __start
766  	 * is at zero.  The solution used is to not relocate zero addresses.
767  	 * This has the negative side effect of not allowing a global data
768  	 * reference to be statically initialised to _stext (I've moved
769  	 * __start to address 4 so that is okay).
770  	 */
771  	if (rev > OLD_FLAT_VERSION) {
772  		for (i = 0; i < relocs; i++) {
773  			u32 addr, relval;
774  			__be32 tmp;
775  
776  			/*
777  			 * Get the address of the pointer to be
778  			 * relocated (of course, the address has to be
779  			 * relocated first).
780  			 */
781  			if (get_user(tmp, reloc + i))
782  				return -EFAULT;
783  			relval = ntohl(tmp);
784  			addr = flat_get_relocate_addr(relval);
785  			rp = (u32 __user *)calc_reloc(addr, libinfo);
786  			if (rp == (u32 __user *)RELOC_FAILED) {
787  				ret = -ENOEXEC;
788  				goto err;
789  			}
790  
791  			/* Get the pointer's value.  */
792  			ret = flat_get_addr_from_rp(rp, relval, flags, &addr);
793  			if (unlikely(ret))
794  				goto err;
795  
796  			if (addr != 0) {
797  				/*
798  				 * Do the relocation.  PIC relocs in the data section are
799  				 * already in target order
800  				 */
801  				if ((flags & FLAT_FLAG_GOTPIC) == 0) {
802  					/*
803  					 * Meh, the same value can have a different
804  					 * byte order based on a flag..
805  					 */
806  					addr = ntohl((__force __be32)addr);
807  				}
808  				addr = calc_reloc(addr, libinfo);
809  				if (addr == RELOC_FAILED) {
810  					ret = -ENOEXEC;
811  					goto err;
812  				}
813  
814  				/* Write back the relocated pointer.  */
815  				ret = flat_put_addr_at_rp(rp, addr, relval);
816  				if (unlikely(ret))
817  					goto err;
818  			}
819  		}
820  #ifdef CONFIG_BINFMT_FLAT_OLD
821  	} else {
822  		for (i = 0; i < relocs; i++) {
823  			__be32 relval;
824  			if (get_user(relval, reloc + i))
825  				return -EFAULT;
826  			old_reloc(ntohl(relval));
827  		}
828  #endif /* CONFIG_BINFMT_FLAT_OLD */
829  	}
830  
831  	flush_icache_user_range(start_code, end_code);
832  
833  	/* zero the BSS,  BRK and stack areas */
834  	if (clear_user((void __user *)(datapos + data_len), bss_len +
835  		       (memp + memp_size - stack_len -		/* end brk */
836  		       libinfo->lib_list[0].start_brk) +	/* start brk */
837  		       stack_len))
838  		return -EFAULT;
839  
840  	return 0;
841  err:
842  	return ret;
843  }
844  
845  
846  /****************************************************************************/
847  
848  /*
849   * These are the functions used to load flat style executables and shared
850   * libraries.  There is no binary dependent code anywhere else.
851   */
852  
load_flat_binary(struct linux_binprm * bprm)853  static int load_flat_binary(struct linux_binprm *bprm)
854  {
855  	struct lib_info libinfo;
856  	struct pt_regs *regs = current_pt_regs();
857  	unsigned long stack_len = 0;
858  	unsigned long start_addr;
859  	int res;
860  	int i, j;
861  
862  	memset(&libinfo, 0, sizeof(libinfo));
863  
864  	/*
865  	 * We have to add the size of our arguments to our stack size
866  	 * otherwise it's too easy for users to create stack overflows
867  	 * by passing in a huge argument list.  And yes,  we have to be
868  	 * pedantic and include space for the argv/envp array as it may have
869  	 * a lot of entries.
870  	 */
871  #ifndef CONFIG_MMU
872  	stack_len += PAGE_SIZE * MAX_ARG_PAGES - bprm->p; /* the strings */
873  #endif
874  	stack_len += (bprm->argc + 1) * sizeof(char *);   /* the argv array */
875  	stack_len += (bprm->envc + 1) * sizeof(char *);   /* the envp array */
876  	stack_len = ALIGN(stack_len, FLAT_STACK_ALIGN);
877  
878  	res = load_flat_file(bprm, &libinfo, &stack_len);
879  	if (res < 0)
880  		return res;
881  
882  	/* Update data segment pointers for all libraries */
883  	for (i = 0; i < MAX_SHARED_LIBS; i++) {
884  		if (!libinfo.lib_list[i].loaded)
885  			continue;
886  		for (j = 0; j < MAX_SHARED_LIBS; j++) {
887  			unsigned long val = libinfo.lib_list[j].loaded ?
888  				libinfo.lib_list[j].start_data : UNLOADED_LIB;
889  			unsigned long __user *p = (unsigned long __user *)
890  				libinfo.lib_list[i].start_data;
891  			p -= j + 1;
892  			if (put_user(val, p))
893  				return -EFAULT;
894  		}
895  	}
896  
897  	set_binfmt(&flat_format);
898  
899  #ifdef CONFIG_MMU
900  	res = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
901  	if (!res)
902  		res = create_flat_tables(bprm, bprm->p);
903  #else
904  	/* Stash our initial stack pointer into the mm structure */
905  	current->mm->start_stack =
906  		((current->mm->context.end_brk + stack_len + 3) & ~3) - 4;
907  	pr_debug("sp=%lx\n", current->mm->start_stack);
908  
909  	/* copy the arg pages onto the stack */
910  	res = transfer_args_to_stack(bprm, &current->mm->start_stack);
911  	if (!res)
912  		res = create_flat_tables(bprm, current->mm->start_stack);
913  #endif
914  	if (res)
915  		return res;
916  
917  	/* Fake some return addresses to ensure the call chain will
918  	 * initialise library in order for us.  We are required to call
919  	 * lib 1 first, then 2, ... and finally the main program (id 0).
920  	 */
921  	start_addr = libinfo.lib_list[0].entry;
922  
923  #ifdef FLAT_PLAT_INIT
924  	FLAT_PLAT_INIT(regs);
925  #endif
926  
927  	finalize_exec(bprm);
928  	pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n",
929  		 regs, start_addr, current->mm->start_stack);
930  	start_thread(regs, start_addr, current->mm->start_stack);
931  
932  	return 0;
933  }
934  
935  /****************************************************************************/
936  
init_flat_binfmt(void)937  static int __init init_flat_binfmt(void)
938  {
939  	register_binfmt(&flat_format);
940  	return 0;
941  }
942  core_initcall(init_flat_binfmt);
943  
944  /****************************************************************************/
945