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#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <elf.h>
#include <getopt.h>
#include <assert.h>
#include <sys/stat.h>
#include <errno.h>
#include "elfload.h"
static int verbose = 1;
static int force = 0;
static int preserve = 0;
const char *curfile;
/* Replace any DT_RELENT .dynamic entry with DT_RELAENT. */
static int
fixrelent(int fd, Elf32_Off dyn_offset)
{
int i;
if (lseek(fd, dyn_offset, SEEK_SET) == -1)
{
fprintf (stderr, "%s: positioning for dynamic: %m\n", curfile);
return -1;
}
for (i = 0; ; i++)
{
Elf32_Dyn dent;
if (read(fd, &dent, sizeof(dent)) != sizeof(dent))
{
fprintf (stderr, "%s: reading .dynamic entry %d: %m\n",
curfile, i);
return -1;
}
switch (dent.d_tag)
{
case DT_NULL:
fprintf(stderr, "%s: No DT_REL[A]ENT??\n", curfile);
return -1;
case DT_RELAENT:
if (verbose > 1)
printf("%s: Already has DT_RELAENT.\n", curfile);
return 0;
case DT_RELENT:
if (lseek(fd, dyn_offset + i*sizeof(Elf32_Dyn), SEEK_SET) == -1)
{
fprintf (stderr, "%s: positioning for write: %m\n",
curfile);
return -1;
}
dent.d_tag = DT_RELAENT;
if (write(fd, &dent, sizeof(dent)) != sizeof(dent))
{
fprintf (stderr, "%s: writing DT_RELAENT: %m\n",
curfile);
return -1;
}
if (verbose)
printf("%s: DT_RELENT fixed.\n", curfile);
return 0;
default:
/* continue */
}
}
}
static int
startcmp(const Elf32_Word *broken_start, const Elf32_Word *start_data,
int length)
{
int i;
for (i = 0; i < length; i++)
if (((broken_start[i] & 0xffff) != 0x5555
|| (broken_start[i] & ~0xffff) != (start_data[i] & ~0xffff))
&& broken_start[i] != start_data[i])
return 0;
return 1;
}
/* Returns -1 on error, 0 otherwise. */
static int
fixstart(int fd, const Elf32_Ehdr *ehdr)
{
enum { start_length = 0xb8 };
static const Elf32_Word broken_start[] = {
0x3da05555, 0x61ad5555, 0x2c1f7654, 0x41820028,
0x7c3d0b78, 0x3821ffc0, 0x807d0000, 0x389d0004,
0x7c852378, 0x84050004, 0x2c000000, 0x4082fff8,
0x38a50004, 0x3fe05555, 0x90bf5555, 0x7c771b78,
0x7c982378, 0x7cb92b78, 0x2c1f7654, 0x41820008,
0x7fa3eb78
};
static const Elf32_Word new_start[] = {
0x3821FFF0, /* addi %r1,%r1,-16 */
0x38000000, /* li %r0,0 */
0x90010000, /* stw %r0,0(1) */
0x7C0803A6, /* mtlr %r0 */
0x7C771B78, /* mr %r23,%r3 */
0x7C982378, /* mr %r24,%r4 */
0x7CE33B79, /* mr. %r3,%r7 */
0x7CB92B78, /* mr %r25,%r5 */
0x41820008, /* beq 0f */
0x48000001, /* bl atexit */
0x7EE3BB78, /* 0: mr %r3,%r23 */
0x7F04C378, /* mr %r4,%r24 */
0x7F25CB78, /* mr %r5,%r25 */
0x48000018, /* b 1f */
0x60000000, /* nop */
0x60000000, /* nop */
0x60000000, /* nop */
0x60000000, /* nop */
0x60000000 /* nop */
/* 1: */
};
Elf32_Word *startp;
Elf32_Off start_offset;
int i;
if (ehdr->e_entry == 0)
{
if (verbose)
printf ("%s: No entry point!\n", curfile);
return 0;
}
startp = (Elf32_Word *)find_location(ehdr->e_entry, 0);
if (!startp)
{
fprintf(stderr,"%s: No section containing entry point (0x%08x).\n",
curfile, ehdr->e_entry);
return -1;
}
/* Check to see that it's the start routine we expect. */
if (find_location(ehdr->e_entry, 26*4)
&& startcmp(broken_start, startp,
sizeof(broken_start)/sizeof(broken_start[0])))
startp += 2;
else if (find_location(ehdr->e_entry, 24*4)
&& startcmp(broken_start+2, startp,
sizeof(broken_start)/sizeof(broken_start[0])-2))
{
if (verbose > 1)
printf("%s: Warning: Start routine does not set r13.\n",
curfile);
}
else
{
if (verbose > 1)
printf("%s: Start routine not known to fail, not changed.\n",
curfile);
return 0;
}
/* Fix it. */
for (i = 0; (size_t)i < sizeof(new_start)/sizeof(new_start[0]); i++)
startp[i] = new_start[i];
/* Get bl instruction for atexit. */
startp[9] |= 0x03fffffc & startp[23] + 56;
changed_segment();
if (verbose)
printf("%s: Start routine fixed.\n", curfile);
return 0;
}
static const char *const fixsyms[][2] = {
{ "sigisemptyset","s!,isemptyset" },
{ "sigemptyset", "s!,emptyset" },
{ "sigfillset", "s!,fillset" },
{ "sigprocmask", "s!,procmask" },
{ "sigpending", "s!,pending" },
{ "sigaction", "s!,action" },
{ "__sigsetjmp", "__s!,setjmp" },
{ "__sigjmp_save","__s!,jmp_save" },
{ "tcgetattr", "!,getattr" },
{ "tcsetattr", "!,setattr" },
{ "__fxstat", "__fx,!at" },
{ "__xstat", "__x,!at" },
{ "__lxstat", "__lx,!at" },
{ "readdir", "readd!," },
{ "readdir_r", "readd!,_r" },
{ "scandir", "scand!," },
{ "alphasort", "alphaso,!" },
{ "getdirentries","getd!,entries" },
{ "__res_init", "res_init" },
{ "__socket", "socket" },
{ "__recv", "recv" },
{ "_Xsetlocale", "setlocale" }
};
/* Returns -1 on error, 0 otherwise. */
static int
checksyms(int fd, int dyn_offset)
{
enum { num_need = 32 };
Elf32_Addr needed[num_need];
int numneeded = 0;
int i;
Elf32_Addr sym_offset, string_offset, hash_offset;
if (lseek(fd, dyn_offset, SEEK_SET) == -1)
{
fprintf (stderr, "%s: positioning for dynamic: %m\n", curfile);
return -1;
}
sym_offset = string_offset = hash_offset = 0;
for (;;)
{
Elf32_Dyn dent;
if (read(fd, &dent, sizeof(dent)) != sizeof(dent))
{
fprintf (stderr, "%s: reading .dynamic entry: %m\n",
curfile);
return -1;
}
#ifndef DT_VERNEED
#define DT_VERNEED 0x6ffffffe
#endif
switch (dent.d_tag)
{
case DT_VERNEED:
if (verbose > 1)
printf("%s: Not looking for problem functions, has versioning.\n",
curfile);
return 0;
case DT_SYMTAB:
sym_offset = dent.d_un.d_ptr;
break;
case DT_STRTAB:
string_offset = dent.d_un.d_ptr;
break;
case DT_HASH:
hash_offset = dent.d_un.d_ptr;
break;
case DT_NEEDED:
if (numneeded == num_need)
{
fprintf(stderr, "%s: uses too many shared objects.\n",
curfile);
return -1;
}
needed[numneeded++] = dent.d_un.d_ptr;
break;
case DT_NULL:
goto endloop;
default:
break;
}
}
endloop:
if (sym_offset == 0 || string_offset == 0 || hash_offset == 0)
{
fprintf(stderr, "%s: No strings or no symbols!\n", curfile);
return -1;
}
#define findlocn(addr) ({ \
char *result = find_location(addr, 1); \
if (result == 0) \
{ \
fprintf (stderr, "%s: Unloaded address %08x!\n", curfile, addr); \
return -1; \
} \
result; \
})
{
Elf32_Word nchain, ichain, nbucket, c;
Elf32_Addr *bucket, *chain;
Elf32_Sym *syms;
int hit = 0;
char *name, *namep;
nchain = *(Elf32_Word *) findlocn(hash_offset + 4);
syms = (Elf32_Sym *) findlocn(sym_offset);
for (ichain = 0; ichain < nchain; ichain++)
if (syms[ichain].st_name != 0)
{
size_t k;
name = findlocn(string_offset + syms[ichain].st_name);
for (k = 0; k < sizeof(fixsyms)/sizeof(fixsyms[0]); k++)
if (strcmp(name, fixsyms[k][0]) == 0)
{
if (!hit && verbose == 1)
printf("%s: Fixing functions.\n", curfile);
else if (verbose > 1)
printf("%s: Changing function %s to %s.\n", curfile,
fixsyms[k][0], fixsyms[k][1]);
assert(strlen(fixsyms[k][0]) >= strlen(fixsyms[k][1]));
strcpy(name, fixsyms[k][1]);
hit = 1;
}
}
if (!hit && verbose > 1)
printf("%s: Found no functions that needed replacing.\n", curfile);
if (!hit)
return 0;
changed_segment();
/* Rebuild the hash table. */
nbucket = *(Elf32_Word *) findlocn(hash_offset);
bucket = (Elf32_Addr *) findlocn(hash_offset + 8);
chain = bucket + nbucket;
memset(bucket, 0, sizeof(Elf32_Addr)*nbucket);
memset(chain, 0, sizeof(Elf32_Addr)*nchain);
for (c = 1; c < nchain; c++)
if (syms[c].st_name != 0)
{
unsigned long h=0, g, j;
name = findlocn(string_offset + syms[c].st_name);
for (j = 0; name[j]; j++)
{
h = (h << 4) + name[j];
if (g = h & 0xf0000000)
h ^= g >> 24;
h &= ~g;
}
h %= nbucket;
if (bucket[h] == 0)
bucket[h] = c;
else
{
for (h = bucket[h]; chain[h] != 0; h = chain[h])
;
chain[h] = c;
}
}
}
{
int libcct = -1;
int ldsoct = -1;
static const char libname[] = "fix!.so";
for (i = 0; i < numneeded; i++)
{
char *name;
name = findlocn(string_offset + needed[i]);
if (strcmp(name, "libc.so.6") == 0)
libcct = i;
else if (strcmp (name, "ld.so.1") == 0)
{
if (verbose > 1)
printf("%s: Replacing %s with %s\n", curfile, name, libname);
strcpy(name, libname);
ldsoct = i;
}
}
if (libcct == -1)
{
fprintf (stderr, "%s: Does not use libc.so.6!\n", curfile);
return -1;
}
if (ldsoct == -1)
{
char *libcname;
libcname = findlocn(string_offset + needed[libcct]);
if (verbose > 1)
printf("%s: Replacing %s with %s\n", curfile, libcname, libname);
strcpy(libcname, libname);
}
}
return 0;
}
/* Returns -1 on error, 0 otherwise. */
static int
fixglobdat(int fd, int dyn_offset)
{
Elf32_Addr rela_offset;
Elf32_Word numrels, i, hit = 0;
Elf32_Rela *rels;
if (lseek(fd, dyn_offset, SEEK_SET) == -1)
{
fprintf (stderr, "%s: positioning for dynamic: %m\n", curfile);
return -1;
}
rela_offset = numrels = 0;
for (;;)
{
Elf32_Dyn dent;
if (read(fd, &dent, sizeof(dent)) != sizeof(dent))
{
fprintf (stderr, "%s: reading .dynamic entry: %m\n",
curfile);
return -1;
}
switch (dent.d_tag)
{
case DT_RELA:
rela_offset = dent.d_un.d_ptr;
break;
case DT_RELASZ:
numrels = dent.d_un.d_val / sizeof(Elf32_Rela);
break;
case DT_RELAENT:
if (dent.d_un.d_val != sizeof(Elf32_Rela))
{
fprintf (stderr, "%s: RELA entry size %d, expected %d!\n",
curfile, dent.d_un.d_val, sizeof(Elf32_Rela));
return -1;
}
break;
case DT_NULL:
goto endloop;
default:
break;
}
}
endloop:
if (rela_offset == 0 || numrels == 0)
{
if (verbose > 1)
printf("%s: No relocations.\n", curfile);
return 0;
}
rels = (Elf32_Rela *) find_location(rela_offset, sizeof(Elf32_Rela)*numrels);
if (rels == NULL)
{
fprintf (stderr, "%s: Relocations (0x%08x-0x%08x) not loaded.\n",
curfile, rela_offset, rela_offset+sizeof(Elf32_Rela)*numrels);
return -1;
}
for (i = 0; i < numrels; i++)
if (ELF32_R_SYM(rels[i].r_info) == SHN_UNDEF
&& ELF32_R_TYPE(rels[i].r_info) == R_PPC_GLOB_DAT)
{
hit++;
rels[i].r_info = ELF32_R_INFO(SHN_UNDEF, R_PPC_RELATIVE);
}
if (hit)
{
if (verbose)
printf("%s: %d R_PPC_GLOB_DAT relocs changed to R_PPC_RELATIVE.\n",
curfile, hit);
changed_segment();
}
else if (verbose > 1)
printf("%s: No broken R_PPC_GLOB_DAT relocs found.\n", curfile);
return 0;
}
static void
fixit(const char *whichfile)
{
Elf32_Ehdr ehdr;
Elf32_Off dyn_offset;
int fd;
struct stat oldperms;
int permschanged = 0;
curfile = whichfile;
if (preserve || force)
if (stat(curfile, &oldperms) != 0)
{
fprintf (stderr, "%s: couldn't stat: %m\n", curfile);
return;
}
fd = open(curfile, O_RDWR);
if (force && fd == -1 && errno == EACCES)
if (chmod(curfile, oldperms.st_mode | S_IRUSR | S_IWUSR) == -1)
{
fprintf (stderr, "%s: couldn't open and couldn't change modes: %m\n",
curfile);
return;
}
else
{
fd = open(curfile, O_RDWR);
permschanged = 1;
}
if (fd == -1)
{
fprintf (stderr, "%s: open failed: %m\n", curfile);
if (permschanged)
chmod(curfile, oldperms.st_mode);
return;
}
{ int ehdr_result = read_check_ehdr(fd, &ehdr);
if (ehdr_result == -2 && verbose > 1)
printf("%s: Not a PPC executable.\n", curfile);
if (ehdr_result != 0)
goto donefile;
}
{ int read_seg_result = read_segment_list(fd, &ehdr, &dyn_offset);
if (read_seg_result == 1 && verbose > 1)
printf("%s: No dynamic section.\n", curfile);
if (read_seg_result != 0)
goto donefile;
}
if (fixrelent(fd, dyn_offset) != 0)
goto donefile;
if (load_segments(fd) != 0)
goto donefile;
if (fixstart(fd, &ehdr) == -1)
goto donefile;
if (checksyms(fd, dyn_offset) == -1)
goto donefile;
if (ehdr.e_type == ET_DYN
&& fixglobdat(fd, dyn_offset) == -1)
goto donefile;
write_segments(fd);
donefile:
free_segments();
if (permschanged || preserve)
fchmod(fd, oldperms.st_mode);
close(fd);
}
int
main(int argc, char **argv)
{
int c;
size_t i, ct;
while (1)
{
static const struct option long_options[] =
{
/* These options set a flag. */
{"verbose", 0, &verbose, 2},
{"quiet", 0, &verbose, 0},
{"force", 0, &force, 1},
{"preserve", 0, &preserve, 1},
{"help", 0, 0, 'h'},
{"version", 0, 0, 'e'},
{0, 0, 0, 0}
};
/* `getopt_long' stores the option index here. */
int option_index = 0;
c = getopt_long (argc, argv, "svpf",
long_options, &option_index);
/* Detect the end of the options. */
if (c == -1)
break;
switch (c)
{
case 0:
break;
case 's':
verbose = 0;
break;
case 'v':
verbose++;
break;
case 'p':
preserve = 1;
break;
case 'f':
force = 1;
break;
case 'h':
printf (
"Usage: %s [OPTION] FILE ...\n"
"Fix FILE to make it work with libc 2.1 on powerpc.\n\n"
" -s, --quiet don't print output indicating changes were made\n"
" -v, --verbose if a file was not changed, say why\n"
" -p, --preserve if the file was originally setuid, leave it that way\n"
" -f, --force ignore absence of read permission\n"
" --help display this help and exit\n"
" --version output version information and exit\n\n"
"The changes made are that:\n"
"1. A DT_RELENT program header entry is changed to the correct DT_RELAENT.\n"
"2. The startup procedure is modified to conform to the PPC version of the\n"
" SVR4 ELF ABI.\n"
"3. Routines which use data structures that changed size between the 971212\n"
" libc and the final libc 2.0, or which use constants that are different\n"
" between the two versions, are redirected to call a stub library that\n"
" emulates the old library behaviour. The affected routines are:\n"
" ", argv[0]);
ct = 9;
for (i = 0; i < sizeof(fixsyms)/sizeof(fixsyms[0]); i++)
ct += printf("%s%s",
(ct + sizeof(fixsyms[i][0]) > 70
? (ct=0), ",\n "
: (i==0 ? "" : ", ")),
fixsyms[i][0]);
printf(".\n"
"4. R_PPC_GLOB_DAT relocations in shared objects that point to an absolute\n"
" address are changed to be R_PPC_RELATIVE relocations.\n\n"
"If FILE is not a PowerPC ELF executable or shared object, or the changes\n"
"have already been made, or the changes don't need to be made, does nothing.\n"
);
exit(0);
case 'e':
printf("Version 1.1\n");
exit(0);
case '?':
/* `getopt_long' already printed an error message. */
fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
exit(1);
default:
abort ();
}
}
while (optind < argc)
fixit(argv[optind++]);
return 0;
}
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