1 /* 2 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com) 3 * Licensed under the GPL 4 */ 5 6 #include <stdio.h> 7 #include <stddef.h> 8 #include <stdarg.h> 9 #include <stdlib.h> 10 #include <string.h> 11 #include <unistd.h> 12 #include <signal.h> 13 #include <sched.h> 14 #include <fcntl.h> 15 #include <errno.h> 16 #include <setjmp.h> 17 #include <sys/time.h> 18 #include <sys/wait.h> 19 #include <sys/mman.h> 20 #include <asm/unistd.h> 21 #include <asm/page.h> 22 #include <sys/types.h> 23 #include "user_util.h" 24 #include "kern_util.h" 25 #include "user.h" 26 #include "signal_kern.h" 27 #include "signal_user.h" 28 #include "sysdep/ptrace.h" 29 #include "sysdep/sigcontext.h" 30 #include "irq_user.h" 31 #include "ptrace_user.h" 32 #include "mem_user.h" 33 #include "time_user.h" 34 #include "init.h" 35 #include "os.h" 36 #include "uml-config.h" 37 #include "choose-mode.h" 38 #include "mode.h" 39 #include "tempfile.h" 40 #include "kern_constants.h" 41 42 #ifdef UML_CONFIG_MODE_SKAS 43 #include "skas.h" 44 #include "skas_ptrace.h" 45 #include "registers.h" 46 #endif 47 48 static int ptrace_child(void *arg) 49 { 50 int ret; 51 int pid = os_getpid(), ppid = getppid(); 52 int sc_result; 53 54 if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){ 55 perror("ptrace"); 56 os_kill_process(pid, 0); 57 } 58 os_stop_process(pid); 59 60 /*This syscall will be intercepted by the parent. Don't call more than 61 * once, please.*/ 62 sc_result = os_getpid(); 63 64 if (sc_result == pid) 65 ret = 1; /*Nothing modified by the parent, we are running 66 normally.*/ 67 else if (sc_result == ppid) 68 ret = 0; /*Expected in check_ptrace and check_sysemu when they 69 succeed in modifying the stack frame*/ 70 else 71 ret = 2; /*Serious trouble! This could be caused by a bug in 72 host 2.6 SKAS3/2.6 patch before release -V6, together 73 with a bug in the UML code itself.*/ 74 _exit(ret); 75 } 76 77 static int start_ptraced_child(void **stack_out) 78 { 79 void *stack; 80 unsigned long sp; 81 int pid, n, status; 82 83 stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, 84 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 85 if(stack == MAP_FAILED) 86 panic("check_ptrace : mmap failed, errno = %d", errno); 87 sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *); 88 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); 89 if(pid < 0) 90 panic("start_ptraced_child : clone failed, errno = %d", errno); 91 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 92 if(n < 0) 93 panic("check_ptrace : clone failed, errno = %d", errno); 94 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 95 panic("check_ptrace : expected SIGSTOP, got status = %d", 96 status); 97 98 *stack_out = stack; 99 return(pid); 100 } 101 102 /* When testing for SYSEMU support, if it is one of the broken versions, we 103 * must just avoid using sysemu, not panic, but only if SYSEMU features are 104 * broken. 105 * So only for SYSEMU features we test mustpanic, while normal host features 106 * must work anyway! 107 */ 108 static int stop_ptraced_child(int pid, void *stack, int exitcode, 109 int mustpanic) 110 { 111 int status, n, ret = 0; 112 113 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 114 panic("check_ptrace : ptrace failed, errno = %d", errno); 115 CATCH_EINTR(n = waitpid(pid, &status, 0)); 116 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 117 int exit_with = WEXITSTATUS(status); 118 if (exit_with == 2) 119 printk("check_ptrace : child exited with status 2. " 120 "Serious trouble happening! Try updating your " 121 "host skas patch!\nDisabling SYSEMU support."); 122 printk("check_ptrace : child exited with exitcode %d, while " 123 "expecting %d; status 0x%x", exit_with, 124 exitcode, status); 125 if (mustpanic) 126 panic("\n"); 127 else 128 printk("\n"); 129 ret = -1; 130 } 131 132 if(munmap(stack, PAGE_SIZE) < 0) 133 panic("check_ptrace : munmap failed, errno = %d", errno); 134 return ret; 135 } 136 137 int ptrace_faultinfo = 1; 138 int proc_mm = 1; 139 140 static int __init skas0_cmd_param(char *str, int* add) 141 { 142 ptrace_faultinfo = proc_mm = 0; 143 return 0; 144 } 145 146 /* The two __uml_setup would conflict, without this stupid alias. */ 147 148 static int __init mode_skas0_cmd_param(char *str, int* add) 149 __attribute__((alias("skas0_cmd_param"))); 150 151 __uml_setup("skas0", skas0_cmd_param, 152 "skas0\n" 153 " Disables SKAS3 usage, so that SKAS0 is used, unless \n" 154 " you specify mode=tt.\n\n"); 155 156 __uml_setup("mode=skas0", mode_skas0_cmd_param, 157 "mode=skas0\n" 158 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 159 " specify mode=tt. Note that this was recently added - on \n" 160 " older kernels you must use simply \"skas0\".\n\n"); 161 162 static int force_sysemu_disabled = 0; 163 164 static int __init nosysemu_cmd_param(char *str, int* add) 165 { 166 force_sysemu_disabled = 1; 167 return 0; 168 } 169 170 __uml_setup("nosysemu", nosysemu_cmd_param, 171 "nosysemu\n" 172 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 173 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 174 " behaviour of ptrace() and helps reducing host context switch rate.\n" 175 " To make it working, you need a kernel patch for your host, too.\n" 176 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 177 " information.\n\n"); 178 179 static void __init check_sysemu(void) 180 { 181 void *stack; 182 int pid, n, status, count=0; 183 184 printk("Checking syscall emulation patch for ptrace..."); 185 sysemu_supported = 0; 186 pid = start_ptraced_child(&stack); 187 188 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 189 goto fail; 190 191 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 192 if (n < 0) 193 panic("check_sysemu : wait failed, errno = %d", errno); 194 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 195 panic("check_sysemu : expected SIGTRAP, " 196 "got status = %d", status); 197 198 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 199 os_getpid()); 200 if(n < 0) 201 panic("check_sysemu : failed to modify system " 202 "call return, errno = %d", errno); 203 204 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 205 goto fail_stopped; 206 207 sysemu_supported = 1; 208 printk("OK\n"); 209 set_using_sysemu(!force_sysemu_disabled); 210 211 printk("Checking advanced syscall emulation patch for ptrace..."); 212 pid = start_ptraced_child(&stack); 213 214 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 215 (void *) PTRACE_O_TRACESYSGOOD) < 0) 216 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", 217 errno); 218 219 while(1){ 220 count++; 221 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 222 goto fail; 223 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 224 if(n < 0) 225 panic("check_ptrace : wait failed, errno = %d", errno); 226 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){ 227 if (!count) 228 panic("check_ptrace : SYSEMU_SINGLESTEP " 229 "doesn't singlestep"); 230 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 231 os_getpid()); 232 if(n < 0) 233 panic("check_sysemu : failed to modify system " 234 "call return, errno = %d", errno); 235 break; 236 } 237 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 238 count++; 239 else 240 panic("check_ptrace : expected SIGTRAP or " 241 "(SIGTRAP|0x80), got status = %d", status); 242 } 243 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 244 goto fail_stopped; 245 246 sysemu_supported = 2; 247 printk("OK\n"); 248 249 if ( !force_sysemu_disabled ) 250 set_using_sysemu(sysemu_supported); 251 return; 252 253 fail: 254 stop_ptraced_child(pid, stack, 1, 0); 255 fail_stopped: 256 printk("missing\n"); 257 } 258 259 static void __init check_ptrace(void) 260 { 261 void *stack; 262 int pid, syscall, n, status; 263 264 printk("Checking that ptrace can change system call numbers..."); 265 pid = start_ptraced_child(&stack); 266 267 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 268 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno); 269 270 while(1){ 271 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 272 panic("check_ptrace : ptrace failed, errno = %d", 273 errno); 274 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 275 if(n < 0) 276 panic("check_ptrace : wait failed, errno = %d", errno); 277 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80))) 278 panic("check_ptrace : expected (SIGTRAP|0x80), " 279 "got status = %d", status); 280 281 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 282 0); 283 if(syscall == __NR_getpid){ 284 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 285 __NR_getppid); 286 if(n < 0) 287 panic("check_ptrace : failed to modify system " 288 "call, errno = %d", errno); 289 break; 290 } 291 } 292 stop_ptraced_child(pid, stack, 0, 1); 293 printk("OK\n"); 294 check_sysemu(); 295 } 296 297 extern int create_tmp_file(unsigned long len); 298 299 static void check_tmpexec(void) 300 { 301 void *addr; 302 int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE); 303 304 addr = mmap(NULL, UM_KERN_PAGE_SIZE, 305 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0); 306 printf("Checking PROT_EXEC mmap in /tmp..."); 307 fflush(stdout); 308 if(addr == MAP_FAILED){ 309 err = errno; 310 perror("failed"); 311 if(err == EPERM) 312 printf("/tmp must be not mounted noexec\n"); 313 exit(1); 314 } 315 printf("OK\n"); 316 munmap(addr, UM_KERN_PAGE_SIZE); 317 318 close(fd); 319 } 320 321 void os_early_checks(void) 322 { 323 check_ptrace(); 324 325 /* Need to check this early because mmapping happens before the 326 * kernel is running. 327 */ 328 check_tmpexec(); 329 } 330 331 static int __init noprocmm_cmd_param(char *str, int* add) 332 { 333 proc_mm = 0; 334 return 0; 335 } 336 337 __uml_setup("noprocmm", noprocmm_cmd_param, 338 "noprocmm\n" 339 " Turns off usage of /proc/mm, even if host supports it.\n" 340 " To support /proc/mm, the host needs to be patched using\n" 341 " the current skas3 patch.\n\n"); 342 343 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 344 { 345 ptrace_faultinfo = 0; 346 return 0; 347 } 348 349 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 350 "noptracefaultinfo\n" 351 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 352 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 353 " using the current skas3 patch.\n\n"); 354 355 #ifdef UML_CONFIG_MODE_SKAS 356 static inline void check_skas3_ptrace_support(void) 357 { 358 struct ptrace_faultinfo fi; 359 void *stack; 360 int pid, n; 361 362 printf("Checking for the skas3 patch in the host..."); 363 pid = start_ptraced_child(&stack); 364 365 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 366 if (n < 0) { 367 ptrace_faultinfo = 0; 368 if(errno == EIO) 369 printf("not found\n"); 370 else 371 perror("not found"); 372 } 373 else { 374 if (!ptrace_faultinfo) 375 printf("found but disabled on command line\n"); 376 else 377 printf("found\n"); 378 } 379 380 init_registers(pid); 381 stop_ptraced_child(pid, stack, 1, 1); 382 } 383 384 int can_do_skas(void) 385 { 386 printf("Checking for /proc/mm..."); 387 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 388 proc_mm = 0; 389 printf("not found\n"); 390 } 391 else { 392 if (!proc_mm) 393 printf("found but disabled on command line\n"); 394 else 395 printf("found\n"); 396 } 397 398 check_skas3_ptrace_support(); 399 return 1; 400 } 401 #else 402 int can_do_skas(void) 403 { 404 return(0); 405 } 406 #endif 407 408 int have_devanon = 0; 409 410 void check_devanon(void) 411 { 412 int fd; 413 414 printk("Checking for /dev/anon on the host..."); 415 fd = open("/dev/anon", O_RDWR); 416 if(fd < 0){ 417 printk("Not available (open failed with errno %d)\n", errno); 418 return; 419 } 420 421 printk("OK\n"); 422 have_devanon = 1; 423 } 424 425 int __init parse_iomem(char *str, int *add) 426 { 427 struct iomem_region *new; 428 struct uml_stat buf; 429 char *file, *driver; 430 int fd, err, size; 431 432 driver = str; 433 file = strchr(str,','); 434 if(file == NULL){ 435 printf("parse_iomem : failed to parse iomem\n"); 436 goto out; 437 } 438 *file = '\0'; 439 file++; 440 fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0); 441 if(fd < 0){ 442 os_print_error(fd, "parse_iomem - Couldn't open io file"); 443 goto out; 444 } 445 446 err = os_stat_fd(fd, &buf); 447 if(err < 0){ 448 os_print_error(err, "parse_iomem - cannot stat_fd file"); 449 goto out_close; 450 } 451 452 new = malloc(sizeof(*new)); 453 if(new == NULL){ 454 perror("Couldn't allocate iomem_region struct"); 455 goto out_close; 456 } 457 458 size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 459 460 *new = ((struct iomem_region) { .next = iomem_regions, 461 .driver = driver, 462 .fd = fd, 463 .size = size, 464 .phys = 0, 465 .virt = 0 }); 466 iomem_regions = new; 467 iomem_size += new->size + UM_KERN_PAGE_SIZE; 468 469 return(0); 470 out_close: 471 os_close_file(fd); 472 out: 473 return(1); 474 } 475 476