1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <stdarg.h> 9 #include <unistd.h> 10 #include <errno.h> 11 #include <fcntl.h> 12 #include <sched.h> 13 #include <signal.h> 14 #include <string.h> 15 #include <sys/mman.h> 16 #include <sys/stat.h> 17 #include <sys/wait.h> 18 #include <sys/time.h> 19 #include <sys/resource.h> 20 #include <asm/ldt.h> 21 #include <asm/unistd.h> 22 #include <init.h> 23 #include <os.h> 24 #include <kern_util.h> 25 #include <mem_user.h> 26 #include <ptrace_user.h> 27 #include <registers.h> 28 #include <skas.h> 29 #include "internal.h" 30 31 static void ptrace_child(void) 32 { 33 int ret; 34 /* Calling os_getpid because some libcs cached getpid incorrectly */ 35 int pid = os_getpid(), ppid = getppid(); 36 int sc_result; 37 38 if (change_sig(SIGWINCH, 0) < 0 || 39 ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) { 40 perror("ptrace"); 41 kill(pid, SIGKILL); 42 } 43 kill(pid, SIGSTOP); 44 45 /* 46 * This syscall will be intercepted by the parent. Don't call more than 47 * once, please. 48 */ 49 sc_result = os_getpid(); 50 51 if (sc_result == pid) 52 /* Nothing modified by the parent, we are running normally. */ 53 ret = 1; 54 else if (sc_result == ppid) 55 /* 56 * Expected in check_ptrace and check_sysemu when they succeed 57 * in modifying the stack frame 58 */ 59 ret = 0; 60 else 61 /* Serious trouble! This could be caused by a bug in host 2.6 62 * SKAS3/2.6 patch before release -V6, together with a bug in 63 * the UML code itself. 64 */ 65 ret = 2; 66 67 exit(ret); 68 } 69 70 static void fatal_perror(const char *str) 71 { 72 perror(str); 73 exit(1); 74 } 75 76 static void fatal(char *fmt, ...) 77 { 78 va_list list; 79 80 va_start(list, fmt); 81 vfprintf(stderr, fmt, list); 82 va_end(list); 83 84 exit(1); 85 } 86 87 static void non_fatal(char *fmt, ...) 88 { 89 va_list list; 90 91 va_start(list, fmt); 92 vfprintf(stderr, fmt, list); 93 va_end(list); 94 } 95 96 static int start_ptraced_child(void) 97 { 98 int pid, n, status; 99 100 fflush(stdout); 101 102 pid = fork(); 103 if (pid == 0) 104 ptrace_child(); 105 else if (pid < 0) 106 fatal_perror("start_ptraced_child : fork failed"); 107 108 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 109 if (n < 0) 110 fatal_perror("check_ptrace : waitpid failed"); 111 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 112 fatal("check_ptrace : expected SIGSTOP, got status = %d", 113 status); 114 115 return pid; 116 } 117 118 static void stop_ptraced_child(int pid, int exitcode) 119 { 120 int status, n; 121 122 if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) 123 fatal_perror("stop_ptraced_child : ptrace failed"); 124 125 CATCH_EINTR(n = waitpid(pid, &status, 0)); 126 if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 127 int exit_with = WEXITSTATUS(status); 128 fatal("stop_ptraced_child : child exited with exitcode %d, " 129 "while expecting %d; status 0x%x\n", exit_with, 130 exitcode, status); 131 } 132 } 133 134 static void __init check_sysemu(void) 135 { 136 int pid, n, status, count=0; 137 138 os_info("Checking syscall emulation for ptrace..."); 139 pid = start_ptraced_child(); 140 141 if ((ptrace(PTRACE_SETOPTIONS, pid, 0, 142 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 143 fatal_perror("check_sysemu: PTRACE_SETOPTIONS failed"); 144 145 while (1) { 146 count++; 147 if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 148 goto fail; 149 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 150 if (n < 0) 151 fatal_perror("check_sysemu: wait failed"); 152 153 if (WIFSTOPPED(status) && 154 (WSTOPSIG(status) == (SIGTRAP|0x80))) { 155 if (!count) { 156 non_fatal("check_sysemu: SYSEMU_SINGLESTEP " 157 "doesn't singlestep"); 158 goto fail; 159 } 160 n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, 161 os_getpid()); 162 if (n < 0) 163 fatal_perror("check_sysemu : failed to modify " 164 "system call return"); 165 break; 166 } 167 else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 168 count++; 169 else { 170 non_fatal("check_sysemu: expected SIGTRAP or " 171 "(SIGTRAP | 0x80), got status = %d\n", 172 status); 173 goto fail; 174 } 175 } 176 stop_ptraced_child(pid, 0); 177 178 os_info("OK\n"); 179 180 return; 181 182 fail: 183 stop_ptraced_child(pid, 1); 184 fatal("missing\n"); 185 } 186 187 static void __init check_ptrace(void) 188 { 189 int pid, syscall, n, status; 190 191 os_info("Checking that ptrace can change system call numbers..."); 192 pid = start_ptraced_child(); 193 194 if ((ptrace(PTRACE_SETOPTIONS, pid, 0, 195 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 196 fatal_perror("check_ptrace: PTRACE_SETOPTIONS failed"); 197 198 while (1) { 199 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 200 fatal_perror("check_ptrace : ptrace failed"); 201 202 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 203 if (n < 0) 204 fatal_perror("check_ptrace : wait failed"); 205 206 if (!WIFSTOPPED(status) || 207 (WSTOPSIG(status) != (SIGTRAP | 0x80))) 208 fatal("check_ptrace : expected (SIGTRAP|0x80), " 209 "got status = %d", status); 210 211 syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET, 212 0); 213 if (syscall == __NR_getpid) { 214 n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, 215 __NR_getppid); 216 if (n < 0) 217 fatal_perror("check_ptrace : failed to modify " 218 "system call"); 219 break; 220 } 221 } 222 stop_ptraced_child(pid, 0); 223 os_info("OK\n"); 224 check_sysemu(); 225 } 226 227 static void __init check_coredump_limit(void) 228 { 229 struct rlimit lim; 230 int err = getrlimit(RLIMIT_CORE, &lim); 231 232 if (err) { 233 perror("Getting core dump limit"); 234 return; 235 } 236 237 os_info("Core dump limits :\n\tsoft - "); 238 if (lim.rlim_cur == RLIM_INFINITY) 239 os_info("NONE\n"); 240 else 241 os_info("%llu\n", (unsigned long long)lim.rlim_cur); 242 243 os_info("\thard - "); 244 if (lim.rlim_max == RLIM_INFINITY) 245 os_info("NONE\n"); 246 else 247 os_info("%llu\n", (unsigned long long)lim.rlim_max); 248 } 249 250 void __init get_host_cpu_features( 251 void (*flags_helper_func)(char *line), 252 void (*cache_helper_func)(char *line)) 253 { 254 FILE *cpuinfo; 255 char *line = NULL; 256 size_t len = 0; 257 int done_parsing = 0; 258 259 cpuinfo = fopen("/proc/cpuinfo", "r"); 260 if (cpuinfo == NULL) { 261 os_info("Failed to get host CPU features\n"); 262 } else { 263 while ((getline(&line, &len, cpuinfo)) != -1) { 264 if (strstr(line, "flags")) { 265 flags_helper_func(line); 266 done_parsing++; 267 } 268 if (strstr(line, "cache_alignment")) { 269 cache_helper_func(line); 270 done_parsing++; 271 } 272 free(line); 273 line = NULL; 274 if (done_parsing > 1) 275 break; 276 } 277 fclose(cpuinfo); 278 } 279 } 280 281 282 void __init os_early_checks(void) 283 { 284 int pid; 285 286 /* Print out the core dump limits early */ 287 check_coredump_limit(); 288 289 check_ptrace(); 290 291 /* Need to check this early because mmapping happens before the 292 * kernel is running. 293 */ 294 check_tmpexec(); 295 296 pid = start_ptraced_child(); 297 if (init_pid_registers(pid)) 298 fatal("Failed to initialize default registers"); 299 stop_ptraced_child(pid, 1); 300 } 301 302 int __init parse_iomem(char *str, int *add) 303 { 304 struct iomem_region *new; 305 struct stat64 buf; 306 char *file, *driver; 307 int fd, size; 308 309 driver = str; 310 file = strchr(str,','); 311 if (file == NULL) { 312 os_warn("parse_iomem : failed to parse iomem\n"); 313 goto out; 314 } 315 *file = '\0'; 316 file++; 317 fd = open(file, O_RDWR, 0); 318 if (fd < 0) { 319 perror("parse_iomem - Couldn't open io file"); 320 goto out; 321 } 322 323 if (fstat64(fd, &buf) < 0) { 324 perror("parse_iomem - cannot stat_fd file"); 325 goto out_close; 326 } 327 328 new = malloc(sizeof(*new)); 329 if (new == NULL) { 330 perror("Couldn't allocate iomem_region struct"); 331 goto out_close; 332 } 333 334 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 335 336 *new = ((struct iomem_region) { .next = iomem_regions, 337 .driver = driver, 338 .fd = fd, 339 .size = size, 340 .phys = 0, 341 .virt = 0 }); 342 iomem_regions = new; 343 iomem_size += new->size + UM_KERN_PAGE_SIZE; 344 345 return 0; 346 out_close: 347 close(fd); 348 out: 349 return 1; 350 } 351