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