1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) 4 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 5 */ 6 7 #include <stdio.h> 8 #include <stdlib.h> 9 #include <unistd.h> 10 #include <errno.h> 11 #include <signal.h> 12 #include <string.h> 13 #include <sys/resource.h> 14 #include <sys/personality.h> 15 #include <as-layout.h> 16 #include <init.h> 17 #include <kern_util.h> 18 #include <os.h> 19 #include <um_malloc.h> 20 #include "internal.h" 21 22 #define STACKSIZE (8 * 1024 * 1024) 23 24 static void __init set_stklim(void) 25 { 26 struct rlimit lim; 27 28 if (getrlimit(RLIMIT_STACK, &lim) < 0) { 29 perror("getrlimit"); 30 exit(1); 31 } 32 if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) { 33 lim.rlim_cur = STACKSIZE; 34 if (setrlimit(RLIMIT_STACK, &lim) < 0) { 35 perror("setrlimit"); 36 exit(1); 37 } 38 } 39 } 40 41 static void last_ditch_exit(int sig) 42 { 43 uml_cleanup(); 44 exit(1); 45 } 46 47 static void __init install_fatal_handler(int sig) 48 { 49 struct sigaction action; 50 51 /* All signals are enabled in this handler ... */ 52 sigemptyset(&action.sa_mask); 53 54 /* 55 * ... including the signal being handled, plus we want the 56 * handler reset to the default behavior, so that if an exit 57 * handler is hanging for some reason, the UML will just die 58 * after this signal is sent a second time. 59 */ 60 action.sa_flags = SA_RESETHAND | SA_NODEFER; 61 action.sa_restorer = NULL; 62 action.sa_handler = last_ditch_exit; 63 if (sigaction(sig, &action, NULL) < 0) { 64 os_warn("failed to install handler for signal %d " 65 "- errno = %d\n", sig, errno); 66 exit(1); 67 } 68 } 69 70 #define UML_LIB_PATH ":" OS_LIB_PATH "/uml" 71 72 static void __init setup_env_path(void) 73 { 74 char *new_path = NULL; 75 char *old_path = NULL; 76 int path_len = 0; 77 78 old_path = getenv("PATH"); 79 /* 80 * if no PATH variable is set or it has an empty value 81 * just use the default + /usr/lib/uml 82 */ 83 if (!old_path || (path_len = strlen(old_path)) == 0) { 84 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH)) 85 perror("couldn't putenv"); 86 return; 87 } 88 89 /* append /usr/lib/uml to the existing path */ 90 path_len += strlen("PATH=" UML_LIB_PATH) + 1; 91 new_path = malloc(path_len); 92 if (!new_path) { 93 perror("couldn't malloc to set a new PATH"); 94 return; 95 } 96 snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path); 97 if (putenv(new_path)) { 98 perror("couldn't putenv to set a new PATH"); 99 free(new_path); 100 } 101 } 102 103 static char **new_argv; 104 105 int __init main(int argc, char **argv, char **envp) 106 { 107 int ret, i; 108 109 /* Disable randomization and re-exec if it was changed successfully */ 110 ret = personality(PER_LINUX | ADDR_NO_RANDOMIZE); 111 if (ret >= 0 && (ret & (PER_LINUX | ADDR_NO_RANDOMIZE)) != 112 (PER_LINUX | ADDR_NO_RANDOMIZE)) { 113 char buf[4096] = {}; 114 ssize_t ret; 115 116 ret = readlink("/proc/self/exe", buf, sizeof(buf)); 117 if (ret < 0 || ret >= sizeof(buf)) { 118 perror("readlink failure"); 119 exit(1); 120 } 121 execve(buf, argv, envp); 122 } 123 124 set_stklim(); 125 126 setup_env_path(); 127 128 setsid(); 129 130 new_argv = malloc((argc + 1) * sizeof(char *)); 131 if (new_argv == NULL) { 132 perror("Mallocing argv"); 133 exit(1); 134 } 135 for (i = 0; i < argc; i++) { 136 new_argv[i] = strdup(argv[i]); 137 if (new_argv[i] == NULL) { 138 perror("Mallocing an arg"); 139 exit(1); 140 } 141 } 142 new_argv[argc] = NULL; 143 144 /* 145 * Allow these signals to bring down a UML if all other 146 * methods of control fail. 147 */ 148 install_fatal_handler(SIGINT); 149 install_fatal_handler(SIGTERM); 150 151 scan_elf_aux(envp); 152 153 change_sig(SIGPIPE, 0); 154 linux_main(argc, argv, envp); 155 } 156 157 void os_exit(bool reboot) 158 { 159 int err; 160 161 /* 162 * Disable SIGPROF - I have no idea why libc doesn't do this or turn 163 * off the profiling time, but UML dies with a SIGPROF just before 164 * exiting when profiling is active. 165 */ 166 change_sig(SIGPROF, 0); 167 168 /* 169 * This signal stuff used to be in the reboot case. However, 170 * sometimes a timer signal can come in when we're halting (reproducably 171 * when writing out gcov information, presumably because that takes 172 * some time) and cause a segfault. 173 */ 174 175 /* stop timers and set timer signal to be ignored */ 176 os_timer_disable(0); 177 178 /* disable SIGIO for the fds and set SIGIO to be ignored */ 179 err = deactivate_all_fds(); 180 if (err) 181 os_warn("deactivate_all_fds failed, errno = %d\n", -err); 182 183 /* 184 * Let any pending signals fire now. This ensures 185 * that they won't be delivered after the exec, when 186 * they are definitely not expected. 187 */ 188 unblock_signals(); 189 190 os_info("\n"); 191 /* Reboot */ 192 if (reboot) { 193 execvp(new_argv[0], new_argv); 194 perror("Failed to exec kernel"); 195 } 196 exit(uml_exitcode); 197 } 198 199 extern void *__real_malloc(int); 200 extern void __real_free(void *); 201 202 /* workaround for -Wmissing-prototypes warnings */ 203 void *__wrap_malloc(int size); 204 void *__wrap_calloc(int n, int size); 205 void __wrap_free(void *ptr); 206 207 void *__wrap_malloc(int size) 208 { 209 void *ret; 210 211 if (!kmalloc_ok) 212 return __real_malloc(size); 213 else if (size <= UM_KERN_PAGE_SIZE) 214 /* finding contiguous pages can be hard*/ 215 ret = uml_kmalloc(size, UM_GFP_KERNEL); 216 else ret = vmalloc(size); 217 218 /* 219 * glibc people insist that if malloc fails, errno should be 220 * set by malloc as well. So we do. 221 */ 222 if (ret == NULL) 223 errno = ENOMEM; 224 225 return ret; 226 } 227 228 void *__wrap_calloc(int n, int size) 229 { 230 void *ptr = __wrap_malloc(n * size); 231 232 if (ptr == NULL) 233 return NULL; 234 memset(ptr, 0, n * size); 235 return ptr; 236 } 237 238 void __wrap_free(void *ptr) 239 { 240 unsigned long addr = (unsigned long) ptr; 241 242 /* 243 * We need to know how the allocation happened, so it can be correctly 244 * freed. This is done by seeing what region of memory the pointer is 245 * in - 246 * physical memory - kmalloc/kfree 247 * kernel virtual memory - vmalloc/vfree 248 * anywhere else - malloc/free 249 * If kmalloc is not yet possible, then either high_physmem and/or 250 * end_vm are still 0 (as at startup), in which case we call free, or 251 * we have set them, but anyway addr has not been allocated from those 252 * areas. So, in both cases __real_free is called. 253 * 254 * CAN_KMALLOC is checked because it would be bad to free a buffer 255 * with kmalloc/vmalloc after they have been turned off during 256 * shutdown. 257 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so 258 * there is a possibility for memory leaks. 259 */ 260 261 if ((addr >= uml_physmem) && (addr < high_physmem)) { 262 if (kmalloc_ok) 263 kfree(ptr); 264 } 265 else if ((addr >= start_vm) && (addr < end_vm)) { 266 if (kmalloc_ok) 267 vfree(ptr); 268 } 269 else __real_free(ptr); 270 } 271