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 int __init main(int argc, char **argv, char **envp) 104 { 105 char **new_argv; 106 int ret, i, err; 107 108 /* Disable randomization and re-exec if it was changed successfully */ 109 ret = personality(PER_LINUX | ADDR_NO_RANDOMIZE); 110 if (ret >= 0 && (ret & (PER_LINUX | ADDR_NO_RANDOMIZE)) != 111 (PER_LINUX | ADDR_NO_RANDOMIZE)) { 112 char buf[4096] = {}; 113 ssize_t ret; 114 115 ret = readlink("/proc/self/exe", buf, sizeof(buf)); 116 if (ret < 0 || ret >= sizeof(buf)) { 117 perror("readlink failure"); 118 exit(1); 119 } 120 execve(buf, argv, envp); 121 } 122 123 set_stklim(); 124 125 setup_env_path(); 126 127 setsid(); 128 129 new_argv = malloc((argc + 1) * sizeof(char *)); 130 if (new_argv == NULL) { 131 perror("Mallocing argv"); 132 exit(1); 133 } 134 for (i = 0; i < argc; i++) { 135 new_argv[i] = strdup(argv[i]); 136 if (new_argv[i] == NULL) { 137 perror("Mallocing an arg"); 138 exit(1); 139 } 140 } 141 new_argv[argc] = NULL; 142 143 /* 144 * Allow these signals to bring down a UML if all other 145 * methods of control fail. 146 */ 147 install_fatal_handler(SIGINT); 148 install_fatal_handler(SIGTERM); 149 150 scan_elf_aux(envp); 151 152 change_sig(SIGPIPE, 0); 153 ret = linux_main(argc, argv, envp); 154 155 /* 156 * Disable SIGPROF - I have no idea why libc doesn't do this or turn 157 * off the profiling time, but UML dies with a SIGPROF just before 158 * exiting when profiling is active. 159 */ 160 change_sig(SIGPROF, 0); 161 162 /* 163 * This signal stuff used to be in the reboot case. However, 164 * sometimes a timer signal can come in when we're halting (reproducably 165 * when writing out gcov information, presumably because that takes 166 * some time) and cause a segfault. 167 */ 168 169 /* stop timers and set timer signal to be ignored */ 170 os_timer_disable(0); 171 172 /* disable SIGIO for the fds and set SIGIO to be ignored */ 173 err = deactivate_all_fds(); 174 if (err) 175 os_warn("deactivate_all_fds failed, errno = %d\n", -err); 176 177 /* 178 * Let any pending signals fire now. This ensures 179 * that they won't be delivered after the exec, when 180 * they are definitely not expected. 181 */ 182 unblock_signals(); 183 184 os_info("\n"); 185 /* Reboot */ 186 if (ret) { 187 execvp(new_argv[0], new_argv); 188 perror("Failed to exec kernel"); 189 ret = 1; 190 } 191 return uml_exitcode; 192 } 193 194 extern void *__real_malloc(int); 195 extern void __real_free(void *); 196 197 /* workaround for -Wmissing-prototypes warnings */ 198 void *__wrap_malloc(int size); 199 void *__wrap_calloc(int n, int size); 200 void __wrap_free(void *ptr); 201 202 void *__wrap_malloc(int size) 203 { 204 void *ret; 205 206 if (!kmalloc_ok) 207 return __real_malloc(size); 208 else if (size <= UM_KERN_PAGE_SIZE) 209 /* finding contiguous pages can be hard*/ 210 ret = uml_kmalloc(size, UM_GFP_KERNEL); 211 else ret = vmalloc(size); 212 213 /* 214 * glibc people insist that if malloc fails, errno should be 215 * set by malloc as well. So we do. 216 */ 217 if (ret == NULL) 218 errno = ENOMEM; 219 220 return ret; 221 } 222 223 void *__wrap_calloc(int n, int size) 224 { 225 void *ptr = __wrap_malloc(n * size); 226 227 if (ptr == NULL) 228 return NULL; 229 memset(ptr, 0, n * size); 230 return ptr; 231 } 232 233 void __wrap_free(void *ptr) 234 { 235 unsigned long addr = (unsigned long) ptr; 236 237 /* 238 * We need to know how the allocation happened, so it can be correctly 239 * freed. This is done by seeing what region of memory the pointer is 240 * in - 241 * physical memory - kmalloc/kfree 242 * kernel virtual memory - vmalloc/vfree 243 * anywhere else - malloc/free 244 * If kmalloc is not yet possible, then either high_physmem and/or 245 * end_vm are still 0 (as at startup), in which case we call free, or 246 * we have set them, but anyway addr has not been allocated from those 247 * areas. So, in both cases __real_free is called. 248 * 249 * CAN_KMALLOC is checked because it would be bad to free a buffer 250 * with kmalloc/vmalloc after they have been turned off during 251 * shutdown. 252 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so 253 * there is a possibility for memory leaks. 254 */ 255 256 if ((addr >= uml_physmem) && (addr < high_physmem)) { 257 if (kmalloc_ok) 258 kfree(ptr); 259 } 260 else if ((addr >= start_vm) && (addr < end_vm)) { 261 if (kmalloc_ok) 262 vfree(ptr); 263 } 264 else __real_free(ptr); 265 } 266