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 PGD_BOUND (4 * 1024 * 1024) 23 #define STACKSIZE (8 * 1024 * 1024) 24 #define THREAD_NAME_LEN (256) 25 26 long elf_aux_hwcap; 27 28 static void set_stklim(void) 29 { 30 struct rlimit lim; 31 32 if (getrlimit(RLIMIT_STACK, &lim) < 0) { 33 perror("getrlimit"); 34 exit(1); 35 } 36 if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) { 37 lim.rlim_cur = STACKSIZE; 38 if (setrlimit(RLIMIT_STACK, &lim) < 0) { 39 perror("setrlimit"); 40 exit(1); 41 } 42 } 43 } 44 45 static void last_ditch_exit(int sig) 46 { 47 uml_cleanup(); 48 exit(1); 49 } 50 51 static void install_fatal_handler(int sig) 52 { 53 struct sigaction action; 54 55 /* All signals are enabled in this handler ... */ 56 sigemptyset(&action.sa_mask); 57 58 /* 59 * ... including the signal being handled, plus we want the 60 * handler reset to the default behavior, so that if an exit 61 * handler is hanging for some reason, the UML will just die 62 * after this signal is sent a second time. 63 */ 64 action.sa_flags = SA_RESETHAND | SA_NODEFER; 65 action.sa_restorer = NULL; 66 action.sa_handler = last_ditch_exit; 67 if (sigaction(sig, &action, NULL) < 0) { 68 os_warn("failed to install handler for signal %d " 69 "- errno = %d\n", sig, errno); 70 exit(1); 71 } 72 } 73 74 #define UML_LIB_PATH ":" OS_LIB_PATH "/uml" 75 76 static void setup_env_path(void) 77 { 78 char *new_path = NULL; 79 char *old_path = NULL; 80 int path_len = 0; 81 82 old_path = getenv("PATH"); 83 /* 84 * if no PATH variable is set or it has an empty value 85 * just use the default + /usr/lib/uml 86 */ 87 if (!old_path || (path_len = strlen(old_path)) == 0) { 88 if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH)) 89 perror("couldn't putenv"); 90 return; 91 } 92 93 /* append /usr/lib/uml to the existing path */ 94 path_len += strlen("PATH=" UML_LIB_PATH) + 1; 95 new_path = malloc(path_len); 96 if (!new_path) { 97 perror("couldn't malloc to set a new PATH"); 98 return; 99 } 100 snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path); 101 if (putenv(new_path)) { 102 perror("couldn't putenv to set a new PATH"); 103 free(new_path); 104 } 105 } 106 107 int __init main(int argc, char **argv, char **envp) 108 { 109 char **new_argv; 110 int ret, i, err; 111 112 /* Disable randomization and re-exec if it was changed successfully */ 113 ret = personality(PER_LINUX | ADDR_NO_RANDOMIZE); 114 if (ret >= 0 && (ret & (PER_LINUX | ADDR_NO_RANDOMIZE)) != 115 (PER_LINUX | ADDR_NO_RANDOMIZE)) { 116 char buf[4096] = {}; 117 ssize_t ret; 118 119 ret = readlink("/proc/self/exe", buf, sizeof(buf)); 120 if (ret < 0 || ret >= sizeof(buf)) { 121 perror("readlink failure"); 122 exit(1); 123 } 124 execve(buf, argv, envp); 125 } 126 127 set_stklim(); 128 129 setup_env_path(); 130 131 setsid(); 132 133 new_argv = malloc((argc + 1) * sizeof(char *)); 134 if (new_argv == NULL) { 135 perror("Mallocing argv"); 136 exit(1); 137 } 138 for (i = 0; i < argc; i++) { 139 new_argv[i] = strdup(argv[i]); 140 if (new_argv[i] == NULL) { 141 perror("Mallocing an arg"); 142 exit(1); 143 } 144 } 145 new_argv[argc] = NULL; 146 147 /* 148 * Allow these signals to bring down a UML if all other 149 * methods of control fail. 150 */ 151 install_fatal_handler(SIGINT); 152 install_fatal_handler(SIGTERM); 153 154 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA 155 scan_elf_aux(envp); 156 #endif 157 158 change_sig(SIGPIPE, 0); 159 ret = linux_main(argc, argv, envp); 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(); 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 (ret) { 193 execvp(new_argv[0], new_argv); 194 perror("Failed to exec kernel"); 195 ret = 1; 196 } 197 return uml_exitcode; 198 } 199 200 extern void *__real_malloc(int); 201 extern void __real_free(void *); 202 203 /* workaround for -Wmissing-prototypes warnings */ 204 void *__wrap_malloc(int size); 205 void *__wrap_calloc(int n, int size); 206 void __wrap_free(void *ptr); 207 208 void *__wrap_malloc(int size) 209 { 210 void *ret; 211 212 if (!kmalloc_ok) 213 return __real_malloc(size); 214 else if (size <= UM_KERN_PAGE_SIZE) 215 /* finding contiguous pages can be hard*/ 216 ret = uml_kmalloc(size, UM_GFP_KERNEL); 217 else ret = vmalloc(size); 218 219 /* 220 * glibc people insist that if malloc fails, errno should be 221 * set by malloc as well. So we do. 222 */ 223 if (ret == NULL) 224 errno = ENOMEM; 225 226 return ret; 227 } 228 229 void *__wrap_calloc(int n, int size) 230 { 231 void *ptr = __wrap_malloc(n * size); 232 233 if (ptr == NULL) 234 return NULL; 235 memset(ptr, 0, n * size); 236 return ptr; 237 } 238 239 void __wrap_free(void *ptr) 240 { 241 unsigned long addr = (unsigned long) ptr; 242 243 /* 244 * We need to know how the allocation happened, so it can be correctly 245 * freed. This is done by seeing what region of memory the pointer is 246 * in - 247 * physical memory - kmalloc/kfree 248 * kernel virtual memory - vmalloc/vfree 249 * anywhere else - malloc/free 250 * If kmalloc is not yet possible, then either high_physmem and/or 251 * end_vm are still 0 (as at startup), in which case we call free, or 252 * we have set them, but anyway addr has not been allocated from those 253 * areas. So, in both cases __real_free is called. 254 * 255 * CAN_KMALLOC is checked because it would be bad to free a buffer 256 * with kmalloc/vmalloc after they have been turned off during 257 * shutdown. 258 * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so 259 * there is a possibility for memory leaks. 260 */ 261 262 if ((addr >= uml_physmem) && (addr < high_physmem)) { 263 if (kmalloc_ok) 264 kfree(ptr); 265 } 266 else if ((addr >= start_vm) && (addr < end_vm)) { 267 if (kmalloc_ok) 268 vfree(ptr); 269 } 270 else __real_free(ptr); 271 } 272