1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <stdarg.h> 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 <termios.h> 14 #include <sys/wait.h> 15 #include <sys/mman.h> 16 #include <sys/utsname.h> 17 #include <sys/random.h> 18 #include <init.h> 19 #include <os.h> 20 stack_protections(unsigned long address)21 void stack_protections(unsigned long address) 22 { 23 if (mprotect((void *) address, UM_THREAD_SIZE, 24 PROT_READ | PROT_WRITE | PROT_EXEC) < 0) 25 panic("protecting stack failed, errno = %d", errno); 26 } 27 raw(int fd)28 int raw(int fd) 29 { 30 struct termios tt; 31 int err; 32 33 CATCH_EINTR(err = tcgetattr(fd, &tt)); 34 if (err < 0) 35 return -errno; 36 37 cfmakeraw(&tt); 38 39 CATCH_EINTR(err = tcsetattr(fd, TCSADRAIN, &tt)); 40 if (err < 0) 41 return -errno; 42 43 /* 44 * XXX tcsetattr could have applied only some changes 45 * (and cfmakeraw() is a set of changes) 46 */ 47 return 0; 48 } 49 setup_machinename(char * machine_out)50 void setup_machinename(char *machine_out) 51 { 52 struct utsname host; 53 54 uname(&host); 55 #if IS_ENABLED(CONFIG_UML_X86) 56 # if !IS_ENABLED(CONFIG_64BIT) 57 if (!strcmp(host.machine, "x86_64")) { 58 strcpy(machine_out, "i686"); 59 return; 60 } 61 # else 62 if (!strcmp(host.machine, "i686")) { 63 strcpy(machine_out, "x86_64"); 64 return; 65 } 66 # endif 67 #endif 68 strcpy(machine_out, host.machine); 69 } 70 setup_hostinfo(char * buf,int len)71 void setup_hostinfo(char *buf, int len) 72 { 73 struct utsname host; 74 75 uname(&host); 76 snprintf(buf, len, "%s %s %s %s %s", host.sysname, host.nodename, 77 host.release, host.version, host.machine); 78 } 79 80 /* 81 * We cannot use glibc's abort(). It makes use of tgkill() which 82 * has no effect within UML's kernel threads. 83 * After that glibc would execute an invalid instruction to kill 84 * the calling process and UML crashes with SIGSEGV. 85 */ uml_abort(void)86 static inline void __attribute__ ((noreturn)) uml_abort(void) 87 { 88 sigset_t sig; 89 90 fflush(NULL); 91 92 if (!sigemptyset(&sig) && !sigaddset(&sig, SIGABRT)) 93 sigprocmask(SIG_UNBLOCK, &sig, 0); 94 95 for (;;) 96 if (kill(getpid(), SIGABRT) < 0) 97 exit(127); 98 } 99 os_getrandom(void * buf,size_t len,unsigned int flags)100 ssize_t os_getrandom(void *buf, size_t len, unsigned int flags) 101 { 102 return getrandom(buf, len, flags); 103 } 104 105 /* 106 * UML helper threads must not handle SIGWINCH/INT/TERM 107 */ os_fix_helper_signals(void)108 void os_fix_helper_signals(void) 109 { 110 signal(SIGWINCH, SIG_IGN); 111 signal(SIGINT, SIG_DFL); 112 signal(SIGTERM, SIG_DFL); 113 } 114 os_dump_core(void)115 void os_dump_core(void) 116 { 117 int pid; 118 119 signal(SIGSEGV, SIG_DFL); 120 121 /* 122 * We are about to SIGTERM this entire process group to ensure that 123 * nothing is around to run after the kernel exits. The 124 * kernel wants to abort, not die through SIGTERM, so we 125 * ignore it here. 126 */ 127 128 signal(SIGTERM, SIG_IGN); 129 kill(0, SIGTERM); 130 /* 131 * Most of the other processes associated with this UML are 132 * likely sTopped, so give them a SIGCONT so they see the 133 * SIGTERM. 134 */ 135 kill(0, SIGCONT); 136 137 /* 138 * Now, having sent signals to everyone but us, make sure they 139 * die by ptrace. Processes can survive what's been done to 140 * them so far - the mechanism I understand is receiving a 141 * SIGSEGV and segfaulting immediately upon return. There is 142 * always a SIGSEGV pending, and (I'm guessing) signals are 143 * processed in numeric order so the SIGTERM (signal 15 vs 144 * SIGSEGV being signal 11) is never handled. 145 * 146 * Run a waitpid loop until we get some kind of error. 147 * Hopefully, it's ECHILD, but there's not a lot we can do if 148 * it's something else. Tell os_kill_ptraced_process not to 149 * wait for the child to report its death because there's 150 * nothing reasonable to do if that fails. 151 */ 152 153 while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0) 154 os_kill_ptraced_process(pid, 0); 155 156 uml_abort(); 157 } 158 um_early_printk(const char * s,unsigned int n)159 void um_early_printk(const char *s, unsigned int n) 160 { 161 printf("%.*s", n, s); 162 } 163 164 static int quiet_info; 165 quiet_cmd_param(char * str,int * add)166 static int __init quiet_cmd_param(char *str, int *add) 167 { 168 quiet_info = 1; 169 return 0; 170 } 171 172 __uml_setup("quiet", quiet_cmd_param, 173 "quiet\n" 174 " Turns off information messages during boot.\n\n"); 175 176 /* 177 * The os_info/os_warn functions will be called by helper threads. These 178 * have a very limited stack size and using the libc formatting functions 179 * may overflow the stack. 180 * So pull in the kernel vscnprintf and use that instead with a fixed 181 * on-stack buffer. 182 */ 183 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args); 184 os_info(const char * fmt,...)185 void os_info(const char *fmt, ...) 186 { 187 char buf[256]; 188 va_list list; 189 int len; 190 191 if (quiet_info) 192 return; 193 194 va_start(list, fmt); 195 len = vscnprintf(buf, sizeof(buf), fmt, list); 196 fwrite(buf, len, 1, stderr); 197 va_end(list); 198 } 199 os_warn(const char * fmt,...)200 void os_warn(const char *fmt, ...) 201 { 202 char buf[256]; 203 va_list list; 204 int len; 205 206 va_start(list, fmt); 207 len = vscnprintf(buf, sizeof(buf), fmt, list); 208 fwrite(buf, len, 1, stderr); 209 va_end(list); 210 } 211