#include <elf.h> #include <poll.h> #include <fcntl.h> #include <signal.h> #include <unistd.h> #include "syscall.h" #include "atomic.h" #include "libc.h" static void dummy(void) {} weak_alias(dummy, _init); extern weak hidden void (*const __init_array_start)(void), (*const __init_array_end)(void); static void dummy1(void *p) {} weak_alias(dummy1, __init_ssp); #define AUX_CNT 38 #ifdef __GNUC__ __attribute__((__noinline__)) #endif void __init_libc(char **envp, char *pn) { size_t i, *auxv, aux[AUX_CNT] = { 0 }; __environ = envp; for (i=0; envp[i]; i++); libc.auxv = auxv = (void *)(envp+i+1); for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) aux[auxv[i]] = auxv[i+1]; __hwcap = aux[AT_HWCAP]; if (aux[AT_SYSINFO]) __sysinfo = aux[AT_SYSINFO]; libc.page_size = aux[AT_PAGESZ]; if (!pn) pn = (void*)aux[AT_EXECFN]; if (!pn) pn = ""; __progname = __progname_full = pn; for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1; __init_tls(aux); __init_ssp((void *)aux[AT_RANDOM]); if (aux[AT_UID]==aux[AT_EUID] && aux[AT_GID]==aux[AT_EGID] && !aux[AT_SECURE]) return; struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} }; int r = #ifdef SYS_poll __syscall(SYS_poll, pfd, 3, 0); #else __syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8); #endif if (r<0) a_crash(); for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL) if (__sys_open("/dev/null", O_RDWR)<0) a_crash(); libc.secure = 1; } static void libc_start_init(void) { _init(); uintptr_t a = (uintptr_t)&__init_array_start; for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)())) (*(void (**)(void))a)(); } weak_alias(libc_start_init, __libc_start_init); typedef int lsm2_fn(int (*)(int,char **,char **), int, char **); static lsm2_fn libc_start_main_stage2; int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv) { char **envp = argv+argc+1; /* External linkage, and explicit noinline attribute if available, * are used to prevent the stack frame used during init from * persisting for the entire process lifetime. */ __init_libc(envp, argv[0]); /* Barrier against hoisting application code or anything using ssp * or thread pointer prior to its initialization above. */ lsm2_fn *stage2 = libc_start_main_stage2; __asm__ ( "" : "+r"(stage2) : : "memory" ); return stage2(main, argc, argv); } static int libc_start_main_stage2(int (*main)(int,char **,char **), int argc, char **argv) { char **envp = argv+argc+1; __libc_start_init(); /* Pass control to the application */ exit(main(argc, argv, envp)); return 0; }