elf.h: add ELFCOMPRESS_ZSTD

[musl] / src / env / __libc_start_main.c

diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c
index ee10b0d..c5b277b 100644 (file)
--- a/src/env/__libc_start_main.c
+++ b/src/env/__libc_start_main.c
@@ -1,14 +1,26 @@
 #include <elf.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include "syscall.h"
+#include "atomic.h"
 #include "libc.h"
 
-void __init_tls(size_t *);
-void __init_security(size_t *);
+static void dummy(void) {}
+weak_alias(dummy, _init);
 
-#define AUX_CNT 38
+extern weak hidden void (*const __init_array_start)(void), (*const __init_array_end)(void);
+
+static void dummy1(void *p) {}
+weak_alias(dummy1, __init_ssp);
 
-extern size_t __hwcap, __sysinfo;
+#define AUX_CNT 38
 
-void __init_libc(char **envp)
+#ifdef __GNUC__
+__attribute__((__noinline__))
+#endif
+void __init_libc(char **envp, char *pn)
 {
        size_t i, *auxv, aux[AUX_CNT] = { 0 };
        __environ = envp;
@@ -16,28 +28,70 @@ void __init_libc(char **envp)
        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];
-       __sysinfo = aux[AT_SYSINFO];
+       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_security(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)();
 }
 
-int __libc_start_main(
-       int (*main)(int, char **, char **), int argc, char **argv,
-       int (*init)(int, char **, char **), void (*fini)(void),
-       void (*ldso_fini)(void))
+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,
+       void (*init_dummy)(), void(*fini_dummy)(), void(*ldso_dummy)())
 {
        char **envp = argv+argc+1;
 
-       __init_libc(envp);
+       /* 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]);
 
-       libc.ldso_fini = ldso_fini;
-       libc.fini = fini;
+       /* 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);
+}
 
-       /* Execute constructors (static) linked into the application */
-       if (init) init(argc, argv, envp);
+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 to application */
+       /* Pass control to the application */
        exit(main(argc, argv, envp));
        return 0;
 }