protect against cancellation in dlopen

[musl] / src / ldso / dynlink.c

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index e1c2ad7..6ff8850 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -47,8 +47,9 @@ struct dso
        size_t map_len;
        dev_t dev;
        ino_t ino;
-       int global;
-       int relocated;
+       char global;
+       char relocated;
+       char constructed;
        struct dso **deps;
        char *name;
        char buf[];
@@ -471,6 +472,20 @@ static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
        return 0;
 }
 
+static void do_init_fini(struct dso *p)
+{
+       size_t dyn[DYN_CNT] = {0};
+       for (; p; p=p->prev) {
+               if (p->constructed) return;
+               decode_vec(p->dynv, dyn, DYN_CNT);
+               if (dyn[0] & (1<<DT_FINI))
+                       atexit((void (*)(void))(p->base + dyn[DT_FINI]));
+               if (dyn[0] & (1<<DT_INIT))
+                       ((void (*)(void))(p->base + dyn[DT_INIT]))();
+               p->constructed = 1;
+       }
+}
+
 void *__dynlink(int argc, char **argv)
 {
        size_t *auxv, aux[AUX_CNT] = {0};
@@ -511,12 +526,16 @@ void *__dynlink(int argc, char **argv)
                ehdr->e_phnum, ehdr->e_phentsize));
        decode_dyn(lib);
 
-       /* Assume base address of 0 for the main program. This is not
-        * valid for PIE code; we will have to search the PHDR to get
-        * the correct load address in the PIE case (not yet supported). */
+       /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
        app->base = 0;
+       phdr = (void *)aux[AT_PHDR];
+       for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
+               if (phdr->p_type == PT_PHDR)
+                       app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
+       }
        app->name = argv[0];
        app->global = 1;
+       app->constructed = 1;
        app->dynv = (void *)(app->base + find_dyn(
                (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
        decode_dyn(app);
@@ -560,10 +579,13 @@ void *__dynlink(int argc, char **argv)
                ehdr->e_phentsize, ehdr->e_phnum);
 
        /* Load preload/needed libraries, add their symbols to the global
-        * namespace, and perform all remaining relocations. */
+        * namespace, and perform all remaining relocations. The main
+        * program must be relocated LAST since it may contain copy
+        * relocations which depend on libraries' relocations. */
        if (env_preload) load_preload(env_preload);
        load_deps(app);
        make_global(app);
+       reloc_all(app->next);
        reloc_all(app);
 
        /* Switch to runtime mode: any further failures in the dynamic
@@ -571,6 +593,9 @@ void *__dynlink(int argc, char **argv)
         * error. If the dynamic loader (dlopen) will not be used, free
         * all memory used by the dynamic linker. */
        runtime = 1;
+
+       do_init_fini(tail);
+
        if (!rtld_used) {
                free_all(head);
                free(sys_path);
@@ -585,9 +610,11 @@ void *dlopen(const char *file, int mode)
 {
        struct dso *volatile p, *orig_tail = tail, *next;
        size_t i;
+       int cs;
 
        if (!file) return head;
 
+       pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
        pthread_rwlock_wrlock(&lock);
 
        if (setjmp(rtld_fail)) {
@@ -603,8 +630,8 @@ void *dlopen(const char *file, int mode)
                }
                tail = orig_tail;
                tail->next = 0;
-               pthread_rwlock_unlock(&lock);
-               return 0;
+               p = 0;
+               goto end;
        }
 
        p = load_library(file);
@@ -630,8 +657,10 @@ void *dlopen(const char *file, int mode)
                p->global = 1;
        }
 
+       do_init_fini(tail);
 end:
        pthread_rwlock_unlock(&lock);
+       pthread_setcancelstate(cs, 0);
        return p;
 }
 
@@ -668,6 +697,16 @@ void *__dlsym(void *p, const char *s, void *ra)
        pthread_rwlock_unlock(&lock);
        return res;
 }
+#else
+void *dlopen(const char *file, int mode)
+{
+       return 0;
+}
+void *__dlsym(void *p, const char *s, void *ra)
+{
+       return 0;
+}
+#endif
 
 char *dlerror()
 {
@@ -678,4 +717,3 @@ int dlclose(void *p)
 {
        return 0;
 }
-#endif