X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fldso%2Fdynlink.c;h=3f3316aaf4ccde3c4ff7e8880d562484f99efc2a;hp=ced1637cf108bf9d5abd0d234179ac7cc8e82cbd;hb=3ec8d29c754542c3f4b3d6c07ab6db17213aff17;hpb=2719cc86285d85df42f13ba0ae5b07b262c39686

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index ced1637c..3f3316aa 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -17,6 +17,11 @@
 #include <ctype.h>
 #include <dlfcn.h>
 
+static int errflag;
+static char errbuf[128];
+
+#ifdef __PIC__
+
 #include "reloc.h"
 
 #if ULONG_MAX == 0xffffffff
@@ -33,34 +38,50 @@ typedef Elf64_Sym Sym;
 #define R_SYM(x) ((x)>>32)
 #endif
 
-struct dso
-{
+struct debug {
+	int ver;
+	void *head;
+	void (*bp)(void);
+	int state;
+	void *base;
+};
+
+struct dso {
+	unsigned char *base;
+	char *name;
+	size_t *dynv;
 	struct dso *next, *prev;
+
 	int refcnt;
-	size_t *dynv;
 	Sym *syms;
 	uint32_t *hashtab;
 	char *strings;
-	unsigned char *base;
 	unsigned char *map;
 	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[];
 };
 
+struct __pthread;
+struct __pthread *__pthread_self_init(void);
+
 static struct dso *head, *tail, *libc;
 static char *env_path, *sys_path, *r_path;
 static int rtld_used;
+static int ssp_used;
 static int runtime;
 static jmp_buf rtld_fail;
 static pthread_rwlock_t lock;
+static struct debug debug;
 
-#define AUX_CNT 15
+struct debug *_dl_debug_addr = &debug;
+
+#define AUX_CNT 24
 #define DYN_CNT 34
 
 static void decode_vec(size_t *v, size_t *a, size_t cnt)
@@ -72,8 +93,9 @@ static void decode_vec(size_t *v, size_t *a, size_t cnt)
 	}
 }
 
-static uint32_t hash(const char *s)
+static uint32_t hash(const char *s0)
 {
+	const unsigned char *s = (void *)s0;
 	uint_fast32_t h = 0;
 	while (*s) {
 		h = 16*h + *s++;
@@ -101,6 +123,7 @@ static void *find_sym(struct dso *dso, const char *s, int need_def)
 	void *def = 0;
 	if (h==0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
 	if (h==0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
+	if (h==0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
 	for (; dso; dso=dso->next) {
 		Sym *sym;
 		if (!dso->global) continue;
@@ -136,8 +159,11 @@ static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t
 			ctx = IS_COPY(type) ? dso->next : dso;
 			sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
 			if (!sym_val && sym->st_info>>4 != STB_WEAK) {
+				snprintf(errbuf, sizeof errbuf,
+					"Error relocating %s: %s: symbol not found",
+					dso->name, name);
 				if (runtime) longjmp(rtld_fail, 1);
-				dprintf(2, "%s: symbol not found\n", name);
+				dprintf(2, "%s\n", errbuf);
 				_exit(127);
 			}
 			sym_size = sym->st_size;
@@ -284,12 +310,20 @@ static int path_open(const char *name, const char *search)
 	}
 }
 
+static void decode_dyn(struct dso *p)
+{
+	size_t dyn[DYN_CNT] = {0};
+	decode_vec(p->dynv, dyn, DYN_CNT);
+	p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
+	p->hashtab = (void *)(p->base + dyn[DT_HASH]);
+	p->strings = (void *)(p->base + dyn[DT_STRTAB]);
+}
+
 static struct dso *load_library(const char *name)
 {
 	unsigned char *base, *map;
 	size_t dyno, map_len;
 	struct dso *p;
-	size_t dyn[DYN_CNT] = {0};
 	int fd;
 	struct stat st;
 
@@ -363,11 +397,8 @@ static struct dso *load_library(const char *name)
 	p->map_len = map_len;
 	p->base = base;
 	p->dynv = (void *)(base + dyno);
-	decode_vec(p->dynv, dyn, DYN_CNT);
+	decode_dyn(p);
 
-	p->syms = (void *)(base + dyn[DT_SYMTAB]);
-	p->hashtab = (void *)(base + dyn[DT_HASH]);
-	p->strings = (void *)(base + dyn[DT_STRTAB]);
 	p->dev = st.st_dev;
 	p->ino = st.st_ino;
 	p->refcnt = 1;
@@ -394,9 +425,11 @@ static void load_deps(struct dso *p)
 			if (p->dynv[i] != DT_NEEDED) continue;
 			dep = load_library(p->strings + p->dynv[i+1]);
 			if (!dep) {
-				if (runtime) longjmp(rtld_fail, 1);
-				dprintf(2, "%s: %m (needed by %s)\n",
+				snprintf(errbuf, sizeof errbuf,
+					"Error loading shared library %s: %m (needed by %s)",
 					p->strings + p->dynv[i+1], p->name);
+				if (runtime) longjmp(rtld_fail, 1);
+				dprintf(2, "%s\n", errbuf);
 				_exit(127);
 			}
 			if (runtime) {
@@ -456,12 +489,35 @@ static void free_all(struct dso *p)
 	}
 }
 
-void *__dynlink(int argc, char **argv, size_t *got)
+static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
+{
+	for (; cnt--; ph = (void *)((char *)ph + stride))
+		if (ph->p_type == PT_DYNAMIC)
+			return ph->p_vaddr;
+	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 _dl_debug_state(void)
+{
+}
+
+void *__dynlink(int argc, char **argv)
 {
 	size_t *auxv, aux[AUX_CNT] = {0};
-	size_t app_dyn[DYN_CNT] = {0};
-	size_t lib_dyn[DYN_CNT] = {0};
-	size_t vdso_dyn[DYN_CNT] = {0};
 	size_t i;
 	Phdr *phdr;
 	Ehdr *ehdr;
@@ -469,7 +525,6 @@ void *__dynlink(int argc, char **argv, size_t *got)
 	struct dso *const app = builtin_dsos+0;
 	struct dso *const lib = builtin_dsos+1;
 	struct dso *const vdso = builtin_dsos+2;
-	size_t vdso_base=0;
 	char *env_preload=0;
 
 	/* Find aux vector just past environ[] */
@@ -482,55 +537,42 @@ void *__dynlink(int argc, char **argv, size_t *got)
 
 	decode_vec(auxv, aux, AUX_CNT);
 
-	for (i=0; auxv[i]; i+=2) {
-		if (auxv[i]==AT_SYSINFO_EHDR) {
-			vdso_base = auxv[i+1];
-			break;
-		}
-	}
-
 	/* Only trust user/env if kernel says we're not suid/sgid */
 	if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
-	  || aux[AT_GID]!=aux[AT_EGID]) {
+	  || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
 		env_path = 0;
 		env_preload = 0;
 	}
 
-	/* Relocate ldso's DYNAMIC pointer and load vector */
-	decode_vec((void *)(got[0] += aux[AT_BASE]), lib_dyn, DYN_CNT);
+	/* The dynamic linker load address is passed by the kernel
+	 * in the AUX vector, so this is easy. */
+	lib->base = (void *)aux[AT_BASE];
+	lib->name = "libc.so";
+	lib->global = 1;
+	ehdr = (void *)lib->base;
+	lib->dynv = (void *)(lib->base + find_dyn(
+		(void *)(aux[AT_BASE]+ehdr->e_phoff),
+		ehdr->e_phnum, ehdr->e_phentsize));
+	decode_dyn(lib);
 
-	/* Find the program image's DYNAMIC section and decode it */
+	/* 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--; phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
-		if (phdr->p_type == PT_DYNAMIC) {
-			decode_vec((void *)phdr->p_vaddr, app_dyn, DYN_CNT);
-			break;
-		}
+	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 = (struct dso){
-		.base = 0,
-		.strings = (void *)(app_dyn[DT_STRTAB]),
-		.hashtab = (void *)(app_dyn[DT_HASH]),
-		.syms = (void *)(app_dyn[DT_SYMTAB]),
-		.dynv = (void *)(phdr->p_vaddr),
-		.name = argv[0],
-		.global = 1,
-		.next = lib
-	};
-
-	*lib = (struct dso){
-		.base = (void *)aux[AT_BASE],
-		.strings = (void *)(aux[AT_BASE]+lib_dyn[DT_STRTAB]),
-		.hashtab = (void *)(aux[AT_BASE]+lib_dyn[DT_HASH]),
-		.syms = (void *)(aux[AT_BASE]+lib_dyn[DT_SYMTAB]),
-		.dynv = (void *)(got[0]),
-		.name = "libc.so",
-		.global = 1,
-		.relocated = 1
-	};
-
-	if (vdso_base) {
+	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);
+
+	/* Attach to vdso, if provided by the kernel */
+	for (i=0; auxv[i]; i+=2) {
+		size_t vdso_base = auxv[i+1];
+		if (auxv[i] != AT_SYSINFO_EHDR) continue;
 		ehdr = (void *)vdso_base;
 		phdr = (void *)(vdso_base + ehdr->e_phoff);
 		for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
@@ -539,47 +581,68 @@ void *__dynlink(int argc, char **argv, size_t *got)
 			if (phdr->p_type == PT_LOAD)
 				vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
 		}
-		decode_vec(vdso->dynv, vdso_dyn, DYN_CNT);
-		vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]);
-		vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]);
-		vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]);
 		vdso->name = "linux-gate.so.1";
 		vdso->global = 1;
-
+		decode_dyn(vdso);
 		vdso->prev = lib;
 		lib->next = vdso;
+		break;
 	}
 
-	/* Relocate the dynamic linker/libc */
-	do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
-		lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);
-	do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_RELA]),
-		lib_dyn[DT_RELASZ], 3, lib->syms, lib->strings, app);
+	/* Initial dso chain consists only of the app. We temporarily
+	 * append the dynamic linker/libc so we can relocate it, then
+	 * restore the initial chain in preparation for loading third
+	 * party libraries (preload/needed). */
+	head = tail = app;
+	libc = lib;
+	app->next = lib;
+	reloc_all(lib);
+	app->next = 0;
 
-	/* At this point the standard library is fully functional */
+	/* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
 
+	/* Donate unused parts of app and library mapping to malloc */
 	reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
 	ehdr = (void *)lib->base;
 	reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
 		ehdr->e_phentsize, ehdr->e_phnum);
 
-	head = tail = app;
-	libc = lib;
-	app->next = 0;
+	/* Load preload/needed libraries, add their symbols to the global
+	 * 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(head);
+	load_deps(app);
+	make_global(app);
+	reloc_all(app->next);
+	reloc_all(app);
+
+	/* Switch to runtime mode: any further failures in the dynamic
+	 * linker are a reportable failure rather than a fatal startup
+	 * error. If the dynamic loader (dlopen) will not be used, free
+	 * all memory used by the dynamic linker. */
+	runtime = 1;
 
-	make_global(head);
-	reloc_all(head->next);
-	reloc_all(head);
+	for (i=0; app->dynv[i]; i+=2)
+		if (app->dynv[i]==DT_DEBUG)
+			app->dynv[i+1] = (size_t)&debug;
+	debug.ver = 1;
+	debug.bp = _dl_debug_state;
+	debug.head = head;
+	debug.base = lib->base;
+	debug.state = 0;
+	_dl_debug_state();
+
+	do_init_fini(tail);
 
-	runtime = 1;
 	if (!rtld_used) {
 		free_all(head);
 		free(sys_path);
 		reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos);
 	}
 
+	if (ssp_used) __pthread_self_init();
+
 	errno = 0;
 	return (void *)aux[AT_ENTRY];
 }
@@ -588,9 +651,11 @@ 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)) {
@@ -606,12 +671,17 @@ void *dlopen(const char *file, int mode)
 		}
 		tail = orig_tail;
 		tail->next = 0;
-		pthread_rwlock_unlock(&lock);
-		return 0;
-	}
+		p = 0;
+		errflag = 1;
+		goto end;
+	} else p = load_library(file);
 
-	p = load_library(file);
-	if (!p) goto end;
+	if (!p) {
+		snprintf(errbuf, sizeof errbuf,
+			"Error loading shared library %s: %m", file);
+		errflag = 1;
+		goto end;
+	}
 
 	/* First load handling */
 	if (!p->deps) {
@@ -633,18 +703,30 @@ void *dlopen(const char *file, int mode)
 		p->global = 1;
 	}
 
+	_dl_debug_state();
+
+	do_init_fini(tail);
 end:
 	pthread_rwlock_unlock(&lock);
+	pthread_setcancelstate(cs, 0);
 	return p;
 }
 
-static void *do_dlsym(struct dso *p, const char *s)
+static void *do_dlsym(struct dso *p, const char *s, void *ra)
 {
 	size_t i;
 	uint32_t h;
 	Sym *sym;
-	if (p == head || p == RTLD_DEFAULT)
-		return find_sym(head, s, 0);
+	if (p == RTLD_NEXT) {
+		for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
+		if (!p) p=head;
+		p=p->next;
+	}
+	if (p == head || p == RTLD_DEFAULT) {
+		void *res = find_sym(head, s, 0);
+		if (!res) errflag = 1;
+		return res;
+	}
 	h = hash(s);
 	sym = lookup(s, h, p->syms, p->hashtab, p->strings);
 	if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
@@ -655,21 +737,35 @@ static void *do_dlsym(struct dso *p, const char *s)
 		if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
 			return p->deps[i]->base + sym->st_value;
 	}
+	errflag = 1;
+	snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
 	return 0;
 }
 
-void *dlsym(void *p, const char *s)
+void *__dlsym(void *p, const char *s, void *ra)
 {
 	void *res;
 	pthread_rwlock_rdlock(&lock);
-	res = do_dlsym(p, s);
+	res = do_dlsym(p, s, 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()
 {
-	return "unknown error";
+	if (!errflag) return 0;
+	errflag = 0;
+	return errbuf;
 }
 
 int dlclose(void *p)