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8f11e6127f
musl/ldso/dynlink.c
Rich Felker 1c84c99913 add new stage 2b to dynamic linker bootstrap for thread pointer 
commit a603a75a72 removed attribute
const from __errno_location and pthread_self, and the same reasoning
forced arch definitions of __pthread_self to use volatile asm,
significantly impacting code generation and imposing manual caching of
pointers where the impact might be noticable.

reorder the thread pointer setup and place it across a strong barrier
(symbolic function lookup) so that there is no assumed ordering
between the initialization and the accesses to the thread pointer in
stage 3.
2018-10-16 13:50:28 -04:00

2091 lines
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C
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#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <elf.h>
#include <sys/mman.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include <link.h>
#include <setjmp.h>
#include <pthread.h>
#include <ctype.h>
#include <dlfcn.h>
#include "pthread_impl.h"
#include "libc.h"
#include "dynlink.h"
#include "malloc_impl.h"
static void error(const char *, ...);
#define MAXP2(a,b) (-(-(a)&-(b)))
#define ALIGN(x,y) ((x)+(y)-1 & -(y))
struct debug {
int ver;
void *head;
void (*bp)(void);
int state;
void *base;
};
struct td_index {
size_t args[2];
struct td_index *next;
};
struct dso {
#if DL_FDPIC
struct fdpic_loadmap *loadmap;
#else
unsigned char *base;
#endif
char *name;
size_t *dynv;
struct dso *next, *prev;
Phdr *phdr;
int phnum;
size_t phentsize;
Sym *syms;
Elf_Symndx *hashtab;
uint32_t *ghashtab;
int16_t *versym;
char *strings;
struct dso *syms_next, *lazy_next;
size_t *lazy, lazy_cnt;
unsigned char *map;
size_t map_len;
dev_t dev;
ino_t ino;
char relocated;
char constructed;
char kernel_mapped;
struct dso **deps, *needed_by;
char *rpath_orig, *rpath;
struct tls_module tls;
size_t tls_id;
size_t relro_start, relro_end;
uintptr_t *new_dtv;
unsigned char *new_tls;
volatile int new_dtv_idx, new_tls_idx;
struct td_index *td_index;
struct dso *fini_next;
char *shortname;
#if DL_FDPIC
unsigned char *base;
#else
struct fdpic_loadmap *loadmap;
#endif
struct funcdesc {
void *addr;
size_t *got;
} *funcdescs;
size_t *got;
char buf[];
};
struct symdef {
Sym *sym;
struct dso *dso;
};
static struct builtin_tls {
char c;
struct pthread pt;
void *space[16];
} builtin_tls[1];
#define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
#define ADDEND_LIMIT 4096
static size_t *saved_addends, *apply_addends_to;
static struct dso ldso;
static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
static char *env_path, *sys_path;
static unsigned long long gencnt;
static int runtime;
static int ldd_mode;
static int ldso_fail;
static int noload;
static jmp_buf *rtld_fail;
static pthread_rwlock_t lock;
static struct debug debug;
static struct tls_module *tls_tail;
static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
static size_t static_tls_cnt;
static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
static struct fdpic_loadmap *app_loadmap;
static struct fdpic_dummy_loadmap app_dummy_loadmap;
static struct dso *const nodeps_dummy;
struct debug *_dl_debug_addr = &debug;
extern hidden int __malloc_replaced;
hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
weak_alias(__init_array_start, __init_array_end);
weak_alias(__fini_array_start, __fini_array_end);
static int dl_strcmp(const char *l, const char *r)
{
for (; *l==*r && *l; l++, r++);
return *(unsigned char *)l - *(unsigned char *)r;
}
#define strcmp(l,r) dl_strcmp(l,r)
/* Compute load address for a virtual address in a given dso. */
#if DL_FDPIC
static void *laddr(const struct dso *p, size_t v)
{
size_t j=0;
if (!p->loadmap) return p->base + v;
for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
}
static void *laddr_pg(const struct dso *p, size_t v)
{
size_t j=0;
size_t pgsz = PAGE_SIZE;
if (!p->loadmap) return p->base + v;
for (j=0; ; j++) {
size_t a = p->loadmap->segs[j].p_vaddr;
size_t b = a + p->loadmap->segs[j].p_memsz;
a &= -pgsz;
b += pgsz-1;
b &= -pgsz;
if (v-a<b-a) break;
}
return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
}
#define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
laddr(p, v), (p)->got })
#else
#define laddr(p, v) (void *)((p)->base + (v))
#define laddr_pg(p, v) laddr(p, v)
#define fpaddr(p, v) ((void (*)())laddr(p, v))
#endif
static void decode_vec(size_t *v, size_t *a, size_t cnt)
{
size_t i;
for (i=0; i<cnt; i++) a[i] = 0;
for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
a[0] |= 1UL<<v[0];
a[v[0]] = v[1];
}
}
static int search_vec(size_t *v, size_t *r, size_t key)
{
for (; v[0]!=key; v+=2)
if (!v[0]) return 0;
*r = v[1];
return 1;
}
static uint32_t sysv_hash(const char *s0)
{
const unsigned char *s = (void *)s0;
uint_fast32_t h = 0;
while (*s) {
h = 16*h + *s++;
h ^= h>>24 & 0xf0;
}
return h & 0xfffffff;
}
static uint32_t gnu_hash(const char *s0)
{
const unsigned char *s = (void *)s0;
uint_fast32_t h = 5381;
for (; *s; s++)
h += h*32 + *s;
return h;
}
static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
{
size_t i;
Sym *syms = dso->syms;
Elf_Symndx *hashtab = dso->hashtab;
char *strings = dso->strings;
for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
if ((!dso->versym || dso->versym[i] >= 0)
&& (!strcmp(s, strings+syms[i].st_name)))
return syms+i;
}
return 0;
}
static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
{
uint32_t nbuckets = hashtab[0];
uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
uint32_t i = buckets[h1 % nbuckets];
if (!i) return 0;
uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
for (h1 |= 1; ; i++) {
uint32_t h2 = *hashval++;
if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
&& !strcmp(s, dso->strings + dso->syms[i].st_name))
return dso->syms+i;
if (h2 & 1) break;
}
return 0;
}
static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
{
const size_t *bloomwords = (const void *)(hashtab+4);
size_t f = bloomwords[fofs & (hashtab[2]-1)];
if (!(f & fmask)) return 0;
f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
if (!(f & 1)) return 0;
return gnu_lookup(h1, hashtab, dso, s);
}
#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
#ifndef ARCH_SYM_REJECT_UND
#define ARCH_SYM_REJECT_UND(s) 0
#endif
static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
{
uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
size_t ghm = 1ul << gh % (8*sizeof(size_t));
struct symdef def = {0};
for (; dso; dso=dso->syms_next) {
Sym *sym;
if ((ght = dso->ghashtab)) {
sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
} else {
if (!h) h = sysv_hash(s);
sym = sysv_lookup(s, h, dso);
}
if (!sym) continue;
if (!sym->st_shndx)
if (need_def || (sym->st_info&0xf) == STT_TLS
|| ARCH_SYM_REJECT_UND(sym))
continue;
if (!sym->st_value)
if ((sym->st_info&0xf) != STT_TLS)
continue;
if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
def.sym = sym;
def.dso = dso;
break;
}
return def;
}
static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
{
unsigned char *base = dso->base;
Sym *syms = dso->syms;
char *strings = dso->strings;
Sym *sym;
const char *name;
void *ctx;
int type;
int sym_index;
struct symdef def;
size_t *reloc_addr;
size_t sym_val;
size_t tls_val;
size_t addend;
int skip_relative = 0, reuse_addends = 0, save_slot = 0;
if (dso == &ldso) {
/* Only ldso's REL table needs addend saving/reuse. */
if (rel == apply_addends_to)
reuse_addends = 1;
skip_relative = 1;
}
for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
type = R_TYPE(rel[1]);
if (type == REL_NONE) continue;
reloc_addr = laddr(dso, rel[0]);
if (stride > 2) {
addend = rel[2];
} else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
addend = 0;
} else if (reuse_addends) {
/* Save original addend in stage 2 where the dso
* chain consists of just ldso; otherwise read back
* saved addend since the inline one was clobbered. */
if (head==&ldso)
saved_addends[save_slot] = *reloc_addr;
addend = saved_addends[save_slot++];
} else {
addend = *reloc_addr;
}
sym_index = R_SYM(rel[1]);
if (sym_index) {
sym = syms + sym_index;
name = strings + sym->st_name;
ctx = type==REL_COPY ? head->syms_next : head;
def = (sym->st_info&0xf) == STT_SECTION
? (struct symdef){ .dso = dso, .sym = sym }
: find_sym(ctx, name, type==REL_PLT);
if (!def.sym && (sym->st_shndx != SHN_UNDEF
|| sym->st_info>>4 != STB_WEAK)) {
if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
dso->lazy[3*dso->lazy_cnt+0] = rel[0];
dso->lazy[3*dso->lazy_cnt+1] = rel[1];
dso->lazy[3*dso->lazy_cnt+2] = addend;
dso->lazy_cnt++;
continue;
}
error("Error relocating %s: %s: symbol not found",
dso->name, name);
if (runtime) longjmp(*rtld_fail, 1);
continue;
}
} else {
sym = 0;
def.sym = 0;
def.dso = dso;
}
sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
tls_val = def.sym ? def.sym->st_value : 0;
if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
&& runtime && def.dso->tls_id > static_tls_cnt) {
error("Error relocating %s: %s: initial-exec TLS "
"resolves to dynamic definition in %s",
dso->name, name, def.dso->name);
longjmp(*rtld_fail, 1);
}
switch(type) {
case REL_NONE:
break;
case REL_OFFSET:
addend -= (size_t)reloc_addr;
case REL_SYMBOLIC:
case REL_GOT:
case REL_PLT:
*reloc_addr = sym_val + addend;
break;
case REL_RELATIVE:
*reloc_addr = (size_t)base + addend;
break;
case REL_SYM_OR_REL:
if (sym) *reloc_addr = sym_val + addend;
else *reloc_addr = (size_t)base + addend;
break;
case REL_COPY:
memcpy(reloc_addr, (void *)sym_val, sym->st_size);
break;
case REL_OFFSET32:
*(uint32_t *)reloc_addr = sym_val + addend
- (size_t)reloc_addr;
break;
case REL_FUNCDESC:
*reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
+ (def.sym - def.dso->syms)) : 0;
break;
case REL_FUNCDESC_VAL:
if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
else *reloc_addr = sym_val;
reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
break;
case REL_DTPMOD:
*reloc_addr = def.dso->tls_id;
break;
case REL_DTPOFF:
*reloc_addr = tls_val + addend - DTP_OFFSET;
break;
#ifdef TLS_ABOVE_TP
case REL_TPOFF:
*reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
break;
#else
case REL_TPOFF:
*reloc_addr = tls_val - def.dso->tls.offset + addend;
break;
case REL_TPOFF_NEG:
*reloc_addr = def.dso->tls.offset - tls_val + addend;
break;
#endif
case REL_TLSDESC:
if (stride<3) addend = reloc_addr[1];
if (runtime && def.dso->tls_id > static_tls_cnt) {
struct td_index *new = malloc(sizeof *new);
if (!new) {
error(
"Error relocating %s: cannot allocate TLSDESC for %s",
dso->name, sym ? name : "(local)" );
longjmp(*rtld_fail, 1);
}
new->next = dso->td_index;
dso->td_index = new;
new->args[0] = def.dso->tls_id;
new->args[1] = tls_val + addend - DTP_OFFSET;
reloc_addr[0] = (size_t)__tlsdesc_dynamic;
reloc_addr[1] = (size_t)new;
} else {
reloc_addr[0] = (size_t)__tlsdesc_static;
#ifdef TLS_ABOVE_TP
reloc_addr[1] = tls_val + def.dso->tls.offset
+ TPOFF_K + addend;
#else
reloc_addr[1] = tls_val - def.dso->tls.offset
+ addend;
#endif
}
#ifdef TLSDESC_BACKWARDS
/* Some archs (32-bit ARM at least) invert the order of
* the descriptor members. Fix them up here. */
size_t tmp = reloc_addr[0];
reloc_addr[0] = reloc_addr[1];
reloc_addr[1] = tmp;
#endif
break;
default:
error("Error relocating %s: unsupported relocation type %d",
dso->name, type);
if (runtime) longjmp(*rtld_fail, 1);
continue;
}
}
}
static void redo_lazy_relocs()
{
struct dso *p = lazy_head, *next;
lazy_head = 0;
for (; p; p=next) {
next = p->lazy_next;
size_t size = p->lazy_cnt*3*sizeof(size_t);
p->lazy_cnt = 0;
do_relocs(p, p->lazy, size, 3);
if (p->lazy_cnt) {
p->lazy_next = lazy_head;
lazy_head = p;
} else {
free(p->lazy);
p->lazy = 0;
p->lazy_next = 0;
}
}
}
/* A huge hack: to make up for the wastefulness of shared libraries
* needing at least a page of dirty memory even if they have no global
* data, we reclaim the gaps at the beginning and end of writable maps
* and "donate" them to the heap. */
static void reclaim(struct dso *dso, size_t start, size_t end)
{
if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
if (start >= end) return;
char *base = laddr_pg(dso, start);
__malloc_donate(base, base+(end-start));
}
static void reclaim_gaps(struct dso *dso)
{
Phdr *ph = dso->phdr;
size_t phcnt = dso->phnum;
for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
if (ph->p_type!=PT_LOAD) continue;
if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
reclaim(dso, ph->p_vaddr+ph->p_memsz,
ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
}
}
static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
{
static int no_map_fixed;
char *q;
if (!no_map_fixed) {
q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
return q;
no_map_fixed = 1;
}
/* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
if (flags & MAP_ANONYMOUS) {
memset(p, 0, n);
return p;
}
ssize_t r;
if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
for (q=p; n; q+=r, off+=r, n-=r) {
r = read(fd, q, n);
if (r < 0 && errno != EINTR) return MAP_FAILED;
if (!r) {
memset(q, 0, n);
break;
}
}
return p;
}
static void unmap_library(struct dso *dso)
{
if (dso->loadmap) {
size_t i;
for (i=0; i<dso->loadmap->nsegs; i++) {
if (!dso->loadmap->segs[i].p_memsz)
continue;
munmap((void *)dso->loadmap->segs[i].addr,
dso->loadmap->segs[i].p_memsz);
}
free(dso->loadmap);
} else if (dso->map && dso->map_len) {
munmap(dso->map, dso->map_len);
}
}
static void *map_library(int fd, struct dso *dso)
{
Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
void *allocated_buf=0;
size_t phsize;
size_t addr_min=SIZE_MAX, addr_max=0, map_len;
size_t this_min, this_max;
size_t nsegs = 0;
off_t off_start;
Ehdr *eh;
Phdr *ph, *ph0;
unsigned prot;
unsigned char *map=MAP_FAILED, *base;
size_t dyn=0;
size_t tls_image=0;
size_t i;
ssize_t l = read(fd, buf, sizeof buf);
eh = buf;
if (l<0) return 0;
if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
goto noexec;
phsize = eh->e_phentsize * eh->e_phnum;
if (phsize > sizeof buf - sizeof *eh) {
allocated_buf = malloc(phsize);
if (!allocated_buf) return 0;
l = pread(fd, allocated_buf, phsize, eh->e_phoff);
if (l < 0) goto error;
if (l != phsize) goto noexec;
ph = ph0 = allocated_buf;
} else if (eh->e_phoff + phsize > l) {
l = pread(fd, buf+1, phsize, eh->e_phoff);
if (l < 0) goto error;
if (l != phsize) goto noexec;
ph = ph0 = (void *)(buf + 1);
} else {
ph = ph0 = (void *)((char *)buf + eh->e_phoff);
}
for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type == PT_DYNAMIC) {
dyn = ph->p_vaddr;
} else if (ph->p_type == PT_TLS) {
tls_image = ph->p_vaddr;
dso->tls.align = ph->p_align;
dso->tls.len = ph->p_filesz;
dso->tls.size = ph->p_memsz;
} else if (ph->p_type == PT_GNU_RELRO) {
dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
} else if (ph->p_type == PT_GNU_STACK) {
if (!runtime && ph->p_memsz > __default_stacksize) {
__default_stacksize =
ph->p_memsz < DEFAULT_STACK_MAX ?
ph->p_memsz : DEFAULT_STACK_MAX;
}
}
if (ph->p_type != PT_LOAD) continue;
nsegs++;
if (ph->p_vaddr < addr_min) {
addr_min = ph->p_vaddr;
off_start = ph->p_offset;
prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
((ph->p_flags&PF_X) ? PROT_EXEC : 0));
}
if (ph->p_vaddr+ph->p_memsz > addr_max) {
addr_max = ph->p_vaddr+ph->p_memsz;
}
}
if (!dyn) goto noexec;
if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
dso->loadmap = calloc(1, sizeof *dso->loadmap
+ nsegs * sizeof *dso->loadmap->segs);
if (!dso->loadmap) goto error;
dso->loadmap->nsegs = nsegs;
for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type != PT_LOAD) continue;
prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
((ph->p_flags&PF_X) ? PROT_EXEC : 0));
map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
prot, MAP_PRIVATE,
fd, ph->p_offset & -PAGE_SIZE);
if (map == MAP_FAILED) {
unmap_library(dso);
goto error;
}
dso->loadmap->segs[i].addr = (size_t)map +
(ph->p_vaddr & PAGE_SIZE-1);
dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
dso->loadmap->segs[i].p_memsz = ph->p_memsz;
i++;
if (prot & PROT_WRITE) {
size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
+ ph->p_filesz;
size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
size_t pgend = brk + ph->p_memsz - ph->p_filesz
+ PAGE_SIZE-1 & -PAGE_SIZE;
if (pgend > pgbrk && mmap_fixed(map+pgbrk,
pgend-pgbrk, prot,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
-1, off_start) == MAP_FAILED)
goto error;
memset(map + brk, 0, pgbrk-brk);
}
}
map = (void *)dso->loadmap->segs[0].addr;
map_len = 0;
goto done_mapping;
}
addr_max += PAGE_SIZE-1;
addr_max &= -PAGE_SIZE;
addr_min &= -PAGE_SIZE;
off_start &= -PAGE_SIZE;
map_len = addr_max - addr_min + off_start;
/* The first time, we map too much, possibly even more than
* the length of the file. This is okay because we will not
* use the invalid part; we just need to reserve the right
* amount of virtual address space to map over later. */
map = DL_NOMMU_SUPPORT
? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
: mmap((void *)addr_min, map_len, prot,
MAP_PRIVATE, fd, off_start);
if (map==MAP_FAILED) goto error;
dso->map = map;
dso->map_len = map_len;
/* If the loaded file is not relocatable and the requested address is
* not available, then the load operation must fail. */
if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
errno = EBUSY;
goto error;
}
base = map - addr_min;
dso->phdr = 0;
dso->phnum = 0;
for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
if (ph->p_type != PT_LOAD) continue;
/* Check if the programs headers are in this load segment, and
* if so, record the address for use by dl_iterate_phdr. */
if (!dso->phdr && eh->e_phoff >= ph->p_offset
&& eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
dso->phdr = (void *)(base + ph->p_vaddr
+ (eh->e_phoff-ph->p_offset));
dso->phnum = eh->e_phnum;
dso->phentsize = eh->e_phentsize;
}
this_min = ph->p_vaddr & -PAGE_SIZE;
this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
off_start = ph->p_offset & -PAGE_SIZE;
prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
((ph->p_flags&PF_X) ? PROT_EXEC : 0));
/* Reuse the existing mapping for the lowest-address LOAD */
if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
goto error;
if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
if (pgbrk-(size_t)base < this_max && mmap_fixed((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
goto error;
}
}
for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
&& errno != ENOSYS)
goto error;
break;
}
done_mapping:
dso->base = base;
dso->dynv = laddr(dso, dyn);
if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
free(allocated_buf);
return map;
noexec:
errno = ENOEXEC;
error:
if (map!=MAP_FAILED) unmap_library(dso);
free(allocated_buf);
return 0;
}
static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
{
size_t l;
int fd;
for (;;) {
s += strspn(s, ":\n");
l = strcspn(s, ":\n");
if (l-1 >= INT_MAX) return -1;
if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
switch (errno) {
case ENOENT:
case ENOTDIR:
case EACCES:
case ENAMETOOLONG:
break;
default:
/* Any negative value but -1 will inhibit
* futher path search. */
return -2;
}
}
s += l;
}
}
static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
{
size_t n, l;
const char *s, *t, *origin;
char *d;
if (p->rpath || !p->rpath_orig) return 0;
if (!strchr(p->rpath_orig, '$')) {
p->rpath = p->rpath_orig;
return 0;
}
n = 0;
s = p->rpath_orig;
while ((t=strchr(s, '$'))) {
if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
return 0;
s = t+1;
n++;
}
if (n > SSIZE_MAX/PATH_MAX) return 0;
if (p->kernel_mapped) {
/* $ORIGIN searches cannot be performed for the main program
* when it is suid/sgid/AT_SECURE. This is because the
* pathname is under the control of the caller of execve.
* For libraries, however, $ORIGIN can be processed safely
* since the library's pathname came from a trusted source
* (either system paths or a call to dlopen). */
if (libc.secure)
return 0;
l = readlink("/proc/self/exe", buf, buf_size);
if (l == -1) switch (errno) {
case ENOENT:
case ENOTDIR:
case EACCES:
break;
default:
return -1;
}
if (l >= buf_size)
return 0;
buf[l] = 0;
origin = buf;
} else {
origin = p->name;
}
t = strrchr(origin, '/');
if (t) {
l = t-origin;
} else {
/* Normally p->name will always be an absolute or relative
* pathname containing at least one '/' character, but in the
* case where ldso was invoked as a command to execute a
* program in the working directory, app.name may not. Fix. */
origin = ".";
l = 1;
}
/* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
if (libc.secure && *origin != '/')
return 0;
p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
if (!p->rpath) return -1;
d = p->rpath;
s = p->rpath_orig;
while ((t=strchr(s, '$'))) {
memcpy(d, s, t-s);
d += t-s;
memcpy(d, origin, l);
d += l;
/* It was determined previously that the '$' is followed
* either by "ORIGIN" or "{ORIGIN}". */
s = t + 7 + 2*(t[1]=='{');
}
strcpy(d, s);
return 0;
}
static void decode_dyn(struct dso *p)
{
size_t dyn[DYN_CNT];
decode_vec(p->dynv, dyn, DYN_CNT);
p->syms = laddr(p, dyn[DT_SYMTAB]);
p->strings = laddr(p, dyn[DT_STRTAB]);
if (dyn[0]&(1<<DT_HASH))
p->hashtab = laddr(p, dyn[DT_HASH]);
if (dyn[0]&(1<<DT_RPATH))
p->rpath_orig = p->strings + dyn[DT_RPATH];
if (dyn[0]&(1<<DT_RUNPATH))
p->rpath_orig = p->strings + dyn[DT_RUNPATH];
if (dyn[0]&(1<<DT_PLTGOT))
p->got = laddr(p, dyn[DT_PLTGOT]);
if (search_vec(p->dynv, dyn, DT_GNU_HASH))
p->ghashtab = laddr(p, *dyn);
if (search_vec(p->dynv, dyn, DT_VERSYM))
p->versym = laddr(p, *dyn);
}
static size_t count_syms(struct dso *p)
{
if (p->hashtab) return p->hashtab[1];
size_t nsym, i;
uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
uint32_t *hashval;
for (i = nsym = 0; i < p->ghashtab[0]; i++) {
if (buckets[i] > nsym)
nsym = buckets[i];
}
if (nsym) {
hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
do nsym++;
while (!(*hashval++ & 1));
}
return nsym;
}
static void *dl_mmap(size_t n)
{
void *p;
int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
#ifdef SYS_mmap2
p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
#else
p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
#endif
return p == MAP_FAILED ? 0 : p;
}
static void makefuncdescs(struct dso *p)
{
static int self_done;
size_t nsym = count_syms(p);
size_t i, size = nsym * sizeof(*p->funcdescs);
if (!self_done) {
p->funcdescs = dl_mmap(size);
self_done = 1;
} else {
p->funcdescs = malloc(size);
}
if (!p->funcdescs) {
if (!runtime) a_crash();
error("Error allocating function descriptors for %s", p->name);
longjmp(*rtld_fail, 1);
}
for (i=0; i<nsym; i++) {
if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
p->funcdescs[i].got = p->got;
} else {
p->funcdescs[i].addr = 0;
p->funcdescs[i].got = 0;
}
}
}
static struct dso *load_library(const char *name, struct dso *needed_by)
{
char buf[2*NAME_MAX+2];
const char *pathname;
unsigned char *map;
struct dso *p, temp_dso = {0};
int fd;
struct stat st;
size_t alloc_size;
int n_th = 0;
int is_self = 0;
if (!*name) {
errno = EINVAL;
return 0;
}
/* Catch and block attempts to reload the implementation itself */
if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
static const char reserved[] =
"c.pthread.rt.m.dl.util.xnet.";
const char *rp, *next;
for (rp=reserved; *rp; rp=next) {
next = strchr(rp, '.') + 1;
if (strncmp(name+3, rp, next-rp) == 0)
break;
}
if (*rp) {
if (ldd_mode) {
/* Track which names have been resolved
* and only report each one once. */
static unsigned reported;
unsigned mask = 1U<<(rp-reserved);
if (!(reported & mask)) {
reported |= mask;
dprintf(1, "\t%s => %s (%p)\n",
name, ldso.name,
ldso.base);
}
}
is_self = 1;
}
}
if (!strcmp(name, ldso.name)) is_self = 1;
if (is_self) {
if (!ldso.prev) {
tail->next = &ldso;
ldso.prev = tail;
tail = &ldso;
}
return &ldso;
}
if (strchr(name, '/')) {
pathname = name;
fd = open(name, O_RDONLY|O_CLOEXEC);
} else {
/* Search for the name to see if it's already loaded */
for (p=head->next; p; p=p->next) {
if (p->shortname && !strcmp(p->shortname, name)) {
return p;
}
}
if (strlen(name) > NAME_MAX) return 0;
fd = -1;
if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
for (p=needed_by; fd == -1 && p; p=p->needed_by) {
if (fixup_rpath(p, buf, sizeof buf) < 0)
fd = -2; /* Inhibit further search. */
if (p->rpath)
fd = path_open(name, p->rpath, buf, sizeof buf);
}
if (fd == -1) {
if (!sys_path) {
char *prefix = 0;
size_t prefix_len;
if (ldso.name[0]=='/') {
char *s, *t, *z;
for (s=t=z=ldso.name; *s; s++)
if (*s=='/') z=t, t=s;
prefix_len = z-ldso.name;
if (prefix_len < PATH_MAX)
prefix = ldso.name;
}
if (!prefix) {
prefix = "";
prefix_len = 0;
}
char etc_ldso_path[prefix_len + 1
+ sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
snprintf(etc_ldso_path, sizeof etc_ldso_path,
"%.*s/etc/ld-musl-" LDSO_ARCH ".path",
(int)prefix_len, prefix);
FILE *f = fopen(etc_ldso_path, "rbe");
if (f) {
if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
free(sys_path);
sys_path = "";
}
fclose(f);
} else if (errno != ENOENT) {
sys_path = "";
}
}
if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
fd = path_open(name, sys_path, buf, sizeof buf);
}
pathname = buf;
}
if (fd < 0) return 0;
if (fstat(fd, &st) < 0) {
close(fd);
return 0;
}
for (p=head->next; p; p=p->next) {
if (p->dev == st.st_dev && p->ino == st.st_ino) {
/* If this library was previously loaded with a
* pathname but a search found the same inode,
* setup its shortname so it can be found by name. */
if (!p->shortname && pathname != name)
p->shortname = strrchr(p->name, '/')+1;
close(fd);
return p;
}
}
map = noload ? 0 : map_library(fd, &temp_dso);
close(fd);
if (!map) return 0;
/* Avoid the danger of getting two versions of libc mapped into the
* same process when an absolute pathname was used. The symbols
* checked are chosen to catch both musl and glibc, and to avoid
* false positives from interposition-hack libraries. */
decode_dyn(&temp_dso);
if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
find_sym(&temp_dso, "stdin", 1).sym) {
unmap_library(&temp_dso);
return load_library("libc.so", needed_by);
}
/* Past this point, if we haven't reached runtime yet, ldso has
* committed either to use the mapped library or to abort execution.
* Unmapping is not possible, so we can safely reclaim gaps. */
if (!runtime) reclaim_gaps(&temp_dso);
/* Allocate storage for the new DSO. When there is TLS, this
* storage must include a reservation for all pre-existing
* threads to obtain copies of both the new TLS, and an
* extended DTV capable of storing an additional slot for
* the newly-loaded DSO. */
alloc_size = sizeof *p + strlen(pathname) + 1;
if (runtime && temp_dso.tls.image) {
size_t per_th = temp_dso.tls.size + temp_dso.tls.align
+ sizeof(void *) * (tls_cnt+3);
n_th = libc.threads_minus_1 + 1;
if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
else alloc_size += n_th * per_th;
}
p = calloc(1, alloc_size);
if (!p) {
unmap_library(&temp_dso);
return 0;
}
memcpy(p, &temp_dso, sizeof temp_dso);
p->dev = st.st_dev;
p->ino = st.st_ino;
p->needed_by = needed_by;
p->name = p->buf;
strcpy(p->name, pathname);
/* Add a shortname only if name arg was not an explicit pathname. */
if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
if (p->tls.image) {
p->tls_id = ++tls_cnt;
tls_align = MAXP2(tls_align, p->tls.align);
#ifdef TLS_ABOVE_TP
p->tls.offset = tls_offset + ( (tls_align-1) &
-(tls_offset + (uintptr_t)p->tls.image) );
tls_offset += p->tls.size;
#else
tls_offset += p->tls.size + p->tls.align - 1;
tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
& (p->tls.align-1);
p->tls.offset = tls_offset;
#endif
p->new_dtv = (void *)(-sizeof(size_t) &
(uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
if (tls_tail) tls_tail->next = &p->tls;
else libc.tls_head = &p->tls;
tls_tail = &p->tls;
}
tail->next = p;
p->prev = tail;
tail = p;
if (DL_FDPIC) makefuncdescs(p);
if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
return p;
}
static void load_deps(struct dso *p)
{
size_t i, ndeps=0;
struct dso ***deps = &p->deps, **tmp, *dep;
for (; p; p=p->next) {
for (i=0; p->dynv[i]; i+=2) {
if (p->dynv[i] != DT_NEEDED) continue;
dep = load_library(p->strings + p->dynv[i+1], p);
if (!dep) {
error("Error loading shared library %s: %m (needed by %s)",
p->strings + p->dynv[i+1], p->name);
if (runtime) longjmp(*rtld_fail, 1);
continue;
}
if (runtime) {
tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
if (!tmp) longjmp(*rtld_fail, 1);
tmp[ndeps++] = dep;
tmp[ndeps] = 0;
*deps = tmp;
}
}
}
if (!*deps) *deps = (struct dso **)&nodeps_dummy;
}
static void load_preload(char *s)
{
int tmp;
char *z;
for (z=s; *z; s=z) {
for ( ; *s && (isspace(*s) || *s==':'); s++);
for (z=s; *z && !isspace(*z) && *z!=':'; z++);
tmp = *z;
*z = 0;
load_library(s, 0);
*z = tmp;
}
}
static void add_syms(struct dso *p)
{
if (!p->syms_next && syms_tail != p) {
syms_tail->syms_next = p;
syms_tail = p;
}
}
static void revert_syms(struct dso *old_tail)
{
struct dso *p, *next;
/* Chop off the tail of the list of dsos that participate in
* the global symbol table, reverting them to RTLD_LOCAL. */
for (p=old_tail; p; p=next) {
next = p->syms_next;
p->syms_next = 0;
}
syms_tail = old_tail;
}
static void do_mips_relocs(struct dso *p, size_t *got)
{
size_t i, j, rel[2];
unsigned char *base = p->base;
i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
if (p==&ldso) {
got += i;
} else {
while (i--) *got++ += (size_t)base;
}
j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
Sym *sym = p->syms + j;
rel[0] = (unsigned char *)got - base;
for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
do_relocs(p, rel, sizeof rel, 2);
}
}
static void reloc_all(struct dso *p)
{
size_t dyn[DYN_CNT];
for (; p; p=p->next) {
if (p->relocated) continue;
decode_vec(p->dynv, dyn, DYN_CNT);
if (NEED_MIPS_GOT_RELOCS)
do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
2+(dyn[DT_PLTREL]==DT_RELA));
do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
if (head != &ldso && p->relro_start != p->relro_end &&
mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
&& errno != ENOSYS) {
error("Error relocating %s: RELRO protection failed: %m",
p->name);
if (runtime) longjmp(*rtld_fail, 1);
}
p->relocated = 1;
}
}
static void kernel_mapped_dso(struct dso *p)
{
size_t min_addr = -1, max_addr = 0, cnt;
Phdr *ph = p->phdr;
for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
if (ph->p_type == PT_DYNAMIC) {
p->dynv = laddr(p, ph->p_vaddr);
} else if (ph->p_type == PT_GNU_RELRO) {
p->relro_start = ph->p_vaddr & -PAGE_SIZE;
p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
} else if (ph->p_type == PT_GNU_STACK) {
if (!runtime && ph->p_memsz > __default_stacksize) {
__default_stacksize =
ph->p_memsz < DEFAULT_STACK_MAX ?
ph->p_memsz : DEFAULT_STACK_MAX;
}
}
if (ph->p_type != PT_LOAD) continue;
if (ph->p_vaddr < min_addr)
min_addr = ph->p_vaddr;
if (ph->p_vaddr+ph->p_memsz > max_addr)
max_addr = ph->p_vaddr+ph->p_memsz;
}
min_addr &= -PAGE_SIZE;
max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
p->map = p->base + min_addr;
p->map_len = max_addr - min_addr;
p->kernel_mapped = 1;
}
void __libc_exit_fini()
{
struct dso *p;
size_t dyn[DYN_CNT];
for (p=fini_head; p; p=p->fini_next) {
if (!p->constructed) continue;
decode_vec(p->dynv, dyn, DYN_CNT);
if (dyn[0] & (1<<DT_FINI_ARRAY)) {
size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
while (n--) ((void (*)(void))*--fn)();
}
#ifndef NO_LEGACY_INITFINI
if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
fpaddr(p, dyn[DT_FINI])();
#endif
}
}
static void do_init_fini(struct dso *p)
{
size_t dyn[DYN_CNT];
int need_locking = libc.threads_minus_1;
/* Allow recursive calls that arise when a library calls
* dlopen from one of its constructors, but block any
* other threads until all ctors have finished. */
if (need_locking) pthread_mutex_lock(&init_fini_lock);
for (; p; p=p->prev) {
if (p->constructed) continue;
p->constructed = 1;
decode_vec(p->dynv, dyn, DYN_CNT);
if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
p->fini_next = fini_head;
fini_head = p;
}
#ifndef NO_LEGACY_INITFINI
if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
fpaddr(p, dyn[DT_INIT])();
#endif
if (dyn[0] & (1<<DT_INIT_ARRAY)) {
size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
while (n--) ((void (*)(void))*fn++)();
}
if (!need_locking && libc.threads_minus_1) {
need_locking = 1;
pthread_mutex_lock(&init_fini_lock);
}
}
if (need_locking) pthread_mutex_unlock(&init_fini_lock);
}
void __libc_start_init(void)
{
do_init_fini(tail);
}
static void dl_debug_state(void)
{
}
weak_alias(dl_debug_state, _dl_debug_state);
void __init_tls(size_t *auxv)
{
}
hidden void *__tls_get_new(tls_mod_off_t *v)
{
pthread_t self = __pthread_self();
/* Block signals to make accessing new TLS async-signal-safe */
sigset_t set;
__block_all_sigs(&set);
if (v[0] <= self->dtv[0]) {
__restore_sigs(&set);
return (void *)(self->dtv[v[0]] + v[1]);
}
/* This is safe without any locks held because, if the caller
* is able to request the Nth entry of the DTV, the DSO list
* must be valid at least that far out and it was synchronized
* at program startup or by an already-completed call to dlopen. */
struct dso *p;
for (p=head; p->tls_id != v[0]; p=p->next);
/* Get new DTV space from new DSO */
uintptr_t *newdtv = p->new_dtv +
(v[0]+1)*a_fetch_add(&p->new_dtv_idx,1);
memcpy(newdtv, self->dtv, (self->dtv[0]+1) * sizeof(uintptr_t));
newdtv[0] = v[0];
self->dtv = self->dtv_copy = newdtv;
/* Get new TLS memory from all new DSOs up to the requested one */
unsigned char *mem;
for (p=head; ; p=p->next) {
if (!p->tls_id || self->dtv[p->tls_id]) continue;
mem = p->new_tls + (p->tls.size + p->tls.align)
* a_fetch_add(&p->new_tls_idx,1);
mem += ((uintptr_t)p->tls.image - (uintptr_t)mem)
& (p->tls.align-1);
self->dtv[p->tls_id] = (uintptr_t)mem + DTP_OFFSET;
memcpy(mem, p->tls.image, p->tls.len);
if (p->tls_id == v[0]) break;
}
__restore_sigs(&set);
return mem + v[1] + DTP_OFFSET;
}
static void update_tls_size()
{
libc.tls_cnt = tls_cnt;
libc.tls_align = tls_align;
libc.tls_size = ALIGN(
(1+tls_cnt) * sizeof(void *) +
tls_offset +
sizeof(struct pthread) +
tls_align * 2,
tls_align);
}
/* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
* following stage 2 and stage 3 functions via primitive symbolic lookup
* since it does not have access to their addresses to begin with. */
/* Stage 2 of the dynamic linker is called after relative relocations
* have been processed. It can make function calls to static functions
* and access string literals and static data, but cannot use extern
* symbols. Its job is to perform symbolic relocations on the dynamic
* linker itself, but some of the relocations performed may need to be
* replaced later due to copy relocations in the main program. */
hidden void __dls2(unsigned char *base, size_t *sp)
{
if (DL_FDPIC) {
void *p1 = (void *)sp[-2];
void *p2 = (void *)sp[-1];
if (!p1) {
size_t *auxv, aux[AUX_CNT];
for (auxv=sp+1+*sp+1; *auxv; auxv++);
auxv++;
decode_vec(auxv, aux, AUX_CNT);
if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
else ldso.base = (void *)(aux[AT_PHDR] & -4096);
}
app_loadmap = p2 ? p1 : 0;
ldso.loadmap = p2 ? p2 : p1;
ldso.base = laddr(&ldso, 0);
} else {
ldso.base = base;
}
Ehdr *ehdr = (void *)ldso.base;
ldso.name = ldso.shortname = "libc.so";
ldso.phnum = ehdr->e_phnum;
ldso.phdr = laddr(&ldso, ehdr->e_phoff);
ldso.phentsize = ehdr->e_phentsize;
kernel_mapped_dso(&ldso);
decode_dyn(&ldso);
if (DL_FDPIC) makefuncdescs(&ldso);
/* Prepare storage for to save clobbered REL addends so they
* can be reused in stage 3. There should be very few. If
* something goes wrong and there are a huge number, abort
* instead of risking stack overflow. */
size_t dyn[DYN_CNT];
decode_vec(ldso.dynv, dyn, DYN_CNT);
size_t *rel = laddr(&ldso, dyn[DT_REL]);
size_t rel_size = dyn[DT_RELSZ];
size_t symbolic_rel_cnt = 0;
apply_addends_to = rel;
for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
size_t addends[symbolic_rel_cnt+1];
saved_addends = addends;
head = &ldso;
reloc_all(&ldso);
ldso.relocated = 0;
/* Call dynamic linker stage-2b, __dls2b, looking it up
* symbolically as a barrier against moving the address
* load across the above relocation processing. */
struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp);
else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp);
}
/* Stage 2b sets up a valid thread pointer, which requires relocations
* completed in stage 2, and on which stage 3 is permitted to depend.
* This is done as a separate stage, with symbolic lookup as a barrier,
* so that loads of the thread pointer and &errno can be pure/const and
* thereby hoistable. */
_Noreturn void __dls2b(size_t *sp)
{
/* Setup early thread pointer in builtin_tls for ldso/libc itself to
* use during dynamic linking. If possible it will also serve as the
* thread pointer at runtime. */
libc.tls_size = sizeof builtin_tls;
libc.tls_align = tls_align;
if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
a_crash();
}
struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
}
/* Stage 3 of the dynamic linker is called with the dynamic linker/libc
* fully functional. Its job is to load (if not already loaded) and
* process dependencies and relocations for the main application and
* transfer control to its entry point. */
_Noreturn void __dls3(size_t *sp)
{
static struct dso app, vdso;
size_t aux[AUX_CNT], *auxv;
size_t i;
char *env_preload=0;
char *replace_argv0=0;
size_t vdso_base;
int argc = *sp;
char **argv = (void *)(sp+1);
char **argv_orig = argv;
char **envp = argv+argc+1;
/* Find aux vector just past environ[] and use it to initialize
* global data that may be needed before we can make syscalls. */
__environ = envp;
for (i=argc+1; argv[i]; i++);
libc.auxv = auxv = (void *)(argv+i+1);
decode_vec(auxv, aux, AUX_CNT);
__hwcap = aux[AT_HWCAP];
libc.page_size = aux[AT_PAGESZ];
libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
|| aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
/* Only trust user/env if kernel says we're not suid/sgid */
if (!libc.secure) {
env_path = getenv("LD_LIBRARY_PATH");
env_preload = getenv("LD_PRELOAD");
}
/* If the main program was already loaded by the kernel,
* AT_PHDR will point to some location other than the dynamic
* linker's program headers. */
if (aux[AT_PHDR] != (size_t)ldso.phdr) {
size_t interp_off = 0;
size_t tls_image = 0;
/* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
app.phnum = aux[AT_PHNUM];
app.phentsize = aux[AT_PHENT];
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);
else if (phdr->p_type == PT_INTERP)
interp_off = (size_t)phdr->p_vaddr;
else if (phdr->p_type == PT_TLS) {
tls_image = phdr->p_vaddr;
app.tls.len = phdr->p_filesz;
app.tls.size = phdr->p_memsz;
app.tls.align = phdr->p_align;
}
}
if (DL_FDPIC) app.loadmap = app_loadmap;
if (app.tls.size) app.tls.image = laddr(&app, tls_image);
if (interp_off) ldso.name = laddr(&app, interp_off);
if ((aux[0] & (1UL<<AT_EXECFN))
&& strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
app.name = (char *)aux[AT_EXECFN];
else
app.name = argv[0];
kernel_mapped_dso(&app);
} else {
int fd;
char *ldname = argv[0];
size_t l = strlen(ldname);
if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
argv++;
while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
char *opt = argv[0]+2;
*argv++ = (void *)-1;
if (!*opt) {
break;
} else if (!memcmp(opt, "list", 5)) {
ldd_mode = 1;
} else if (!memcmp(opt, "library-path", 12)) {
if (opt[12]=='=') env_path = opt+13;
else if (opt[12]) *argv = 0;
else if (*argv) env_path = *argv++;
} else if (!memcmp(opt, "preload", 7)) {
if (opt[7]=='=') env_preload = opt+8;
else if (opt[7]) *argv = 0;
else if (*argv) env_preload = *argv++;
} else if (!memcmp(opt, "argv0", 5)) {
if (opt[5]=='=') replace_argv0 = opt+6;
else if (opt[5]) *argv = 0;
else if (*argv) replace_argv0 = *argv++;
} else {
argv[0] = 0;
}
}
argv[-1] = (void *)(argc - (argv-argv_orig));
if (!argv[0]) {
dprintf(2, "musl libc (" LDSO_ARCH ")\n"
"Version %s\n"
"Dynamic Program Loader\n"
"Usage: %s [options] [--] pathname%s\n",
__libc_version, ldname,
ldd_mode ? "" : " [args]");
_exit(1);
}
fd = open(argv[0], O_RDONLY);
if (fd < 0) {
dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
_exit(1);
}
Ehdr *ehdr = (void *)map_library(fd, &app);
if (!ehdr) {
dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
_exit(1);
}
close(fd);
ldso.name = ldname;
app.name = argv[0];
aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
/* Find the name that would have been used for the dynamic
* linker had ldd not taken its place. */
if (ldd_mode) {
for (i=0; i<app.phnum; i++) {
if (app.phdr[i].p_type == PT_INTERP)
ldso.name = laddr(&app, app.phdr[i].p_vaddr);
}
dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
}
}
if (app.tls.size) {
libc.tls_head = tls_tail = &app.tls;
app.tls_id = tls_cnt = 1;
#ifdef TLS_ABOVE_TP
app.tls.offset = GAP_ABOVE_TP;
app.tls.offset += -GAP_ABOVE_TP & (app.tls.align-1);
tls_offset = app.tls.offset + app.tls.size
+ ( -((uintptr_t)app.tls.image + app.tls.size)
& (app.tls.align-1) );
#else
tls_offset = app.tls.offset = app.tls.size
+ ( -((uintptr_t)app.tls.image + app.tls.size)
& (app.tls.align-1) );
#endif
tls_align = MAXP2(tls_align, app.tls.align);
}
decode_dyn(&app);
if (DL_FDPIC) {
makefuncdescs(&app);
if (!app.loadmap) {
app.loadmap = (void *)&app_dummy_loadmap;
app.loadmap->nsegs = 1;
app.loadmap->segs[0].addr = (size_t)app.map;
app.loadmap->segs[0].p_vaddr = (size_t)app.map
- (size_t)app.base;
app.loadmap->segs[0].p_memsz = app.map_len;
}
argv[-3] = (void *)app.loadmap;
}
/* Initial dso chain consists only of the app. */
head = tail = syms_tail = &app;
/* Donate unused parts of app and library mapping to malloc */
reclaim_gaps(&app);
reclaim_gaps(&ldso);
/* Load preload/needed libraries, add symbols to global namespace. */
if (env_preload) load_preload(env_preload);
load_deps(&app);
for (struct dso *p=head; p; p=p->next)
add_syms(p);
/* Attach to vdso, if provided by the kernel, last so that it does
* not become part of the global namespace. */
if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
Ehdr *ehdr = (void *)vdso_base;
Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
vdso.phnum = ehdr->e_phnum;
vdso.phentsize = ehdr->e_phentsize;
for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
if (phdr->p_type == PT_DYNAMIC)
vdso.dynv = (void *)(vdso_base + phdr->p_offset);
if (phdr->p_type == PT_LOAD)
vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
}
vdso.name = "";
vdso.shortname = "linux-gate.so.1";
vdso.relocated = 1;
decode_dyn(&vdso);
vdso.prev = tail;
tail->next = &vdso;
tail = &vdso;
}
for (i=0; app.dynv[i]; i+=2) {
if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
app.dynv[i+1] = (size_t)&debug;
if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
size_t *ptr = (size_t *) app.dynv[i+1];
*ptr = (size_t)&debug;
}
}
/* The main program must be relocated LAST since it may contin
* copy relocations which depend on libraries' relocations. */
reloc_all(app.next);
reloc_all(&app);
update_tls_size();
if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
void *initial_tls = calloc(libc.tls_size, 1);
if (!initial_tls) {
dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
argv[0], libc.tls_size);
_exit(127);
}
if (__init_tp(__copy_tls(initial_tls)) < 0) {
a_crash();
}
} else {
size_t tmp_tls_size = libc.tls_size;
pthread_t self = __pthread_self();
/* Temporarily set the tls size to the full size of
* builtin_tls so that __copy_tls will use the same layout
* as it did for before. Then check, just to be safe. */
libc.tls_size = sizeof builtin_tls;
if (__copy_tls((void*)builtin_tls) != self) a_crash();
libc.tls_size = tmp_tls_size;
}
static_tls_cnt = tls_cnt;
if (ldso_fail) _exit(127);
if (ldd_mode) _exit(0);
/* Determine if malloc was interposed by a replacement implementation
* so that calloc and the memalign family can harden against the
* possibility of incomplete replacement. */
if (find_sym(head, "malloc", 1).dso != &ldso)
__malloc_replaced = 1;
/* Switch to runtime mode: any further failures in the dynamic
* linker are a reportable failure rather than a fatal startup
* error. */
runtime = 1;
debug.ver = 1;
debug.bp = dl_debug_state;
debug.head = head;
debug.base = ldso.base;
debug.state = 0;
_dl_debug_state();
if (replace_argv0) argv[0] = replace_argv0;
errno = 0;
CRTJMP((void *)aux[AT_ENTRY], argv-1);
for(;;);
}
static void prepare_lazy(struct dso *p)
{
size_t dyn[DYN_CNT], n, flags1=0;
decode_vec(p->dynv, dyn, DYN_CNT);
search_vec(p->dynv, &flags1, DT_FLAGS_1);
if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
return;
n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
if (NEED_MIPS_GOT_RELOCS) {
size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
n += i-j;
}
p->lazy = calloc(n, 3*sizeof(size_t));
if (!p->lazy) {
error("Error preparing lazy relocation for %s: %m", p->name);
longjmp(*rtld_fail, 1);
}
p->lazy_next = lazy_head;
lazy_head = p;
}
void *dlopen(const char *file, int mode)
{
struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
struct tls_module *orig_tls_tail;
size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
size_t i;
int cs;
jmp_buf jb;
if (!file) return head;
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
pthread_rwlock_wrlock(&lock);
__inhibit_ptc();
p = 0;
orig_tls_tail = tls_tail;
orig_tls_cnt = tls_cnt;
orig_tls_offset = tls_offset;
orig_tls_align = tls_align;
orig_lazy_head = lazy_head;
orig_syms_tail = syms_tail;
orig_tail = tail;
noload = mode & RTLD_NOLOAD;
rtld_fail = &jb;
if (setjmp(*rtld_fail)) {
/* Clean up anything new that was (partially) loaded */
revert_syms(orig_syms_tail);
for (p=orig_tail->next; p; p=next) {
next = p->next;
while (p->td_index) {
void *tmp = p->td_index->next;
free(p->td_index);
p->td_index = tmp;
}
free(p->funcdescs);
if (p->rpath != p->rpath_orig)
free(p->rpath);
if (p->deps != &nodeps_dummy)
free(p->deps);
unmap_library(p);
free(p);
}
if (!orig_tls_tail) libc.tls_head = 0;
tls_tail = orig_tls_tail;
if (tls_tail) tls_tail->next = 0;
tls_cnt = orig_tls_cnt;
tls_offset = orig_tls_offset;
tls_align = orig_tls_align;
lazy_head = orig_lazy_head;
tail = orig_tail;
tail->next = 0;
p = 0;
goto end;
} else p = load_library(file, head);
if (!p) {
error(noload ?
"Library %s is not already loaded" :
"Error loading shared library %s: %m",
file);
goto end;
}
/* First load handling */
int first_load = !p->deps;
if (first_load) {
load_deps(p);
if (!p->relocated && (mode & RTLD_LAZY)) {
prepare_lazy(p);
for (i=0; p->deps[i]; i++)
if (!p->deps[i]->relocated)
prepare_lazy(p->deps[i]);
}
}
if (first_load || (mode & RTLD_GLOBAL)) {
/* Make new symbols global, at least temporarily, so we can do
* relocations. If not RTLD_GLOBAL, this is reverted below. */
add_syms(p);
for (i=0; p->deps[i]; i++)
add_syms(p->deps[i]);
}
if (first_load) {
reloc_all(p);
}
/* If RTLD_GLOBAL was not specified, undo any new additions
* to the global symbol table. This is a nop if the library was
* previously loaded and already global. */
if (!(mode & RTLD_GLOBAL))
revert_syms(orig_syms_tail);
/* Processing of deferred lazy relocations must not happen until
* the new libraries are committed; otherwise we could end up with
* relocations resolved to symbol definitions that get removed. */
redo_lazy_relocs();
update_tls_size();
_dl_debug_state();
orig_tail = tail;
end:
__release_ptc();
if (p) gencnt++;
pthread_rwlock_unlock(&lock);
if (p) do_init_fini(orig_tail);
pthread_setcancelstate(cs, 0);
return p;
}
hidden int __dl_invalid_handle(void *h)
{
struct dso *p;
for (p=head; p; p=p->next) if (h==p) return 0;
error("Invalid library handle %p", (void *)h);
return 1;
}
static void *addr2dso(size_t a)
{
struct dso *p;
size_t i;
if (DL_FDPIC) for (p=head; p; p=p->next) {
i = count_syms(p);
if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
return p;
}
for (p=head; p; p=p->next) {
if (DL_FDPIC && p->loadmap) {
for (i=0; i<p->loadmap->nsegs; i++) {
if (a-p->loadmap->segs[i].p_vaddr
< p->loadmap->segs[i].p_memsz)
return p;
}
} else {
Phdr *ph = p->phdr;
size_t phcnt = p->phnum;
size_t entsz = p->phentsize;
size_t base = (size_t)p->base;
for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
if (ph->p_type != PT_LOAD) continue;
if (a-base-ph->p_vaddr < ph->p_memsz)
return p;
}
if (a-(size_t)p->map < p->map_len)
return 0;
}
}
return 0;
}
static void *do_dlsym(struct dso *p, const char *s, void *ra)
{
size_t i;
uint32_t h = 0, gh = 0, *ght;
Sym *sym;
if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
if (p == RTLD_DEFAULT) {
p = head;
} else if (p == RTLD_NEXT) {
p = addr2dso((size_t)ra);
if (!p) p=head;
p = p->next;
}
struct symdef def = find_sym(p, s, 0);
if (!def.sym) goto failed;
if ((def.sym->st_info&0xf) == STT_TLS)
return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
return def.dso->funcdescs + (def.sym - def.dso->syms);
return laddr(def.dso, def.sym->st_value);
}
if (__dl_invalid_handle(p))
return 0;
if ((ght = p->ghashtab)) {
gh = gnu_hash(s);
sym = gnu_lookup(gh, ght, p, s);
} else {
h = sysv_hash(s);
sym = sysv_lookup(s, h, p);
}
if (sym && (sym->st_info&0xf) == STT_TLS)
return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
return p->funcdescs + (sym - p->syms);
if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
return laddr(p, sym->st_value);
for (i=0; p->deps[i]; i++) {
if ((ght = p->deps[i]->ghashtab)) {
if (!gh) gh = gnu_hash(s);
sym = gnu_lookup(gh, ght, p->deps[i], s);
} else {
if (!h) h = sysv_hash(s);
sym = sysv_lookup(s, h, p->deps[i]);
}
if (sym && (sym->st_info&0xf) == STT_TLS)
return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
return laddr(p->deps[i], sym->st_value);
}
failed:
error("Symbol not found: %s", s);
return 0;
}
int dladdr(const void *addr_arg, Dl_info *info)
{
size_t addr = (size_t)addr_arg;
struct dso *p;
Sym *sym, *bestsym;
uint32_t nsym;
char *strings;
size_t best = 0;
size_t besterr = -1;
pthread_rwlock_rdlock(&lock);
p = addr2dso(addr);
pthread_rwlock_unlock(&lock);
if (!p) return 0;
sym = p->syms;
strings = p->strings;
nsym = count_syms(p);
if (DL_FDPIC) {
size_t idx = (addr-(size_t)p->funcdescs)
/ sizeof(*p->funcdescs);
if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
best = (size_t)(p->funcdescs + idx);
bestsym = sym + idx;
besterr = 0;
}
}
if (!best) for (; nsym; nsym--, sym++) {
if (sym->st_value
&& (1<<(sym->st_info&0xf) & OK_TYPES)
&& (1<<(sym->st_info>>4) & OK_BINDS)) {
size_t symaddr = (size_t)laddr(p, sym->st_value);
if (symaddr > addr || symaddr <= best)
continue;
best = symaddr;
bestsym = sym;
besterr = addr - symaddr;
if (addr == symaddr)
break;
}
}
if (bestsym && besterr > bestsym->st_size-1) {
best = 0;
bestsym = 0;
}
info->dli_fname = p->name;
info->dli_fbase = p->map;
if (!best) {
info->dli_sname = 0;
info->dli_saddr = 0;
return 1;
}
if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
best = (size_t)(p->funcdescs + (bestsym - p->syms));
info->dli_sname = strings + bestsym->st_name;
info->dli_saddr = (void *)best;
return 1;
}
hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
{
void *res;
pthread_rwlock_rdlock(&lock);
res = do_dlsym(p, s, ra);
pthread_rwlock_unlock(&lock);
return res;
}
int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
{
struct dso *current;
struct dl_phdr_info info;
int ret = 0;
for(current = head; current;) {
info.dlpi_addr = (uintptr_t)current->base;
info.dlpi_name = current->name;
info.dlpi_phdr = current->phdr;
info.dlpi_phnum = current->phnum;
info.dlpi_adds = gencnt;
info.dlpi_subs = 0;
info.dlpi_tls_modid = current->tls_id;
info.dlpi_tls_data = current->tls.image;
ret = (callback)(&info, sizeof (info), data);
if (ret != 0) break;
pthread_rwlock_rdlock(&lock);
current = current->next;
pthread_rwlock_unlock(&lock);
}
return ret;
}
static void error(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (!runtime) {
vdprintf(2, fmt, ap);
dprintf(2, "\n");
ldso_fail = 1;
va_end(ap);
return;
}
__dl_vseterr(fmt, ap);
va_end(ap);
}
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