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mojo / mojo-tools / 24614f9961413d4527a5b1bc525102380f825705 / . / fusl / ldso / dynlink.c
blob: 32b4156494250f6feb1d615880b610780644fc87 [file] [log] [blame]
#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"
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;
int refcnt;
Sym* syms;
uint32_t* hashtab;
uint32_t* ghashtab;
int16_t* versym;
char* strings;
unsigned char* map;
size_t map_len;
dev_t dev;
ino_t ino;
signed char global;
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;
void** 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;
};
int __init_tp(void*);
void __init_libc(char**, char*);
void* __copy_tls(unsigned char*);
__attribute__((__visibility__("hidden"))) const char* __libc_get_version(void);
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;
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;
struct debug* _dl_debug_addr = &debug;
__attribute__((__visibility__("hidden"))) void (*const __init_array_start)(
void) = 0,
(*const __fini_array_start)(void) = 0;
__attribute__((__visibility__("hidden"))) extern 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);
}
#define fpaddr(p, v) ((void (*)()) & (struct funcdesc){laddr(p, v), (p)->got})
#else
#define laddr(p, v) (void*)((p)->base + (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;
uint32_t* 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, gho, *ght;
size_t ghm = 0;
struct symdef def = {0};
for (; dso; dso = dso->next) {
Sym* sym;
if (!dso->global)
continue;
if ((ght = dso->ghashtab)) {
if (!ghm) {
gh = gnu_hash(s);
int maskbits = 8 * sizeof ghm;
gho = gh / maskbits;
ghm = 1ul << gh % maskbits;
}
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;
if (def.sym && sym->st_info >> 4 == STB_WEAK)
continue;
def.sym = sym;
def.dso = dso;
if (sym->st_info >> 4 == STB_GLOBAL)
break;
}
return def;
}
__attribute__((__visibility__("hidden"))) ptrdiff_t __tlsdesc_static(),
__tlsdesc_dynamic();
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;
sym_index = R_SYM(rel[1]);
reloc_addr = laddr(dso, rel[0]);
if (sym_index) {
sym = syms + sym_index;
name = strings + sym->st_name;
ctx = type == REL_COPY ? head->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)) {
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;
}
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_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
tls_val = def.sym ? def.sym->st_value : 0;
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;
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
}
break;
default:
error("Error relocating %s: unsupported relocation type %d", dso->name,
type);
if (runtime)
longjmp(*rtld_fail, 1);
continue;
}
}
}
/* 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 by setting up minimal malloc
* structures and then freeing them. */
static void reclaim(struct dso* dso, size_t start, size_t end) {
size_t *a, *z;
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;
start = start + 6 * sizeof(size_t) - 1 & -4 * sizeof(size_t);
end = (end & -4 * sizeof(size_t)) - 2 * sizeof(size_t);
if (start > end || end - start < 4 * sizeof(size_t))
return;
a = laddr(dso, start);
z = laddr(dso, end);
a[-2] = 1;
a[-1] = z[0] = end - start + 2 * sizeof(size_t) | 1;
z[1] = 1;
free(a);
}
static void reclaim_gaps(struct dso* dso) {
Phdr* ph = dso->phdr;
size_t phcnt = dso->phnum;
if (DL_FDPIC)
return; // FIXME
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;
}
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;
}
/* Reuse the existing mapping for the lowest-address LOAD */
if ((ph->p_vaddr & -PAGE_SIZE) == addr_min && !DL_NOMMU_SUPPORT)
continue;
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));
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) {
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);
if (!runtime)
reclaim_gaps(dso);
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, $ORIGIN can be processed safely
* since the library's pathname came from a trusted source
* (either system paths or a call to dlopen). */
if (libc.secure)
return 0;
l = readlink("/proc/self/exe", buf, buf_size);
if (l == -1)
switch (errno) {
case ENOENT:
case ENOTDIR:
case EACCES:
break;
default:
return -1;
}
if (l >= buf_size)
return 0;
buf[l] = 0;
origin = buf;
} else {
origin = p->name;
}
t = strrchr(origin, '/');
l = t ? t - origin : 0;
p->rpath = malloc(strlen(p->rpath_orig) + n * l + 1);
if (!p->rpath)
return -1;
d = p->rpath;
s = p->rpath_orig;
while ((t = strchr(s, '$'))) {
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 *rp, reserved[] = "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
char* z = strchr(name, '.');
if (z) {
size_t l = z - name;
for (rp = reserved; *rp && strncmp(name + 3, rp, l - 3);
rp += strlen(rp) + 1)
;
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.next ? ldso.next : &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)) {
p->refcnt++;
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);
p->refcnt++;
return p;
}
}
map = noload ? 0 : map_library(fd, &temp_dso);
close(fd);
if (!map)
return 0;
/* 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);
decode_dyn(p);
p->dev = st.st_dev;
p->ino = st.st_ino;
p->refcnt = 1;
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;
}
}
}
}
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 make_global(struct dso* p) {
for (; p; p = p->next)
p->global = 1;
}
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] = (sym - p->syms) << 8 | 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;
}
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) {}
__attribute__((__visibility__("hidden"))) void* __tls_get_new(size_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] <= (size_t)self->dtv[0]) {
__restore_sigs(&set);
return (char*)self->dtv[v[0]] + v[1] + DTP_OFFSET;
}
/* 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 if needed */
if (v[0] > (size_t)self->dtv[0]) {
void** newdtv = p->new_dtv + (v[0] + 1) * a_fetch_add(&p->new_dtv_idx, 1);
memcpy(newdtv, self->dtv, ((size_t)self->dtv[0] + 1) * sizeof(void*));
newdtv[0] = (void*)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] = mem;
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. */
__attribute__((__visibility__("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++)
; // Pass
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.global = 1;
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-3, __dls3, looking it up
* symbolically as a barrier against moving the address
* load across the above relocation processing. */
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;
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]);
/* 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();
}
/* 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 {
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_get_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);
}
runtime = 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);
}
runtime = 0;
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 = 0;
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);
}
app.global = 1;
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;
}
/* Attach to vdso, if provided by the kernel */
if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
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.global = 1;
vdso.relocated = 1;
decode_dyn(&vdso);
vdso.prev = &ldso;
ldso.next = &vdso;
}
/* Initial dso chain consists only of the app. */
head = tail = &app;
/* Donate unused parts of app and library mapping to malloc */
reclaim_gaps(&app);
reclaim_gaps(&ldso);
/* Load preload/needed libraries, add their symbols to the global
* namespace, and perform all remaining relocations. */
if (env_preload)
load_preload(env_preload);
load_deps(&app);
make_global(&app);
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);
/* 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();
errno = 0;
CRTJMP((void*)aux[AT_ENTRY], argv - 1);
for (;;)
;
}
void* dlopen(const char* file, int mode) {
struct dso* volatile p, *orig_tail, *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_tail = tail;
noload = mode & RTLD_NOLOAD;
rtld_fail = &jb;
if (setjmp(*rtld_fail)) {
/* Clean up anything new that was (partially) loaded */
if (p && p->deps)
for (i = 0; p->deps[i]; i++)
if (p->deps[i]->global < 0)
p->deps[i]->global = 0;
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);
free(p->deps);
unmap_library(p);
free(p);
}
if (!orig_tls_tail)
libc.tls_head = 0;
tls_tail = orig_tls_tail;
tls_cnt = orig_tls_cnt;
tls_offset = orig_tls_offset;
tls_align = orig_tls_align;
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 */
if (!p->deps) {
load_deps(p);
if (p->deps)
for (i = 0; p->deps[i]; i++)
if (!p->deps[i]->global)
p->deps[i]->global = -1;
if (!p->global)
p->global = -1;
reloc_all(p);
if (p->deps)
for (i = 0; p->deps[i]; i++)
if (p->deps[i]->global < 0)
p->deps[i]->global = 0;
if (p->global < 0)
p->global = 0;
}
if (mode & RTLD_GLOBAL) {
if (p->deps)
for (i = 0; p->deps[i]; i++)
p->deps[i]->global = 1;
p->global = 1;
}
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;
}
__attribute__((__visibility__("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 {
if (a - (size_t)p->map < p->map_len)
return p;
}
}
return 0;
}
void* __tls_get_addr(size_t*);
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((size_t[]){def.dso->tls_id, def.sym->st_value});
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((size_t[]){p->tls_id, sym->st_value});
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);
if (p->deps)
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((size_t[]){p->deps[i]->tls_id, sym->st_value});
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, Dl_info* info) {
struct dso* p;
Sym *sym, *bestsym;
uint32_t nsym;
char* strings;
void* best = 0;
pthread_rwlock_rdlock(&lock);
p = addr2dso((size_t)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 = ((size_t)addr - (size_t)p->funcdescs) / sizeof(*p->funcdescs);
if (idx < nsym && (sym[idx].st_info & 0xf) == STT_FUNC) {
best = p->funcdescs + idx;
bestsym = sym + idx;
}
}
if (!best)
for (; nsym; nsym--, sym++) {
if (sym->st_value && (1 << (sym->st_info & 0xf) & OK_TYPES) &&
(1 << (sym->st_info >> 4) & OK_BINDS)) {
void* symaddr = laddr(p, sym->st_value);
if (symaddr > addr || symaddr < best)
continue;
best = symaddr;
bestsym = sym;
if (addr == symaddr)
break;
}
}
if (!best)
return 0;
if (DL_FDPIC && (bestsym->st_info & 0xf) == STT_FUNC)
best = p->funcdescs + (bestsym - p->syms);
info->dli_fname = p->name;
info->dli_fbase = p->base;
info->dli_sname = strings + bestsym->st_name;
info->dli_saddr = best;
return 1;
}
__attribute__((__visibility__("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;
}
__attribute__((__visibility__("hidden"))) void __dl_vseterr(const char*,
va_list);
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);
}