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1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 | #define _GNU_SOURCE #include <stdio.h> #include <stdlib.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" static int errflag; static char errbuf[128]; #ifdef SHARED #if ULONG_MAX == 0xffffffff typedef Elf32_Ehdr Ehdr; typedef Elf32_Phdr Phdr; typedef Elf32_Sym Sym; #define R_TYPE(x) ((x)&255) #define R_SYM(x) ((x)>>8) #else typedef Elf64_Ehdr Ehdr; typedef Elf64_Phdr Phdr; typedef Elf64_Sym Sym; #define R_TYPE(x) ((x)&0xffffffff) #define R_SYM(x) ((x)>>32) #endif #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 dso { unsigned char *base; 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; void *tls_image; size_t tls_len, tls_size, tls_align, tls_id, tls_offset; size_t relro_start, relro_end; void **new_dtv; unsigned char *new_tls; int new_dtv_idx, new_tls_idx; struct dso *fini_next; char *shortname; char buf[]; }; struct symdef { Sym *sym; struct dso *dso; }; #include "reloc.h" int __init_tp(void *); void __init_libc(char **, char *); const char *__libc_get_version(void); static struct dso *head, *tail, *ldso, *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 size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t); static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE }; static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)]; struct debug *_dl_debug_addr = &debug; #define AUX_CNT 38 #define DYN_CNT 34 static void decode_vec(size_t *v, size_t *a, size_t cnt) { memset(a, 0, cnt*sizeof(size_t)); for (; v[0]; v+=2) if (v[0]<cnt) { a[0] |= 1ULL<<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*33 + *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(const char *s, uint32_t h1, struct dso *dso) { Sym *syms = dso->syms; char *strings = dso->strings; uint32_t *hashtab = dso->ghashtab; uint32_t nbuckets = hashtab[0]; uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4); uint32_t h2; uint32_t *hashval; uint32_t i = buckets[h1 % nbuckets]; if (!i) return 0; hashval = buckets + nbuckets + (i - hashtab[1]); for (h1 |= 1; ; i++) { h2 = *hashval++; if ((!dso->versym || dso->versym[i] >= 0) && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name)) return syms+i; if (h2 & 1) break; } return 0; } #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) static struct symdef find_sym(struct dso *dso, const char *s, int need_def) { uint32_t h = 0, gh = 0; struct symdef def = {0}; for (; dso; dso=dso->next) { Sym *sym; if (!dso->global) continue; if (dso->ghashtab) { if (!gh) gh = gnu_hash(s); sym = gnu_lookup(s, gh, dso); } 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) 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; } 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; for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) { type = R_TYPE(rel[1]); sym_index = R_SYM(rel[1]); if (sym_index) { sym = syms + sym_index; name = strings + sym->st_name; ctx = IS_COPY(type) ? head->next : head; def = find_sym(ctx, name, IS_PLT(type)); if (!def.sym && (sym->st_shndx != SHN_UNDEF || sym->st_info>>4 != STB_WEAK)) { snprintf(errbuf, sizeof errbuf, "Error relocating %s: %s: symbol not found", dso->name, name); if (runtime) longjmp(*rtld_fail, 1); dprintf(2, "%s\n", errbuf); ldso_fail = 1; continue; } } else { sym = 0; def.sym = 0; def.dso = 0; } do_single_reloc(dso, base, (void *)(base + rel[0]), type, stride>2 ? rel[2] : 0, sym, sym?sym->st_size:0, def, def.sym?(size_t)(def.dso->base+def.sym->st_value):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 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 = (size_t *)(dso->base + start); z = (size_t *)(dso->base + 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; 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 *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; 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; 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; 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 = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start); if (map==MAP_FAILED) goto error; /* 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) 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(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((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) < 0) goto error; break; } dso->map = map; dso->map_len = map_len; dso->base = base; dso->dynv = (void *)(base+dyn); if (dso->tls_size) dso->tls_image = (void *)(base+tls_image); if (!runtime) reclaim_gaps(dso); free(allocated_buf); return map; noexec: errno = ENOEXEC; error: if (map!=MAP_FAILED) munmap(map, map_len); 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) continue; if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd; 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) return 0; if (!p->rpath_orig) return -1; 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 -1; s = t+1; n++; } if (n > SSIZE_MAX/PATH_MAX) return -1; 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, $ORIGIN can be processed safely * since the library's pathname came from a trusted source * (either system paths or a call to dlopen). */ if (libc.secure) return -1; l = readlink("/proc/self/exe", buf, buf_size); if (l >= buf_size) return -1; buf[l] = 0; origin = buf; } else { origin = p->name; } t = strrchr(origin, '/'); l = t ? t-origin : 0; p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1); if (!p->rpath) return -1; d = p->rpath; s = p->rpath_orig; while ((t=strchr(s, '$'))) { 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] = {0}; decode_vec(p->dynv, dyn, DYN_CNT); p->syms = (void *)(p->base + dyn[DT_SYMTAB]); p->strings = (void *)(p->base + dyn[DT_STRTAB]); if (dyn[0]&(1<<DT_HASH)) p->hashtab = (void *)(p->base + dyn[DT_HASH]); if (dyn[0]&(1<<DT_RPATH)) p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]); if (search_vec(p->dynv, dyn, DT_GNU_HASH)) p->ghashtab = (void *)(p->base + *dyn); if (search_vec(p->dynv, dyn, DT_VERSYM)) p->versym = (void *)(p->base + *dyn); } 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; /* 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 < 0 && p; p=p->needed_by) if (!fixup_rpath(p, buf, sizeof buf)) fd = path_open(name, p->rpath, buf, sizeof buf); if (fd < 0) { 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) { munmap(map, temp_dso.map_len); 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) { if (runtime && !libc.has_thread_pointer) { munmap(map, p->map_len); free(p); errno = ENOSYS; return 0; } 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)); } tail->next = p; p->prev = tail; tail = 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) { snprintf(errbuf, sizeof errbuf, "Error loading shared library %s: %m (needed by %s)", p->strings + p->dynv[i+1], p->name); if (runtime) longjmp(*rtld_fail, 1); dprintf(2, "%s\n", errbuf); ldso_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++); for (z=s; *z && !isspace(*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 reloc_all(struct dso *p) { size_t dyn[DYN_CNT] = {0}; for (; p; p=p->next) { if (p->relocated) continue; decode_vec(p->dynv, dyn, DYN_CNT); #ifdef NEED_ARCH_RELOCS do_arch_relocs(p, head); #endif do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ], 2+(dyn[DT_PLTREL]==DT_RELA)); do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2); do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3); if (p->relro_start != p->relro_end && mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) { snprintf(errbuf, sizeof errbuf, "Error relocating %s: RELRO protection failed: %m", p->name); if (runtime) longjmp(*rtld_fail, 1); dprintf(2, "%s\n", errbuf); ldso_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 = (void *)(p->base + 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; } static void do_fini() { struct dso *p; size_t dyn[DYN_CNT] = {0}; 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 *)(p->base + dyn[DT_FINI_ARRAY])+n; while (n--) ((void (*)(void))*--fn)(); } #ifndef NO_LEGACY_INITFINI if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI]) ((void (*)(void))(p->base + dyn[DT_FINI]))(); #endif } } static void do_init_fini(struct dso *p) { size_t dyn[DYN_CNT] = {0}; 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]) ((void (*)(void))(p->base + dyn[DT_INIT]))(); #endif if (dyn[0] & (1<<DT_INIT_ARRAY)) { size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t); size_t *fn = (void *)(p->base + 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 _dl_debug_state(void) { } void __reset_tls() { pthread_t self = __pthread_self(); struct dso *p; for (p=head; p; p=p->next) { if (!p->tls_id || !self->dtv[p->tls_id]) continue; memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len); memset((char *)self->dtv[p->tls_id]+p->tls_len, 0, p->tls_size - p->tls_len); if (p->tls_id == (size_t)self->dtv[0]) break; } } void *__copy_tls(unsigned char *mem) { pthread_t td; struct dso *p; void **dtv = (void *)mem; dtv[0] = (void *)tls_cnt; if (!tls_cnt) { td = (void *)(dtv+1); td->dtv = dtv; return td; } #ifdef TLS_ABOVE_TP mem += sizeof(void *) * (tls_cnt+1); mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1); td = (pthread_t)mem; mem += sizeof(struct pthread); for (p=head; p; p=p->next) { if (!p->tls_id) continue; dtv[p->tls_id] = mem + p->tls_offset; memcpy(dtv[p->tls_id], p->tls_image, p->tls_len); } #else mem += libc.tls_size - sizeof(struct pthread); mem -= (uintptr_t)mem & (tls_align-1); td = (pthread_t)mem; for (p=head; p; p=p->next) { if (!p->tls_id) continue; dtv[p->tls_id] = mem - p->tls_offset; memcpy(dtv[p->tls_id], p->tls_image, p->tls_len); } #endif td->dtv = dtv; return td; } void *__tls_get_addr(size_t *v) { pthread_t self = __pthread_self(); if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) return (char *)self->dtv[v[0]]+v[1]; /* Block signals to make accessing new TLS async-signal-safe */ sigset_t set; pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set); if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) { pthread_sigmask(SIG_SETMASK, &set, 0); return (char *)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 if needed */ if (v[0] > (size_t)self->dtv[0]) { void **newdtv = p->new_dtv + (v[0]+1)*sizeof(void *)*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 = newdtv; } /* Get new TLS memory from new DSO */ unsigned char *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[v[0]] = mem; memcpy(mem, p->tls_image, p->tls_len); pthread_sigmask(SIG_SETMASK, &set, 0); return mem + v[1]; } static void update_tls_size() { libc.tls_size = ALIGN( (1+tls_cnt) * sizeof(void *) + tls_offset + sizeof(struct pthread) + tls_align * 2, tls_align); } void *__dynlink(int argc, char **argv) { size_t aux[AUX_CNT] = {0}; size_t i; Phdr *phdr; Ehdr *ehdr; static struct dso builtin_dsos[3]; struct dso *const app = builtin_dsos+0; struct dso *const lib = builtin_dsos+1; struct dso *const vdso = builtin_dsos+2; char *env_preload=0; size_t vdso_base; size_t *auxv; char **envp = argv+argc+1; void *initial_tls; /* Find aux vector just past environ[] */ for (i=argc+1; argv[i]; i++) if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16)) env_path = argv[i]+16; else if (!memcmp(argv[i], "LD_PRELOAD=", 11)) env_preload = argv[i]+11; auxv = (void *)(argv+i+1); decode_vec(auxv, aux, AUX_CNT); /* Only trust user/env if kernel says we're not suid/sgid */ if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID] || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) { env_path = 0; env_preload = 0; libc.secure = 1; } libc.page_size = aux[AT_PAGESZ]; /* If the dynamic linker was invoked as a program itself, AT_BASE * will not be set. In that case, we assume the base address is * the start of the page containing the PHDRs; I don't know any * better approach... */ if (!aux[AT_BASE]) { aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE; aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0; } /* The dynamic linker load address is passed by the kernel * in the AUX vector, so this is easy. */ lib->base = (void *)aux[AT_BASE]; lib->name = lib->shortname = "libc.so"; lib->global = 1; ehdr = (void *)lib->base; lib->phnum = ehdr->e_phnum; lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff); lib->phentsize = ehdr->e_phentsize; kernel_mapped_dso(lib); decode_dyn(lib); if (aux[AT_PHDR]) { size_t interp_off = 0; size_t tls_image = 0; /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */ app->phdr = 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 (app->tls_size) app->tls_image = (char *)app->base + tls_image; if (interp_off) lib->name = (char *)app->base + 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++ = (void *)-1; if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1; if (!argv[0]) { dprintf(2, "musl libc\n" "Version %s\n" "Dynamic Program Loader\n" "Usage: %s [--] 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 = (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); lib->name = ldname; app->name = argv[0]; aux[AT_ENTRY] = (size_t)app->base + 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) lib->name = (void *)(app->base + app->phdr[i].p_vaddr); } dprintf(1, "\t%s (%p)\n", lib->name, lib->base); } } if (app->tls_size) { 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); /* Attach to vdso, if provided by the kernel */ if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) { ehdr = (void *)vdso_base; vdso->phdr = 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; decode_dyn(vdso); vdso->prev = lib; lib->next = vdso; } /* Initial dso chain consists only of the app. We temporarily * append the dynamic linker/libc so we can relocate it, then * restore the initial chain in preparation for loading third * party libraries (preload/needed). */ head = tail = app; ldso = lib; app->next = lib; reloc_all(lib); app->next = 0; /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */ /* Donate unused parts of app and library mapping to malloc */ reclaim_gaps(app); reclaim_gaps(lib); /* Load preload/needed libraries, add their symbols to the global * namespace, and perform all remaining relocations. The main * program must be relocated LAST since it may contain copy * relocations which depend on libraries' relocations. */ if (env_preload) load_preload(env_preload); load_deps(app); make_global(app); #ifndef DYNAMIC_IS_RO for (i=0; app->dynv[i]; i+=2) if (app->dynv[i]==DT_DEBUG) app->dynv[i+1] = (size_t)&debug; #endif reloc_all(app->next); reloc_all(app); update_tls_size(); if (libc.tls_size > sizeof builtin_tls) { 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); } } else { initial_tls = builtin_tls; } if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) { dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]); _exit(127); } 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. If the dynamic loader (dlopen) will not be used, free * all memory used by the dynamic linker. */ runtime = 1; debug.ver = 1; debug.bp = _dl_debug_state; debug.head = head; debug.base = lib->base; debug.state = 0; _dl_debug_state(); __init_libc(envp, argv[0]); atexit(do_fini); errno = 0; do_init_fini(tail); return (void *)aux[AT_ENTRY]; } void *dlopen(const char *file, int mode) { struct dso *volatile p, *orig_tail, *next; 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_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; munmap(p->map, p->map_len); free(p->deps); free(p); } tls_cnt = orig_tls_cnt; tls_offset = orig_tls_offset; tls_align = orig_tls_align; tail = orig_tail; tail->next = 0; p = 0; errflag = 1; goto end; } else p = load_library(file, head); if (!p) { snprintf(errbuf, sizeof errbuf, noload ? "Library %s is not already loaded" : "Error loading shared library %s: %m", file); errflag = 1; 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; } static int invalid_dso_handle(void *h) { struct dso *p; for (p=head; p; p=p->next) if (h==p) return 0; snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h); errflag = 1; return 1; } static void *do_dlsym(struct dso *p, const char *s, void *ra) { size_t i; uint32_t h = 0, gh = 0; Sym *sym; if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) { if (p == RTLD_DEFAULT) { p = head; } else if (p == RTLD_NEXT) { for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next); if (!p) p=head; p = p->next; } 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}); return def.dso->base + def.sym->st_value; } if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p)) return 0; if (p->ghashtab) { gh = gnu_hash(s); sym = gnu_lookup(s, gh, p); } 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 (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES)) return p->base + sym->st_value; if (p->deps) for (i=0; p->deps[i]; i++) { if (p->deps[i]->ghashtab) { if (!gh) gh = gnu_hash(s); sym = gnu_lookup(s, gh, p->deps[i]); } 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 (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES)) return p->deps[i]->base + sym->st_value; } failed: errflag = 1; snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s); return 0; } int __dladdr(const void *addr, Dl_info *info) { struct dso *p; Sym *sym; uint32_t nsym; char *strings; size_t i; void *best = 0; char *bestname; pthread_rwlock_rdlock(&lock); for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next); pthread_rwlock_unlock(&lock); if (!p) return 0; sym = p->syms; strings = p->strings; if (p->hashtab) { nsym = p->hashtab[1]; } else { uint32_t *buckets; uint32_t *hashval; buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4); sym += p->ghashtab[1]; for (i = nsym = 0; i < p->ghashtab[0]; i++) { if (buckets[i] > nsym) nsym = buckets[i]; } if (nsym) { nsym -= p->ghashtab[1]; hashval = buckets + p->ghashtab[0] + nsym; do nsym++; while (!(*hashval++ & 1)); } } for (; nsym; nsym--, sym++) { if (sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES) && (1<<(sym->st_info>>4) & OK_BINDS)) { void *symaddr = p->base + sym->st_value; if (symaddr > addr || symaddr < best) continue; best = symaddr; bestname = strings + sym->st_name; if (addr == symaddr) break; } } if (!best) return 0; info->dli_fname = p->name; info->dli_fbase = p->base; info->dli_sname = bestname; info->dli_saddr = best; return 1; } 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; } #else static int invalid_dso_handle(void *h) { snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h); errflag = 1; return 1; } void *dlopen(const char *file, int mode) { return 0; } void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra) { return 0; } int __dladdr (const void *addr, Dl_info *info) { return 0; } #endif int __dlinfo(void *dso, int req, void *res) { if (invalid_dso_handle(dso)) return -1; if (req != RTLD_DI_LINKMAP) { snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req); errflag = 1; return -1; } *(struct link_map **)res = dso; return 0; } char *dlerror() { if (!errflag) return 0; errflag = 0; return errbuf; } int dlclose(void *p) { return invalid_dso_handle(p); } |