X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fldso%2Fdynlink.c;h=df54230c8cf2517ce9941f14b711f51297b3fcae;hp=03f0920830d4ec10761945d7823f3a15eebb6e04;hb=e12fe65c928f038fb8db0caddcf535ab0a980c58;hpb=6b3d5e508fcf16abe18c163c4c31a47f2d35a306 diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index 03f09208..df54230c 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -1,3 +1,4 @@ +#ifdef __PIC__ #include #include #include @@ -13,6 +14,9 @@ #include #include #include +#include +#include +#include #include "reloc.h" @@ -45,16 +49,19 @@ struct dso ino_t ino; int global; int relocated; + struct dso **deps; char *name; char buf[]; }; static struct dso *head, *tail, *libc; -static char *env_path, *sys_path; +static char *env_path, *sys_path, *r_path; +static int rtld_used; static int runtime; static jmp_buf rtld_fail; +static pthread_rwlock_t lock; -#define AUX_CNT 15 +#define AUX_CNT 24 #define DYN_CNT 34 static void decode_vec(size_t *v, size_t *a, size_t cnt) @@ -66,8 +73,9 @@ static void decode_vec(size_t *v, size_t *a, size_t cnt) } } -static uint32_t hash(const char *s) +static uint32_t hash(const char *s0) { + const unsigned char *s = (void *)s0; uint_fast32_t h = 0; while (*s) { h = 16*h + *s++; @@ -87,17 +95,27 @@ static Sym *lookup(const char *s, uint32_t h, Sym *syms, uint32_t *hashtab, char } #define OK_TYPES (1<next) { - Sym *sym = lookup(s, h, dso->syms, dso->hashtab, dso->strings); + Sym *sym; + if (!dso->global) continue; + sym = lookup(s, h, dso->syms, dso->hashtab, dso->strings); if (sym && (!need_def || sym->st_shndx) && sym->st_value - && (1<<(sym->st_info&0xf) & OK_TYPES)) - return dso->base + sym->st_value; + && (1<<(sym->st_info&0xf) & OK_TYPES) + && (1<<(sym->st_info>>4) & OK_BINDS)) { + if (def && sym->st_info>>4 == STB_WEAK) continue; + def = dso->base + sym->st_value; + if (sym->st_info>>4 == STB_GLOBAL) break; + } } - return 0; + return def; } static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t stride, Sym *syms, char *strings, struct dso *dso) @@ -130,6 +148,37 @@ static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t } } +/* 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(unsigned char *base, size_t start, size_t end) +{ + size_t *a, *z; + 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 *)(base + start); + z = (size_t *)(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(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt) +{ + for (; phcnt--; ph=(void *)((char *)ph+phent)) { + if (ph->p_type!=PT_LOAD) continue; + if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue; + reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr); + reclaim(base, ph->p_vaddr+ph->p_memsz, + ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE); + } +} + static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dynp) { Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)]; @@ -180,7 +229,7 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy * 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(0, map_len, prot, MAP_PRIVATE, fd, off_start); + map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start); if (map==MAP_FAILED) return 0; base = map - addr_min; ph = (void *)((char *)buf + eh->e_phoff); @@ -208,6 +257,13 @@ static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dy } } } + for (i=0; ((size_t *)(base+dyn))[i]; i+=2) + if (((size_t *)(base+dyn))[i]==DT_TEXTREL) { + mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC); + break; + } + if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff), + eh->e_phentsize, eh->e_phnum); *lenp = map_len; *basep = base; *dynp = dyn; @@ -230,12 +286,20 @@ static int path_open(const char *name, const char *search) } } +static void decode_dyn(struct dso *p) +{ + size_t dyn[DYN_CNT] = {0}; + decode_vec(p->dynv, dyn, DYN_CNT); + p->syms = (void *)(p->base + dyn[DT_SYMTAB]); + p->hashtab = (void *)(p->base + dyn[DT_HASH]); + p->strings = (void *)(p->base + dyn[DT_STRTAB]); +} + static struct dso *load_library(const char *name) { unsigned char *base, *map; size_t dyno, map_len; struct dso *p; - size_t dyn[DYN_CNT] = {0}; int fd; struct stat st; @@ -251,7 +315,7 @@ static struct dso *load_library(const char *name) if (!libc->prev) { tail->next = libc; libc->prev = tail; - tail = libc; + tail = libc->next ? libc->next : libc; } return libc; } @@ -264,12 +328,13 @@ static struct dso *load_library(const char *name) return p; } } - if (name[0] == '/') { + if (strchr(name, '/')) { fd = open(name, O_RDONLY); } else { - if (strlen(name) > NAME_MAX || strchr(name, '/')) return 0; + if (strlen(name) > NAME_MAX) return 0; fd = -1; - if (env_path) fd = path_open(name, env_path); + if (r_path) fd = path_open(name, r_path); + if (fd < 0 && env_path) fd = path_open(name, env_path); if (fd < 0) { if (!sys_path) { FILE *f = fopen(ETC_LDSO_PATH, "r"); @@ -308,14 +373,10 @@ static struct dso *load_library(const char *name) p->map_len = map_len; p->base = base; p->dynv = (void *)(base + dyno); - decode_vec(p->dynv, dyn, DYN_CNT); + decode_dyn(p); - p->syms = (void *)(base + dyn[DT_SYMTAB]); - p->hashtab = (void *)(base + dyn[DT_HASH]); - p->strings = (void *)(base + dyn[DT_STRTAB]); p->dev = st.st_dev; p->ino = st.st_ino; - p->global = 1; p->refcnt = 1; p->name = p->buf; strcpy(p->name, name); @@ -329,20 +390,53 @@ static struct dso *load_library(const char *name) static void load_deps(struct dso *p) { - size_t i; + 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_RPATH) continue; + r_path = (void *)(p->strings + p->dynv[i+1]); + } for (i=0; p->dynv[i]; i+=2) { if (p->dynv[i] != DT_NEEDED) continue; - if (!load_library(p->strings + p->dynv[i+1])) { + dep = load_library(p->strings + p->dynv[i+1]); + if (!dep) { if (runtime) longjmp(rtld_fail, 1); dprintf(2, "%s: %m (needed by %s)\n", p->strings + p->dynv[i+1], p->name); _exit(127); } + if (runtime) { + tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2)); + if (!tmp) longjmp(rtld_fail, 1); + tmp[ndeps++] = dep; + tmp[ndeps] = 0; + *deps = tmp; + } } + r_path = 0; } } +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); + *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}; @@ -369,79 +463,222 @@ static void free_all(struct dso *p) } } -void *__dynlink(int argc, char **argv, size_t *got) +static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride) +{ + for (; cnt--; ph = (void *)((char *)ph + stride)) + if (ph->p_type == PT_DYNAMIC) + return ph->p_vaddr; + return 0; +} + +void *__dynlink(int argc, char **argv) { size_t *auxv, aux[AUX_CNT] = {0}; - size_t app_dyn[DYN_CNT] = {0}; - size_t lib_dyn[DYN_CNT] = {0}; size_t i; Phdr *phdr; - struct dso lib, app; + 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; /* 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_GID]!=aux[AT_EGID] || aux[AT_SECURE]) { env_path = 0; + env_preload = 0; } - /* Relocate ldso's DYNAMIC pointer and load vector */ - decode_vec((void *)(got[0] += aux[AT_BASE]), lib_dyn, DYN_CNT); - - /* Find the program image's DYNAMIC section and decode it */ + /* The dynamic linker load address is passed by the kernel + * in the AUX vector, so this is easy. */ + lib->base = (void *)aux[AT_BASE]; + lib->name = "libc.so"; + lib->global = 1; + ehdr = (void *)lib->base; + lib->dynv = (void *)(lib->base + find_dyn( + (void *)(aux[AT_BASE]+ehdr->e_phoff), + ehdr->e_phnum, ehdr->e_phentsize)); + decode_dyn(lib); + + /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */ + app->base = 0; phdr = (void *)aux[AT_PHDR]; - for (i=aux[AT_PHNUM]; i--; phdr=(void *)((char *)phdr + aux[AT_PHENT])) { - if (phdr->p_type == PT_DYNAMIC) { - decode_vec((void *)phdr->p_vaddr, app_dyn, DYN_CNT); - break; + for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) { + if (phdr->p_type == PT_PHDR) + app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr); + } + app->name = argv[0]; + app->global = 1; + app->dynv = (void *)(app->base + find_dyn( + (void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT])); + decode_dyn(app); + + /* Attach to vdso, if provided by the kernel */ + for (i=0; auxv[i]; i+=2) { + size_t vdso_base = auxv[i+1]; + if (auxv[i] != AT_SYSINFO_EHDR) continue; + ehdr = (void *)vdso_base; + phdr = (void *)(vdso_base + ehdr->e_phoff); + for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) { + 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 = "linux-gate.so.1"; + vdso->global = 1; + decode_dyn(vdso); + vdso->prev = lib; + lib->next = vdso; + break; } - app = (struct dso){ - .base = 0, - .strings = (void *)(app_dyn[DT_STRTAB]), - .hashtab = (void *)(app_dyn[DT_HASH]), - .syms = (void *)(app_dyn[DT_SYMTAB]), - .dynv = (void *)(phdr->p_vaddr), - .name = argv[0], - .next = &lib - }; - - lib = (struct dso){ - .base = (void *)aux[AT_BASE], - .strings = (void *)(aux[AT_BASE]+lib_dyn[DT_STRTAB]), - .hashtab = (void *)(aux[AT_BASE]+lib_dyn[DT_HASH]), - .syms = (void *)(aux[AT_BASE]+lib_dyn[DT_SYMTAB]), - .dynv = (void *)(got[0]), - .name = "libc.so", - .relocated = 1 - }; - - /* Relocate the dynamic linker/libc */ - do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]), - lib_dyn[DT_RELSZ], 2, lib.syms, lib.strings, &app); - do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_RELA]), - lib_dyn[DT_RELASZ], 3, lib.syms, lib.strings, &app); - - /* At this point the standard library is fully functional */ - - head = tail = &app; - libc = &lib; - app.next = 0; - load_deps(head); - - reloc_all(head); - - free_all(head); - free(sys_path); + /* Initial dso chain consists only of the app. We temporarily + * append the dynamic linker/libc so we can relocate it, then + * restore the initial chain in preparation for loading third + * party libraries (preload/needed). */ + head = tail = app; + libc = lib; + app->next = lib; + reloc_all(lib); + app->next = 0; + + /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */ + + /* Donate unused parts of app and library mapping to malloc */ + reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]); + ehdr = (void *)lib->base; + reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff), + ehdr->e_phentsize, ehdr->e_phnum); + + /* 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); + reloc_all(app); + + /* Switch to runtime mode: any further failures in the dynamic + * linker are a reportable failure rather than a fatal startup + * error. If the dynamic loader (dlopen) will not be used, free + * all memory used by the dynamic linker. */ + runtime = 1; + if (!rtld_used) { + free_all(head); + free(sys_path); + reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos); + } errno = 0; return (void *)aux[AT_ENTRY]; } + +void *dlopen(const char *file, int mode) +{ + struct dso *volatile p, *orig_tail = tail, *next; + size_t i; + + if (!file) return head; + + pthread_rwlock_wrlock(&lock); + + if (setjmp(rtld_fail)) { + /* Clean up anything new that was (partially) loaded */ + if (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); + } + tail = orig_tail; + tail->next = 0; + pthread_rwlock_unlock(&lock); + return 0; + } + + p = load_library(file); + if (!p) 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; + } + +end: + pthread_rwlock_unlock(&lock); + return p; +} + +static void *do_dlsym(struct dso *p, const char *s, void *ra) +{ + size_t i; + uint32_t h; + Sym *sym; + if (p == RTLD_NEXT) { + for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next); + if (!p) p=head; + p=p->next; + } + if (p == head || p == RTLD_DEFAULT) + return find_sym(head, s, 0); + h = hash(s); + sym = lookup(s, h, p->syms, p->hashtab, p->strings); + if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES)) + return p->base + sym->st_value; + if (p->deps) for (i=0; p->deps[i]; i++) { + sym = lookup(s, h, p->deps[i]->syms, + p->deps[i]->hashtab, p->deps[i]->strings); + if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES)) + return p->deps[i]->base + sym->st_value; + } + return 0; +} + +void *__dlsym(void *p, const char *s, void *ra) +{ + void *res; + pthread_rwlock_rdlock(&lock); + res = do_dlsym(p, s, ra); + pthread_rwlock_unlock(&lock); + return res; +} + +char *dlerror() +{ + return "unknown error"; +} + +int dlclose(void *p) +{ + return 0; +} +#endif