X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fldso%2Fdynlink.c;h=57a5ba46044264374b77889108e14e7dd9a163bf;hp=527b36bd12cdc6c01764e7a6cf79e470300d4d2a;hb=cf8506ad94caa91fc1cd44b9134494dd6ecd6caf;hpb=bf30100ad7e208dbac5835b38881c98ceb5b928f diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index 527b36bd..57a5ba46 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include "reloc.h" @@ -53,13 +54,13 @@ struct dso }; 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) @@ -92,10 +93,12 @@ static Sym *lookup(const char *s, uint32_t h, Sym *syms, uint32_t *hashtab, char } #define OK_TYPES (1<next) { @@ -103,10 +106,14 @@ static void *find_sym(struct dso *dso, const char *s, int need_def) 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) @@ -139,6 +146,37 @@ 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)]; @@ -217,6 +255,13 @@ 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; @@ -260,7 +305,7 @@ 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; } @@ -278,7 +323,8 @@ static struct dso *load_library(const char *name) } else { 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"); @@ -340,6 +386,10 @@ 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_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; dep = load_library(p->strings + p->dynv[i+1]); @@ -357,6 +407,21 @@ static void load_deps(struct dso *p) *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; } } @@ -396,22 +461,39 @@ void *__dynlink(int argc, char **argv, size_t *got) size_t *auxv, aux[AUX_CNT] = {0}; size_t app_dyn[DYN_CNT] = {0}; size_t lib_dyn[DYN_CNT] = {0}; + size_t vdso_dyn[DYN_CNT] = {0}; size_t i; Phdr *phdr; - 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; + size_t vdso_base=0; + 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; + } + + for (i=0; auxv[i]; i+=2) { + if (auxv[i]==AT_SYSINFO_EHDR) { + vdso_base = auxv[i+1]; + break; + } } /* Relocate ldso's DYNAMIC pointer and load vector */ @@ -426,7 +508,7 @@ void *__dynlink(int argc, char **argv, size_t *got) } } - app = (struct dso){ + *app = (struct dso){ .base = 0, .strings = (void *)(app_dyn[DT_STRTAB]), .hashtab = (void *)(app_dyn[DT_HASH]), @@ -434,10 +516,10 @@ void *__dynlink(int argc, char **argv, size_t *got) .dynv = (void *)(phdr->p_vaddr), .name = argv[0], .global = 1, - .next = &lib + .next = lib }; - lib = (struct dso){ + *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]), @@ -448,36 +530,54 @@ void *__dynlink(int argc, char **argv, size_t *got) .relocated = 1 }; + if (vdso_base) { + 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); + } + decode_vec(vdso->dynv, vdso_dyn, DYN_CNT); + vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]); + vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]); + vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]); + vdso->name = "linux-gate.so.1"; + vdso->global = 1; + + vdso->prev = lib; + lib->next = vdso; + } + /* 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); + 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); + 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; + reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]); + ehdr = (void *)lib->base; + reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff), + ehdr->e_phentsize, ehdr->e_phnum); + + head = tail = app; + libc = lib; + app->next = 0; + if (env_preload) load_preload(env_preload); load_deps(head); make_global(head); reloc_all(head->next); reloc_all(head); - if (rtld_used) { - runtime = 1; - head->next->prev = malloc(sizeof *head); - *head->next->prev = *head; - head = head->next->prev; - libc->prev->next = malloc(sizeof *libc); - *libc->prev->next = *libc; - libc = libc->prev->next; - if (libc->next) libc->next->prev = libc; - if (tail == &lib) tail = libc; - } else { + runtime = 1; + if (!rtld_used) { free_all(head); free(sys_path); + reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos); } errno = 0; @@ -486,7 +586,7 @@ void *__dynlink(int argc, char **argv, size_t *got) void *dlopen(const char *file, int mode) { - struct dso *p, *orig_tail = tail, *next; + struct dso *volatile p, *orig_tail = tail, *next; size_t i; if (!file) return head; @@ -538,11 +638,16 @@ end: return p; } -static void *do_dlsym(struct dso *p, const char *s) +static void *do_dlsym(struct dso *p, const char *s, void *ra) { size_t i; uint32_t h; Sym *sym; + if (p == 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); @@ -558,11 +663,11 @@ static void *do_dlsym(struct dso *p, const char *s) return 0; } -void *dlsym(void *p, const char *s) +void *__dlsym(void *p, const char *s, void *ra) { void *res; pthread_rwlock_rdlock(&lock); - res = do_dlsym(p, s); + res = do_dlsym(p, s, ra); pthread_rwlock_unlock(&lock); return res; }