diff options
Diffstat (limited to 'src/ldso/dynlink.c')
-rw-r--r-- | src/ldso/dynlink.c | 347 |
1 files changed, 174 insertions, 173 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index f6ed8011..1008e3ea 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -19,26 +19,13 @@ #include <dlfcn.h> #include "pthread_impl.h" #include "libc.h" +#include "dynlink.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)) @@ -88,6 +75,7 @@ struct dso { volatile int new_dtv_idx, new_tls_idx; struct td_index *td_index; struct dso *fini_next; + int rel_early_relative, rel_update_got; char *shortname; char buf[]; }; @@ -97,26 +85,6 @@ struct symdef { struct dso *dso; }; -enum { - REL_ERR, - REL_SYMBOLIC, - REL_GOT, - REL_PLT, - REL_RELATIVE, - REL_OFFSET, - REL_OFFSET32, - REL_COPY, - REL_SYM_OR_REL, - REL_TLS, /* everything past here is TLS */ - REL_DTPMOD, - REL_DTPOFF, - REL_TPOFF, - REL_TPOFF_NEG, - REL_TLSDESC, -}; - -#include "reloc.h" - int __init_tp(void *); void __init_libc(char **, char *); @@ -129,7 +97,8 @@ static struct builtin_tls { } builtin_tls[1]; #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt) -static struct dso *head, *tail, *ldso, *fini_head; +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; @@ -145,14 +114,19 @@ static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE }; struct debug *_dl_debug_addr = &debug; -#define AUX_CNT 38 -#define DYN_CNT 34 +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) 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]; + 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]; } } @@ -276,8 +250,6 @@ static struct symdef find_sym(struct dso *dso, const char *s, int need_def) return def; } -#define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT) - ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic(); static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride) @@ -288,7 +260,7 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri Sym *sym; const char *name; void *ctx; - int astype, type; + int type; int sym_index; struct symdef def; size_t *reloc_addr; @@ -297,14 +269,8 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri size_t addend; for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) { - astype = R_TYPE(rel[1]); - if (!astype) continue; - type = remap_rel(astype); - if (!type) { - error("Error relocating %s: unsupported relocation type %d", - dso->name, astype); - continue; - } + if (dso->rel_early_relative && IS_RELATIVE(rel[1])) continue; + type = R_TYPE(rel[1]); sym_index = R_SYM(rel[1]); reloc_addr = (void *)(base + rel[0]); if (sym_index) { @@ -324,14 +290,19 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri def.dso = dso; } + int gotplt = (type == REL_GOT || type == REL_PLT); + if (dso->rel_update_got && !gotplt) continue; + addend = stride>2 ? rel[2] - : (1<<type & NO_INLINE_ADDEND) ? 0 + : gotplt || type==REL_COPY ? 0 : *reloc_addr; sym_val = def.sym ? (size_t)def.dso->base+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: @@ -395,6 +366,10 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri #endif } break; + default: + error("Error relocating %s: unsupported relocation type %d", + dso->name, type); + continue; } } } @@ -711,22 +686,22 @@ static struct dso *load_library(const char *name, struct dso *needed_by) if (!(reported & mask)) { reported |= mask; dprintf(1, "\t%s => %s (%p)\n", - name, ldso->name, - ldso->base); + name, ldso.name, + ldso.base); } } is_self = 1; } } } - if (!strcmp(name, ldso->name)) 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; + if (!ldso.prev) { + tail->next = &ldso; + ldso.prev = tail; + tail = ldso.next ? ldso.next : &ldso; } - return ldso; + return &ldso; } if (strchr(name, '/')) { pathname = name; @@ -752,13 +727,13 @@ static struct dso *load_library(const char *name, struct dso *needed_by) if (!sys_path) { char *prefix = 0; size_t prefix_len; - if (ldso->name[0]=='/') { + if (ldso.name[0]=='/') { char *s, *t, *z; - for (s=t=z=ldso->name; *s; s++) + for (s=t=z=ldso.name; *s; s++) if (*s=='/') z=t, t=s; - prefix_len = z-ldso->name; + prefix_len = z-ldso.name; if (prefix_len < PATH_MAX) - prefix = ldso->name; + prefix = ldso.name; } if (!prefix) { prefix = ""; @@ -910,21 +885,40 @@ 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->rel_early_relative) { + 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] = {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 + if (NEED_MIPS_GOT_RELOCS) + do_mips_relocs(p, (void *)(p->base+dyn[DT_PLTGOT])); 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 && + if (head != &ldso && p->relro_start != p->relro_end && mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) { error("Error relocating %s: RELRO protection failed: %m", p->name); @@ -1121,19 +1115,52 @@ static void update_tls_size() tls_align); } -void *__dynlink(int argc, char **argv) +/* 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. */ + +void __dls2(unsigned char *base) { - size_t aux[AUX_CNT] = {0}; + Ehdr *ehdr = (void *)base; + ldso.base = base; + ldso.name = ldso.shortname = "libc.so"; + ldso.global = 1; + ldso.phnum = ehdr->e_phnum; + ldso.phdr = (void *)(base + ehdr->e_phoff); + ldso.phentsize = ehdr->e_phentsize; + ldso.rel_early_relative = 1; + kernel_mapped_dso(&ldso); + decode_dyn(&ldso); + + head = &ldso; + reloc_all(&ldso); + + ldso.relocated = 0; + ldso.rel_update_got = 1; +} + +/* 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] = {0}, *auxv; 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; + int argc = *sp; + char **argv = (void *)(sp+1); + char **argv_orig = argv; char **envp = argv+argc+1; void *initial_tls; @@ -1157,60 +1184,42 @@ void *__dynlink(int argc, char **argv) libc.page_size = aux[AT_PAGESZ]; libc.auxv = auxv; - /* 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]) { + /* 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. */ - app->phdr = phdr = (void *)aux[AT_PHDR]; - app->phnum = aux[AT_PHNUM]; - app->phentsize = aux[AT_PHENT]; + 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); + 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; + 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 (app.tls_size) app.tls_image = (char *)app.base + tls_image; + if (interp_off) ldso.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]; + app.name = (char *)aux[AT_EXECFN]; else - app->name = argv[0]; - kernel_mapped_dso(app); + 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; + argv++; while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') { char *opt = argv[0]+2; *argv++ = (void *)-1; @@ -1229,8 +1238,8 @@ void *__dynlink(int argc, char **argv) } else { argv[0] = 0; } - argv[-1] = (void *)-1; } + argv[-1] = (void *)(argc - (argv-argv_orig)); if (!argv[0]) { dprintf(2, "musl libc\n" "Version %s\n" @@ -1246,96 +1255,88 @@ void *__dynlink(int argc, char **argv) _exit(1); } runtime = 1; - ehdr = (void *)map_library(fd, app); + 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); - lib->name = ldname; - app->name = argv[0]; - aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry; + ldso.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); + for (i=0; i<app.phnum; i++) { + if (app.phdr[i].p_type == PT_INTERP) + ldso.name = (void *)(app.base + + app.phdr[i].p_vaddr); } - dprintf(1, "\t%s (%p)\n", lib->name, lib->base); + dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base); } } - if (app->tls_size) { - app->tls_id = tls_cnt = 1; + 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) ); + 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) ); + 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); + tls_align = MAXP2(tls_align, app.tls_align); } - app->global = 1; - decode_dyn(app); + 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; + 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); + 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.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; + 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. 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. */ + /* 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(lib); + reclaim_gaps(&app); + reclaim_gaps(&ldso); /* 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. */ + * namespace, and perform all remaining relocations. */ if (env_preload) load_preload(env_preload); - load_deps(app); - make_global(app); + 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; + 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); + /* 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) { @@ -1359,14 +1360,13 @@ void *__dynlink(int argc, char **argv) /* 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. */ + * error. */ runtime = 1; debug.ver = 1; debug.bp = _dl_debug_state; debug.head = head; - debug.base = lib->base; + debug.base = ldso.base; debug.state = 0; _dl_debug_state(); @@ -1375,7 +1375,8 @@ void *__dynlink(int argc, char **argv) errno = 0; do_init_fini(tail); - return (void *)aux[AT_ENTRY]; + CRTJMP((void *)aux[AT_ENTRY], argv-1); + for(;;); } void *dlopen(const char *file, int mode) |