}
}
+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;
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->refcnt = 1;
}
}
-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 vdso_dyn[DYN_CNT] = {0};
size_t i;
Phdr *phdr;
Ehdr *ehdr;
- size_t *lib_dynv;
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[] */
env_preload = 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 = "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);
+
+ /* Assume base address of 0 for the main program. This is not
+ * valid for PIE code; we will have to search the PHDR to get
+ * the correct load address in the PIE case (not yet supported). */
+ app->base = 0;
+ 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) {
- if (auxv[i]==AT_SYSINFO_EHDR) {
- vdso_base = auxv[i+1];
- break;
- }
- }
-
- /* Find the dynamic linker's DYNAMIC section and decode it */
- ehdr = (void *)aux[AT_BASE];
- phdr = (void *)(aux[AT_BASE] + ehdr->e_phoff);
- for (i=ehdr->e_phnum; i--; phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
- if (phdr->p_type == PT_DYNAMIC) {
- lib_dynv = (void *)(aux[AT_BASE] + phdr->p_vaddr);
- decode_vec(lib_dynv, lib_dyn, DYN_CNT);
- break;
- }
- }
-
- /* Find the program image's DYNAMIC section and decode it */
- 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;
- }
- }
-
- *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],
- .global = 1,
- .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 = lib_dynv,
- .name = "libc.so",
- .global = 1,
- .relocated = 1
- };
-
- if (vdso_base) {
+ 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_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;
-
+ decode_dyn(vdso);
vdso->prev = lib;
lib->next = vdso;
+ break;
}
- /* 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);
+ /* 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;
- /* At this point the standard library is fully functional */
+ /* 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);
- head = tail = app;
- libc = lib;
- app->next = 0;
+ /* 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(head);
-
- make_global(head);
- reloc_all(head->next);
- reloc_all(head);
-
+ 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);
projects / musl / blobdiff