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-rw-r--r--linker/linker.c230
1 files changed, 160 insertions, 70 deletions
diff --git a/linker/linker.c b/linker/linker.c
index bb3b8e7..77f995e 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -53,6 +53,10 @@
#define SO_MAX 96
+/* Assume average path length of 64 and max 8 paths */
+#define LDPATH_BUFSIZE 512
+#define LDPATH_MAX 8
+
/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<<
*
* Do NOT use malloc() and friends or pthread_*() code here.
@@ -66,7 +70,6 @@
* - should we do anything special for STB_WEAK symbols?
* - are we doing everything we should for ARM_COPY relocations?
* - cleaner error reporting
- * - configuration for paths (LD_LIBRARY_PATH?)
* - after linking, set as much stuff as possible to READONLY
* and NOEXEC
* - linker hardcodes PAGE_SIZE and PAGE_MASK because the kernel
@@ -89,6 +92,9 @@ static soinfo *freelist = NULL;
static soinfo *solist = &libdl_info;
static soinfo *sonext = &libdl_info;
+static char ldpaths_buf[LDPATH_BUFSIZE];
+static const char *ldpaths[LDPATH_MAX + 1];
+
int debug_verbosity;
static int pid;
@@ -104,6 +110,32 @@ unsigned bitmask[4096];
#define PT_ARM_EXIDX 0x70000001 /* .ARM.exidx segment */
#endif
+#define HOODLUM(name, ret, ...) \
+ ret name __VA_ARGS__ \
+ { \
+ char errstr[] = "ERROR: " #name " called from the dynamic linker!\n"; \
+ write(2, errstr, sizeof(errstr)); \
+ abort(); \
+ }
+HOODLUM(malloc, void *, (size_t size));
+HOODLUM(free, void, (void *ptr));
+HOODLUM(realloc, void *, (void *ptr, size_t size));
+HOODLUM(calloc, void *, (size_t cnt, size_t size));
+
+static char tmp_err_buf[768];
+static char __linker_dl_err_buf[768];
+#define DL_ERR(fmt, x...) \
+ do { \
+ snprintf(__linker_dl_err_buf, sizeof(__linker_dl_err_buf), \
+ "%s[%d]: " fmt, __func__, __LINE__, ##x); \
+ ERROR(fmt, ##x); \
+ } while(0)
+
+const char *linker_get_error(void)
+{
+ return (const char *)&__linker_dl_err_buf[0];
+}
+
/*
* This function is an empty stub where GDB locates a breakpoint to get notified
* about linker activity.
@@ -207,7 +239,7 @@ static soinfo *alloc_info(const char *name)
soinfo *si;
if(strlen(name) >= SOINFO_NAME_LEN) {
- ERROR("%5d library name %s too long\n", pid, name);
+ DL_ERR("%5d library name %s too long\n", pid, name);
return 0;
}
@@ -216,7 +248,7 @@ static soinfo *alloc_info(const char *name)
*/
if (!freelist) {
if(socount == SO_MAX) {
- ERROR("%5d too many libraries when loading %s\n", pid, name);
+ DL_ERR("%5d too many libraries when loading %s\n", pid, name);
return NULL;
}
freelist = sopool + socount++;
@@ -252,7 +284,7 @@ static void free_info(soinfo *si)
}
if (trav == NULL) {
/* si was not ni solist */
- ERROR("%5d name %s is not in solist!\n", pid, si->name);
+ DL_ERR("%5d name %s is not in solist!\n", pid, si->name);
return;
}
@@ -477,13 +509,12 @@ static int _open_lib(const char *name)
return -1;
}
-/* TODO: Need to add support for initializing the so search path with
- * LD_LIBRARY_PATH env variable for non-setuid programs. */
static int open_library(const char *name)
{
int fd;
char buf[512];
const char **path;
+ int n;
TRACE("[ %5d opening %s ]\n", pid, name);
@@ -493,8 +524,21 @@ static int open_library(const char *name)
if ((name[0] == '/') && ((fd = _open_lib(name)) >= 0))
return fd;
+ for (path = ldpaths; *path; path++) {
+ n = snprintf(buf, sizeof(buf), "%s/%s", *path, name);
+ if (n < 0 || n >= (int)sizeof(buf)) {
+ WARN("Ignoring very long library path: %s/%s\n", *path, name);
+ continue;
+ }
+ if ((fd = _open_lib(buf)) >= 0)
+ return fd;
+ }
for (path = sopaths; *path; path++) {
- snprintf(buf, sizeof(buf), "%s/%s", *path, name);
+ n = snprintf(buf, sizeof(buf), "%s/%s", *path, name);
+ if (n < 0 || n >= (int)sizeof(buf)) {
+ WARN("Ignoring very long library path: %s/%s\n", *path, name);
+ continue;
+ }
if ((fd = _open_lib(buf)) >= 0)
return fd;
}
@@ -521,7 +565,7 @@ is_prelinked(int fd, const char *name)
sz = lseek(fd, -sizeof(prelink_info_t), SEEK_END);
if (sz < 0) {
- ERROR("lseek() failed!\n");
+ DL_ERR("lseek() failed!\n");
return 0;
}
@@ -597,7 +641,7 @@ get_lib_extents(int fd, const char *name, void *__hdr, unsigned *total_sz)
TRACE("[ %5d Computing extents for '%s'. ]\n", pid, name);
if (verify_elf_object(_hdr, name) < 0) {
- ERROR("%5d - %s is not a valid ELF object\n", pid, name);
+ DL_ERR("%5d - %s is not a valid ELF object\n", pid, name);
return (unsigned)-1;
}
@@ -625,7 +669,7 @@ get_lib_extents(int fd, const char *name, void *__hdr, unsigned *total_sz)
}
if ((min_vaddr == 0xffffffff) && (max_vaddr == 0)) {
- ERROR("%5d - No loadable segments found in %s.\n", pid, name);
+ DL_ERR("%5d - No loadable segments found in %s.\n", pid, name);
return (unsigned)-1;
}
@@ -661,13 +705,13 @@ static int reserve_mem_region(soinfo *si)
void *base = mmap((void *)si->base, si->size, PROT_READ | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (base == MAP_FAILED) {
- ERROR("%5d can NOT map (%sprelinked) library '%s' at 0x%08x "
+ DL_ERR("%5d can NOT map (%sprelinked) library '%s' at 0x%08x "
"as requested, will try general pool: %d (%s)\n",
pid, (si->base ? "" : "non-"), si->name, si->base,
errno, strerror(errno));
return -1;
} else if (base != (void *)si->base) {
- ERROR("OOPS: %5d %sprelinked library '%s' mapped at 0x%08x, "
+ DL_ERR("OOPS: %5d %sprelinked library '%s' mapped at 0x%08x, "
"not at 0x%08x\n", pid, (si->base ? "" : "non-"),
si->name, (unsigned)base, si->base);
munmap(base, si->size);
@@ -705,7 +749,7 @@ alloc_mem_region(soinfo *si)
}
err:
- ERROR("OOPS: %5d cannot map library '%s'. no vspace available.\n",
+ DL_ERR("OOPS: %5d cannot map library '%s'. no vspace available.\n",
pid, si->name);
return -1;
}
@@ -764,7 +808,7 @@ load_segments(int fd, void *header, soinfo *si)
MAP_PRIVATE | MAP_FIXED, fd,
phdr->p_offset & (~PAGE_MASK));
if (pbase == MAP_FAILED) {
- ERROR("%d failed to map segment from '%s' @ 0x%08x (0x%08x). "
+ DL_ERR("%d failed to map segment from '%s' @ 0x%08x (0x%08x). "
"p_vaddr=0x%08x p_offset=0x%08x\n", pid, si->name,
(unsigned)tmp, len, phdr->p_vaddr, phdr->p_offset);
goto fail;
@@ -820,8 +864,8 @@ load_segments(int fd, void *header, soinfo *si)
MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS,
-1, 0);
if (extra_base == MAP_FAILED) {
- ERROR("[ %5d - failed to extend segment from '%s' @ 0x%08x "
- "(0x%08x) ]\n", pid, si->name, (unsigned)tmp,
+ DL_ERR("[ %5d - failed to extend segment from '%s' @ 0x%08x"
+ " (0x%08x) ]\n", pid, si->name, (unsigned)tmp,
extra_len);
goto fail;
}
@@ -873,7 +917,7 @@ load_segments(int fd, void *header, soinfo *si)
/* Sanity check */
if (total_sz > si->size) {
- ERROR("%5d - Total length (0x%08x) of mapped segments from '%s' is "
+ DL_ERR("%5d - Total length (0x%08x) of mapped segments from '%s' is "
"greater than what was allocated (0x%08x). THIS IS BAD!\n",
pid, total_sz, si->name, si->size);
goto fail;
@@ -940,18 +984,20 @@ load_library(const char *name)
soinfo *si = NULL;
Elf32_Ehdr *hdr;
- if(fd == -1)
+ if(fd == -1) {
+ DL_ERR("Library '%s' not found\n", name);
return NULL;
+ }
/* We have to read the ELF header to figure out what to do with this image
*/
if (lseek(fd, 0, SEEK_SET) < 0) {
- ERROR("lseek() failed!\n");
+ DL_ERR("lseek() failed!\n");
goto fail;
}
if ((cnt = read(fd, &__header[0], PAGE_SIZE)) < 0) {
- ERROR("read() failed!\n");
+ DL_ERR("read() failed!\n");
goto fail;
}
@@ -1042,8 +1088,8 @@ soinfo *find_library(const char *name)
if(!strcmp(name, si->name)) {
if(si->flags & FLAG_ERROR) return 0;
if(si->flags & FLAG_LINKED) return si;
- ERROR("OOPS: %5d recursive link to '%s'\n", pid, si->name);
- return 0;
+ DL_ERR("OOPS: %5d recursive link to '%s'\n", pid, si->name);
+ return NULL;
}
}
@@ -1074,7 +1120,7 @@ unsigned unload_library(soinfo *si)
if(lsi)
unload_library(lsi);
else
- ERROR("%5d could not unload '%s'\n",
+ DL_ERR("%5d could not unload '%s'\n",
pid, si->strtab + d[1]);
}
}
@@ -1124,19 +1170,19 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
sym_name = (char *)(strtab + symtab[sym].st_name);
s = _do_lookup(si, sym_name, &base);
if(s == 0) {
- ERROR("%5d cannot locate '%s'...\n", pid, sym_name);
+ DL_ERR("%5d cannot locate '%s'...\n", pid, sym_name);
return -1;
}
#if 0
if((base == 0) && (si->base != 0)){
/* linking from libraries to main image is bad */
- ERROR("%5d cannot locate '%s'...\n",
+ DL_ERR("%5d cannot locate '%s'...\n",
pid, strtab + symtab[sym].st_name);
return -1;
}
#endif
if ((s->st_shndx == SHN_UNDEF) && (s->st_value != 0)) {
- ERROR("%5d In '%s', shndx=%d && value=0x%08x. We do not "
+ DL_ERR("%5d In '%s', shndx=%d && value=0x%08x. We do not "
"handle this yet\n", pid, si->name, s->st_shndx,
s->st_value);
return -1;
@@ -1198,7 +1244,7 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
COUNT_RELOC(RELOC_RELATIVE);
MARK(rel->r_offset);
if(sym){
- ERROR("%5d odd RELATIVE form...\n", pid);
+ DL_ERR("%5d odd RELATIVE form...\n", pid);
return -1;
}
TRACE_TYPE(RELO, "%5d RELO RELATIVE %08x <- +%08x\n", pid,
@@ -1239,7 +1285,7 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
#endif /* ANDROID_ARM_LINKER */
default:
- ERROR("%5d unknown reloc type %d @ %p (%d)\n",
+ DL_ERR("%5d unknown reloc type %d @ %p (%d)\n",
pid, type, rel, (int) (rel - start));
return -1;
}
@@ -1248,13 +1294,38 @@ static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count)
return 0;
}
-static void call_array(unsigned *ctor, int count)
+
+/* Please read the "Initialization and Termination functions" functions.
+ * of the linker design note in bionic/linker/README.TXT to understand
+ * what the following code is doing.
+ *
+ * The important things to remember are:
+ *
+ * DT_PREINIT_ARRAY must be called first for executables, and should
+ * not appear in shared libraries.
+ *
+ * DT_INIT should be called before DT_INIT_ARRAY if both are present
+ *
+ * DT_FINI should be called after DT_FINI_ARRAY if both are present
+ *
+ * DT_FINI_ARRAY must be parsed in reverse order.
+ */
+
+static void call_array(unsigned *ctor, int count, int reverse)
{
- int n;
- for(n = count; n > 0; n--){
- TRACE("[ %5d Looking at ctor *0x%08x == 0x%08x ]\n", pid,
+ int n, inc = 1;
+
+ if (reverse) {
+ ctor += (count-1);
+ inc = -1;
+ }
+
+ for(n = count; n > 0; n--) {
+ TRACE("[ %5d Looking at %s *0x%08x == 0x%08x ]\n", pid,
+ reverse ? "dtor" : "ctor",
(unsigned)ctor, (unsigned)*ctor);
- void (*func)() = (void (*)()) *ctor++;
+ void (*func)() = (void (*)()) *ctor;
+ ctor += inc;
if(((int) func == 0) || ((int) func == -1)) continue;
TRACE("[ %5d Calling func @ 0x%08x ]\n", pid, (unsigned)func);
func();
@@ -1263,31 +1334,20 @@ static void call_array(unsigned *ctor, int count)
static void call_constructors(soinfo *si)
{
- /* TODO: THE ORIGINAL CODE SEEMED TO CALL THE INIT FUNCS IN THE WRONG ORDER.
- * Old order: init, init_array, preinit_array..
- * Correct order: preinit_array, init, init_array.
- * Verify WHY.
- */
-
if (si->flags & FLAG_EXE) {
TRACE("[ %5d Calling preinit_array @ 0x%08x [%d] for '%s' ]\n",
pid, (unsigned)si->preinit_array, si->preinit_array_count,
si->name);
- call_array(si->preinit_array, si->preinit_array_count);
+ call_array(si->preinit_array, si->preinit_array_count, 0);
TRACE("[ %5d Done calling preinit_array for '%s' ]\n", pid, si->name);
} else {
if (si->preinit_array) {
- ERROR("%5d Shared library '%s' has a preinit_array table @ 0x%08x."
- " This is INVALID.\n", pid, si->name,
- (unsigned)si->preinit_array);
+ DL_ERR("%5d Shared library '%s' has a preinit_array table @ 0x%08x."
+ " This is INVALID.\n", pid, si->name,
+ (unsigned)si->preinit_array);
}
}
- // If we have an init section, then we should call it now, to make sure
- // that all the funcs in the .ctors section get run.
- // Note: For ARM, we shouldn't have a .ctor section (should be empty)
- // when we have an (pre)init_array section, but let's be compatible with
- // old (non-eabi) binaries and try the _init (DT_INIT) anyway.
if (si->init_func) {
TRACE("[ %5d Calling init_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->init_func, si->name);
@@ -1298,25 +1358,21 @@ static void call_constructors(soinfo *si)
if (si->init_array) {
TRACE("[ %5d Calling init_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->init_array, si->init_array_count, si->name);
- call_array(si->init_array, si->init_array_count);
+ call_array(si->init_array, si->init_array_count, 0);
TRACE("[ %5d Done calling init_array for '%s' ]\n", pid, si->name);
}
}
+
static void call_destructors(soinfo *si)
{
if (si->fini_array) {
TRACE("[ %5d Calling fini_array @ 0x%08x [%d] for '%s' ]\n", pid,
(unsigned)si->fini_array, si->fini_array_count, si->name);
- call_array(si->fini_array, si->fini_array_count);
+ call_array(si->fini_array, si->fini_array_count, 1);
TRACE("[ %5d Done calling fini_array for '%s' ]\n", pid, si->name);
}
- // If we have an fini section, then we should call it now, to make sure
- // that all the funcs in the .dtors section get run.
- // Note: For ARM, we shouldn't have a .dtor section (should be empty)
- // when we have an fini_array section, but let's be compatible with
- // old (non-eabi) binaries and try the _fini (DT_FINI) anyway.
if (si->fini_func) {
TRACE("[ %5d Calling fini_func @ 0x%08x for '%s' ]\n", pid,
(unsigned)si->fini_func, si->name);
@@ -1334,7 +1390,7 @@ static int nullify_closed_stdio (void)
dev_null = open("/dev/null", O_RDWR);
if (dev_null < 0) {
- ERROR("Cannot open /dev/null.\n");
+ DL_ERR("Cannot open /dev/null.\n");
return -1;
}
TRACE("[ %5d Opened /dev/null file-descriptor=%d]\n", pid, dev_null);
@@ -1360,7 +1416,7 @@ static int nullify_closed_stdio (void)
/* The only error we allow is that the file descriptor does not
exist, in which case we dup /dev/null to it. */
if (errno != EBADF) {
- ERROR("nullify_stdio: unhandled error %s\n", strerror(errno));
+ DL_ERR("nullify_stdio: unhandled error %s\n", strerror(errno));
return_value = -1;
continue;
}
@@ -1371,9 +1427,9 @@ static int nullify_closed_stdio (void)
do {
status = dup2(dev_null, i);
} while (status < 0 && errno == EINTR);
-
+
if (status < 0) {
- ERROR("nullify_stdio: dup2 error %s\n", strerror(errno));
+ DL_ERR("nullify_stdio: dup2 error %s\n", strerror(errno));
return_value = -1;
continue;
}
@@ -1382,12 +1438,12 @@ static int nullify_closed_stdio (void)
/* If /dev/null is not one of the stdio file descriptors, close it. */
if (dev_null > 2) {
TRACE("[ %5d Closing /dev/null file-descriptor=%d]\n", pid, dev_null);
- do {
+ do {
status = close(dev_null);
} while (status < 0 && errno == EINTR);
if (status < 0) {
- ERROR("nullify_stdio: close error %s\n", strerror(errno));
+ DL_ERR("nullify_stdio: close error %s\n", strerror(errno));
return_value = -1;
}
}
@@ -1455,7 +1511,7 @@ static int link_image(soinfo *si, unsigned wr_offset)
}
} else if (phdr->p_type == PT_DYNAMIC) {
if (si->dynamic != (unsigned *)-1) {
- ERROR("%5d multiple PT_DYNAMIC segments found in '%s'. "
+ DL_ERR("%5d multiple PT_DYNAMIC segments found in '%s'. "
"Segment at 0x%08x, previously one found at 0x%08x\n",
pid, si->name, si->base + phdr->p_vaddr,
(unsigned)si->dynamic);
@@ -1468,7 +1524,7 @@ static int link_image(soinfo *si, unsigned wr_offset)
}
if (si->dynamic == (unsigned *)-1) {
- ERROR("%5d missing PT_DYNAMIC?!\n", pid);
+ DL_ERR("%5d missing PT_DYNAMIC?!\n", pid);
goto fail;
}
@@ -1492,7 +1548,7 @@ static int link_image(soinfo *si, unsigned wr_offset)
break;
case DT_PLTREL:
if(*d != DT_REL) {
- ERROR("DT_RELA not supported\n");
+ DL_ERR("DT_RELA not supported\n");
goto fail;
}
break;
@@ -1517,7 +1573,7 @@ static int link_image(soinfo *si, unsigned wr_offset)
*d = (int) &_r_debug;
break;
case DT_RELA:
- ERROR("%5d DT_RELA not supported\n", pid);
+ DL_ERR("%5d DT_RELA not supported\n", pid);
goto fail;
case DT_INIT:
si->init_func = (void (*)(void))(si->base + *d);
@@ -1569,16 +1625,18 @@ static int link_image(soinfo *si, unsigned wr_offset)
pid, si->base, si->strtab, si->symtab);
if((si->strtab == 0) || (si->symtab == 0)) {
- ERROR("%5d missing essential tables\n", pid);
+ DL_ERR("%5d missing essential tables\n", pid);
goto fail;
}
for(d = si->dynamic; *d; d += 2) {
if(d[0] == DT_NEEDED){
DEBUG("%5d %s needs %s\n", pid, si->name, si->strtab + d[1]);
- soinfo *lsi = find_library(si->strtab + d[1]);
+ soinfo *lsi = find_library(si->strtab + d[1]);
if(lsi == 0) {
- ERROR("%5d could not load '%s'\n", pid, si->strtab + d[1]);
+ strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf));
+ DL_ERR("%5d could not load needed library '%s' for '%s' (%s)\n",
+ pid, si->strtab + d[1], si->name, tmp_err_buf);
goto fail;
}
lsi->refcount++;
@@ -1643,6 +1701,29 @@ fail:
return -1;
}
+static void parse_library_path(char *path, char *delim)
+{
+ size_t len;
+ char *ldpaths_bufp = ldpaths_buf;
+ int i = 0;
+
+ len = strlcpy(ldpaths_buf, path, sizeof(ldpaths_buf));
+
+ while (i < LDPATH_MAX && (ldpaths[i] = strsep(&ldpaths_bufp, delim))) {
+ if (*ldpaths[i] != '\0')
+ ++i;
+ }
+
+ /* Forget the last path if we had to truncate; this occurs if the 2nd to
+ * last char isn't '\0' (i.e. not originally a delim). */
+ if (i > 0 && len >= sizeof(ldpaths_buf) &&
+ ldpaths_buf[sizeof(ldpaths_buf) - 2] != '\0') {
+ ldpaths[i - 1] = NULL;
+ } else {
+ ldpaths[i] = NULL;
+ }
+}
+
int main(int argc, char **argv)
{
return 0;
@@ -1661,6 +1742,7 @@ unsigned __linker_init(unsigned **elfdata)
unsigned *vecs = (unsigned*) (argv + argc + 1);
soinfo *si;
struct link_map * map;
+ char *ldpath_env = NULL;
pid = getpid();
@@ -1678,6 +1760,8 @@ unsigned __linker_init(unsigned **elfdata)
while(vecs[0] != 0) {
if(!strncmp((char*) vecs[0], "DEBUG=", 6)) {
debug_verbosity = atoi(((char*) vecs[0]) + 6);
+ } else if(!strncmp((char*) vecs[0], "LD_LIBRARY_PATH=", 16)) {
+ ldpath_env = (char*) vecs[0] + 16;
}
vecs++;
}
@@ -1737,8 +1821,14 @@ unsigned __linker_init(unsigned **elfdata)
si->wrprotect_start = 0xffffffff;
si->wrprotect_end = 0;
- if(link_image(si, 0)){
- ERROR("CANNOT LINK EXECUTABLE '%s'\n", argv[0]);
+ /* Use LD_LIBRARY_PATH if we aren't setuid/setgid */
+ if (ldpath_env && getuid() == geteuid() && getgid() == getegid())
+ parse_library_path(ldpath_env, ":");
+
+ if(link_image(si, 0)) {
+ char errmsg[] = "CANNOT LINK EXECUTABLE\n";
+ write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf));
+ write(2, errmsg, sizeof(errmsg));
exit(-1);
}
generated by cgit v1.1 at 2024-12-23 08:12:02 +0000