From 2e85579c34047c305caf15fb0ebe02bf3d001d0e Mon Sep 17 00:00:00 2001 From: Dima Zavin Date: Wed, 20 May 2009 18:28:09 -0700 Subject: linker: Make the errors reported by dlopen/dlsym be more useful. Changed it so that when the linker generates error messages, they are scribbled away into a buffer that dlfcn and friends can read from. Since the error messages are generetad with snprintf, and snprintf MAY call malloc during some code paths, we now link against a version of libc that does not contain malloc/free/realloc/calloc. We then define malloc and friends in the dynamic loader, and make them abort() if they are ever called. Signed-off-by: Dima Zavin --- linker/linker.c | 113 +++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 71 insertions(+), 42 deletions(-) (limited to 'linker/linker.c') diff --git a/linker/linker.c b/linker/linker.c index 5180ae0..08a591a 100644 --- a/linker/linker.c +++ b/linker/linker.c @@ -104,6 +104,31 @@ 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 __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 +232,7 @@ 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 +241,7 @@ 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 +277,7 @@ 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; } @@ -521,7 +546,7 @@ 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 +622,7 @@ 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 +650,7 @@ 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 +686,13 @@ 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 +730,7 @@ 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 +789,7 @@ 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 +845,8 @@ 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 +898,7 @@ 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 +965,20 @@ 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 +1069,8 @@ 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 +1101,7 @@ 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 +1151,19 @@ 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 +1225,7 @@ 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 +1266,7 @@ 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; } @@ -1296,9 +1323,9 @@ static void call_constructors(soinfo *si) 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); } } @@ -1344,7 +1371,7 @@ 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); @@ -1370,7 +1397,7 @@ 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; } @@ -1381,9 +1408,9 @@ 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; } @@ -1392,12 +1419,12 @@ 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; } } @@ -1465,7 +1492,7 @@ 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); @@ -1478,7 +1505,7 @@ 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; } @@ -1502,7 +1529,7 @@ 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; @@ -1527,7 +1554,7 @@ 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); @@ -1579,16 +1606,16 @@ 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]); + DL_ERR("%5d could not load '%s'\n", pid, si->strtab + d[1]); goto fail; } lsi->refcount++; @@ -1747,8 +1774,10 @@ 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]); + 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); } -- cgit v1.1