Fix ldd to work with more ELF files.
- Use libelf to parse ELF data structures and remove code duplication for ELF32. - Don't require the OSABI field to be set to the FreeBSD OSABI for shared libraries. Both AArch64 and RISC-V leave it set to "none" and instead depend on the ABI tag note. For ldd, this means falling back to walking the notes in PT_NOTE segments to find the ABI tag note to determine if an ELF shared library without OSABI set in the header file is a FreeBSD shared library. Reviewed by: kib MFC after: 5 days Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D28342
This commit is contained in:
John Baldwin
parent
e25ee296c9
commit
9d4104b214
@ -3,4 +3,6 @@
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PROG?= ldd
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SRCS= ldd.c
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LIBADD= elf
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.include <bsd.prog.mk>
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@ -33,6 +33,7 @@
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/wait.h>
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#include <machine/elf.h>
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@ -43,6 +44,9 @@ __FBSDID("$FreeBSD$");
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <gelf.h>
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#include <libelf.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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@ -259,179 +263,210 @@ usage(void)
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exit(1);
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}
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static bool
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has_freebsd_abi_tag(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset,
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size_t len)
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{
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Elf_Data dst, src;
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const Elf_Note *note;
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char *buf;
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const char *name;
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void *copy;
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size_t namesz, descsz;
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bool has_abi_tag;
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buf = elf_rawfile(elf, NULL);
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if (buf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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memset(&src, 0, sizeof(src));
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src.d_buf = buf + offset;
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src.d_size = len;
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src.d_type = ELF_T_NOTE;
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src.d_version = EV_CURRENT;
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memset(&dst, 0, sizeof(dst));
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dst.d_buf = copy = malloc(len);
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dst.d_size = len;
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dst.d_type = ELF_T_NOTE;
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dst.d_version = EV_CURRENT;
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if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
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warnx("%s: failed to parse notes: %s", fname, elf_errmsg(0));
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free(copy);
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return (false);
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}
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buf = copy;
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has_abi_tag = false;
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for (;;) {
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if (len < sizeof(*note))
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break;
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note = (const void *)buf;
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buf += sizeof(*note);
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len -= sizeof(*note);
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namesz = roundup2(note->n_namesz, sizeof(uint32_t));
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descsz = roundup2(note->n_descsz, sizeof(uint32_t));
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if (len < namesz + descsz)
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break;
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name = buf;
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if (note->n_namesz == sizeof(ELF_NOTE_FREEBSD) &&
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strncmp(name, ELF_NOTE_FREEBSD, note->n_namesz) == 0 &&
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note->n_type == NT_FREEBSD_ABI_TAG &&
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note->n_descsz == sizeof(uint32_t)) {
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has_abi_tag = true;
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break;
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}
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buf += namesz + descsz;
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len -= namesz + descsz;
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}
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free(copy);
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return (has_abi_tag);
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}
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static bool
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is_pie(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset, size_t len)
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{
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Elf_Data dst, src;
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char *buf;
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void *copy;
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const GElf_Dyn *dyn;
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size_t dynsize;
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u_int count, i;
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bool pie;
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buf = elf_rawfile(elf, NULL);
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if (buf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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dynsize = gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
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if (dynsize == 0) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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count = len / dynsize;
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memset(&src, 0, sizeof(src));
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src.d_buf = buf + offset;
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src.d_size = len;
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src.d_type = ELF_T_DYN;
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src.d_version = EV_CURRENT;
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memset(&dst, 0, sizeof(dst));
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dst.d_buf = copy = malloc(count * sizeof(*dyn));
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dst.d_size = count * sizeof(*dyn);
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dst.d_type = ELF_T_DYN;
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dst.d_version = EV_CURRENT;
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if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
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warnx("%s: failed to parse .dynamic: %s", fname, elf_errmsg(0));
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free(copy);
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return (false);
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}
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dyn = copy;
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pie = false;
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for (i = 0; i < count; i++) {
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if (dyn[i].d_tag != DT_FLAGS_1)
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continue;
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pie = (dyn[i].d_un.d_val & DF_1_PIE) != 0;
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break;
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}
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free(copy);
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return (pie);
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}
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static int
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is_executable(const char *fname, int fd, int *is_shlib, int *type)
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{
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union {
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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Elf32_Ehdr elf32;
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#endif
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Elf_Ehdr elf;
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} hdr;
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Elf_Phdr phdr, dynphdr;
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Elf_Dyn *dynp;
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void *dyndata;
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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Elf32_Phdr phdr32, dynphdr32;
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Elf32_Dyn *dynp32;
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#endif
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int df1pie, dynamic, i, n;
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Elf *elf;
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GElf_Ehdr ehdr;
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GElf_Phdr phdr;
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bool dynamic, freebsd, pie;
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int i;
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*is_shlib = 0;
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*type = TYPE_UNKNOWN;
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df1pie = 0;
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dynamic = false;
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freebsd = false;
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pie = false;
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if ((n = read(fd, &hdr, sizeof(hdr))) == -1) {
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warn("%s: can't read program header", fname);
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if (elf_version(EV_CURRENT) == EV_NONE) {
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warnx("unsupported libelf");
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return (0);
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}
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elf = elf_begin(fd, ELF_C_READ, NULL);
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if (elf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (0);
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}
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if (elf_kind(elf) != ELF_K_ELF) {
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elf_end(elf);
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (gelf_getehdr(elf, &ehdr) == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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elf_end(elf);
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return (0);
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}
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*type = TYPE_ELF;
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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if ((size_t)n >= sizeof(hdr.elf32) && IS_ELF(hdr.elf32) &&
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hdr.elf32.e_ident[EI_CLASS] == ELFCLASS32) {
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/* Handle 32 bit ELF objects */
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dynamic = 0;
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if (gelf_getclass(elf) == ELFCLASS32) {
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*type = TYPE_ELF32;
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if (lseek(fd, hdr.elf32.e_phoff, SEEK_SET) == -1) {
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warnx("%s: header too short", fname);
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return (0);
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}
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for (i = 0; i < hdr.elf32.e_phnum; i++) {
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if (read(fd, &phdr32, hdr.elf32.e_phentsize) !=
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sizeof(phdr32)) {
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warnx("%s: can't read program header", fname);
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return (0);
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}
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if (phdr32.p_type == PT_DYNAMIC) {
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dynamic = 1;
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dynphdr32 = phdr32;
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break;
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}
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}
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if (!dynamic) {
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (hdr.elf32.e_type == ET_DYN) {
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if (lseek(fd, dynphdr32.p_offset, SEEK_SET) == -1) {
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warnx("%s: dynamic segment out of range",
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fname);
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return (0);
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}
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dyndata = malloc(dynphdr32.p_filesz);
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if (dyndata == NULL) {
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warn("malloc");
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return (0);
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}
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if (read(fd, dyndata, dynphdr32.p_filesz) !=
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(ssize_t)dynphdr32.p_filesz) {
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free(dyndata);
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warnx("%s: can't read dynamic segment", fname);
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return (0);
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}
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for (dynp32 = dyndata; dynp32->d_tag != DT_NULL;
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dynp32++) {
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if (dynp32->d_tag != DT_FLAGS_1)
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continue;
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df1pie = (dynp32->d_un.d_val & DF_1_PIE) != 0;
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break;
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}
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free(dyndata);
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if (hdr.elf32.e_ident[EI_OSABI] == ELFOSABI_FREEBSD) {
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if (!df1pie)
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*is_shlib = 1;
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return (1);
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}
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warnx("%s: not a FreeBSD ELF shared object", fname);
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return (0);
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}
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return (1);
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}
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#endif
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if ((size_t)n >= sizeof(hdr.elf) && IS_ELF(hdr.elf) &&
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hdr.elf.e_ident[EI_CLASS] == ELF_TARG_CLASS) {
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/* Handle default ELF objects on this architecture */
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dynamic = 0;
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*type = TYPE_ELF;
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if (lseek(fd, hdr.elf.e_phoff, SEEK_SET) == -1) {
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warnx("%s: header too short", fname);
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freebsd = ehdr.e_ident[EI_OSABI] == ELFOSABI_FREEBSD;
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for (i = 0; i < ehdr.e_phnum; i++) {
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if (gelf_getphdr(elf, i, &phdr) == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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elf_end(elf);
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return (0);
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}
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for (i = 0; i < hdr.elf.e_phnum; i++) {
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if (read(fd, &phdr, hdr.elf.e_phentsize)
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!= sizeof(phdr)) {
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warnx("%s: can't read program header", fname);
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return (0);
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}
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if (phdr.p_type == PT_DYNAMIC) {
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dynamic = 1;
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dynphdr = phdr;
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break;
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}
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switch (phdr.p_type) {
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case PT_NOTE:
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if (ehdr.e_ident[EI_OSABI] == ELFOSABI_NONE && !freebsd)
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freebsd = has_freebsd_abi_tag(fname, elf, &ehdr,
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phdr.p_offset, phdr.p_filesz);
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break;
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case PT_DYNAMIC:
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dynamic = true;
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if (ehdr.e_type == ET_DYN)
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pie = is_pie(fname, elf, &ehdr, phdr.p_offset,
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phdr.p_filesz);
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break;
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}
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}
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if (!dynamic) {
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (!dynamic) {
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elf_end(elf);
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (hdr.elf.e_type == ET_DYN) {
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if (lseek(fd, dynphdr.p_offset, SEEK_SET) == -1) {
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warnx("%s: dynamic segment out of range",
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fname);
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return (0);
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}
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dyndata = malloc(dynphdr.p_filesz);
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if (dyndata == NULL) {
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warn("malloc");
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return (0);
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}
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if (read(fd, dyndata, dynphdr.p_filesz) !=
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(ssize_t)dynphdr.p_filesz) {
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free(dyndata);
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warnx("%s: can't read dynamic segment", fname);
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return (0);
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}
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for (dynp = dyndata; dynp->d_tag != DT_NULL; dynp++) {
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if (dynp->d_tag != DT_FLAGS_1)
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continue;
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df1pie = (dynp->d_un.d_val & DF_1_PIE) != 0;
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break;
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}
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free(dyndata);
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if (ehdr.e_type == ET_DYN && !pie) {
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*is_shlib = 1;
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switch (hdr.elf.e_ident[EI_OSABI]) {
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case ELFOSABI_FREEBSD:
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if (!df1pie)
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*is_shlib = 1;
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return (1);
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#ifdef __ARM_EABI__
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case ELFOSABI_NONE:
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if (hdr.elf.e_machine != EM_ARM)
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break;
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if (EF_ARM_EABI_VERSION(hdr.elf.e_flags) <
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EF_ARM_EABI_FREEBSD_MIN)
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break;
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*is_shlib = 1;
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return (1);
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#endif
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}
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if (!freebsd) {
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elf_end(elf);
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warnx("%s: not a FreeBSD ELF shared object", fname);
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return (0);
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}
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return (1);
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}
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warnx("%s: not a dynamic executable", fname);
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return (0);
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elf_end(elf);
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return (1);
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}
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