git: fa3b2ad265d3 - stable/13 - Fix ldd to work with more ELF files.
John Baldwin
jhb at FreeBSD.org
Fri Feb 5 00:04:31 UTC 2021
The branch stable/13 has been updated by jhb:
URL: https://cgit.FreeBSD.org/src/commit/?id=fa3b2ad265d311191c1c8337bf3aa356f28480cb
commit fa3b2ad265d311191c1c8337bf3aa356f28480cb
Author: John Baldwin <jhb at FreeBSD.org>
AuthorDate: 2021-01-29 18:53:50 +0000
Commit: John Baldwin <jhb at FreeBSD.org>
CommitDate: 2021-02-05 00:03:20 +0000
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.
(cherry picked from commit 9d4104b214963bb3371ada05cae8006940121634)
---
usr.bin/ldd/Makefile | 2 +
usr.bin/ldd/ldd.c | 335 ++++++++++++++++++++++++++++-----------------------
2 files changed, 187 insertions(+), 150 deletions(-)
diff --git a/usr.bin/ldd/Makefile b/usr.bin/ldd/Makefile
index 5d2beb7bb6c0..78e551d80a33 100644
--- a/usr.bin/ldd/Makefile
+++ b/usr.bin/ldd/Makefile
@@ -3,4 +3,6 @@
PROG?= ldd
SRCS= ldd.c
+LIBADD= elf
+
.include <bsd.prog.mk>
diff --git a/usr.bin/ldd/ldd.c b/usr.bin/ldd/ldd.c
index 08c91d829bd7..f948b7312863 100644
--- a/usr.bin/ldd/ldd.c
+++ b/usr.bin/ldd/ldd.c
@@ -33,6 +33,7 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
+#include <sys/param.h>
#include <sys/wait.h>
#include <machine/elf.h>
@@ -43,6 +44,9 @@ __FBSDID("$FreeBSD$");
#include <err.h>
#include <errno.h>
#include <fcntl.h>
+#include <gelf.h>
+#include <libelf.h>
+#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -259,179 +263,210 @@ usage(void)
exit(1);
}
-static int
-is_executable(const char *fname, int fd, int *is_shlib, int *type)
+static bool
+has_freebsd_abi_tag(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset,
+ size_t len)
{
- union {
-#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
- Elf32_Ehdr elf32;
-#endif
- Elf_Ehdr elf;
- } hdr;
- Elf_Phdr phdr, dynphdr;
- Elf_Dyn *dynp;
- void *dyndata;
-#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
- Elf32_Phdr phdr32, dynphdr32;
- Elf32_Dyn *dynp32;
-#endif
- int df1pie, dynamic, i, n;
-
- *is_shlib = 0;
- *type = TYPE_UNKNOWN;
- df1pie = 0;
+ Elf_Data dst, src;
+ const Elf_Note *note;
+ char *buf;
+ const char *name;
+ void *copy;
+ size_t namesz, descsz;
+ bool has_abi_tag;
+
+ buf = elf_rawfile(elf, NULL);
+ if (buf == NULL) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ return (false);
+ }
- if ((n = read(fd, &hdr, sizeof(hdr))) == -1) {
- warn("%s: can't read program header", fname);
- return (0);
+ memset(&src, 0, sizeof(src));
+ src.d_buf = buf + offset;
+ src.d_size = len;
+ src.d_type = ELF_T_NOTE;
+ src.d_version = EV_CURRENT;
+
+ memset(&dst, 0, sizeof(dst));
+ dst.d_buf = copy = malloc(len);
+ dst.d_size = len;
+ dst.d_type = ELF_T_NOTE;
+ dst.d_version = EV_CURRENT;
+
+ if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
+ warnx("%s: failed to parse notes: %s", fname, elf_errmsg(0));
+ free(copy);
+ return (false);
}
-#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
- if ((size_t)n >= sizeof(hdr.elf32) && IS_ELF(hdr.elf32) &&
- hdr.elf32.e_ident[EI_CLASS] == ELFCLASS32) {
- /* Handle 32 bit ELF objects */
+ buf = copy;
+ has_abi_tag = false;
+ for (;;) {
+ if (len < sizeof(*note))
+ break;
- dynamic = 0;
- *type = TYPE_ELF32;
+ note = (const void *)buf;
+ buf += sizeof(*note);
+ len -= sizeof(*note);
- if (lseek(fd, hdr.elf32.e_phoff, SEEK_SET) == -1) {
- warnx("%s: header too short", fname);
- return (0);
- }
- for (i = 0; i < hdr.elf32.e_phnum; i++) {
- if (read(fd, &phdr32, hdr.elf32.e_phentsize) !=
- sizeof(phdr32)) {
- warnx("%s: can't read program header", fname);
- return (0);
- }
- if (phdr32.p_type == PT_DYNAMIC) {
- dynamic = 1;
- dynphdr32 = phdr32;
- break;
- }
- }
+ namesz = roundup2(note->n_namesz, sizeof(uint32_t));
+ descsz = roundup2(note->n_descsz, sizeof(uint32_t));
+ if (len < namesz + descsz)
+ break;
- if (!dynamic) {
- warnx("%s: not a dynamic ELF executable", fname);
- return (0);
+ name = buf;
+ if (note->n_namesz == sizeof(ELF_NOTE_FREEBSD) &&
+ strncmp(name, ELF_NOTE_FREEBSD, note->n_namesz) == 0 &&
+ note->n_type == NT_FREEBSD_ABI_TAG &&
+ note->n_descsz == sizeof(uint32_t)) {
+ has_abi_tag = true;
+ break;
}
- if (hdr.elf32.e_type == ET_DYN) {
- if (lseek(fd, dynphdr32.p_offset, SEEK_SET) == -1) {
- warnx("%s: dynamic segment out of range",
- fname);
- return (0);
- }
- dyndata = malloc(dynphdr32.p_filesz);
- if (dyndata == NULL) {
- warn("malloc");
- return (0);
- }
- if (read(fd, dyndata, dynphdr32.p_filesz) !=
- (ssize_t)dynphdr32.p_filesz) {
- free(dyndata);
- warnx("%s: can't read dynamic segment", fname);
- return (0);
- }
- for (dynp32 = dyndata; dynp32->d_tag != DT_NULL;
- dynp32++) {
- if (dynp32->d_tag != DT_FLAGS_1)
- continue;
- df1pie = (dynp32->d_un.d_val & DF_1_PIE) != 0;
- break;
- }
- free(dyndata);
+ buf += namesz + descsz;
+ len -= namesz + descsz;
+ }
- if (hdr.elf32.e_ident[EI_OSABI] == ELFOSABI_FREEBSD) {
- if (!df1pie)
- *is_shlib = 1;
- return (1);
- }
- warnx("%s: not a FreeBSD ELF shared object", fname);
- return (0);
- }
+ free(copy);
+ return (has_abi_tag);
+}
- return (1);
+static bool
+is_pie(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset, size_t len)
+{
+ Elf_Data dst, src;
+ char *buf;
+ void *copy;
+ const GElf_Dyn *dyn;
+ size_t dynsize;
+ u_int count, i;
+ bool pie;
+
+ buf = elf_rawfile(elf, NULL);
+ if (buf == NULL) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ return (false);
}
-#endif
- if ((size_t)n >= sizeof(hdr.elf) && IS_ELF(hdr.elf) &&
- hdr.elf.e_ident[EI_CLASS] == ELF_TARG_CLASS) {
- /* Handle default ELF objects on this architecture */
+ dynsize = gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
+ if (dynsize == 0) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ return (false);
+ }
+ count = len / dynsize;
+
+ memset(&src, 0, sizeof(src));
+ src.d_buf = buf + offset;
+ src.d_size = len;
+ src.d_type = ELF_T_DYN;
+ src.d_version = EV_CURRENT;
+
+ memset(&dst, 0, sizeof(dst));
+ dst.d_buf = copy = malloc(count * sizeof(*dyn));
+ dst.d_size = count * sizeof(*dyn);
+ dst.d_type = ELF_T_DYN;
+ dst.d_version = EV_CURRENT;
+
+ if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
+ warnx("%s: failed to parse .dynamic: %s", fname, elf_errmsg(0));
+ free(copy);
+ return (false);
+ }
+
+ dyn = copy;
+ pie = false;
+ for (i = 0; i < count; i++) {
+ if (dyn[i].d_tag != DT_FLAGS_1)
+ continue;
+
+ pie = (dyn[i].d_un.d_val & DF_1_PIE) != 0;
+ break;
+ }
+
+ free(copy);
+ return (pie);
+}
+
+static int
+is_executable(const char *fname, int fd, int *is_shlib, int *type)
+{
+ Elf *elf;
+ GElf_Ehdr ehdr;
+ GElf_Phdr phdr;
+ bool dynamic, freebsd, pie;
+ int i;
+
+ *is_shlib = 0;
+ *type = TYPE_UNKNOWN;
+ dynamic = false;
+ freebsd = false;
+ pie = false;
+
+ if (elf_version(EV_CURRENT) == EV_NONE) {
+ warnx("unsupported libelf");
+ return (0);
+ }
+ elf = elf_begin(fd, ELF_C_READ, NULL);
+ if (elf == NULL) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ return (0);
+ }
+ if (elf_kind(elf) != ELF_K_ELF) {
+ elf_end(elf);
+ warnx("%s: not a dynamic ELF executable", fname);
+ return (0);
+ }
+ if (gelf_getehdr(elf, &ehdr) == NULL) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ elf_end(elf);
+ return (0);
+ }
- dynamic = 0;
- *type = TYPE_ELF;
+ *type = TYPE_ELF;
+#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
+ if (gelf_getclass(elf) == ELFCLASS32) {
+ *type = TYPE_ELF32;
+ }
+#endif
- if (lseek(fd, hdr.elf.e_phoff, SEEK_SET) == -1) {
- warnx("%s: header too short", fname);
+ freebsd = ehdr.e_ident[EI_OSABI] == ELFOSABI_FREEBSD;
+ for (i = 0; i < ehdr.e_phnum; i++) {
+ if (gelf_getphdr(elf, i, &phdr) == NULL) {
+ warnx("%s: %s", fname, elf_errmsg(0));
+ elf_end(elf);
return (0);
}
- for (i = 0; i < hdr.elf.e_phnum; i++) {
- if (read(fd, &phdr, hdr.elf.e_phentsize)
- != sizeof(phdr)) {
- warnx("%s: can't read program header", fname);
- return (0);
- }
- if (phdr.p_type == PT_DYNAMIC) {
- dynamic = 1;
- dynphdr = phdr;
- break;
- }
+ switch (phdr.p_type) {
+ case PT_NOTE:
+ if (ehdr.e_ident[EI_OSABI] == ELFOSABI_NONE && !freebsd)
+ freebsd = has_freebsd_abi_tag(fname, elf, &ehdr,
+ phdr.p_offset, phdr.p_filesz);
+ break;
+ case PT_DYNAMIC:
+ dynamic = true;
+ if (ehdr.e_type == ET_DYN)
+ pie = is_pie(fname, elf, &ehdr, phdr.p_offset,
+ phdr.p_filesz);
+ break;
}
+ }
- if (!dynamic) {
- warnx("%s: not a dynamic ELF executable", fname);
- return (0);
- }
+ if (!dynamic) {
+ elf_end(elf);
+ warnx("%s: not a dynamic ELF executable", fname);
+ return (0);
+ }
- if (hdr.elf.e_type == ET_DYN) {
- if (lseek(fd, dynphdr.p_offset, SEEK_SET) == -1) {
- warnx("%s: dynamic segment out of range",
- fname);
- return (0);
- }
- dyndata = malloc(dynphdr.p_filesz);
- if (dyndata == NULL) {
- warn("malloc");
- return (0);
- }
- if (read(fd, dyndata, dynphdr.p_filesz) !=
- (ssize_t)dynphdr.p_filesz) {
- free(dyndata);
- warnx("%s: can't read dynamic segment", fname);
- return (0);
- }
- for (dynp = dyndata; dynp->d_tag != DT_NULL; dynp++) {
- if (dynp->d_tag != DT_FLAGS_1)
- continue;
- df1pie = (dynp->d_un.d_val & DF_1_PIE) != 0;
- break;
- }
- free(dyndata);
-
- switch (hdr.elf.e_ident[EI_OSABI]) {
- case ELFOSABI_FREEBSD:
- if (!df1pie)
- *is_shlib = 1;
- return (1);
-#ifdef __ARM_EABI__
- case ELFOSABI_NONE:
- if (hdr.elf.e_machine != EM_ARM)
- break;
- if (EF_ARM_EABI_VERSION(hdr.elf.e_flags) <
- EF_ARM_EABI_FREEBSD_MIN)
- break;
- *is_shlib = 1;
- return (1);
-#endif
- }
+ if (ehdr.e_type == ET_DYN && !pie) {
+ *is_shlib = 1;
+
+ if (!freebsd) {
+ elf_end(elf);
warnx("%s: not a FreeBSD ELF shared object", fname);
return (0);
}
-
- return (1);
}
- warnx("%s: not a dynamic executable", fname);
- return (0);
+ elf_end(elf);
+ return (1);
}
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