Date: Fri, 5 Feb 2021 00:04:31 GMT From: John Baldwin <jhb@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: fa3b2ad265d3 - stable/13 - Fix ldd to work with more ELF files. Message-ID: <202102050004.11504VeU026815@gitrepo.freebsd.org>
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The branch stable/13 has been updated by jhb: URL: https://cgit.FreeBSD.org/src/commit/?id=fa3b2ad265d311191c1c8337bf3aa356f28480cb commit fa3b2ad265d311191c1c8337bf3aa356f28480cb Author: John Baldwin <jhb@FreeBSD.org> AuthorDate: 2021-01-29 18:53:50 +0000 Commit: John Baldwin <jhb@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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