[PATCH] tools: sstrip: update to latest version

[Paul Spooren]

On Wed Nov 11, 2020 at 1:53 PM HST, Rui Salvaterra wrote:
> Drop our local sstrip copy and use the current ELFKickers upstream
> version.
> Patch the original makefile in order to avoid building elftoc, since it
> fails
> with musl's elf.h. This is fine, since we only need sstrip anyway.
> Finally, add the possibility to pass additional arguments to sstrip (-z
> being
> the obvious candidate).
>
> Signed-off-by: Rui Salvaterra <rsalvaterra at gmail.com>

LGTM, tested and works fine.

Could you please create a slightly more verbose patch name for
001-compile.patch?

Do you see any possible success in pinging upstream to unify their
versioning? sstrip 3.1a still outputs version 2.0.

Please create an additional patch to enable -z by default.

> ---
> config/Config-build.in | 8 +
> rules.mk | 2 +-
> tools/sstrip/Makefile | 15 +-
> tools/sstrip/patches/001-compile.patch | 19 +
> tools/sstrip/src/sstrip.c | 466 -------------------------
> 5 files changed, 36 insertions(+), 474 deletions(-)
> create mode 100644 tools/sstrip/patches/001-compile.patch
> delete mode 100644 tools/sstrip/src/sstrip.c
>
> diff --git a/config/Config-build.in b/config/Config-build.in
> index 178afbdb94..c54bc243c5 100644
> --- a/config/Config-build.in
> +++ b/config/Config-build.in
> @@ -182,6 +182,14 @@ menu "Global build settings"
> help
> Specifies arguments passed to the strip command when stripping binaries.
>  
> + config SSTRIP_ARGS
> + string
> + prompt "Sstrip arguments"
> + depends on USE_SSTRIP
> + default ""
> + help
> + Specifies arguments passed to the sstrip command when stripping
> binaries.
> +
> config STRIP_KERNEL_EXPORTS
> bool "Strip unnecessary exports from the kernel image"
> help
> diff --git a/rules.mk b/rules.mk
> index e416126030..5c1c141c11 100644
> --- a/rules.mk
> +++ b/rules.mk
> @@ -328,7 +328,7 @@ else
> STRIP:=$(TARGET_CROSS)strip $(call qstrip,$(CONFIG_STRIP_ARGS))
> else
> ifneq ($(CONFIG_USE_SSTRIP),)
> - STRIP:=$(STAGING_DIR_HOST)/bin/sstrip
> + STRIP:=$(STAGING_DIR_HOST)/bin/sstrip $(call
> qstrip,$(CONFIG_SSTRIP_ARGS))
> endif
> endif
> RSTRIP= \
> diff --git a/tools/sstrip/Makefile b/tools/sstrip/Makefile
> index bab172a95a..590d183db0 100644
> --- a/tools/sstrip/Makefile
> +++ b/tools/sstrip/Makefile
> @@ -6,18 +6,19 @@
> #
> include $(TOPDIR)/rules.mk
>  
> -PKG_NAME:=sstrip
> -PKG_VERSION:=2.0
> +PKG_NAME:=ELFkickers
> +PKG_VERSION:=3.1a
> +
> +PKG_SOURCE_URL:=https://www.muppetlabs.com/~breadbox/pub/software
> +PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
> +PKG_HASH:=06430880aaf4919c5f99fc629da7000347421668c2cf32bced2d401aac276508
> +
> PKG_RELEASE:=1
>  
> include $(INCLUDE_DIR)/host-build.mk
>  
> -define Host/Compile
> - $(HOSTCC) $(HOST_CFLAGS) -include endian.h -o $(HOST_BUILD_DIR)/sstrip
> src/sstrip.c
> -endef
> -
> define Host/Install
> - $(CP) $(HOST_BUILD_DIR)/sstrip $(STAGING_DIR_HOST)/bin/
> + $(CP) $(HOST_BUILD_DIR)/bin/sstrip $(STAGING_DIR_HOST)/bin/
> endef
>  
> define Host/Clean
> diff --git a/tools/sstrip/patches/001-compile.patch
> b/tools/sstrip/patches/001-compile.patch
> new file mode 100644
> index 0000000000..9d3346edfb
> --- /dev/null
> +++ b/tools/sstrip/patches/001-compile.patch
> @@ -0,0 +1,19 @@
> +--- a/Makefile
> ++++ b/Makefile
> +@@ -2,7 +2,7 @@
> +
> + prefix = /usr/local
> +
> +-PROGRAMS = elfls objres rebind sstrip elftoc ebfc infect
> ++PROGRAMS = elfls objres rebind sstrip ebfc infect
> +
> + all: $(PROGRAMS)
> +
> +@@ -19,7 +19,6 @@ elfls: bin/elfls doc/elfls.1
> + objres: bin/objres doc/objres.1
> + rebind: bin/rebind doc/rebind.1
> + sstrip: bin/sstrip doc/sstrip.1
> +-elftoc: bin/elftoc doc/elftoc.1
> + ebfc: bin/ebfc doc/ebfc.1
> + infect: bin/infect doc/infect.1
> +
> diff --git a/tools/sstrip/src/sstrip.c b/tools/sstrip/src/sstrip.c
> deleted file mode 100644
> index 12cf12e095..0000000000
> --- a/tools/sstrip/src/sstrip.c
> +++ /dev/null
> @@ -1,466 +0,0 @@
> -/* http://www.muppetlabs.com/~breadbox/software/elfkickers.html */
> -
> -/* sstrip: Copyright (C) 1999-2001 by Brian Raiter, under the GNU
> - * General Public License. No warranty. See COPYING for details.
> - *
> - * Aug 23, 2004 Hacked by Manuel Novoa III <mjn3 at codepoet.org> to
> - * handle targets of different endianness and/or elf class, making
> - * it more useful in a cross-devel environment.
> - */
> -
> -/* ============== original README ===================
> - *
> - * sstrip is a small utility that removes the contents at the end of an
> - * ELF file that are not part of the program's memory image.
> - *
> - * Most ELF executables are built with both a program header table and
> a
> - * section header table. However, only the former is required in order
> - * for the OS to load, link and execute a program. sstrip attempts to
> - * extract the ELF header, the program header table, and its contents,
> - * leaving everything else in the bit bucket. It can only remove parts
> of
> - * the file that occur at the end, after the parts to be saved.
> However,
> - * this almost always includes the section header table, and
> occasionally
> - * a few random sections that are not used when running a program.
> - *
> - * It should be noted that the GNU bfd library is (understandably)
> - * dependent on the section header table as an index to the file's
> - * contents. Thus, an executable file that has no section header table
> - * cannot be used with gdb, objdump, or any other program based upon
> the
> - * bfd library, at all. In fact, the program will not even recognize
> the
> - * file as a valid executable. (This limitation is noted in the source
> - * code comments for bfd, and is marked "FIXME", so this may change at
> - * some future date. However, I would imagine that it is a pretty
> - * low-priority item, as executables without a section header table are
> - * rare in the extreme.) This probably also explains why strip doesn't
> - * offer the option to do this.
> - *
> - * Shared library files may also have their section header table
> removed.
> - * Such a library will still function; however, it will no longer be
> - * possible for a compiler to link a new program against it.
> - *
> - * As an added bonus, sstrip also tries to removes trailing zero bytes
> - * from the end of the file. (This normally cannot be done with an
> - * executable that has a section header table.)
> - *
> - * sstrip is a very simplistic program. It depends upon the common
> - * practice of putting the parts of the file that contribute to the
> - * memory image at the front, and the remaining material at the end.
> This
> - * permits it to discard the latter material without affecting file
> - * offsets and memory addresses in what remains. Of course, the ELF
> - * standard permits files to be organized in almost any order, so if a
> - * pathological linker decided to put its section headers at the top,
> - * sstrip would be useless on such executables.
> - */
> -
> -#include <stdio.h>
> -#include <stdlib.h>
> -#include <string.h>
> -#include <errno.h>
> -#include <unistd.h>
> -#include <fcntl.h>
> -#include <elf.h>
> -#include <byteswap.h>
> -
> -#ifndef TRUE
> -#define TRUE 1
> -#define FALSE 0
> -#endif
> -
> -/* The name of the program.
> - */
> -static char const *progname;
> -
> -/* The name of the current file.
> - */
> -static char const *filename;
> -
> -
> -/* A simple error-handling function. FALSE is always returned for the
> - * convenience of the caller.
> - */
> -static int err(char const *errmsg)
> -{
> - fprintf(stderr, "%s: %s: %s\n", progname, filename, errmsg);
> - return FALSE;
> -}
> -
> -/* A flag to signal the need for endian reversal.
> - */
> -static int do_reverse_endian;
> -
> -/* Get a value from the elf header, compensating for endianness.
> - */
> -#define EGET(X) \
> - (__extension__ ({ \
> - uint64_t __res; \
> - if (!do_reverse_endian) { \
> - __res = (X); \
> - } else if (sizeof(X) == 1) { \
> - __res = (X); \
> - } else if (sizeof(X) == 2) { \
> - __res = bswap_16((X)); \
> - } else if (sizeof(X) == 4) { \
> - __res = bswap_32((X)); \
> - } else if (sizeof(X) == 8) { \
> - __res = bswap_64((X)); \
> - } else { \
> - fprintf(stderr, "%s: %s: EGET failed for size %zu\n", \
> - progname, filename, sizeof(X)); \
> - exit(EXIT_FAILURE); \
> - } \
> - __res; \
> - }))
> -
> -/* Set a value 'Y' in the elf header to 'X', compensating for
> endianness.
> - */
> -#define ESET(Y,X) \
> - do if (!do_reverse_endian) { \
> - Y = (X); \
> - } else if (sizeof(Y) == 1) { \
> - Y = (X); \
> - } else if (sizeof(Y) == 2) { \
> - Y = bswap_16((uint16_t)(X)); \
> - } else if (sizeof(Y) == 4) { \
> - Y = bswap_32((uint32_t)(X)); \
> - } else if (sizeof(Y) == 8) { \
> - Y = bswap_64((uint64_t)(X)); \
> - } else { \
> - fprintf(stderr, "%s: %s: ESET failed for size %zu\n", \
> - progname, filename, sizeof(Y)); \
> - exit(EXIT_FAILURE); \
> - } while (0)
> -
> -
> -/* A macro for I/O errors: The given error message is used only when
> - * errno is not set.
> - */
> -#define ferr(msg) (err(errno ? strerror(errno) : (msg)))
> -
> -
> -
> -#define HEADER_FUNCTIONS(CLASS) \
> - \
> -/* readelfheader() reads the ELF header into our global variable, and \
> - * checks to make sure that this is in fact a file that we should be \
> - * munging. \
> - */ \
> -static int readelfheader ## CLASS (int fd, Elf ## CLASS ## _Ehdr *ehdr)
> \
> -{ \
> - if (read(fd, ((char *)ehdr)+EI_NIDENT, sizeof(*ehdr) - EI_NIDENT) \
> - != sizeof(*ehdr) - EI_NIDENT) \
> - return ferr("missing or incomplete ELF header."); \
> - \
> - /* Verify the sizes of the ELF header and the program segment \
> - * header table entries. \
> - */ \
> - if (EGET(ehdr->e_ehsize) != sizeof(Elf ## CLASS ## _Ehdr)) \
> - return err("unrecognized ELF header size."); \
> - if (EGET(ehdr->e_phentsize) != sizeof(Elf ## CLASS ## _Phdr)) \
> - return err("unrecognized program segment header size."); \
> - \
> - /* Finally, check the file type. \
> - */ \
> - if (EGET(ehdr->e_type) != ET_EXEC && EGET(ehdr->e_type) != ET_DYN) \
> - return err("not an executable or shared-object library."); \
> - \
> - return TRUE; \
> -} \
> - \
> -/* readphdrtable() loads the program segment header table into memory.
> \
> - */ \
> -static int readphdrtable ## CLASS (int fd, Elf ## CLASS ## _Ehdr const
> *ehdr, \
> - Elf ## CLASS ## _Phdr **phdrs) \
> -{ \
> - size_t size; \
> - \
> - if (!EGET(ehdr->e_phoff) || !EGET(ehdr->e_phnum) \
> -) return err("ELF file has no program header table."); \
> - \
> - size = EGET(ehdr->e_phnum) * sizeof **phdrs; \
> - if (!(*phdrs = malloc(size))) \
> - return err("Out of memory!"); \
> - \
> - errno = 0; \
> - if (read(fd, *phdrs, size) != (ssize_t)size) \
> - return ferr("missing or incomplete program segment header table."); \
> - \
> - return TRUE; \
> -} \
> - \
> -/* getmemorysize() determines the offset of the last byte of the file \
> - * that is referenced by an entry in the program segment header table.
> \
> - * (Anything in the file after that point is not used when the program
> \
> - * is executing, and thus can be safely discarded.) \
> - */ \
> -static int getmemorysize ## CLASS (Elf ## CLASS ## _Ehdr const *ehdr, \
> - Elf ## CLASS ## _Phdr const *phdrs, \
> - unsigned long *newsize) \
> -{ \
> - Elf ## CLASS ## _Phdr const *phdr; \
> - unsigned long size, n; \
> - size_t i; \
> - \
> - /* Start by setting the size to include the ELF header and the \
> - * complete program segment header table. \
> - */ \
> - size = EGET(ehdr->e_phoff) + EGET(ehdr->e_phnum) * sizeof *phdrs; \
> - if (size < sizeof *ehdr) \
> - size = sizeof *ehdr; \
> - \
> - /* Then keep extending the size to include whatever data the \
> - * program segment header table references. \
> - */ \
> - for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \
> - if (EGET(phdr->p_type) != PT_NULL) { \
> - n = EGET(phdr->p_offset) + EGET(phdr->p_filesz); \
> - if (n > size) \
> - size = n; \
> - } \
> - } \
> - \
> - *newsize = size; \
> - return TRUE; \
> -} \
> - \
> -/* modifyheaders() removes references to the section header table if \
> - * it was stripped, and reduces program header table entries that \
> - * included truncated bytes at the end of the file. \
> - */ \
> -static int modifyheaders ## CLASS (Elf ## CLASS ## _Ehdr *ehdr, \
> - Elf ## CLASS ## _Phdr *phdrs, \
> - unsigned long newsize) \
> -{ \
> - Elf ## CLASS ## _Phdr *phdr; \
> - size_t i; \
> - \
> - /* If the section header table is gone, then remove all references \
> - * to it in the ELF header. \
> - */ \
> - if (EGET(ehdr->e_shoff) >= newsize) { \
> - ESET(ehdr->e_shoff,0); \
> - ESET(ehdr->e_shnum,0); \
> - ESET(ehdr->e_shentsize,0); \
> - ESET(ehdr->e_shstrndx,0); \
> - } \
> - \
> - /* The program adjusts the file size of any segment that was \
> - * truncated. The case of a segment being completely stripped out \
> - * is handled separately. \
> - */ \
> - for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \
> - if (EGET(phdr->p_offset) >= newsize) { \
> - ESET(phdr->p_offset,newsize); \
> - ESET(phdr->p_filesz,0); \
> - } else if (EGET(phdr->p_offset) + EGET(phdr->p_filesz) > newsize) { \
> - ESET(phdr->p_filesz, newsize - EGET(phdr->p_offset)); \
> - } \
> - } \
> - \
> - return TRUE; \
> -} \
> - \
> -/* commitchanges() writes the new headers back to the original file \
> - * and sets the file to its new size. \
> - */ \
> -static int commitchanges ## CLASS (int fd, Elf ## CLASS ## _Ehdr const
> *ehdr, \
> - Elf ## CLASS ## _Phdr *phdrs, \
> - unsigned long newsize) \
> -{ \
> - size_t n; \
> - \
> - /* Save the changes to the ELF header, if any. \
> - */ \
> - if (lseek(fd, 0, SEEK_SET)) \
> - return ferr("could not rewind file"); \
> - errno = 0; \
> - if (write(fd, ehdr, sizeof *ehdr) != sizeof *ehdr) \
> - return err("could not modify file"); \
> - \
> - /* Save the changes to the program segment header table, if any. \
> - */ \
> - if (lseek(fd, EGET(ehdr->e_phoff), SEEK_SET) == (off_t)-1) { \
> - err("could not seek in file."); \
> - goto warning; \
> - } \
> - n = EGET(ehdr->e_phnum) * sizeof *phdrs; \
> - if (write(fd, phdrs, n) != (ssize_t)n) { \
> - err("could not write to file"); \
> - goto warning; \
> - } \
> - \
> - /* Eleventh-hour sanity check: don't truncate before the end of \
> - * the program segment header table. \
> - */ \
> - if (newsize < EGET(ehdr->e_phoff) + n) \
> - newsize = EGET(ehdr->e_phoff) + n; \
> - \
> - /* Chop off the end of the file. \
> - */ \
> - if (ftruncate(fd, newsize)) { \
> - err("could not resize file"); \
> - goto warning; \
> - } \
> - \
> - return TRUE; \
> - \
> - warning: \
> - return err("ELF file may have been corrupted!"); \
> -}
> -
> -
> -/* First elements of Elf32_Ehdr and Elf64_Ehdr are common.
> - */
> -static int readelfheaderident(int fd, Elf32_Ehdr *ehdr)
> -{
> - errno = 0;
> - if (read(fd, ehdr, EI_NIDENT) != EI_NIDENT)
> - return ferr("missing or incomplete ELF header.");
> -
> - /* Check the ELF signature.
> - */
> - if (!(ehdr->e_ident[EI_MAG0] == ELFMAG0 &&
> - ehdr->e_ident[EI_MAG1] == ELFMAG1 &&
> - ehdr->e_ident[EI_MAG2] == ELFMAG2 &&
> - ehdr->e_ident[EI_MAG3] == ELFMAG3))
> - {
> - err("missing ELF signature.");
> - return -1;
> - }
> -
> - /* Compare the file's class and endianness with the program's.
> - */
> -#if __BYTE_ORDER == __LITTLE_ENDIAN
> - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) {
> - do_reverse_endian = 0;
> - } else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) {
> -/* fprintf(stderr, "ELF file has different endianness.\n"); */
> - do_reverse_endian = 1;
> - }
> -#elif __BYTE_ORDER == __BIG_ENDIAN
> - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) {
> -/* fprintf(stderr, "ELF file has different endianness.\n"); */
> - do_reverse_endian = 1;
> - } else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) {
> - do_reverse_endian = 0;
> - }
> -#else
> -#error unkown endianness
> -#endif
> - else {
> - err("Unsupported endianness");
> - return -1;
> - }
> -
> - /* Check the target architecture.
> - */
> -/* if (EGET(ehdr->e_machine) != ELF_ARCH) { */
> -/* /\* return err("ELF file created for different architecture."); *\/
> */
> -/* fprintf(stderr, "ELF file created for different architecture.\n");
> */
> -/* } */
> - return ehdr->e_ident[EI_CLASS];
> -}
> -
> -
> -HEADER_FUNCTIONS(32)
> -
> -HEADER_FUNCTIONS(64)
> -
> -/* truncatezeros() examines the bytes at the end of the file's
> - * size-to-be, and reduces the size to exclude any trailing zero
> - * bytes.
> - */
> -static int truncatezeros(int fd, unsigned long *newsize)
> -{
> - unsigned char contents[1024];
> - unsigned long size, n;
> -
> - size = *newsize;
> - do {
> - n = sizeof contents;
> - if (n > size)
> - n = size;
> - if (lseek(fd, size - n, SEEK_SET) == (off_t)-1)
> - return ferr("cannot seek in file.");
> - if (read(fd, contents, n) != (ssize_t)n)
> - return ferr("cannot read file contents");
> - while (n && !contents[--n])
> - --size;
> - } while (size && !n);
> -
> - /* Sanity check.
> - */
> - if (!size)
> - return err("ELF file is completely blank!");
> -
> - *newsize = size;
> - return TRUE;
> -}
> -
> -/* main() loops over the cmdline arguments, leaving all the real work
> - * to the other functions.
> - */
> -int main(int argc, char *argv[])
> -{
> - int fd;
> - union {
> - Elf32_Ehdr ehdr32;
> - Elf64_Ehdr ehdr64;
> - } e;
> - union {
> - Elf32_Phdr *phdrs32;
> - Elf64_Phdr *phdrs64;
> - } p;
> - unsigned long newsize;
> - char **arg;
> - int failures = 0;
> -
> - if (argc < 2 || argv[1][0] == '-') {
> - printf("Usage: sstrip FILE...\n"
> - "sstrip discards all nonessential bytes from an executable.\n\n"
> - "Version 2.0-X Copyright (C) 2000,2001 Brian Raiter.\n"
> - "Cross-devel hacks Copyright (C) 2004 Manuel Novoa III.\n"
> - "This program is free software, licensed under the GNU\n"
> - "General Public License. There is absolutely no warranty.\n");
> - return EXIT_SUCCESS;
> - }
> -
> - progname = argv[0];
> -
> - for (arg = argv + 1 ; *arg != NULL ; ++arg) {
> - filename = *arg;
> -
> - fd = open(*arg, O_RDWR);
> - if (fd < 0) {
> - ferr("can't open");
> - ++failures;
> - continue;
> - }
> -
> - switch (readelfheaderident(fd, &e.ehdr32)) {
> - case ELFCLASS32:
> - if (!(readelfheader32(fd, &e.ehdr32) &&
> - readphdrtable32(fd, &e.ehdr32, &p.phdrs32) &&
> - getmemorysize32(&e.ehdr32, p.phdrs32, &newsize) &&
> - truncatezeros(fd, &newsize) &&
> - modifyheaders32(&e.ehdr32, p.phdrs32, newsize) &&
> - commitchanges32(fd, &e.ehdr32, p.phdrs32, newsize)))
> - ++failures;
> - break;
> - case ELFCLASS64:
> - if (!(readelfheader64(fd, &e.ehdr64) &&
> - readphdrtable64(fd, &e.ehdr64, &p.phdrs64) &&
> - getmemorysize64(&e.ehdr64, p.phdrs64, &newsize) &&
> - truncatezeros(fd, &newsize) &&
> - modifyheaders64(&e.ehdr64, p.phdrs64, newsize) &&
> - commitchanges64(fd, &e.ehdr64, p.phdrs64, newsize)))
> - ++failures;
> - break;
> - default:
> - ++failures;
> - break;
> - }
> - close(fd);
> - }
> -
> - return failures ? EXIT_FAILURE : EXIT_SUCCESS;
> -}
> --
> 2.29.2
>
>
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