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checkrt tool rewritten

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darealshinji 2022-06-23 17:36:53 +02:00
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.gitignore vendored Normal file
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*.o
*.so
*.gz
src/*_test
src/checkrt
src/res.h
src/cxx/
src/gcc/

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AppRun Executable file
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#!/bin/sh -e
# add your command to execute here
exec=
cd "$(dirname "$0")"
if [ "x$exec" = "x" ]; then
exec="$(sed -n 's|^Exec=||p' *.desktop | head -1)"
fi
if [ -x "./usr/optional/checkrt" ]; then
extra_libs="$(./usr/optional/checkrt)"
fi
if [ -n "$extra_libs" ]; then
export LD_LIBRARY_PATH="${extra_libs}${LD_LIBRARY_PATH}"
if [ -e "$PWD/usr/optional/exec.so" ]; then
export LD_PRELOAD="$PWD/usr/optional/exec.so:${LD_PRELOAD}"
fi
fi
#echo ">>>>> $LD_LIBRARY_PATH"
#echo ">>>>> $LD_PRELOAD"
./usr/bin/$exec "$*"
exit $?

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COPYING Normal file
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checkrt.c: 2022 <djcj@gmx.de>
env.c exec.c: 2018 Pablo Marcos Oltra <pablo.marcos.oltra@gmail.com>
The MIT License
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# The problem
Some projects require newer C++ standards to build them. To keep the glibc
dependency low you can build a newer GCC version on an older distro and use it
to compile the project. This project however will now require a newer version of
the `libstdc++.so.6` library than available on that distro.
Blindly bundling `libstdc++.so.6` however will in most cases break compatibility
with distros that have a newer library version installed into their system than
the bundled one.
By the way, while this is primarily an issue with `libstdc++.so.6` in some cases
this might also occur with `libgcc_s.so.1`. That's because both libraries are
part of GCC.
# The solution
You would have to know the library version of the host system and decide whether
to use a bundled library or not before the application is started. This is
exactly what the `checkrt` tool does. It will search for a bundled `libstdc++.so.6`
and `libgcc_s.so.1` library inside the AppImage or AppDir. If found it will
compare their internal versions with the ones found on the system (using dlopen())
and prepend their paths to `LD_LIBRARY_PATH` if necessary.
# Usage
Compile with `make -C src`. Inside your AppDir create the directory `usr/optional/`
and put the binary `checkrt` inside there. Execute `usr/optional/checkrt --copy-libraries`
to bundle your system's `libstdc++.so.6` and `libgcc_s.so.1` libraries.
Use the provided AppRun script or write/modify your own. `checkrt` will either
return a path that can be added to `LD_LIBRARY_PATH` or an empty string.
Error messages, help and verbosity will always be returned to stderr.
# exec.so
You might also want to bundle `exec.so` inside `usr/optional/`. This library is
intended to restore the environment of the AppImage to its parent. This is done
to avoid library clashing of bundled libraries with external processes, e.g. when
running the web browser.
The intended usage is as follows:
1. This library is injected to the dynamic loader through LD_PRELOAD
automatically in AppRun **only** if `usr/optional/exec.so` exists:
e.g `LD_PRELOAD=$APPDIR/usr/optional/exec.so My.AppImage`
2. This library will intercept calls to new processes and will detect whether
those calls are for binaries within the AppImage bundle or external ones.
3. In case it's an internal process, it will not change anything.
In case it's an external process, it will restore the environment of
the AppImage parent by reading `/proc/[pid]/environ`.
This is the conservative approach taken.

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GCC RUNTIME LIBRARY EXCEPTION
Version 3.1, 31 March 2009
Copyright (C) 2009 Free Software Foundation, Inc. <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
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Copyright (C) 1989-2022 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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Under Section 7 of GPL version 3, you are granted additional
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3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>.

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Copyright (C) 1997-2022 Free Software Foundation, Inc.
This file is part of the GNU ISO C++ Library. This library is free
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terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option)
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This library is distributed in the hope that it will be useful,
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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Under Section 7 of GPL version 3, you are granted additional
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3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>.

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Corresponding Source of the work from the predecessor in interest, if
the predecessor has it or can get it with reasonable efforts.
You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License. For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation
(including a cross-claim or counterclaim in a lawsuit) alleging that
any patent claim is infringed by making, using, selling, offering for
sale, or importing the Program or any portion of it.
11. Patents.
A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based. The
work thus licensed is called the contributor's "contributor version".
A contributor's "essential patent claims" are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner, permitted
by this License, of making, using, or selling its contributor version,
but do not include claims that would be infringed only as a
consequence of further modification of the contributor version. For
purposes of this definition, "control" includes the right to grant
patent sublicenses in a manner consistent with the requirements of
this License.
Each contributor grants you a non-exclusive, worldwide, royalty-free
patent license under the contributor's essential patent claims, to
make, use, sell, offer for sale, import and otherwise run, modify and
propagate the contents of its contributor version.
In the following three paragraphs, a "patent license" is any express
agreement or commitment, however denominated, not to enforce a patent
(such as an express permission to practice a patent or covenant not to
sue for patent infringement). To "grant" such a patent license to a
party means to make such an agreement or commitment not to enforce a
patent against the party.
If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients. "Knowingly relying" means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient's use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate, modify
or convey a specific copy of the covered work, then the patent license
you grant is automatically extended to all recipients of the covered
work and works based on it.
A patent license is "discriminatory" if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that are
specifically granted under this License. You may not convey a covered
work if you are a party to an arrangement with a third party that is
in the business of distributing software, under which you make payment
to the third party based on the extent of your activity of conveying
the work, and under which the third party grants, to any of the
parties who would receive the covered work from you, a discriminatory
patent license (a) in connection with copies of the covered work
conveyed by you (or copies made from those copies), or (b) primarily
for and in connection with specific products or compilations that
contain the covered work, unless you entered into that arrangement,
or that patent license was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
12. No Surrender of Others' Freedom.
If conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License. If you cannot convey a
covered work so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may
not convey it at all. For example, if you agree to terms that obligate you
to collect a royalty for further conveying from those to whom you convey
the Program, the only way you could satisfy both those terms and this
License would be to refrain entirely from conveying the Program.
13. Use with the GNU Affero General Public License.
Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work. The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.
14. Revised Versions of this License.
The Free Software Foundation may publish revised and/or new versions of
the GNU General Public License from time to time. Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.
Each version is given a distinguishing version number. If the
Program specifies that a certain numbered version of the GNU General
Public License "or any later version" applies to it, you have the
option of following the terms and conditions either of that numbered
version or of any later version published by the Free Software
Foundation. If the Program does not specify a version number of the
GNU General Public License, you may choose any version ever published
by the Free Software Foundation.
If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that proxy's
public statement of acceptance of a version permanently authorizes you
to choose that version for the Program.
Later license versions may give you additional or different
permissions. However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.
15. Disclaimer of Warranty.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
16. Limitation of Liability.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.
17. Interpretation of Sections 15 and 16.
If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:
<program> Copyright (C) <year> <name of author>
This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".
You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.
The GNU General Public License does not permit incorporating your program
into proprietary programs. If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library. If this is what you want to do, use the GNU Lesser General
Public License instead of this License. But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

51
src/Makefile Normal file
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BIN = checkrt
LIB = exec.so
EXEC_TEST = exec_test
ENV_TEST = env_test
CHECKRT_TEST = checkrt_test
CFLAGS := -Wall -O3
LDFLAGS := -s
all: $(BIN) $(LIB)
clean:
-rm -f *.o *.gz res.h $(BIN) $(LIB) $(EXEC_TEST) $(ENV_TEST) $(CHECKRT_TEST)
distclean: clean
-rm -rf cxx gcc
$(BIN): checkrt.o
$(CC) -o $@ $^ $(LDFLAGS) -ldl
checkrt.c: res.h
res.h:
gzip -k -f COPYING.RUNTIME COPYING3 && \
xxd -i COPYING.RUNTIME.gz > $@ && \
xxd -i COPYING3.gz >> $@ && \
xxd -i COPYING.libgcc >> $@ && \
xxd -i COPYING.libstdc++ >> $@
exec.o env.o: CFLAGS += -fPIC
$(LIB): exec.o env.o
$(CC) -o $@ $^ -shared $(LDFLAGS) -ldl
$(CHECKRT_TEST): checkrt.c
$(CC) -o $@ $(CFLAGS) -DCHECKRT_TEST $^ -ldl
$(EXEC_TEST): exec.c env.o
$(CC) -o $@ $(CFLAGS) -DEXEC_TEST $^ -ldl
$(ENV_TEST): env.c
$(CC) -o $@ $(CFLAGS) -DENV_TEST $^
run_tests: $(EXEC_TEST) $(ENV_TEST) $(CHECKRT_TEST)
./$(ENV_TEST)
./$(EXEC_TEST)
./$(CHECKRT_TEST)
.PHONY: $(BIN) all clean

392
src/checkrt.c Normal file
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/* Copyright (c) 2022 <djcj@gmx.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <link.h>
#include <dlfcn.h>
#include <elf.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <unistd.h>
#include "res.h"
#ifdef __x86_64__
typedef Elf64_Ehdr Elf_Ehdr;
typedef Elf64_Shdr Elf_Shdr;
typedef Elf64_Sym Elf_Sym;
#else
typedef Elf32_Ehdr Elf_Ehdr;
typedef Elf32_Shdr Elf_Shdr;
typedef Elf32_Sym Elf_Sym;
#endif
#define LIBGCC_S_SO "libgcc_s.so.1"
#define LIBSTDCXX_SO "libstdc++.so.6"
#define LIBGCC_DIR "gcc"
#define STDCXX_DIR "cxx"
#define MAX(X,Y) (((X) > (Y)) ? (X) : (Y))
#define PRINT_VERBOSE(FMT, ...) if (verbose) { fprintf(stderr, FMT, __VA_ARGS__); }
static char *get_libname(const char *lib, char verbose)
{
struct link_map *map = NULL;
char *path;
void *handle = dlopen(lib, RTLD_LAZY);
if (!handle) {
PRINT_VERBOSE("error: failed to dlopen() file: %s\n", lib);
return NULL;
}
if (dlinfo(handle, RTLD_DI_LINKMAP, &map) == -1) {
PRINT_VERBOSE("error: could not retrieve information: %s\n", lib);
dlclose(handle);
return NULL;
}
path = strdup(map->l_name);
dlclose(handle);
return path;
}
static int symbol_version(const char *lib, const char *symbol, char verbose)
{
int fd = -1;
void *addr = NULL;
const char *error = "";
/* let dlopen() do all the compatibility checks */
char *orig = get_libname(lib, verbose);
if (!orig) return -1;
fd = open(orig, O_RDONLY);
if (fd < 0) {
PRINT_VERBOSE("error: failed to open() file: %s\n", orig);
free(orig);
return -1;
}
PRINT_VERBOSE("%s\n", orig);
free(orig);
/* make sure file size is larger than the required ELF header size */
struct stat st;
if (fstat(fd, &st) < 0 || st.st_size < sizeof(Elf_Ehdr)) {
error = "fstat() failed or returned a too low file size";
goto symbol_version_error;
}
/* mmap() library */
addr = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (addr == MAP_FAILED) {
error = "mmap() failed";
goto symbol_version_error;
}
/* ELF header */
Elf_Ehdr *ehdr = addr;
error = "offset exceeding filesize";
if (ehdr->e_shoff > st.st_size) {
goto symbol_version_error;
}
Elf_Shdr *shdr = addr + ehdr->e_shoff;
int shnum = ehdr->e_shnum;
Elf_Shdr *sh_strtab = &shdr[ehdr->e_shstrndx];
if (sh_strtab->sh_offset > st.st_size) {
goto symbol_version_error;
}
const char *sh_strtab_p = addr + sh_strtab->sh_offset;
const char *sh_dynstr_p = sh_strtab_p;
const char * const sh_strtab_p_const = sh_strtab_p;
/* get strtab/dynstr */
for (int i = 0; i < shnum; ++i) {
if (shdr[i].sh_type != SHT_STRTAB) continue;
const char *name = sh_strtab_p_const + shdr[i].sh_name;
if (strcmp(name, ".strtab") == 0) {
if (shdr[i].sh_offset > st.st_size) {
goto symbol_version_error;
}
sh_strtab_p = addr + shdr[i].sh_offset;
break;
} else if (strcmp(name, ".dynstr") == 0) {
if (shdr[i].sh_offset > st.st_size) {
goto symbol_version_error;
}
sh_dynstr_p = addr + shdr[i].sh_offset;
break;
}
}
/* iterate through sections */
size_t len = strlen(symbol);
int maj = 0, min = 0, pat = 0;
for (int i = 0; i < shnum; ++i) {
if (shdr[i].sh_type != SHT_SYMTAB && shdr[i].sh_type != SHT_DYNSYM) {
continue;
}
if (shdr[i].sh_offset > st.st_size) {
goto symbol_version_error;
}
Elf_Sym *syms_data = addr + shdr[i].sh_offset;
/* iterate through symbols */
for (size_t j = 0; j < shdr[i].sh_size / sizeof(Elf_Sym); ++j) {
if (syms_data[j].st_shndx != SHN_ABS) {
continue;
}
const char *symbol_name;
if (shdr[i].sh_type == SHT_DYNSYM) {
symbol_name = sh_dynstr_p + syms_data[j].st_name;
} else {
symbol_name = sh_strtab_p + syms_data[j].st_name;
}
if (strncmp(symbol_name, symbol, len) != 0) {
continue;
}
int tmp_maj = 0, tmp_min = 0, tmp_pat = 0;
if (sscanf(symbol_name + len, "%d.%d.%d", &tmp_maj, &tmp_min, &tmp_pat) < 1) {
continue;
}
if (tmp_maj < maj) {
continue;
} else if (tmp_maj > maj) {
maj = tmp_maj;
min = tmp_min;
pat = tmp_pat;
continue;
}
if (tmp_min < min) {
continue;
} else if (tmp_min > min) {
min = tmp_min;
pat = tmp_pat;
continue;
}
if (tmp_pat > pat) {
pat = tmp_pat;
}
}
}
PRINT_VERBOSE("%s%d.%d.%d\n", symbol, maj, min, pat);
munmap(addr, st.st_size);
close(fd);
return (pat + min*1000 + maj*1000000);
symbol_version_error:
PRINT_VERBOSE("error: %s: %s\n", error, orig);
munmap(addr, st.st_size);
close(fd);
return -1;
}
static void dump_file(const char *dest, unsigned char *data, unsigned int len)
{
int fd = creat(dest, DEFFILEMODE);
if (fd == -1) return;
if (write(fd, data, len) != len) unlink(dest);
close(fd);
}
static int copy_lib(const char *lib, const char *destDir, char verbose)
{
char *destFull = NULL;
int fdIn = -1, fdOut = -1;
/* get full source and target paths */
char *srcFull = get_libname(lib, verbose);
if (!srcFull) goto copy_lib_error;
char *base = basename(srcFull);
if (!base) goto copy_lib_error;
size_t len = strlen(destDir);
size_t len2 = strlen(base);
destFull = malloc(len + MAX(len2,32) + 2);
sprintf(destFull, "%s/%s", destDir, base);
/* open source for reading */
fdIn = open(srcFull, O_RDONLY|O_CLOEXEC);
if (fdIn == -1) goto copy_lib_error;
/* open target for writing */
mkdir(destDir, ACCESSPERMS);
fdOut = creat(destFull, DEFFILEMODE);
if (fdOut == -1) goto copy_lib_error;
/* copy data into target */
ssize_t n;
unsigned char buf[512*1024];
while ((n = read(fdIn, &buf, sizeof(buf))) > 0) {
if (write(fdOut, &buf, n) != n) {
goto copy_lib_error;
}
}
int rv = 0;
fprintf(stderr, ">> %s\ncopied to -> %s\n", srcFull, destFull);
/* dump COPYING files */
char *p = destFull + len + 1;
strcpy(p, "COPYING.RUNTIME.gz");
dump_file(destFull, COPYING_RUNTIME_gz, COPYING_RUNTIME_gz_len);
p += 7;
strcpy(p, "3.gz");
dump_file(destFull, COPYING3_gz, COPYING3_gz_len);
strcpy(p, ".libgcc");
dump_file(destFull, COPYING_libgcc, COPYING_libgcc_len);
strcpy(p, ".libstdc++");
dump_file(destFull, COPYING_libstdc__, COPYING_libstdc___len);
fprintf(stderr, "(COPYING files were added too)\n");
goto copy_lib_end;
copy_lib_error:
rv = -1;
copy_lib_end:
if (fdOut != -1) close(fdOut);
if (fdIn != -1) close(fdIn);
if (srcFull) free(srcFull);
if (destFull) free(destFull);
return rv;
}
int main(int argc, char **argv)
{
#if CHECKRT_TEST == 1
printf("Test:\n");
copy_lib(LIBGCC_S_SO, "./" LIBGCC_DIR, 1);
copy_lib(LIBSTDCXX_SO, "./" STDCXX_DIR, 1);
symbol_version(LIBGCC_S_SO, "GCC_", 1);
symbol_version(LIBSTDCXX_SO, "GLIBCXX_", 1);
symbol_version("./" LIBGCC_DIR "/" LIBGCC_S_SO, "GCC_", 1);
symbol_version("./" STDCXX_DIR "/" LIBSTDCXX_SO, "GLIBCXX_", 1);
#else
char v = 0, copy = 0;
for (int i=1; i < argc; i++) {
if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
fprintf(stderr,
"usage:\n"
" %s -c|--copy-libraries\n"
" %s -h|--help\n"
" %s -v|--verbose\n"
"\n"
"This program will look for the following libraries relative to its\n"
"location, check if they are usable and add them to LD_LIBRARY_PATH\n"
"if they are newer than the system's equivalent:\n"
"\n"
" " LIBGCC_DIR "/" LIBGCC_S_SO "\n"
" " STDCXX_DIR "/" LIBSTDCXX_SO "\n", argv[0], argv[0], argv[0]);
return 0;
} else if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
v = 1;
} else if (strcmp(argv[i], "-c") == 0 || strcmp(argv[i], "--copy-libraries") == 0) {
copy = 1;
} else {
fprintf(stderr, "error: invalid argument: %s\nTry `%s --help' for more information.\n", argv[i], argv[0]);
return 1;
}
}
char *currdir = realpath("/proc/self/exe", NULL);
if (!currdir) {
fprintf(stderr, "error: realpath() failed to resolve /proc/self/exe\n");
return 1;
}
char *p = strrchr(currdir, '/');
if (!p) {
perror("strrchr()");
free(currdir);
return 1;
}
*(p+1) = 0;
int ver;
size_t len = strlen(currdir);
char *libpath = malloc(len + MAX(sizeof(STDCXX_DIR), sizeof(LIBGCC_DIR)) +
MAX(sizeof(LIBSTDCXX_SO), sizeof(LIBGCC_S_SO)) + 2);
strcpy(libpath, currdir);
p = libpath + len;
if (copy) {
/* copy system libraries */
strcpy(p, LIBGCC_DIR);
copy_lib(LIBGCC_S_SO, libpath, v);
strcpy(p, STDCXX_DIR);
copy_lib(LIBSTDCXX_SO, libpath, v);
} else {
/* get symbol versions */
strcpy(p, LIBGCC_DIR "/" LIBGCC_S_SO);
ver = symbol_version(libpath, "GCC_", v);
if (ver != -1 && ver > symbol_version(LIBGCC_S_SO, "GCC_", v)) {
printf("%s" LIBGCC_DIR ":", currdir);
}
strcpy(p, STDCXX_DIR "/" LIBSTDCXX_SO);
ver = symbol_version(libpath, "GLIBCXX_", v);
if (ver != -1 && ver > symbol_version(LIBSTDCXX_SO, "GLIBCXX_", v)) {
printf("%s" STDCXX_DIR ":", currdir);
}
putchar('\n');
}
free(libpath);
free(currdir);
#endif
return 0;
}

134
src/env.c Normal file
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@ -0,0 +1,134 @@
/* Copyright (c) 2018 Pablo Marcos Oltra <pablo.marcos.oltra@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include "env.h"
static char** env_allocate(size_t size) {
return calloc(size + 1, sizeof(char*));
}
void env_free(char* const *env) {
size_t len = 0;
while (env[len] != 0) {
free(env[len]);
len++;
}
free((char**)env);
}
pid_t get_parent_pid() {
pid_t ppid = 0;
char *s_ppid = getenv("PPID");
if(s_ppid) {
ppid = atoi(s_ppid);
}
if (!ppid) {
ppid = getppid();
}
return ppid;
}
static size_t get_number_of_variables(FILE *file, char **buffer, size_t *len) {
size_t number = 0;
if (getline(buffer, len, file) < 0)
return -1;
char *ptr = *buffer;
while (ptr < *buffer + *len) {
size_t var_len = strlen(ptr);
ptr += var_len + 1;
if (var_len == 0)
break;
number++;
}
return number != 0 ? (ssize_t)number : -1;
}
static char* const* env_from_buffer(FILE *file) {
char *buffer = NULL;
size_t len = 0;
size_t num_vars = get_number_of_variables(file, &buffer, &len);
char** env = env_allocate(num_vars);
size_t n = 0;
char *ptr = buffer;
while (ptr < buffer + len && n < num_vars) {
size_t var_len = strlen(ptr);
if (var_len == 0)
break;
env[n] = calloc(sizeof(char*), var_len + 1);
strncpy(env[n], ptr, var_len + 1);
DEBUG("\tenv var copied: %s\n", env[n]);
ptr += var_len + 1;
n++;
}
free(buffer);
return env;
}
static char* const* read_env_from_process(pid_t pid) {
char buffer[256] = {0};
snprintf(buffer, sizeof(buffer), "/proc/%d/environ", pid);
DEBUG("Reading env from parent process: %s\n", buffer);
FILE *env_file = fopen(buffer, "r");
if (!env_file) {
DEBUG("Error reading file: %s (%s)\n", buffer, strerror(errno));
return NULL;
}
char* const* env = env_from_buffer(env_file);
fclose(env_file);
return env;
}
char* const* read_parent_env() {
pid_t ppid = get_parent_pid();
return read_env_from_process(ppid);
}
#ifdef ENV_TEST
int main() {
putenv("APPIMAGE_CHECKRT_DEBUG=1");
DEBUG("ENV TEST\n");
char **env = NULL;
read_parent_env(&env);
return 0;
}
#endif

16
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#ifndef ENV_H
#define END_H
#include <stdio.h>
#include <unistd.h>
pid_t get_parent_pid();
char* const* read_parent_env();
void env_free(char* const *env);
#define DEBUG(...) do { \
if (getenv("APPIMAGE_CHECKRT_DEBUG")) \
printf("APPIMAGE_CHECKRT>> " __VA_ARGS__); \
} while (0)
#endif

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/* Copyright (c) 2018 Pablo Marcos Oltra <pablo.marcos.oltra@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
/*
* This exec.so library is intended to restore the environment of the AppImage's
* parent process. This is done to avoid library clashing of bundled libraries
* with external processes. e.g when running the web browser
*
* The intended usage is as follows:
*
* 1. This library is injected to the dynamic loader through LD_PRELOAD
* automatically in AppRun **only** if `usr/optional/exec.so` exists:
* e.g `LD_PRELOAD=$APPDIR/usr/optional/exec.so My.AppImage`
*
* 2. This library will intercept calls to new processes and will detect whether
* those calls are for binaries within the AppImage bundle or external ones.
*
* 3. In case it's an internal process, it will not change anything.
* In case it's an external process, it will restore the environment of
* the AppImage parent by reading `/proc/[pid]/environ`.
* This is the conservative approach taken.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <unistd.h>
#include <dlfcn.h>
#include <string.h>
#include <errno.h>
#include "env.h"
typedef int (*execve_func_t)(const char *filename, char *const argv[], char *const envp[]);
#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))
static const char* get_fullpath(const char *filename) {
// Try to get the canonical path in case it's a relative path or symbolic
// link. Otherwise, use which to get the fullpath of the binary
char *fullpath = canonicalize_file_name(filename);
DEBUG("filename %s, canonical path %s\n", filename, fullpath);
if (fullpath)
return fullpath;
return filename;
}
static int is_external_process(const char *filename) {
const char *appdir = getenv("APPDIR");
if (!appdir)
return 0;
DEBUG("APPDIR = %s\n", appdir);
return strncmp(filename, appdir, MIN(strlen(filename), strlen(appdir)));
}
static int exec_common(execve_func_t function, const char *filename, char* const argv[], char* const envp[]) {
const char *fullpath = get_fullpath(filename);
DEBUG("filename %s, fullpath %s\n", filename, fullpath);
char* const *env = envp;
if (is_external_process(fullpath)) {
DEBUG("External process detected. Restoring env vars from parent %d\n", get_parent_pid());
env = read_parent_env();
if (!env) {
env = envp;
DEBUG("Error restoring env vars from parent\n");
}
}
int ret = function(filename, argv, env);
if (fullpath != filename)
free((char*)fullpath);
if (env != envp)
env_free(env);
return ret;
}
int execve(const char *filename, char *const argv[], char *const envp[]) {
DEBUG("execve call hijacked: %s\n", filename);
execve_func_t execve_orig = dlsym(RTLD_NEXT, "execve");
if (!execve_orig)
DEBUG("Error getting execve original symbol: %s\n", strerror(errno));
return exec_common(execve_orig, filename, argv, envp);
}
int execv(const char *filename, char *const argv[]) {
DEBUG("execv call hijacked: %s\n", filename);
return execve(filename, argv, environ);
}
int execvpe(const char *filename, char *const argv[], char *const envp[]) {
DEBUG("execvpe call hijacked: %s\n", filename);
execve_func_t execve_orig = dlsym(RTLD_NEXT, "execvpe");
if (!execve_orig)
DEBUG("Error getting execvpe original symbol: %s\n", strerror(errno));
return exec_common(execve_orig, filename, argv, envp);
}
int execvp(const char *filename, char *const argv[]) {
DEBUG("execvp call hijacked: %s\n", filename);
return execvpe(filename, argv, environ);
}
#ifdef EXEC_TEST
int main(int argc, char *argv[]) {
putenv("APPIMAGE_CHECKRT_DEBUG=1");
DEBUG("EXEC TEST\n");
execv("./env_test", argv);
return 0;
}
#endif