pack: Add relocation via ld.so and fakechroot.
* gnu/packages/aux-files/run-in-namespace.c (HAVE_EXEC_WITH_LOADER): New macro. (bind_mount): Rename to... (mirror_directory): ... this. Add 'firmlink' argument and use it instead of calling mkdir/open/close/mount directly. (bind_mount, make_symlink): New functions. (exec_in_user_namespace): Adjust accordingly. (exec_with_loader) [HAVE_EXEC_WITH_LOADER]: New function. (exec_performance): New function. (engines): Add them. * guix/scripts/pack.scm (wrapped-package)[fakechroot-library] [audit-module]: New procedures. [audit-source]: New variable. [build](elf-interpreter, elf-loader-compile-flags): New procedures. (build-wrapper): Use them. * tests/guix-pack-relocatable.sh: Test with 'GUIX_EXECUTION_ENGINE=fakechroot'. * doc/guix.texi (Invoking guix pack): Document the 'performance' and 'fakechroot' engines. * gnu/packages/aux-files/pack-audit.c: New file. * Makefile.am (AUX_FILES): Add it.
This commit is contained in:
Ludovic Courtès
Ludovic Courtès
parent
4449e7c5e4
commit
6456232164
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@ -338,6 +338,7 @@ AUX_FILES = \
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gnu/packages/aux-files/linux-libre/4.9-x86_64.conf \
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gnu/packages/aux-files/linux-libre/4.4-i686.conf \
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gnu/packages/aux-files/linux-libre/4.4-x86_64.conf \
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gnu/packages/aux-files/pack-audit.c \
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gnu/packages/aux-files/run-in-namespace.c
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# Templates, examples.
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@ -5230,6 +5230,10 @@ following execution engines are supported:
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Try user namespaces and fall back to PRoot if user namespaces are not
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supported (see below).
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@item performance
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Try user namespaces and fall back to Fakechroot if user namespaces are
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not supported (see below).
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@item userns
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Run the program through user namespaces and abort if they are not
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supported.
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@ -5241,6 +5245,15 @@ support for file system virtualization. It achieves that by using the
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@code{ptrace} system call on the running program. This approach has the
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advantage to work without requiring special kernel support, but it incurs
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run-time overhead every time a system call is made.
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@item fakechroot
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Run through Fakechroot. @uref{https://github.com/dex4er/fakechroot/,
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Fakechroot} virtualizes file system accesses by intercepting calls to C
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library functions such as @code{open}, @code{stat}, @code{exec}, and so
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on. Unlike PRoot, it incurs very little overhead. However, it does not
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always work: for example, some file system accesses made from within the
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C library are not intercepted, and file system accesses made @i{via}
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direct syscalls are not intercepted either, leading to erratic behavior.
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@end table
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@vindex GUIX_EXECUTION_ENGINE
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@ -0,0 +1,85 @@
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/* GNU Guix --- Functional package management for GNU
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Copyright (C) 2020 Ludovic Courtès <ludo@gnu.org>
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This file is part of GNU Guix.
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GNU Guix is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at
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your option) any later version.
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GNU Guix is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. */
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/* This file implements part of the GNU ld.so audit interface. It is used by
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the "fakechroot" engine of the 'guix pack -RR' wrappers to make sure the
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loader looks for shared objects under the "fake" root directory. */
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#define _GNU_SOURCE 1
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#include <link.h>
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#include <error.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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/* The pseudo root directory and store that we are relocating to. */
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static const char *root_directory;
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static char *store;
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/* The original store, "/gnu/store" by default. */
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static const char original_store[] = "@STORE_DIRECTORY@";
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/* Like 'malloc', but abort if 'malloc' returns NULL. */
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static void *
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xmalloc (size_t size)
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{
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void *result = malloc (size);
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assert (result != NULL);
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return result;
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}
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unsigned int
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la_version (unsigned int v)
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{
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if (v != LAV_CURRENT)
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error (1, 0, "cannot handle interface version %u", v);
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root_directory = getenv ("FAKECHROOT_BASE");
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if (root_directory == NULL)
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error (1, 0, "'FAKECHROOT_BASE' is not set");
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store = xmalloc (strlen (root_directory) + sizeof original_store);
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strcpy (store, root_directory);
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strcat (store, original_store);
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return v;
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}
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/* Return NAME, a shared object file name, relocated under STORE. This
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function is called by the loader whenever it looks for a shared object. */
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char *
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la_objsearch (const char *name, uintptr_t *cookie, unsigned int flag)
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{
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char *result;
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if (strncmp (name, original_store,
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sizeof original_store - 1) == 0)
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{
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size_t len = strlen (name) - sizeof original_store
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+ strlen (store) + 1;
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result = xmalloc (len);
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strcpy (result, store);
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strcat (result, name + sizeof original_store - 1);
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}
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else
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result = strdup (name);
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return result;
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}
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@ -42,6 +42,11 @@
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#include <dirent.h>
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#include <sys/syscall.h>
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/* Whether we're building the ld.so/libfakechroot wrapper. */
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#define HAVE_EXEC_WITH_LOADER \
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(defined PROGRAM_INTERPRETER) && (defined LOADER_AUDIT_MODULE) \
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&& (defined FAKECHROOT_LIBRARY)
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/* The original store, "/gnu/store" by default. */
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static const char original_store[] = "@STORE_DIRECTORY@";
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@ -117,9 +122,42 @@ rm_rf (const char *directory)
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assert_perror (errno);
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}
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/* Bind mount all the top-level entries in SOURCE to TARGET. */
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/* Make TARGET a bind-mount of SOURCE. Take into account ENTRY's type, which
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corresponds to SOURCE. */
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static int
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bind_mount (const char *source, const struct dirent *entry,
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const char *target)
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{
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if (entry->d_type == DT_DIR)
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{
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int err = mkdir (target, 0700);
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if (err != 0)
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return err;
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}
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else
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close (open (target, O_WRONLY | O_CREAT));
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return mount (source, target, "none",
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MS_BIND | MS_REC | MS_RDONLY, NULL);
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}
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#if HAVE_EXEC_WITH_LOADER
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/* Make TARGET a symlink to SOURCE. */
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static int
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make_symlink (const char *source, const struct dirent *entry,
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const char *target)
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{
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return symlink (source, target);
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}
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#endif
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/* Mirror with FIRMLINK all the top-level entries in SOURCE to TARGET. */
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static void
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bind_mount (const char *source, const char *target)
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mirror_directory (const char *source, const char *target,
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int (* firmlink) (const char *, const struct dirent *,
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const char *))
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{
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DIR *stream = opendir (source);
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@ -154,17 +192,7 @@ bind_mount (const char *source, const char *target)
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else
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{
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/* Create the mount point. */
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if (entry->d_type == DT_DIR)
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{
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int err = mkdir (new_entry, 0700);
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if (err != 0)
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assert_perror (errno);
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}
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else
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close (open (new_entry, O_WRONLY | O_CREAT));
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int err = mount (abs_source, new_entry, "none",
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MS_BIND | MS_REC | MS_RDONLY, NULL);
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int err = firmlink (abs_source, entry, new_entry);
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/* It used to be that only directories could be bind-mounted. Thus,
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keep going if we fail to bind-mount a non-directory entry.
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@ -248,7 +276,7 @@ exec_in_user_namespace (const char *store, int argc, char *argv[])
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/* Note: Due to <https://bugzilla.kernel.org/show_bug.cgi?id=183461>
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we cannot make NEW_ROOT a tmpfs (which would have saved the need
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for 'rm_rf'.) */
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bind_mount ("/", new_root);
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mirror_directory ("/", new_root, bind_mount);
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mkdir_p (new_store);
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err = mount (store, new_store, "none", MS_BIND | MS_REC | MS_RDONLY,
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NULL);
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@ -340,6 +368,92 @@ exec_with_proot (const char *store, int argc, char *argv[])
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#endif
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#if HAVE_EXEC_WITH_LOADER
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/* Execute the wrapped program by invoking the loader (ld.so) directly,
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passing it the audit module and preloading libfakechroot.so. */
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static void
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exec_with_loader (const char *store, int argc, char *argv[])
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{
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char *loader = concat (store,
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PROGRAM_INTERPRETER + sizeof original_store);
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size_t loader_specific_argc = 6;
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size_t loader_argc = argc + loader_specific_argc;
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char *loader_argv[loader_argc + 1];
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loader_argv[0] = argv[0];
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loader_argv[1] = "--audit";
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loader_argv[2] = concat (store,
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LOADER_AUDIT_MODULE + sizeof original_store);
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loader_argv[3] = "--preload";
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loader_argv[4] = concat (store,
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FAKECHROOT_LIBRARY + sizeof original_store);
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loader_argv[5] = concat (store,
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"@WRAPPED_PROGRAM@" + sizeof original_store);
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for (size_t i = 0; i < argc; i++)
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loader_argv[i + loader_specific_argc] = argv[i + 1];
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loader_argv[loader_argc] = NULL;
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/* Set up the root directory. */
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int err;
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char *new_root = mkdtemp (strdup ("/tmp/guix-exec-XXXXXX"));
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mirror_directory ("/", new_root, make_symlink);
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char *new_store = concat (new_root, original_store);
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char *new_store_parent = dirname (strdup (new_store));
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mkdir_p (new_store_parent);
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symlink (store, new_store);
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#ifdef GCONV_DIRECTORY
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/* Tell libc where to find its gconv modules. This is necessary because
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gconv uses non-interposable 'open' calls. */
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char *gconv_path = concat (store,
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GCONV_DIRECTORY + sizeof original_store);
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setenv ("GCONV_PATH", gconv_path, 1);
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free (gconv_path);
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#endif
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setenv ("FAKECHROOT_BASE", new_root, 1);
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pid_t child = fork ();
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switch (child)
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{
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case 0:
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err = execv (loader, loader_argv);
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if (err < 0)
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assert_perror (errno);
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exit (EXIT_FAILURE);
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break;
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case -1:
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assert_perror (errno);
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exit (EXIT_FAILURE);
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break;
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default:
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{
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int status;
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waitpid (child, &status, 0);
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chdir ("/"); /* avoid EBUSY */
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rm_rf (new_root);
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free (new_root);
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close (2); /* flushing stderr should be silent */
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if (WIFEXITED (status))
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exit (WEXITSTATUS (status));
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else
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/* Abnormal termination cannot really be reproduced, so exit
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with 255. */
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exit (255);
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}
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}
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}
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#endif
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/* Execution engines. */
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@ -356,7 +470,7 @@ buffer_stderr (void)
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setvbuf (stderr, stderr_buffer, _IOFBF, sizeof stderr_buffer);
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}
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/* The default engine. */
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/* The default engine: choose a robust method. */
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static void
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exec_default (const char *store, int argc, char *argv[])
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{
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@ -370,13 +484,29 @@ exec_default (const char *store, int argc, char *argv[])
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#endif
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}
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/* The "performance" engine: choose performance over robustness. */
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static void
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exec_performance (const char *store, int argc, char *argv[])
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{
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buffer_stderr ();
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exec_in_user_namespace (store, argc, argv);
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#if HAVE_EXEC_WITH_LOADER
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exec_with_loader (store, argc, argv);
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#endif
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}
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/* List of supported engines. */
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static const struct engine engines[] =
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{
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{ "default", exec_default },
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{ "performance", exec_performance },
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{ "userns", exec_in_user_namespace },
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#ifdef PROOT_PROGRAM
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{ "proot", exec_with_proot },
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#endif
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#if HAVE_EXEC_WITH_LOADER
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{ "fakechroot", exec_with_loader },
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#endif
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{ NULL, NULL }
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};
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|
|
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@ -684,18 +684,50 @@ last resort for relocation."
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(define runner
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(local-file (search-auxiliary-file "run-in-namespace.c")))
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(define audit-source
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(local-file (search-auxiliary-file "pack-audit.c")))
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(define (proot)
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(specification->package "proot-static"))
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(define (fakechroot-library)
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(computed-file "libfakechroot.so"
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#~(copy-file #$(file-append
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(specification->package "fakechroot")
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"/lib/fakechroot/libfakechroot.so")
|
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#$output)))
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|
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(define (audit-module)
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;; Return an ld.so audit module for use by the 'fakechroot' execution
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;; engine that translates file names of all the files ld.so loads.
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(computed-file "pack-audit.so"
|
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(with-imported-modules '((guix build utils))
|
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#~(begin
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(use-modules (guix build utils))
|
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|
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(copy-file #$audit-source "audit.c")
|
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(substitute* "audit.c"
|
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(("@STORE_DIRECTORY@")
|
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(%store-directory)))
|
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|
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(invoke #$compiler "-std=gnu99"
|
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"-shared" "-fPIC" "-Os" "-g0"
|
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"-Wall" "audit.c" "-o" #$output)))))
|
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|
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(define build
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(with-imported-modules (source-module-closure
|
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'((guix build utils)
|
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(guix build union)))
|
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(guix build union)
|
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(guix elf)))
|
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#~(begin
|
||||
(use-modules (guix build utils)
|
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((guix build union) #:select (relative-file-name))
|
||||
(guix elf)
|
||||
(ice-9 binary-ports)
|
||||
(ice-9 ftw)
|
||||
(ice-9 match))
|
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(ice-9 match)
|
||||
(srfi srfi-1)
|
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(rnrs bytevectors))
|
||||
|
||||
(define input
|
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;; The OUTPUT* output of PACKAGE.
|
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|
|
@ -714,6 +746,48 @@ last resort for relocation."
|
|||
(#f base)
|
||||
(index (string-drop base index)))))
|
||||
|
||||
(define (elf-interpreter elf)
|
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;; Return the interpreter of ELF as a string, or #f if ELF has no
|
||||
;; interpreter segment.
|
||||
(match (find (lambda (segment)
|
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(= (elf-segment-type segment) PT_INTERP))
|
||||
(elf-segments elf))
|
||||
(#f #f) ;maybe a .so
|
||||
(segment
|
||||
(let ((bv (make-bytevector (- (elf-segment-memsz segment) 1))))
|
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(bytevector-copy! (elf-bytes elf)
|
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(elf-segment-offset segment)
|
||||
bv 0 (bytevector-length bv))
|
||||
(utf8->string bv)))))
|
||||
|
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(define (elf-loader-compile-flags program)
|
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;; Return the cpp flags defining macros for the ld.so/fakechroot
|
||||
;; wrapper of PROGRAM.
|
||||
|
||||
;; TODO: Handle scripts by wrapping their interpreter.
|
||||
(if (elf-file? program)
|
||||
(let* ((bv (call-with-input-file program
|
||||
get-bytevector-all))
|
||||
(elf (parse-elf bv))
|
||||
(interp (elf-interpreter elf))
|
||||
(gconv (and interp
|
||||
(string-append (dirname interp)
|
||||
"/gconv"))))
|
||||
(if interp
|
||||
(list (string-append "-DPROGRAM_INTERPRETER=\""
|
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interp "\"")
|
||||
(string-append "-DFAKECHROOT_LIBRARY=\""
|
||||
#$(fakechroot-library) "\"")
|
||||
|
||||
(string-append "-DLOADER_AUDIT_MODULE=\""
|
||||
#$(audit-module) "\"")
|
||||
(if gconv
|
||||
(string-append "-DGCONV_DIRECTORY=\""
|
||||
gconv "\"")
|
||||
"-UGCONV_DIRECTORY"))
|
||||
'()))
|
||||
'()))
|
||||
|
||||
(define (build-wrapper program)
|
||||
;; Build a user-namespace wrapper for PROGRAM.
|
||||
(format #t "building wrapper for '~a'...~%" program)
|
||||
|
|
@ -733,10 +807,11 @@ last resort for relocation."
|
|||
(mkdir-p (dirname result))
|
||||
(apply invoke #$compiler "-std=gnu99" "-static" "-Os" "-g0" "-Wall"
|
||||
"run.c" "-o" result
|
||||
(if proot
|
||||
(list (string-append "-DPROOT_PROGRAM=\""
|
||||
proot "\""))
|
||||
'()))
|
||||
(append (if proot
|
||||
(list (string-append "-DPROOT_PROGRAM=\""
|
||||
proot "\""))
|
||||
'())
|
||||
(elf-loader-compile-flags program)))
|
||||
(delete-file "run.c")))
|
||||
|
||||
(setvbuf (current-output-port) 'line)
|
||||
|
|
|
|||
|
|
@ -94,6 +94,12 @@ case "`uname -m`" in
|
|||
export GUIX_EXECUTION_ENGINE
|
||||
"$test_directory/Bin/sed" --version > "$test_directory/output"
|
||||
grep 'GNU sed' "$test_directory/output"
|
||||
|
||||
# Now with fakechroot.
|
||||
GUIX_EXECUTION_ENGINE="fakechroot"
|
||||
"$test_directory/Bin/sed" --version > "$test_directory/output"
|
||||
grep 'GNU sed' "$test_directory/output"
|
||||
|
||||
chmod -Rf +w "$test_directory"; rm -rf "$test_directory"/*
|
||||
;;
|
||||
*)
|
||||
|
|
|
|||
Loading…
Reference in New Issue