256 lines
9.3 KiB
Diff
256 lines
9.3 KiB
Diff
commit c1cb2deeca1a85c6fc5bd41b90816d48a95bc434
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Sun Dec 5 11:28:34 2021 +0100
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elf: execve statically linked programs instead of crashing [BZ #28648]
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Programs without dynamic dependencies and without a program
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interpreter are now run via execve.
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Previously, the dynamic linker either crashed while attempting to
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read a non-existing dynamic segment (looking for DT_AUDIT/DT_DEPAUDIT
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data), or the self-relocated in the static PIE executable crashed
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because the outer dynamic linker had already applied RELRO protection.
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<dl-execve.h> is needed because execve is not available in the
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dynamic loader on Hurd.
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
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Conflicts:
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elf/Makefile
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(some missing backports)
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elf/rtld.c
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(missing rework of ld.so self-relocation downstream,
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always print error as a number due to missing
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sterrorname_np, also fix errcode/errno glitch)
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sysdeps/unix/sysv/linux/dl-execve.h
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(missing INTERNAL_SYSCALL_CALL refactoring to Linux-like
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calling convention)
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diff --git a/elf/Makefile b/elf/Makefile
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index d246f1c0d9e019fd..b3e8ab2792608de7 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -214,7 +214,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
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tst-tls-ie tst-tls-ie-dlmopen \
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argv0test \
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tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
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- tst-tls20 tst-tls21
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+ tst-tls20 tst-tls21 \
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+ tst-rtld-run-static \
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# reldep9
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tests-internal += loadtest unload unload2 circleload1 \
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neededtest neededtest2 neededtest3 neededtest4 \
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@@ -1917,3 +1918,5 @@ $(objpfx)tst-tls20.out: $(objpfx)tst-tls20mod-bad.so \
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$(objpfx)tst-tls21: $(libdl) $(shared-thread-library)
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$(objpfx)tst-tls21.out: $(objpfx)tst-tls21mod.so
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$(objpfx)tst-tls21mod.so: $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
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+
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+$(objpfx)tst-rtld-run-static.out: $(objpfx)/ldconfig
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diff --git a/elf/rtld.c b/elf/rtld.c
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index d14c388f548d6d51..461d8c114a875a9b 100644
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--- a/elf/rtld.c
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+++ b/elf/rtld.c
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@@ -48,6 +48,7 @@
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#include <dl-main.h>
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#include <gnu/lib-names.h>
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#include <dl-tunables.h>
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+#include <dl-execve.h>
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#include <assert.h>
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@@ -1114,6 +1115,40 @@ load_audit_modules (struct link_map *main_map, struct audit_list *audit_list)
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}
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}
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+/* Check if the executable is not actualy dynamically linked, and
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+ invoke it directly in that case. */
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+static void
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+rtld_chain_load (struct link_map *main_map, char *argv0)
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+{
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+ /* The dynamic loader run against itself. */
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+ const char *rtld_soname
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+ = ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
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+ + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val);
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+ if (main_map->l_info[DT_SONAME] != NULL
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+ && strcmp (rtld_soname,
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+ ((const char *) D_PTR (main_map, l_info[DT_STRTAB])
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+ + main_map->l_info[DT_SONAME]->d_un.d_val)) == 0)
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+ _dl_fatal_printf ("%s: loader cannot load itself\n", rtld_soname);
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+
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+ /* With DT_NEEDED dependencies, the executable is dynamically
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+ linked. */
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+ if (__glibc_unlikely (main_map->l_info[DT_NEEDED] != NULL))
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+ return;
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+
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+ /* If the executable has program interpreter, it is dynamically
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+ linked. */
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+ for (size_t i = 0; i < main_map->l_phnum; ++i)
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+ if (main_map->l_phdr[i].p_type == PT_INTERP)
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+ return;
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+
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+ const char *pathname = _dl_argv[0];
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+ if (argv0 != NULL)
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+ _dl_argv[0] = argv0;
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+ int errcode = __rtld_execve (pathname, _dl_argv, _environ);
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+ _dl_fatal_printf("%s: cannot execute %s: %d\n",
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+ rtld_soname, pathname, errcode);
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+}
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+
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static void
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dl_main (const ElfW(Phdr) *phdr,
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ElfW(Word) phnum,
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@@ -1384,14 +1419,8 @@ dl_main (const ElfW(Phdr) *phdr,
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/* Now the map for the main executable is available. */
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main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
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- if (__glibc_likely (state.mode == rtld_mode_normal)
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- && GL(dl_rtld_map).l_info[DT_SONAME] != NULL
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- && main_map->l_info[DT_SONAME] != NULL
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- && strcmp ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
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- + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val,
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- (const char *) D_PTR (main_map, l_info[DT_STRTAB])
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- + main_map->l_info[DT_SONAME]->d_un.d_val) == 0)
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- _dl_fatal_printf ("loader cannot load itself\n");
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+ if (__glibc_likely (state.mode == rtld_mode_normal))
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+ rtld_chain_load (main_map, argv0);
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phdr = main_map->l_phdr;
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phnum = main_map->l_phnum;
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diff --git a/elf/tst-rtld-run-static.c b/elf/tst-rtld-run-static.c
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new file mode 100644
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index 0000000000000000..7281093504b675c4
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--- /dev/null
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+++ b/elf/tst-rtld-run-static.c
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@@ -0,0 +1,62 @@
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+/* Test running statically linked programs using ld.so.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <support/check.h>
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+#include <support/support.h>
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+#include <support/capture_subprocess.h>
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+#include <string.h>
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+#include <stdlib.h>
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+
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+static int
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+do_test (void)
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+{
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+ char *ldconfig_path = xasprintf ("%s/elf/ldconfig", support_objdir_root);
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+
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+ {
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+ char *argv[] = { (char *) "ld.so", ldconfig_path, (char *) "--help", NULL };
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+ struct support_capture_subprocess cap
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+ = support_capture_subprogram (support_objdir_elf_ldso, argv);
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+ support_capture_subprocess_check (&cap, "no --argv0", 0, sc_allow_stdout);
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+ puts ("info: output without --argv0:");
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+ puts (cap.out.buffer);
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+ TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig [OPTION...]\n")
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+ == cap.out.buffer);
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+ support_capture_subprocess_free (&cap);
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+ }
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+
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+ {
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+ char *argv[] =
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+ {
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+ (char *) "ld.so", (char *) "--argv0", (char *) "ldconfig-argv0",
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+ ldconfig_path, (char *) "--help", NULL
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+ };
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+ struct support_capture_subprocess cap
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+ = support_capture_subprogram (support_objdir_elf_ldso, argv);
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+ support_capture_subprocess_check (&cap, "with --argv0", 0, sc_allow_stdout);
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+ puts ("info: output with --argv0:");
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+ puts (cap.out.buffer);
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+ TEST_VERIFY (strstr (cap.out.buffer, "Usage: ldconfig-argv0 [OPTION...]\n")
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+ == cap.out.buffer);
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+ support_capture_subprocess_free (&cap);
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+ }
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+
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+ free (ldconfig_path);
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/sysdeps/generic/dl-execve.h b/sysdeps/generic/dl-execve.h
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new file mode 100644
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index 0000000000000000..5fd097df69e1770c
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--- /dev/null
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+++ b/sysdeps/generic/dl-execve.h
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@@ -0,0 +1,25 @@
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+/* execve for the dynamic linker. Generic stub version.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <errno.h>
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+
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+static int
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+__rtld_execve (const char *path, char *const *argv, char *const *envp)
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+{
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+ return ENOSYS;
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+}
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diff --git a/sysdeps/unix/sysv/linux/dl-execve.h b/sysdeps/unix/sysv/linux/dl-execve.h
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new file mode 100644
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index 0000000000000000..9ec6539286bb0589
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--- /dev/null
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+++ b/sysdeps/unix/sysv/linux/dl-execve.h
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@@ -0,0 +1,30 @@
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+/* execve for the dynamic linker. Linux version.
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+ Copyright (C) 2021 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <errno.h>
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+
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+static inline int
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+__rtld_execve (const char *path, char *const *argv, char *const *envp)
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+{
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+ INTERNAL_SYSCALL_DECL (err);
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+ long int r = INTERNAL_SYSCALL_CALL (execve, err, path, argv, envp);
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+ if (INTERNAL_SYSCALL_ERROR_P (r, err))
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+ return INTERNAL_SYSCALL_ERRNO (r, err);
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+ else
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+ return 0;
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+}
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