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selftests/exec: Build both static and non-static load_address tests

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[ Upstream commit b57a2907c9d96c56494ef25f8ec821cd0b355dd6 ]

After commit 4d1cd3b2c5 ("tools/testing/selftests/exec: fix link
error"), the load address alignment tests tried to build statically.
This was silently ignored in some cases. However, after attempting to
further fix the build by switching to "-static-pie", the test started
failing. This appears to be due to non-PT_INTERP ET_DYN execs ("static
PIE") not doing alignment correctly, which remains unfixed[1]. See commit
aeb7923733 ("revert "fs/binfmt_elf: use PT_LOAD p_align values for
static PIE"") for more details.

Provide rules to build both static and non-static PIE binaries, improve
debug reporting, and perform several test steps instead of a single
all-or-nothing test. However, do not actually enable static-pie tests;
alignment specification is only supported for ET_DYN with PT_INTERP
("regular PIE").

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215275 [1]
Link: https://lore.kernel.org/r/20240508173149.677910-1-keescook@chromium.org
Signed-off-by: Kees Cook <kees@kernel.org>
Stable-dep-of: 11854fe263eb ("binfmt_elf: Move brk for static PIE even if ASLR disabled")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kees Cook
2024-05-08 10:31:46 -07:00
committed by Greg Kroah-Hartman
parent 7435fa1c53
commit d3642f29f5
2 changed files with 66 additions and 20 deletions
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19
tools/testing/selftests/exec/Makefile
View File

@@ -3,8 +3,13 @@ CFLAGS = -Wall
CFLAGS += -Wno-nonnull
CFLAGS += -D_GNU_SOURCE
ALIGNS := 0x1000 0x200000 0x1000000
ALIGN_PIES := $(patsubst %,load_address.%,$(ALIGNS))
ALIGN_STATIC_PIES := $(patsubst %,load_address.static.%,$(ALIGNS))
ALIGNMENT_TESTS := $(ALIGN_PIES)
TEST_PROGS := binfmt_script.py
TEST_GEN_PROGS := execveat load_address_4096 load_address_2097152 load_address_16777216 non-regular
TEST_GEN_PROGS := execveat non-regular $(ALIGNMENT_TESTS)
TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir
# Makefile is a run-time dependency, since it's accessed by the execveat test
TEST_FILES := Makefile
@@ -28,9 +33,9 @@ $(OUTPUT)/execveat.symlink: $(OUTPUT)/execveat
$(OUTPUT)/execveat.denatured: $(OUTPUT)/execveat
cp $< $@
chmod -x $@
$(OUTPUT)/load_address_4096: load_address.c
$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x1000 -pie -static $< -o $@
$(OUTPUT)/load_address_2097152: load_address.c
$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x200000 -pie -static $< -o $@
$(OUTPUT)/load_address_16777216: load_address.c
$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=0x1000000 -pie -static $< -o $@
$(OUTPUT)/load_address.0x%: load_address.c
$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=$(lastword $(subst ., ,$@)) \
-fPIE -pie $< -o $@
$(OUTPUT)/load_address.static.0x%: load_address.c
$(CC) $(CFLAGS) $(LDFLAGS) -Wl,-z,max-page-size=$(lastword $(subst ., ,$@)) \
-fPIE -static-pie $< -o $@

67
tools/testing/selftests/exec/load_address.c
View File

@@ -5,11 +5,13 @@
#include <link.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "../kselftest.h"
struct Statistics {
unsigned long long load_address;
unsigned long long alignment;
bool interp;
};
int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data)
@@ -26,11 +28,20 @@ int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data)
stats->alignment = 0;
for (i = 0; i < info->dlpi_phnum; i++) {
unsigned long long align;
if (info->dlpi_phdr[i].p_type == PT_INTERP) {
stats->interp = true;
continue;
}
if (info->dlpi_phdr[i].p_type != PT_LOAD)
continue;
if (info->dlpi_phdr[i].p_align > stats->alignment)
stats->alignment = info->dlpi_phdr[i].p_align;
align = info->dlpi_phdr[i].p_align;
if (align > stats->alignment)
stats->alignment = align;
}
return 1; // Terminate dl_iterate_phdr.
@@ -38,27 +49,57 @@ int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data)
int main(int argc, char **argv)
{
struct Statistics extracted;
unsigned long long misalign;
struct Statistics extracted = { };
unsigned long long misalign, pow2;
bool interp_needed;
char buf[1024];
FILE *maps;
int ret;
ksft_print_header();
ksft_set_plan(1);
ksft_set_plan(4);
/* Dump maps file for debugging reference. */
maps = fopen("/proc/self/maps", "r");
if (!maps)
ksft_exit_fail_msg("FAILED: /proc/self/maps: %s\n", strerror(errno));
while (fgets(buf, sizeof(buf), maps)) {
ksft_print_msg("%s", buf);
}
fclose(maps);
/* Walk the program headers. */
ret = dl_iterate_phdr(ExtractStatistics, &extracted);
if (ret != 1)
ksft_exit_fail_msg("FAILED: dl_iterate_phdr\n");
if (extracted.alignment == 0)
ksft_exit_fail_msg("FAILED: No alignment found\n");
else if (extracted.alignment & (extracted.alignment - 1))
ksft_exit_fail_msg("FAILED: Alignment is not a power of 2\n");
/* Report our findings. */
ksft_print_msg("load_address=%#llx alignment=%#llx\n",
extracted.load_address, extracted.alignment);
/* If we're named with ".static." we expect no INTERP. */
interp_needed = strstr(argv[0], ".static.") == NULL;
/* Were we built as expected? */
ksft_test_result(interp_needed == extracted.interp,
"%s INTERP program header %s\n",
interp_needed ? "Wanted" : "Unwanted",
extracted.interp ? "seen" : "missing");
/* Did we find an alignment? */
ksft_test_result(extracted.alignment != 0,
"Alignment%s found\n", extracted.alignment ? "" : " NOT");
/* Is the alignment sane? */
pow2 = extracted.alignment & (extracted.alignment - 1);
ksft_test_result(pow2 == 0,
"Alignment is%s a power of 2: %#llx\n",
pow2 == 0 ? "" : " NOT", extracted.alignment);
/* Is the load address aligned? */
misalign = extracted.load_address & (extracted.alignment - 1);
if (misalign)
ksft_exit_fail_msg("FAILED: alignment = %llu, load_address = %llu\n",
extracted.alignment, extracted.load_address);
ksft_test_result(misalign == 0, "Load Address is %saligned (%#llx)\n",
misalign ? "MIS" : "", misalign);
ksft_test_result_pass("Completed\n");
ksft_finished();
}