6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook kees@kernel.org
[ Upstream commit b57a2907c9d96c56494ef25f8ec821cd0b355dd6 ]
After commit 4d1cd3b2c5c1 ("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 aeb7923733d1 ("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 --- tools/testing/selftests/exec/Makefile | 19 +++--- tools/testing/selftests/exec/load_address.c | 67 +++++++++++++++++---- 2 files changed, 66 insertions(+), 20 deletions(-)
diff --git a/tools/testing/selftests/exec/Makefile b/tools/testing/selftests/exec/Makefile index a0b8688b08369..b54986078d7ea 100644 --- a/tools/testing/selftests/exec/Makefile +++ b/tools/testing/selftests/exec/Makefile @@ -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 $@ diff --git a/tools/testing/selftests/exec/load_address.c b/tools/testing/selftests/exec/load_address.c index 17e3207d34ae7..8257fddba8c8d 100644 --- a/tools/testing/selftests/exec/load_address.c +++ b/tools/testing/selftests/exec/load_address.c @@ -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(); }