When building with gcc -mbranch-protection= we might get a gnu property note indicating BTI (Branch Target Identification) and/or PAC (Pointer Authentication Code) is being used. Add a small testcase to show eu-readelf -n now properly lists those bits in the gnu property note. Signed-off-by: Mark Wielaard <mark@klomp.org>
The GNU property note data is padded. Make sure the extra padding still fits in the note description. https://sourceware.org/bugzilla/show_bug.cgi?id=24075 Signed-off-by: Mark Wielaard <mark@klomp.org>
Before printing the data values, make sure pr_datasz doesn't go beyond the end of the note description data. https://sourceware.org/bugzilla/show_bug.cgi?id=24075 Signed-off-by: Mark Wielaard <mark@klomp.org>
When reading a GNU_PROPERTY_STACK_SIZE we need to use the proper data type. GElf_Addr is 64bit always and when reading a 32bit size part of it would not be initialized. Use either Elf32_Addr or Elf64_Addr to read and print the data. Add 32bit and 64bit, little and big endian testcases. Signed-off-by: Mark Wielaard <mark@klomp.org>
GNU Build Attribute ELF Notes are generated by the GCC annobin plugin
and described at https://fedoraproject.org/wiki/Toolchain/Watermark
Unfortunately the constants aren't yet described in the standard glibc
elf.h so they have been added to the elfutils specific elf-knowledge.h.
The notes abuse the name owner field to encode some data not in the
description. This makes it a bit hard to parse. We have to match the
note owner name prefix (to "GA") to be sure the type is valid. We also
cannot rely on the owner name being a valid C string since the attribute
name and value can contain zero (terminators). So pass around namesz
to the ebl note parsing functions.
eu-elflint will recognize and eu-readelf -n will now show the notes:
Note section [27] '.gnu.build.attributes' of 56080 bytes at offset 0x114564:
Owner Data size Type
GA 16 GNU Build Attribute OPEN
Address Range: 0x2f30f - 0x2f30f
VERSION: "3p8"
GA 0 GNU Build Attribute OPEN
TOOL: "gcc 8.2.1 20180801"
GA 0 GNU Build Attribute OPEN
"GOW": 45
GA 0 GNU Build Attribute OPEN
STACK_PROT: 0
GA 0 GNU Build Attribute OPEN
"stack_clash": TRUE
GA 0 GNU Build Attribute OPEN
"cf_protection": 0
GA 0 GNU Build Attribute OPEN
"GLIBCXX_ASSERTIONS": TRUE
GA 0 GNU Build Attribute OPEN
"FORTIFY": 0
GA 0 GNU Build Attribute OPEN
PIC: 3
GA 0 GNU Build Attribute OPEN
SHORT_ENUM: FALSE
GA 0 GNU Build Attribute OPEN
ABI: c001100000012
GA 0 GNU Build Attribute OPEN
"stack_realign": FALSE
A new test was added to run-readelf -n for the existing annobin file.
Signed-off-by: Mark Wielaard <mark@klomp.org>
NT_VERSION notes are emitted by the gas .version directive. They have an empty description and (ab)use the owner name to store the version data string. Signed-off-by: Mark Wielaard <mark@klomp.org>
GNU Property notes are different from normal notes because they use variable alignment/padding of their fields. They are 8 byte aligned, but use 4 byte fields. The name is aligned at 4 bytes and padded so that, the desc is aligned at 8 bytes. The whole note is padded to 8 bytes again. For normal notes all fields are both 4 bytes wide and 4 bytes aligned. To recognize these new kind of ELF Notes a new Elf_Type is introduced, ELF_T_NHDR8. This type is used in the xlate functions to determine how to align and pad the various fields. Since the fields themselves can now have different alignments we will have to keep track of the current alignement and use either NOTE_ALIGN4 or NOTE_ALIGN8 to determine the padding. To set the correct Elf_Type on the Elf_Data we use either the section sh_addralign or the segment p_align values. Assuming 8 means the section or segment contains the new style notes, otherwise normal notes. When we cannot determine the "alignment" directly, like when parsing special kernel sys files, we check the name "GNU" and type "GNU_PROPERTY_TYPE_0" fields. ebl_object_note now parses the new NT_GNU_PROPERTY_TYPE_0 and can extract the GNU_PROPERTY_STACK_SIZE, GNU_PROPERTY_NO_COPY_ON_PROTECTED and GNU_PROPERTY_X86_FEATURE_1_AND types GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK. Tests are added for extracting the note from sections or segments as set by gcc -fcf-protection. Signed-off-by: Mark Wielaard <mark@klomp.org>
Use __attribute__ ((fallthrough)) to indicate switch case fall through instead of a comment. This ensures that the fallthrough warning is not triggered even if the file is pre-processed (hence stripping the comments) before it is compiled. The actual fallback implementation is hidden behind a FALLBACK macro in case the compiler doesn't support it. Finally, the -Wimplict-fallthrough warning was upgraded to only allow the attribute to satisfy it; a comment alone is no longer sufficient. Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
GCC6 [will have] a nice new warning that showed a real bug:
elfutils/libebl/eblobjnote.c: In function ‘ebl_object_note’:
elfutils/libebl/eblobjnote.c:135:5: error: statement is indented as if it were guarded by... [-Werror=misleading-indentation]
switch (type)
^~~~~~
elfutils/libebl/eblobjnote.c:45:3: note: ...this ‘if’ clause, but it is not
if (! ebl->object_note (name, type, descsz, desc))
^~
And indeed, it should have been under the if, but wasn't because of missing
brackets. Added brackets (and reindent).
Signed-off-by: Mark Wielaard <mjw@redhat.com>
We already require -std=gnu99 and old-style function definitions might hide some compiler warnings. Signed-off-by: Mark Wielaard <mjw@redhat.com>