From: Adhemerval Zanella Date: Wed, 14 Aug 2024 17:04:55 +0000 (+0000) Subject: elf: Add GNU_PROPERTY_MEMORY_SEAL gnu property X-Git-Tag: binutils-2_44~145 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4d890484df4b2cf004f6f1f6d8c39a69fa39c875;p=thirdparty%2Fbinutils-gdb.git elf: Add GNU_PROPERTY_MEMORY_SEAL gnu property The GNU_PROPERTY_MEMORY_SEAL gnu property is a way to mark binaries to be memory sealed by the loader, to avoid further changes of PT_LOAD segments (such as unmapping or change permission flags). This is done along with Linux kernel (the mseal syscall [1]), and C runtime supports to instruct the kernel on the correct time during program startup (for instance, after RELRO handling). This support is added along the glibc support to handle the new gnu property [2]. This is a opt-in security features, like other security hardening ones like NX-stack or RELRO. The new property is ignored if present on ET_REL objects, and only added on ET_EXEC/ET_DYN if the linker option is used. A gnu property is used instead of DT_FLAGS_1 flag to allow memory sealing to work with ET_EXEC without PT_DYNAMIC support (at least on glibc some ports still do no support static-pie). [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8be7258aad44b5e25977a98db136f677fa6f4370 [2] https://sourceware.org/pipermail/libc-alpha/2024-September/160291.html Change-Id: Id47fadabecd24be0e83cff45653f7ce9a900ecf4 --- diff --git a/bfd/elf-properties.c b/bfd/elf-properties.c index 61f01bf5380..23634a9d9c9 100644 --- a/bfd/elf-properties.c +++ b/bfd/elf-properties.c @@ -177,6 +177,20 @@ _bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note) prop->pr_kind = property_number; goto next; + case GNU_PROPERTY_MEMORY_SEAL: + if (datasz != 0) + { + _bfd_error_handler + (_("warning: %pB: corrupt memory sealing size: 0x%x"), + abfd, datasz); + /* Clear all properties. */ + elf_properties (abfd) = NULL; + return false; + } + prop = _bfd_elf_get_property (abfd, type, datasz); + prop->pr_kind = property_number; + goto next; + default: if ((type >= GNU_PROPERTY_UINT32_AND_LO && type <= GNU_PROPERTY_UINT32_AND_HI) @@ -254,6 +268,7 @@ elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd, bfd *bbfd, /* FALLTHROUGH */ case GNU_PROPERTY_NO_COPY_ON_PROTECTED: + case GNU_PROPERTY_MEMORY_SEAL: /* Return TRUE if APROP is NULL to indicate that BPROP should be added to ABFD. */ return aprop == NULL; @@ -607,6 +622,33 @@ elf_write_gnu_properties (struct bfd_link_info *info, } } +static asection * +_bfd_elf_link_create_gnu_property_sec (struct bfd_link_info *info, bfd *elf_bfd, + unsigned int elfclass) +{ + asection *sec; + + sec = bfd_make_section_with_flags (elf_bfd, + NOTE_GNU_PROPERTY_SECTION_NAME, + (SEC_ALLOC + | SEC_LOAD + | SEC_IN_MEMORY + | SEC_READONLY + | SEC_HAS_CONTENTS + | SEC_DATA)); + if (sec == NULL) + info->callbacks->einfo (_("%F%P: failed to create GNU property section\n")); + + if (!bfd_set_section_alignment (sec, + elfclass == ELFCLASS64 ? 3 : 2)) + info->callbacks->einfo (_("%F%pA: failed to align section\n"), + sec); + + elf_section_type (sec) = SHT_NOTE; + return sec; +} + + /* Set up GNU properties. Return the first relocatable ELF input with GNU properties if found. Otherwise, return NULL. */ @@ -656,23 +698,7 @@ _bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info) /* Support -z indirect-extern-access. */ if (first_pbfd == NULL) { - sec = bfd_make_section_with_flags (elf_bfd, - NOTE_GNU_PROPERTY_SECTION_NAME, - (SEC_ALLOC - | SEC_LOAD - | SEC_IN_MEMORY - | SEC_READONLY - | SEC_HAS_CONTENTS - | SEC_DATA)); - if (sec == NULL) - info->callbacks->einfo (_("%F%P: failed to create GNU property section\n")); - - if (!bfd_set_section_alignment (sec, - elfclass == ELFCLASS64 ? 3 : 2)) - info->callbacks->einfo (_("%F%pA: failed to align section\n"), - sec); - - elf_section_type (sec) = SHT_NOTE; + sec = _bfd_elf_link_create_gnu_property_sec (info, elf_bfd, elfclass); first_pbfd = elf_bfd; has_properties = true; } @@ -690,6 +716,31 @@ _bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info) |= GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS; } + if (elf_bfd != NULL) + { + if (info->memory_seal) + { + /* Support -z no-memory-seal. */ + if (first_pbfd == NULL) + { + sec = _bfd_elf_link_create_gnu_property_sec (info, elf_bfd, elfclass); + first_pbfd = elf_bfd; + has_properties = true; + } + + p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_MEMORY_SEAL, 0); + if (p->pr_kind == property_unknown) + { + /* Create GNU_PROPERTY_NO_MEMORY_SEAL. */ + p->u.number = GNU_PROPERTY_MEMORY_SEAL; + p->pr_kind = property_number; + } + } + else + elf_find_and_remove_property (&elf_properties (elf_bfd), + GNU_PROPERTY_MEMORY_SEAL, true); + } + /* Do nothing if there is no .note.gnu.property section. */ if (!has_properties) return NULL; diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c index 60e81f518a7..7c164e9c131 100644 --- a/bfd/elfxx-x86.c +++ b/bfd/elfxx-x86.c @@ -4892,7 +4892,8 @@ _bfd_x86_elf_link_fixup_gnu_properties for (p = *listp; p; p = p->next) { unsigned int type = p->property.pr_type; - if (type == GNU_PROPERTY_X86_COMPAT_ISA_1_USED + if (type == GNU_PROPERTY_MEMORY_SEAL + || type == GNU_PROPERTY_X86_COMPAT_ISA_1_USED || type == GNU_PROPERTY_X86_COMPAT_ISA_1_NEEDED || (type >= GNU_PROPERTY_X86_UINT32_AND_LO && type <= GNU_PROPERTY_X86_UINT32_AND_HI) diff --git a/binutils/readelf.c b/binutils/readelf.c index 949395483bb..694d8267efa 100644 --- a/binutils/readelf.c +++ b/binutils/readelf.c @@ -21477,6 +21477,12 @@ print_gnu_property_note (Filedata * filedata, Elf_Internal_Note * pnote) printf (_(" "), datasz); goto next; + case GNU_PROPERTY_MEMORY_SEAL: + printf ("memory seal "); + if (datasz) + printf (_(" "), datasz); + goto next; + default: if ((type >= GNU_PROPERTY_UINT32_AND_LO && type <= GNU_PROPERTY_UINT32_AND_HI) diff --git a/include/bfdlink.h b/include/bfdlink.h index 85e7da84406..ae451075996 100644 --- a/include/bfdlink.h +++ b/include/bfdlink.h @@ -429,6 +429,9 @@ struct bfd_link_info /* TRUE if only one read-only, non-code segment should be created. */ unsigned int one_rosegment: 1; + /* TRUE if GNU_PROPERTY_MEMORY_SEAL should be generated. */ + unsigned int memory_seal: 1; + /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment should be created. 1 for DWARF2 tables, 2 for compact tables. */ unsigned int eh_frame_hdr_type: 2; diff --git a/include/elf/common.h b/include/elf/common.h index b0b54d87ab4..fd032d1e03e 100644 --- a/include/elf/common.h +++ b/include/elf/common.h @@ -891,6 +891,7 @@ /* Values used in GNU .note.gnu.property notes (NT_GNU_PROPERTY_TYPE_0). */ #define GNU_PROPERTY_STACK_SIZE 1 #define GNU_PROPERTY_NO_COPY_ON_PROTECTED 2 +#define GNU_PROPERTY_MEMORY_SEAL 3 /* A 4-byte unsigned integer property: A bit is set if it is set in all relocatable inputs. */ diff --git a/ld/NEWS b/ld/NEWS index 4a19f5a7d5d..5d5fec4aed3 100644 --- a/ld/NEWS +++ b/ld/NEWS @@ -33,6 +33,9 @@ Changes in 2.43: * Add -plugin-save-temps to store plugin intermediate files permanently. +* Add -z memory-seal/-z nomemory-seal options to ELF linker to mark the + object to memory sealed. + Changes in 2.42: * Add -z mark-plt/-z nomark-plt options to x86-64 ELF linker to mark PLT diff --git a/ld/emultempl/elf.em b/ld/emultempl/elf.em index 0bad25d3a46..8492251ff33 100644 --- a/ld/emultempl/elf.em +++ b/ld/emultempl/elf.em @@ -1083,6 +1083,10 @@ fragment <