| Message ID | 20230818134422.380032-16-ardb@kernel.org |
|---|---|
| State | Accepted |
| Commit | 34951f3c28bdf6481d949a20413b2ce7693687b2 |
| Headers | show |
| Series | x86/boot: Rework PE header generation | expand |
Hi Ard, Thanks for your effort! Not sure what the documentation policies are, but might it be worth mentioning that we cannot have .rdata at this time, because current-gen EFI will map it as RW? Best regards, Marvin > On Aug 18, 2023, at 15:45, Ard Biesheuvel <ardb@kernel.org> wrote: > Describe the code and data of the decompressor binary using separate > .text and .data PE/COFF sections, so that we will be able to map them > using restricted permissions once we increase the section and file > alignment sufficiently. This avoids the need for memory mappings that > are writable and executable at the same time, which is something that > is best avoided for security reasons. > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/x86/boot/Makefile | 2 +- > arch/x86/boot/header.S | 19 +++++++++++++++---- > 2 files changed, 16 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile > index b26e30a2d865f72d..50c50fce646e2417 100644 > --- a/arch/x86/boot/Makefile > +++ b/arch/x86/boot/Makefile > @@ -90,7 +90,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE > > SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) > > -sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p' > +sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p' > > quiet_cmd_zoffset = ZOFFSET $@ > cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ > diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S > index ccfb7a7d8c29275e..25dda40dacb52292 100644 > --- a/arch/x86/boot/header.S > +++ b/arch/x86/boot/header.S > @@ -79,9 +79,9 @@ optional_header: > .byte 0x02 # MajorLinkerVersion > .byte 0x14 # MinorLinkerVersion > > - .long setup_size + ZO__end - 0x200 # SizeOfCode > + .long ZO__data # SizeOfCode > > - .long 0 # SizeOfInitializedData > + .long ZO__end - ZO__data # SizeOfInitializedData > .long 0 # SizeOfUninitializedData > > .long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint > @@ -182,9 +182,9 @@ section_table: > .byte 0 > .byte 0 > .byte 0 > - .long ZO__end > + .long ZO__data > .long setup_size > - .long ZO__edata # Size of initialized data > + .long ZO__data # Size of initialized data > # on disk > .long setup_size > .long 0 # PointerToRelocations > @@ -195,6 +195,17 @@ section_table: > IMAGE_SCN_MEM_READ | \ > IMAGE_SCN_MEM_EXECUTE # Characteristics > > + .ascii ".data\0\0\0" > + .long ZO__end - ZO__data # VirtualSize > + .long setup_size + ZO__data # VirtualAddress > + .long ZO__edata - ZO__data # SizeOfRawData > + .long setup_size + ZO__data # PointerToRawData > + > + .long 0, 0, 0 > + .long IMAGE_SCN_CNT_INITIALIZED_DATA | \ > + IMAGE_SCN_MEM_READ | \ > + IMAGE_SCN_MEM_WRITE # Characteristics > + > .set section_count, (. - section_table) / 40 > #endif /* CONFIG_EFI_STUB */ > > -- > 2.39.2
On Fri, 18 Aug 2023 at 16:35, Marvin Häuser <mhaeuser@posteo.de> wrote: > > Hi Ard, > > Thanks for your effort! Not sure what the documentation policies are, but might it be worth mentioning that we cannot have .rdata at this time, because current-gen EFI will map it as RW? > Yeah I'll mention this in the next version. > Best regards, > Marvin > > > On Aug 18, 2023, at 15:45, Ard Biesheuvel <ardb@kernel.org> wrote: > > Describe the code and data of the decompressor binary using separate > > .text and .data PE/COFF sections, so that we will be able to map them > > using restricted permissions once we increase the section and file > > alignment sufficiently. This avoids the need for memory mappings that > > are writable and executable at the same time, which is something that > > is best avoided for security reasons. > > > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > > --- > > arch/x86/boot/Makefile | 2 +- > > arch/x86/boot/header.S | 19 +++++++++++++++---- > > 2 files changed, 16 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile > > index b26e30a2d865f72d..50c50fce646e2417 100644 > > --- a/arch/x86/boot/Makefile > > +++ b/arch/x86/boot/Makefile > > @@ -90,7 +90,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE > > > > SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) > > > > -sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p' > > +sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p' > > > > quiet_cmd_zoffset = ZOFFSET $@ > > cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ > > diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S > > index ccfb7a7d8c29275e..25dda40dacb52292 100644 > > --- a/arch/x86/boot/header.S > > +++ b/arch/x86/boot/header.S > > @@ -79,9 +79,9 @@ optional_header: > > .byte 0x02 # MajorLinkerVersion > > .byte 0x14 # MinorLinkerVersion > > > > - .long setup_size + ZO__end - 0x200 # SizeOfCode > > + .long ZO__data # SizeOfCode > > > > - .long 0 # SizeOfInitializedData > > + .long ZO__end - ZO__data # SizeOfInitializedData > > .long 0 # SizeOfUninitializedData > > > > .long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint > > @@ -182,9 +182,9 @@ section_table: > > .byte 0 > > .byte 0 > > .byte 0 > > - .long ZO__end > > + .long ZO__data > > .long setup_size > > - .long ZO__edata # Size of initialized data > > + .long ZO__data # Size of initialized data > > # on disk > > .long setup_size > > .long 0 # PointerToRelocations > > @@ -195,6 +195,17 @@ section_table: > > IMAGE_SCN_MEM_READ | \ > > IMAGE_SCN_MEM_EXECUTE # Characteristics > > > > + .ascii ".data\0\0\0" > > + .long ZO__end - ZO__data # VirtualSize > > + .long setup_size + ZO__data # VirtualAddress > > + .long ZO__edata - ZO__data # SizeOfRawData > > + .long setup_size + ZO__data # PointerToRawData > > + > > + .long 0, 0, 0 > > + .long IMAGE_SCN_CNT_INITIALIZED_DATA | \ > > + IMAGE_SCN_MEM_READ | \ > > + IMAGE_SCN_MEM_WRITE # Characteristics > > + > > .set section_count, (. - section_table) / 40 > > #endif /* CONFIG_EFI_STUB */ > > > > -- > > 2.39.2 >
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index b26e30a2d865f72d..50c50fce646e2417 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -90,7 +90,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) -sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p' +sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p' quiet_cmd_zoffset = ZOFFSET $@ cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index ccfb7a7d8c29275e..25dda40dacb52292 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -79,9 +79,9 @@ optional_header: .byte 0x02 # MajorLinkerVersion .byte 0x14 # MinorLinkerVersion - .long setup_size + ZO__end - 0x200 # SizeOfCode + .long ZO__data # SizeOfCode - .long 0 # SizeOfInitializedData + .long ZO__end - ZO__data # SizeOfInitializedData .long 0 # SizeOfUninitializedData .long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint @@ -182,9 +182,9 @@ section_table: .byte 0 .byte 0 .byte 0 - .long ZO__end + .long ZO__data .long setup_size - .long ZO__edata # Size of initialized data + .long ZO__data # Size of initialized data # on disk .long setup_size .long 0 # PointerToRelocations @@ -195,6 +195,17 @@ section_table: IMAGE_SCN_MEM_READ | \ IMAGE_SCN_MEM_EXECUTE # Characteristics + .ascii ".data\0\0\0" + .long ZO__end - ZO__data # VirtualSize + .long setup_size + ZO__data # VirtualAddress + .long ZO__edata - ZO__data # SizeOfRawData + .long setup_size + ZO__data # PointerToRawData + + .long 0, 0, 0 + .long IMAGE_SCN_CNT_INITIALIZED_DATA | \ + IMAGE_SCN_MEM_READ | \ + IMAGE_SCN_MEM_WRITE # Characteristics + .set section_count, (. - section_table) / 40 #endif /* CONFIG_EFI_STUB */
Describe the code and data of the decompressor binary using separate .text and .data PE/COFF sections, so that we will be able to map them using restricted permissions once we increase the section and file alignment sufficiently. This avoids the need for memory mappings that are writable and executable at the same time, which is something that is best avoided for security reasons. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/x86/boot/Makefile | 2 +- arch/x86/boot/header.S | 19 +++++++++++++++---- 2 files changed, 16 insertions(+), 5 deletions(-)