| Message ID | 20231226140250.224516-1-ytcoode@gmail.com |
|---|---|
| State | Accepted |
| Commit | 01638431c465741e071ab34acf3bef3c2570f878 |
| Headers | show |
| Series | x86/efistub: fix the missing KASLR_FLAG bit in boot_params->hdr.loadflags | expand |
On Tue, 26 Dec 2023 at 15:03, Yuntao Wang <ytcoode@gmail.com> wrote: > > When KASLR is enabled, the KASLR_FLAG bit in boot_params->hdr.loadflags > should be set to 1 to propagate KASLR status from compressed kernel to > kernel, just as the choose_random_location() function does. > > Currently, when kernel is booted via efi stub, the KASLR_FLAG bit in > boot_params->hdr.loadflags is not set, even though it should be. This > causes some functions, such as kernel_randomize_memory(), not to execute > as expected. Fix it. > > Signed-off-by: Yuntao Wang <ytcoode@gmail.com> > --- > drivers/firmware/efi/libstub/x86-stub.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c > index da9b7b8d0716..b0c68593ad40 100644 > --- a/drivers/firmware/efi/libstub/x86-stub.c > +++ b/drivers/firmware/efi/libstub/x86-stub.c > @@ -787,7 +787,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry) > efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n"); > seed[0] = 0; > } > - } > + > + boot_params_ptr->hdr.loadflags |= KASLR_FLAG; > + } else > + boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG; > Thanks for the fix. I'll queue this up right away, but I am going to drop the 'else' part, given that the KASLR flag is never set by the EFI stub so clearing it should never be needed. > status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr, > seed[0], EFI_LOADER_CODE, > -- > 2.43.0 >
On 1/2/24 09:29, Ard Biesheuvel wrote: > On Tue, 26 Dec 2023 at 15:03, Yuntao Wang <ytcoode@gmail.com> wrote: >> >> When KASLR is enabled, the KASLR_FLAG bit in boot_params->hdr.loadflags >> should be set to 1 to propagate KASLR status from compressed kernel to >> kernel, just as the choose_random_location() function does. >> >> Currently, when kernel is booted via efi stub, the KASLR_FLAG bit in >> boot_params->hdr.loadflags is not set, even though it should be. This >> causes some functions, such as kernel_randomize_memory(), not to execute >> as expected. Fix it. >> >> Signed-off-by: Yuntao Wang <ytcoode@gmail.com> >> --- >> drivers/firmware/efi/libstub/x86-stub.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c >> index da9b7b8d0716..b0c68593ad40 100644 >> --- a/drivers/firmware/efi/libstub/x86-stub.c >> +++ b/drivers/firmware/efi/libstub/x86-stub.c >> @@ -787,7 +787,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry) >> efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n"); >> seed[0] = 0; >> } >> - } >> + >> + boot_params_ptr->hdr.loadflags |= KASLR_FLAG; >> + } else >> + boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG; >> > > Thanks for the fix. Does it need a Fixes: tag? Thanks, Tom > > I'll queue this up right away, but I am going to drop the 'else' part, > given that the KASLR flag is never set by the EFI stub so clearing it > should never be needed. > > >> status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr, >> seed[0], EFI_LOADER_CODE, >> -- >> 2.43.0 >>
On Tue, 2 Jan 2024 at 17:26, Tom Lendacky <thomas.lendacky@amd.com> wrote: > > On 1/2/24 09:29, Ard Biesheuvel wrote: > > On Tue, 26 Dec 2023 at 15:03, Yuntao Wang <ytcoode@gmail.com> wrote: > >> > >> When KASLR is enabled, the KASLR_FLAG bit in boot_params->hdr.loadflags > >> should be set to 1 to propagate KASLR status from compressed kernel to > >> kernel, just as the choose_random_location() function does. > >> > >> Currently, when kernel is booted via efi stub, the KASLR_FLAG bit in > >> boot_params->hdr.loadflags is not set, even though it should be. This > >> causes some functions, such as kernel_randomize_memory(), not to execute > >> as expected. Fix it. > >> > >> Signed-off-by: Yuntao Wang <ytcoode@gmail.com> > >> --- > >> drivers/firmware/efi/libstub/x86-stub.c | 5 ++++- > >> 1 file changed, 4 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c > >> index da9b7b8d0716..b0c68593ad40 100644 > >> --- a/drivers/firmware/efi/libstub/x86-stub.c > >> +++ b/drivers/firmware/efi/libstub/x86-stub.c > >> @@ -787,7 +787,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry) > >> efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n"); > >> seed[0] = 0; > >> } > >> - } > >> + > >> + boot_params_ptr->hdr.loadflags |= KASLR_FLAG; > >> + } else > >> + boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG; > >> > > > > Thanks for the fix. > > Does it need a Fixes: tag? > Yes, I've added that.
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index da9b7b8d0716..b0c68593ad40 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -787,7 +787,10 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry) efi_debug("AMI firmware v2.0 or older detected - disabling physical KASLR\n"); seed[0] = 0; } - } + + boot_params_ptr->hdr.loadflags |= KASLR_FLAG; + } else + boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG; status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr, seed[0], EFI_LOADER_CODE,
When KASLR is enabled, the KASLR_FLAG bit in boot_params->hdr.loadflags should be set to 1 to propagate KASLR status from compressed kernel to kernel, just as the choose_random_location() function does. Currently, when kernel is booted via efi stub, the KASLR_FLAG bit in boot_params->hdr.loadflags is not set, even though it should be. This causes some functions, such as kernel_randomize_memory(), not to execute as expected. Fix it. Signed-off-by: Yuntao Wang <ytcoode@gmail.com> --- drivers/firmware/efi/libstub/x86-stub.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)