| Message ID | 7038A8ED-AC52-4966-836B-7B346713AEE9@live.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] efi: Do not import certificates from UEFI Secure Boot for T2 Macs | expand |
On Thu, Feb 10, 2022 at 10:47:25AM +0000, Aditya Garg wrote: > +/* Apple Macs with T2 Security chip don't support these UEFI variables. > + * The T2 chip manages the Secure Boot and does not allow Linux to boot > + * if it is turned on. If turned off, an attempt to get certificates > + * causes a crash, so we simply return 0 for them in each function. > + */ > + > +static const struct dmi_system_id uefi_skip_cert[] = { > + > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacMini8,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") }, > + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") }, > + { } > +}; The T2 is represented by a PCI device with ID 106B:1802. I think it would be more elegant to sense presence of that device instead of hardcoding a long dmi list, i.e.: static bool apple_t2_present(void) { struct pci_dev *pdev; if (!x86_apple_machine) return false; pdev = pci_get_device(PCI_VENDOR_ID_APPLE, 0x1802, NULL); if (pdev) { pci_put_dev(pdev); return true; } return false; }
> > The T2 is represented by a PCI device with ID 106B:1802. I think it > would be more elegant to sense presence of that device instead of > hardcoding a long dmi list, i.e.: > > static bool apple_t2_present(void) > { > struct pci_dev *pdev; > > if (!x86_apple_machine) > return false; > > pdev = pci_get_device(PCI_VENDOR_ID_APPLE, 0x1802, NULL); > if (pdev) { > pci_put_dev(pdev); > return true; > } > > return false; > } I’d rather prefer DMI cause :- 1. There are chances that some non T2 Macs may require this quirk as well. (After all we are talking about Apple) 2. There are slight chances that some non Apple Machines may require this as well I also am not used to pci based quirks, making it a bit difficult for me to make a patch based on that :(. The code length is anyways short now.
> On 10-Feb-2022, at 4:17 PM, Aditya Garg <gargaditya08@live.com> wrote: > > From: Aditya Garg <gargaditya08@live.com> > > On T2 Macs, the secure boot is handled by the T2 Chip. If enabled, only > macOS and Windows are allowed to boot on these machines. Thus we need to > disable secure boot for Linux. If we boot into Linux after disabling > secure boot, if CONFIG_LOAD_UEFI_KEYS is enabled, EFI Runtime services > fail to start, with the following logs in dmesg > > Call Trace: > <TASK> > page_fault_oops+0x4f/0x2c0 > ? search_bpf_extables+0x6b/0x80 > ? search_module_extables+0x50/0x80 > ? search_exception_tables+0x5b/0x60 > kernelmode_fixup_or_oops+0x9e/0x110 > __bad_area_nosemaphore+0x155/0x190 > bad_area_nosemaphore+0x16/0x20 > do_kern_addr_fault+0x8c/0xa0 > exc_page_fault+0xd8/0x180 > asm_exc_page_fault+0x1e/0x30 > (Removed some logs from here) > ? __efi_call+0x28/0x30 > ? switch_mm+0x20/0x30 > ? efi_call_rts+0x19a/0x8e0 > ? process_one_work+0x222/0x3f0 > ? worker_thread+0x4a/0x3d0 > ? kthread+0x17a/0x1a0 > ? process_one_work+0x3f0/0x3f0 > ? set_kthread_struct+0x40/0x40 > ? ret_from_fork+0x22/0x30 > </TASK> > ---[ end trace 1f82023595a5927f ]--- > efi: Froze efi_rts_wq and disabled EFI Runtime Services > integrity: Couldn't get size: 0x8000000000000015 > integrity: MODSIGN: Couldn't get UEFI db list > efi: EFI Runtime Services are disabled! > integrity: Couldn't get size: 0x8000000000000015 > integrity: Couldn't get UEFI dbx list > integrity: Couldn't get size: 0x8000000000000015 > integrity: Couldn't get mokx list > integrity: Couldn't get size: 0x80000000 > > This patch prevents querying of these UEFI variables, since these Macs > seem to use a non-standard EFI hardware > > Cc: stable@vger.kernel.org > Signed-off-by: Aditya Garg <gargaditya08@live.com> > --- > v2 :- Reduce code size of the table. > V3 :- Close the brackets which were left open by mistake. > .../platform_certs/keyring_handler.h | 8 ++++ > security/integrity/platform_certs/load_uefi.c | 48 +++++++++++++++++++ > 2 files changed, 56 insertions(+) > Hi May I have any updates on this patch?
diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h index 2462bfa08..cd06bd607 100644 --- a/security/integrity/platform_certs/keyring_handler.h +++ b/security/integrity/platform_certs/keyring_handler.h @@ -30,3 +30,11 @@ efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type); efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type); #endif + +#ifndef UEFI_QUIRK_SKIP_CERT +#define UEFI_QUIRK_SKIP_CERT(vendor, product) \ + .matches = { \ + DMI_MATCH(DMI_BOARD_VENDOR, vendor), \ + DMI_MATCH(DMI_PRODUCT_NAME, product), \ + }, +#endif diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c index 08b6d12f9..f246c8732 100644 --- a/security/integrity/platform_certs/load_uefi.c +++ b/security/integrity/platform_certs/load_uefi.c @@ -3,6 +3,7 @@ #include <linux/kernel.h> #include <linux/sched.h> #include <linux/cred.h> +#include <linux/dmi.h> #include <linux/err.h> #include <linux/efi.h> #include <linux/slab.h> @@ -12,6 +13,32 @@ #include "../integrity.h" #include "keyring_handler.h" +/* Apple Macs with T2 Security chip don't support these UEFI variables. + * The T2 chip manages the Secure Boot and does not allow Linux to boot + * if it is turned on. If turned off, an attempt to get certificates + * causes a crash, so we simply return 0 for them in each function. + */ + +static const struct dmi_system_id uefi_skip_cert[] = { + + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacMini8,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") }, + { UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") }, + { } +}; + /* * Look to see if a UEFI variable called MokIgnoreDB exists and return true if * it does. @@ -21,12 +48,18 @@ * is set, we should ignore the db variable also and the true return indicates * this. */ + static __init bool uefi_check_ignore_db(void) { efi_status_t status; unsigned int db = 0; unsigned long size = sizeof(db); efi_guid_t guid = EFI_SHIM_LOCK_GUID; + const struct dmi_system_id *dmi_id; + + dmi_id = dmi_first_match(uefi_skip_cert); + if (dmi_id) + return 0; status = efi.get_variable(L"MokIgnoreDB", &guid, NULL, &size, &db); return status == EFI_SUCCESS; @@ -41,6 +74,11 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, unsigned long lsize = 4; unsigned long tmpdb[4]; void *db; + const struct dmi_system_id *dmi_id; + + dmi_id = dmi_first_match(uefi_skip_cert); + if (dmi_id) + return 0; *status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb); if (*status == EFI_NOT_FOUND) @@ -85,6 +123,11 @@ static int __init load_moklist_certs(void) unsigned long moksize; efi_status_t status; int rc; + const struct dmi_system_id *dmi_id; + + dmi_id = dmi_first_match(uefi_skip_cert); + if (dmi_id) + return 0; /* First try to load certs from the EFI MOKvar config table. * It's not an error if the MOKvar config table doesn't exist @@ -138,6 +181,11 @@ static int __init load_uefi_certs(void) unsigned long dbsize = 0, dbxsize = 0, mokxsize = 0; efi_status_t status; int rc = 0; + const struct dmi_system_id *dmi_id; + + dmi_id = dmi_first_match(uefi_skip_cert); + if (dmi_id) + return 0; if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) return false;