| Message ID | 20230914063325.85503-18-weijiang.yang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Enable CET Virtualization | expand |
On Thu, 2023-09-14 at 02:33 -0400, Yang Weijiang wrote: > Control-flow Enforcement Technology (CET) is a kind of CPU feature used > to prevent Return/CALL/Jump-Oriented Programming (ROP/COP/JOP) attacks. > It provides two sub-features(SHSTK,IBT) to defend against ROP/COP/JOP > style control-flow subversion attacks. > > Shadow Stack (SHSTK): > A shadow stack is a second stack used exclusively for control transfer > operations. The shadow stack is separate from the data/normal stack and > can be enabled individually in user and kernel mode. When shadow stack > is enabled, CALL pushes the return address on both the data and shadow > stack. RET pops the return address from both stacks and compares them. > If the return addresses from the two stacks do not match, the processor > generates a #CP. > > Indirect Branch Tracking (IBT): > IBT introduces instruction(ENDBRANCH)to mark valid target addresses of > indirect branches (CALL, JMP etc...). If an indirect branch is executed > and the next instruction is _not_ an ENDBRANCH, the processor generates > a #CP. These instruction behaves as a NOP on platforms that have no CET. > > Several new CET MSRs are defined to support CET: > MSR_IA32_{U,S}_CET: CET settings for {user,supervisor} CET respectively. > > MSR_IA32_PL{0,1,2,3}_SSP: SHSTK pointer linear address for CPL{0,1,2,3}. > > MSR_IA32_INT_SSP_TAB: Linear address of SHSTK pointer table, whose entry > is indexed by IST of interrupt gate desc. > > Two XSAVES state bits are introduced for CET: > IA32_XSS:[bit 11]: Control saving/restoring user mode CET states > IA32_XSS:[bit 12]: Control saving/restoring supervisor mode CET states. > > Six VMCS fields are introduced for CET: > {HOST,GUEST}_S_CET: Stores CET settings for kernel mode. > {HOST,GUEST}_SSP: Stores current active SSP. > {HOST,GUEST}_INTR_SSP_TABLE: Stores current active MSR_IA32_INT_SSP_TAB. > > On Intel platforms, two additional bits are defined in VM_EXIT and VM_ENTRY > control fields: > If VM_EXIT_LOAD_CET_STATE = 1, host CET states are loaded from following > VMCS fields at VM-Exit: > HOST_S_CET > HOST_SSP > HOST_INTR_SSP_TABLE > > If VM_ENTRY_LOAD_CET_STATE = 1, guest CET states are loaded from following > VMCS fields at VM-Entry: > GUEST_S_CET > GUEST_SSP > GUEST_INTR_SSP_TABLE > > Reviewed-by: Chao Gao <chao.gao@intel.com> > Co-developed-by: Zhang Yi Z <yi.z.zhang@linux.intel.com> > Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> > --- > arch/x86/include/asm/vmx.h | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h > index 0e73616b82f3..451fd4f4fedc 100644 > --- a/arch/x86/include/asm/vmx.h > +++ b/arch/x86/include/asm/vmx.h > @@ -104,6 +104,7 @@ > #define VM_EXIT_CLEAR_BNDCFGS 0x00800000 > #define VM_EXIT_PT_CONCEAL_PIP 0x01000000 > #define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000 > +#define VM_EXIT_LOAD_CET_STATE 0x10000000 Bit 28, matches PRM. > > #define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff > > @@ -117,6 +118,7 @@ > #define VM_ENTRY_LOAD_BNDCFGS 0x00010000 > #define VM_ENTRY_PT_CONCEAL_PIP 0x00020000 > #define VM_ENTRY_LOAD_IA32_RTIT_CTL 0x00040000 > +#define VM_ENTRY_LOAD_CET_STATE 0x00100000 Bit 20, matches PRM. I wish we redefine these masks with BIT_ULL(n) macros for the sake of having less chance of a mistake. Patches to refactor this are welcome! > > #define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff > > @@ -345,6 +347,9 @@ enum vmcs_field { > GUEST_PENDING_DBG_EXCEPTIONS = 0x00006822, > GUEST_SYSENTER_ESP = 0x00006824, > GUEST_SYSENTER_EIP = 0x00006826, > + GUEST_S_CET = 0x00006828, > + GUEST_SSP = 0x0000682a, > + GUEST_INTR_SSP_TABLE = 0x0000682c, Matches the PRM. > HOST_CR0 = 0x00006c00, > HOST_CR3 = 0x00006c02, > HOST_CR4 = 0x00006c04, > @@ -357,6 +362,9 @@ enum vmcs_field { > HOST_IA32_SYSENTER_EIP = 0x00006c12, > HOST_RSP = 0x00006c14, > HOST_RIP = 0x00006c16, > + HOST_S_CET = 0x00006c18, > + HOST_SSP = 0x00006c1a, > + HOST_INTR_SSP_TABLE = 0x00006c1c Matches the PRM as well. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Best regards, Maxim Levitsky > }; > > /*
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h index 0e73616b82f3..451fd4f4fedc 100644 --- a/arch/x86/include/asm/vmx.h +++ b/arch/x86/include/asm/vmx.h @@ -104,6 +104,7 @@ #define VM_EXIT_CLEAR_BNDCFGS 0x00800000 #define VM_EXIT_PT_CONCEAL_PIP 0x01000000 #define VM_EXIT_CLEAR_IA32_RTIT_CTL 0x02000000 +#define VM_EXIT_LOAD_CET_STATE 0x10000000 #define VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR 0x00036dff @@ -117,6 +118,7 @@ #define VM_ENTRY_LOAD_BNDCFGS 0x00010000 #define VM_ENTRY_PT_CONCEAL_PIP 0x00020000 #define VM_ENTRY_LOAD_IA32_RTIT_CTL 0x00040000 +#define VM_ENTRY_LOAD_CET_STATE 0x00100000 #define VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR 0x000011ff @@ -345,6 +347,9 @@ enum vmcs_field { GUEST_PENDING_DBG_EXCEPTIONS = 0x00006822, GUEST_SYSENTER_ESP = 0x00006824, GUEST_SYSENTER_EIP = 0x00006826, + GUEST_S_CET = 0x00006828, + GUEST_SSP = 0x0000682a, + GUEST_INTR_SSP_TABLE = 0x0000682c, HOST_CR0 = 0x00006c00, HOST_CR3 = 0x00006c02, HOST_CR4 = 0x00006c04, @@ -357,6 +362,9 @@ enum vmcs_field { HOST_IA32_SYSENTER_EIP = 0x00006c12, HOST_RSP = 0x00006c14, HOST_RIP = 0x00006c16, + HOST_S_CET = 0x00006c18, + HOST_SSP = 0x00006c1a, + HOST_INTR_SSP_TABLE = 0x00006c1c }; /*
Control-flow Enforcement Technology (CET) is a kind of CPU feature used to prevent Return/CALL/Jump-Oriented Programming (ROP/COP/JOP) attacks. It provides two sub-features(SHSTK,IBT) to defend against ROP/COP/JOP style control-flow subversion attacks. Shadow Stack (SHSTK): A shadow stack is a second stack used exclusively for control transfer operations. The shadow stack is separate from the data/normal stack and can be enabled individually in user and kernel mode. When shadow stack is enabled, CALL pushes the return address on both the data and shadow stack. RET pops the return address from both stacks and compares them. If the return addresses from the two stacks do not match, the processor generates a #CP. Indirect Branch Tracking (IBT): IBT introduces instruction(ENDBRANCH)to mark valid target addresses of indirect branches (CALL, JMP etc...). If an indirect branch is executed and the next instruction is _not_ an ENDBRANCH, the processor generates a #CP. These instruction behaves as a NOP on platforms that have no CET. Several new CET MSRs are defined to support CET: MSR_IA32_{U,S}_CET: CET settings for {user,supervisor} CET respectively. MSR_IA32_PL{0,1,2,3}_SSP: SHSTK pointer linear address for CPL{0,1,2,3}. MSR_IA32_INT_SSP_TAB: Linear address of SHSTK pointer table, whose entry is indexed by IST of interrupt gate desc. Two XSAVES state bits are introduced for CET: IA32_XSS:[bit 11]: Control saving/restoring user mode CET states IA32_XSS:[bit 12]: Control saving/restoring supervisor mode CET states. Six VMCS fields are introduced for CET: {HOST,GUEST}_S_CET: Stores CET settings for kernel mode. {HOST,GUEST}_SSP: Stores current active SSP. {HOST,GUEST}_INTR_SSP_TABLE: Stores current active MSR_IA32_INT_SSP_TAB. On Intel platforms, two additional bits are defined in VM_EXIT and VM_ENTRY control fields: If VM_EXIT_LOAD_CET_STATE = 1, host CET states are loaded from following VMCS fields at VM-Exit: HOST_S_CET HOST_SSP HOST_INTR_SSP_TABLE If VM_ENTRY_LOAD_CET_STATE = 1, guest CET states are loaded from following VMCS fields at VM-Entry: GUEST_S_CET GUEST_SSP GUEST_INTR_SSP_TABLE Reviewed-by: Chao Gao <chao.gao@intel.com> Co-developed-by: Zhang Yi Z <yi.z.zhang@linux.intel.com> Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> --- arch/x86/include/asm/vmx.h | 8 ++++++++ 1 file changed, 8 insertions(+)