diff options
| -rw-r--r-- | arch/x86/entry/vdso/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/entry/vdso/vdso.lds.S | 1 | ||||
| -rw-r--r-- | arch/x86/entry/vdso/vsgx.S | 151 | ||||
| -rw-r--r-- | arch/x86/include/asm/enclu.h | 9 | ||||
| -rw-r--r-- | arch/x86/include/uapi/asm/sgx.h | 91 |
5 files changed, 254 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 2ad757fb3c23..02e3e42f380b 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -27,6 +27,7 @@ VDSO32-$(CONFIG_IA32_EMULATION) := y vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o vobjs32-y += vdso32/vclock_gettime.o +vobjs-$(CONFIG_X86_SGX) += vsgx.o # files to link into kernel obj-y += vma.o extable.o @@ -98,6 +99,7 @@ $(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS CFLAGS_REMOVE_vclock_gettime.o = -pg CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg CFLAGS_REMOVE_vgetcpu.o = -pg +CFLAGS_REMOVE_vsgx.o = -pg # # X32 processes use x32 vDSO to access 64bit kernel data. diff --git a/arch/x86/entry/vdso/vdso.lds.S b/arch/x86/entry/vdso/vdso.lds.S index 36b644e16272..4bf48462fca7 100644 --- a/arch/x86/entry/vdso/vdso.lds.S +++ b/arch/x86/entry/vdso/vdso.lds.S @@ -27,6 +27,7 @@ VERSION { __vdso_time; clock_getres; __vdso_clock_getres; + __vdso_sgx_enter_enclave; local: *; }; } diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S new file mode 100644 index 000000000000..86a0e94f68df --- /dev/null +++ b/arch/x86/entry/vdso/vsgx.S @@ -0,0 +1,151 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include <linux/linkage.h> +#include <asm/export.h> +#include <asm/errno.h> +#include <asm/enclu.h> + +#include "extable.h" + +/* Relative to %rbp. */ +#define SGX_ENCLAVE_OFFSET_OF_RUN 16 + +/* The offsets relative to struct sgx_enclave_run. */ +#define SGX_ENCLAVE_RUN_TCS 0 +#define SGX_ENCLAVE_RUN_LEAF 8 +#define SGX_ENCLAVE_RUN_EXCEPTION_VECTOR 12 +#define SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE 14 +#define SGX_ENCLAVE_RUN_EXCEPTION_ADDR 16 +#define SGX_ENCLAVE_RUN_USER_HANDLER 24 +#define SGX_ENCLAVE_RUN_USER_DATA 32 /* not used */ +#define SGX_ENCLAVE_RUN_RESERVED_START 40 +#define SGX_ENCLAVE_RUN_RESERVED_END 256 + +.code64 +.section .text, "ax" + +SYM_FUNC_START(__vdso_sgx_enter_enclave) + /* Prolog */ + .cfi_startproc + push %rbp + .cfi_adjust_cfa_offset 8 + .cfi_rel_offset %rbp, 0 + mov %rsp, %rbp + .cfi_def_cfa_register %rbp + push %rbx + .cfi_rel_offset %rbx, -8 + + mov %ecx, %eax +.Lenter_enclave: + /* EENTER <= function <= ERESUME */ + cmp $EENTER, %eax + jb .Linvalid_input + cmp $ERESUME, %eax + ja .Linvalid_input + + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rcx + + /* Validate that the reserved area contains only zeros. */ + mov $SGX_ENCLAVE_RUN_RESERVED_START, %rbx +1: + cmpq $0, (%rcx, %rbx) + jne .Linvalid_input + add $8, %rbx + cmpq $SGX_ENCLAVE_RUN_RESERVED_END, %rbx + jne 1b + + /* Load TCS and AEP */ + mov SGX_ENCLAVE_RUN_TCS(%rcx), %rbx + lea .Lasync_exit_pointer(%rip), %rcx + + /* Single ENCLU serving as both EENTER and AEP (ERESUME) */ +.Lasync_exit_pointer: +.Lenclu_eenter_eresume: + enclu + + /* EEXIT jumps here unless the enclave is doing something fancy. */ + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx + + /* Set exit_reason. */ + movl $EEXIT, SGX_ENCLAVE_RUN_LEAF(%rbx) + + /* Invoke userspace's exit handler if one was provided. */ +.Lhandle_exit: + cmpq $0, SGX_ENCLAVE_RUN_USER_HANDLER(%rbx) + jne .Linvoke_userspace_handler + + /* Success, in the sense that ENCLU was attempted. */ + xor %eax, %eax + +.Lout: + pop %rbx + leave + .cfi_def_cfa %rsp, 8 + ret + + /* The out-of-line code runs with the pre-leave stack frame. */ + .cfi_def_cfa %rbp, 16 + +.Linvalid_input: + mov $(-EINVAL), %eax + jmp .Lout + +.Lhandle_exception: + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx + + /* Set the exception info. */ + mov %eax, (SGX_ENCLAVE_RUN_LEAF)(%rbx) + mov %di, (SGX_ENCLAVE_RUN_EXCEPTION_VECTOR)(%rbx) + mov %si, (SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE)(%rbx) + mov %rdx, (SGX_ENCLAVE_RUN_EXCEPTION_ADDR)(%rbx) + jmp .Lhandle_exit + +.Linvoke_userspace_handler: + /* Pass the untrusted RSP (at exit) to the callback via %rcx. */ + mov %rsp, %rcx + + /* Save struct sgx_enclave_exception %rbx is about to be clobbered. */ + mov %rbx, %rax + + /* Save the untrusted RSP offset in %rbx (non-volatile register). */ + mov %rsp, %rbx + and $0xf, %rbx + + /* + * Align stack per x86_64 ABI. Note, %rsp needs to be 16-byte aligned + * _after_ pushing the parameters on the stack, hence the bonus push. + */ + and $-0x10, %rsp + push %rax + + /* Push struct sgx_enclave_exception as a param to the callback. */ + push %rax + + /* Clear RFLAGS.DF per x86_64 ABI */ + cld + + /* + * Load the callback pointer to %rax and lfence for LVI (load value + * injection) protection before making the call. + */ + mov SGX_ENCLAVE_RUN_USER_HANDLER(%rax), %rax + lfence + call *%rax + + /* Undo the post-exit %rsp adjustment. */ + lea 0x10(%rsp, %rbx), %rsp + + /* + * If the return from callback is zero or negative, return immediately, + * else re-execute ENCLU with the postive return value interpreted as + * the requested ENCLU function. + */ + cmp $0, %eax + jle .Lout + jmp .Lenter_enclave + + .cfi_endproc + +_ASM_VDSO_EXTABLE_HANDLE(.Lenclu_eenter_eresume, .Lhandle_exception) + +SYM_FUNC_END(__vdso_sgx_enter_enclave) diff --git a/arch/x86/include/asm/enclu.h b/arch/x86/include/asm/enclu.h new file mode 100644 index 000000000000..b1314e41a744 --- /dev/null +++ b/arch/x86/include/asm/enclu.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_ENCLU_H +#define _ASM_X86_ENCLU_H + +#define EENTER 0x02 +#define ERESUME 0x03 +#define EEXIT 0x04 + +#endif /* _ASM_X86_ENCLU_H */ diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h index c32210235bf5..791e45334a4a 100644 --- a/arch/x86/include/uapi/asm/sgx.h +++ b/arch/x86/include/uapi/asm/sgx.h @@ -74,4 +74,95 @@ struct sgx_enclave_provision { __u64 fd; }; +struct sgx_enclave_run; + +/** + * typedef sgx_enclave_user_handler_t - Exit handler function accepted by + * __vdso_sgx_enter_enclave() + * @run: The run instance given by the caller + * + * The register parameters contain the snapshot of their values at enclave + * exit. An invalid ENCLU function number will cause -EINVAL to be returned + * to the caller. + * + * Return: + * - <= 0: The given value is returned back to the caller. + * - > 0: ENCLU function to invoke, either EENTER or ERESUME. + */ +typedef int (*sgx_enclave_user_handler_t)(long rdi, long rsi, long rdx, + long rsp, long r8, long r9, + struct sgx_enclave_run *run); + +/** + * struct sgx_enclave_run - the execution context of __vdso_sgx_enter_enclave() + * @tcs: TCS used to enter the enclave + * @function: The last seen ENCLU function (EENTER, ERESUME or EEXIT) + * @exception_vector: The interrupt vector of the exception + * @exception_error_code: The exception error code pulled out of the stack + * @exception_addr: The address that triggered the exception + * @user_handler: User provided callback run on exception + * @user_data: Data passed to the user handler + * @reserved Reserved for future extensions + * + * If @user_handler is provided, the handler will be invoked on all return paths + * of the normal flow. The user handler may transfer control, e.g. via a + * longjmp() call or a C++ exception, without returning to + * __vdso_sgx_enter_enclave(). + */ +struct sgx_enclave_run { + __u64 tcs; + __u32 function; + __u16 exception_vector; + __u16 exception_error_code; + __u64 exception_addr; + __u64 user_handler; + __u64 user_data; + __u8 reserved[216]; +}; + +/** + * typedef vdso_sgx_enter_enclave_t - Prototype for __vdso_sgx_enter_enclave(), + * a vDSO function to enter an SGX enclave. + * @rdi: Pass-through value for RDI + * @rsi: Pass-through value for RSI + * @rdx: Pass-through value for RDX + * @function: ENCLU function, must be EENTER or ERESUME + * @r8: Pass-through value for R8 + * @r9: Pass-through value for R9 + * @run: struct sgx_enclave_run, must be non-NULL + * + * NOTE: __vdso_sgx_enter_enclave() does not ensure full compliance with the + * x86-64 ABI, e.g. doesn't handle XSAVE state. Except for non-volatile + * general purpose registers, EFLAGS.DF, and RSP alignment, preserving/setting + * state in accordance with the x86-64 ABI is the responsibility of the enclave + * and its runtime, i.e. __vdso_sgx_enter_enclave() cannot be called from C + * code without careful consideration by both the enclave and its runtime. + * + * All general purpose registers except RAX, RBX and RCX are passed as-is to the + * enclave. RAX, RBX and RCX are consumed by EENTER and ERESUME and are loaded + * with @function, asynchronous exit pointer, and @run.tcs respectively. + * + * RBP and the stack are used to anchor __vdso_sgx_enter_enclave() to the + * pre-enclave state, e.g. to retrieve @run.exception and @run.user_handler + * after an enclave exit. All other registers are available for use by the + * enclave and its runtime, e.g. an enclave can push additional data onto the + * stack (and modify RSP) to pass information to the optional user handler (see + * below). + * + * Most exceptions reported on ENCLU, including those that occur within the + * enclave, are fixed up and reported synchronously instead of being delivered + * via a standard signal. Debug Exceptions (#DB) and Breakpoints (#BP) are + * never fixed up and are always delivered via standard signals. On synchrously + * reported exceptions, -EFAULT is returned and details about the exception are + * recorded in @run.exception, the optional sgx_enclave_exception struct. + * + * Return: + * - 0: ENCLU function was successfully executed. + * - -EINVAL: Invalid ENCL number (neither EENTER nor ERESUME). + */ +typedef int (*vdso_sgx_enter_enclave_t)(unsigned long rdi, unsigned long rsi, + unsigned long rdx, unsigned int function, + unsigned long r8, unsigned long r9, + struct sgx_enclave_run *run); + #endif /* _UAPI_ASM_X86_SGX_H */ |