diff options
| -rw-r--r-- | arch/x86/include/asm/sgx.h | 31 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/sgx/encls.h | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/sgx/main.c | 75 |
3 files changed, 96 insertions, 15 deletions
diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h index 73348cf4fd78..c2c4c0d22ca4 100644 --- a/arch/x86/include/asm/sgx.h +++ b/arch/x86/include/asm/sgx.h @@ -28,21 +28,22 @@ #define SGX_CPUID_EPC_MASK GENMASK(3, 0) enum sgx_encls_function { - ECREATE = 0x00, - EADD = 0x01, - EINIT = 0x02, - EREMOVE = 0x03, - EDGBRD = 0x04, - EDGBWR = 0x05, - EEXTEND = 0x06, - ELDU = 0x08, - EBLOCK = 0x09, - EPA = 0x0A, - EWB = 0x0B, - ETRACK = 0x0C, - EAUG = 0x0D, - EMODPR = 0x0E, - EMODT = 0x0F, + ECREATE = 0x00, + EADD = 0x01, + EINIT = 0x02, + EREMOVE = 0x03, + EDGBRD = 0x04, + EDGBWR = 0x05, + EEXTEND = 0x06, + ELDU = 0x08, + EBLOCK = 0x09, + EPA = 0x0A, + EWB = 0x0B, + ETRACK = 0x0C, + EAUG = 0x0D, + EMODPR = 0x0E, + EMODT = 0x0F, + EUPDATESVN = 0x18, }; /** diff --git a/arch/x86/kernel/cpu/sgx/encls.h b/arch/x86/kernel/cpu/sgx/encls.h index 42a088a337c5..74be751199a4 100644 --- a/arch/x86/kernel/cpu/sgx/encls.h +++ b/arch/x86/kernel/cpu/sgx/encls.h @@ -233,4 +233,9 @@ static inline int __eaug(struct sgx_pageinfo *pginfo, void *addr) return __encls_2(EAUG, pginfo, addr); } +/* Attempt to update CPUSVN at runtime. */ +static inline int __eupdatesvn(void) +{ + return __encls_ret_1(EUPDATESVN, ""); +} #endif /* _X86_ENCLS_H */ diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 3a5cbd1c170e..ffc7b9496218 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -16,6 +16,7 @@ #include <linux/vmalloc.h> #include <asm/msr.h> #include <asm/sgx.h> +#include <asm/archrandom.h> #include "driver.h" #include "encl.h" #include "encls.h" @@ -917,6 +918,80 @@ int sgx_set_attribute(unsigned long *allowed_attributes, } EXPORT_SYMBOL_GPL(sgx_set_attribute); +/* Counter to count the active SGX users */ +static int sgx_usage_count; + +/** + * sgx_update_svn() - Attempt to call ENCLS[EUPDATESVN]. + * + * This instruction attempts to update CPUSVN to the + * currently loaded microcode update SVN and generate new + * cryptographic assets. + * + * Return: + * * %0: - Success or not supported + * * %-EAGAIN: - Can be safely retried, failure is due to lack of + * * entropy in RNG + * * %-EIO: - Unexpected error, retries are not advisable + */ +static int __maybe_unused sgx_update_svn(void) +{ + int ret; + + /* + * If EUPDATESVN is not available, it is ok to + * silently skip it to comply with legacy behavior. + */ + if (!cpu_feature_enabled(X86_FEATURE_SGX_EUPDATESVN)) + return 0; + + /* + * EPC is guaranteed to be empty when there are no users. + * Ensure we are on our first user before proceeding further. + */ + WARN(sgx_usage_count, "Elevated usage count when calling EUPDATESVN\n"); + + for (int i = 0; i < RDRAND_RETRY_LOOPS; i++) { + ret = __eupdatesvn(); + + /* Stop on success or unexpected errors: */ + if (ret != SGX_INSUFFICIENT_ENTROPY) + break; + } + + switch (ret) { + case 0: + /* + * SVN successfully updated. + * Let users know when the update was successful. + */ + pr_info("SVN updated successfully\n"); + return 0; + case SGX_NO_UPDATE: + /* + * SVN update failed since the current SVN is + * not newer than CPUSVN. This is the most + * common case and indicates no harm. + */ + return 0; + case SGX_INSUFFICIENT_ENTROPY: + /* + * SVN update failed due to lack of entropy in DRNG. + * Indicate to userspace that it should retry. + */ + return -EAGAIN; + default: + break; + } + + /* + * EUPDATESVN was called when EPC is empty, all other error + * codes are unexpected. + */ + ENCLS_WARN(ret, "EUPDATESVN"); + return -EIO; +} + int sgx_inc_usage_count(void) { return 0; |