diff options
Diffstat (limited to 'arch/x86/kernel/cet.c')
-rw-r--r-- | arch/x86/kernel/cet.c | 94 |
1 files changed, 85 insertions, 9 deletions
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c index 7ad22b705b64..cc10d8be9d74 100644 --- a/arch/x86/kernel/cet.c +++ b/arch/x86/kernel/cet.c @@ -4,10 +4,6 @@ #include <asm/bugs.h> #include <asm/traps.h> -static __ro_after_init bool ibt_fatal = true; - -extern void ibt_selftest_ip(void); /* code label defined in asm below */ - enum cp_error_code { CP_EC = (1 << 15) - 1, @@ -20,15 +16,80 @@ enum cp_error_code { CP_ENCL = 1 << 15, }; -DEFINE_IDTENTRY_ERRORCODE(exc_control_protection) +static const char cp_err[][10] = { + [0] = "unknown", + [1] = "near ret", + [2] = "far/iret", + [3] = "endbranch", + [4] = "rstorssp", + [5] = "setssbsy", +}; + +static const char *cp_err_string(unsigned long error_code) +{ + unsigned int cpec = error_code & CP_EC; + + if (cpec >= ARRAY_SIZE(cp_err)) + cpec = 0; + return cp_err[cpec]; +} + +static void do_unexpected_cp(struct pt_regs *regs, unsigned long error_code) +{ + WARN_ONCE(1, "Unexpected %s #CP, error_code: %s\n", + user_mode(regs) ? "user mode" : "kernel mode", + cp_err_string(error_code)); +} + +static DEFINE_RATELIMIT_STATE(cpf_rate, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + +static void do_user_cp_fault(struct pt_regs *regs, unsigned long error_code) { - if (!cpu_feature_enabled(X86_FEATURE_IBT)) { - pr_err("Unexpected #CP\n"); - BUG(); + struct task_struct *tsk; + unsigned long ssp; + + /* + * An exception was just taken from userspace. Since interrupts are disabled + * here, no scheduling should have messed with the registers yet and they + * will be whatever is live in userspace. So read the SSP before enabling + * interrupts so locking the fpregs to do it later is not required. + */ + rdmsrl(MSR_IA32_PL3_SSP, ssp); + + cond_local_irq_enable(regs); + + tsk = current; + tsk->thread.error_code = error_code; + tsk->thread.trap_nr = X86_TRAP_CP; + + /* Ratelimit to prevent log spamming. */ + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && + __ratelimit(&cpf_rate)) { + pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)%s", + tsk->comm, task_pid_nr(tsk), + regs->ip, regs->sp, ssp, error_code, + cp_err_string(error_code), + error_code & CP_ENCL ? " in enclave" : ""); + print_vma_addr(KERN_CONT " in ", regs->ip); + pr_cont("\n"); } - if (WARN_ON_ONCE(user_mode(regs) || (error_code & CP_EC) != CP_ENDBR)) + force_sig_fault(SIGSEGV, SEGV_CPERR, (void __user *)0); + cond_local_irq_disable(regs); +} + +static __ro_after_init bool ibt_fatal = true; + +/* code label defined in asm below */ +extern void ibt_selftest_ip(void); + +static void do_kernel_cp_fault(struct pt_regs *regs, unsigned long error_code) +{ + if ((error_code & CP_EC) != CP_ENDBR) { + do_unexpected_cp(regs, error_code); return; + } if (unlikely(regs->ip == (unsigned long)&ibt_selftest_ip)) { regs->ax = 0; @@ -74,3 +135,18 @@ static int __init ibt_setup(char *str) } __setup("ibt=", ibt_setup); + +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection) +{ + if (user_mode(regs)) { + if (cpu_feature_enabled(X86_FEATURE_USER_SHSTK)) + do_user_cp_fault(regs, error_code); + else + do_unexpected_cp(regs, error_code); + } else { + if (cpu_feature_enabled(X86_FEATURE_IBT)) + do_kernel_cp_fault(regs, error_code); + else + do_unexpected_cp(regs, error_code); + } +} |