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Bamvor
在 2022/2/15 10:48，“Laibin Qiu”qiulaibin@huawei.com 写入:
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mainline inclusion from mainline-v5.11-rc1 commit 334872a0919890a70cccd00b8e11931020a819be category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4SIGI CVE: NA
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vDSO functions can now leverage an exception fixup mechanism similar to kernel exception fixup. For vDSO exception fixup, the initial user is Intel's Software Guard Extensions (SGX), which will wrap the low-level transitions to/from the enclave, i.e. EENTER and ERESUME instructions, in a vDSO function and leverage fixup to intercept exceptions that would otherwise generate a signal. This allows the vDSO wrapper to return the fault information directly to its caller, obviating the need for SGX applications and libraries to juggle signal handlers.
Attempt to fixup vDSO exceptions immediately prior to populating and sending signal information. Except for the delivery mechanism, an exception in a vDSO function should be treated like any other exception in userspace, e.g. any fault that is successfully handled by the kernel should not be directly visible to userspace.
Although it's debatable whether or not all exceptions are of interest to enclaves, defer to the vDSO fixup to decide whether to do fixup or generate a signal. Future users of vDSO fixup, if there ever are any, will undoubtedly have different requirements than SGX enclaves, e.g. the fixup vs. signal logic can be made function specific if/when necessary.
Intel-SIG: commit 334872a09198 x86/traps: Attempt to fixup exceptions in vDSO before signaling Backport for SGX Foundations support
Suggested-by: Andy Lutomirski luto@amacapital.net Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Acked-by: Jethro Beekman jethro@fortanix.com Link: 20201112220135.165028-19-jarkko@kernel.org <https://lkml.kernel.org/r/<a href=>">https://lkml.kernel.org/r/20201112220135.165028-19-jarkko@kernel.org Signed-off-by: Fan Du fan.du@intel.com #openEuler_contributor Signed-off-by: Laibin Qiu qiulaibin@huawei.com --- arch/x86/kernel/traps.c | 10 ++++++++++ arch/x86/mm/fault.c | 6 ++++++ 2 files changed, 16 insertions(+)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 2d4ecd50e69b..5da01819fb47 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -60,6 +60,7 @@ #include <asm/umip.h> #include <asm/insn.h> #include <asm/insn-eval.h> +#include <asm/vdso.h>
#ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -117,6 +118,9 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str, tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; die(str, regs, error_code); + } else { + if (fixup_vdso_exception(regs, trapnr, error_code, 0)) + return 0; }
/* @@ -585,6 +589,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP;
+ if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0)) + return; + show_signal(tsk, SIGSEGV, "", desc, regs, error_code); force_sig(SIGSEGV); goto exit; @@ -1083,6 +1090,9 @@ static void math_error(struct pt_regs *regs, int trapnr) if (!si_code) goto exit;
+ if (fixup_vdso_exception(regs, trapnr, 0, 0)) + return; + force_sig_fault(SIGFPE, si_code, (void __user *)uprobe_get_trap_addr(regs)); exit: diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index e86cdbb9692e..67d050a9bbd9 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -31,6 +31,7 @@ #include <asm/cpu_entry_area.h> /* exception stack */ #include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ #include <asm/kvm_para.h> /* kvm_handle_async_pf */ +#include <asm/vdso.h> /* fixup_vdso_exception() */
#define CREATE_TRACE_POINTS #include <asm/trace/exceptions.h> @@ -827,6 +828,8 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
sanitize_error_code(address, &error_code);
+ if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; if (likely(show_unhandled_signals)) show_signal_msg(regs, error_code, address, tsk);
@@ -946,6 +949,9 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
sanitize_error_code(address, &error_code);
+ if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; + set_signal_archinfo(address, error_code);
#ifdef CONFIG_MEMORY_FAILURE