Merge pull request #8388 from avagin:arm64-regs

PiperOrigin-RevId: 502688823

pkg/abi/linux/ptrace_arm64.go

@@ -17,6 +17,37 @@
 
 package linux
 
+const (
+	//PSR bits
+	PSR_MODE_EL0t = 0x00000000
+	PSR_MODE_EL1t = 0x00000004
+	PSR_MODE_EL1h = 0x00000005
+	PSR_MODE_EL2t = 0x00000008
+	PSR_MODE_EL2h = 0x00000009
+	PSR_MODE_EL3t = 0x0000000c
+	PSR_MODE_EL3h = 0x0000000d
+	PSR_MODE_MASK = 0x0000000f
+
+	// AArch32 CPSR bits
+	PSR_MODE32_BIT = 0x00000010
+
+	// AArch64 SPSR bits
+	PSR_F_BIT      = 0x00000040
+	PSR_I_BIT      = 0x00000080
+	PSR_A_BIT      = 0x00000100
+	PSR_D_BIT      = 0x00000200
+	PSR_BTYPE_MASK = 0x00000c00
+	PSR_SSBS_BIT   = 0x00001000
+	PSR_PAN_BIT    = 0x00400000
+	PSR_UAO_BIT    = 0x00800000
+	PSR_DIT_BIT    = 0x01000000
+	PSR_TCO_BIT    = 0x02000000
+	PSR_V_BIT      = 0x10000000
+	PSR_C_BIT      = 0x20000000
+	PSR_Z_BIT      = 0x40000000
+	PSR_N_BIT      = 0x80000000
+)
+
 // PtraceRegs is the set of CPU registers exposed by ptrace. Source:
 // syscall.PtraceRegs.
 //

pkg/sentry/arch/arch_aarch64.go

@@ -196,6 +196,9 @@ func (s *State) PtraceSetRegs(src io.Reader) (int, error) {
 		return 0, err
 	}
 	regs.UnmarshalUnsafe(buf)
+	if !regs.validRegs() {
+		return 0, linuxerr.EINVAL
+	}
 	s.Regs = regs
 	return ptraceRegistersSize, nil
 }

pkg/sentry/arch/signal_arm64.go

@@ -138,6 +138,29 @@ func (c *Context64) SignalSetup(st *Stack, act *linux.SigAction, info *linux.Sig
 	return nil
 }
 
+// SPSR_ELx bits which are always architecturally RES0 per ARM DDI 0487D.a.
+const _SPSR_EL1_AARCH64_RES0_BITS = uint64(0xffffffff0cdfe020)
+
+func (regs *Registers) userMode() bool {
+	return (regs.Pstate & linux.PSR_MODE_MASK) == linux.PSR_MODE_EL0t
+}
+
+func (regs *Registers) validRegs() bool {
+	regs.Pstate &= ^_SPSR_EL1_AARCH64_RES0_BITS
+
+	if regs.userMode() && (regs.Pstate&linux.PSR_MODE32_BIT) == 0 &&
+		(regs.Pstate&linux.PSR_D_BIT) == 0 &&
+		(regs.Pstate&linux.PSR_A_BIT) == 0 &&
+		(regs.Pstate&linux.PSR_I_BIT) == 0 &&
+		(regs.Pstate&linux.PSR_F_BIT) == 0 {
+		return true
+	}
+
+	// Force PSR to a valid 64-bit EL0t
+	regs.Pstate &= linux.PSR_N_BIT | linux.PSR_Z_BIT | linux.PSR_C_BIT | linux.PSR_V_BIT
+	return false
+}
+
 // SignalRestore implements Context.SignalRestore.
 func (c *Context64) SignalRestore(st *Stack, rt bool, featureSet cpuid.FeatureSet) (linux.SignalSet, linux.SignalStack, error) {
 	// Copy out the stack frame.
@@ -156,6 +179,10 @@ func (c *Context64) SignalRestore(st *Stack, rt bool, featureSet cpuid.FeatureSe
 	c.Regs.Sp = uc.MContext.Sp
 	c.Regs.Pstate = uc.MContext.Pstate
 
+	if !c.Regs.validRegs() {
+		return 0, linux.SignalStack{}, unix.EFAULT
+	}
+
 	// Restore floating point state.
 	l := len(c.sigFPState)
 	if l > 0 {
@@ -170,6 +197,7 @@ func (c *Context64) SignalRestore(st *Stack, rt bool, featureSet cpuid.FeatureSe
 		// don't bother to do anything fancy with the floating point
 		// state.
 		log.Warningf("sigreturn unable to restore application fpstate")
+		return 0, linux.SignalStack{}, unix.EFAULT
 	}
 
 	return uc.Sigset, uc.Stack, nil