lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Tue,  5 Mar 2019 21:18:14 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, ruscur@...sell.cc
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 1/7] powerpc/64s: Implement KUAP for Radix MMU (SQUASH)

Squashed version of the v4 series, not intended to be merged as is.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 Documentation/admin-guide/kernel-parameters.txt |  4 +-
 arch/powerpc/include/asm/book3s/64/kup-radix.h  | 79 +++++++++++++++++++++++++
 arch/powerpc/include/asm/exception-64s.h        |  2 +
 arch/powerpc/include/asm/feature-fixups.h       |  3 +
 arch/powerpc/include/asm/futex.h                |  4 ++
 arch/powerpc/include/asm/kup.h                  | 53 +++++++++++++++++
 arch/powerpc/include/asm/mmu.h                  | 10 +++-
 arch/powerpc/include/asm/ptrace.h               | 11 +++-
 arch/powerpc/include/asm/reg.h                  |  1 +
 arch/powerpc/include/asm/uaccess.h              | 38 +++++++++---
 arch/powerpc/kernel/asm-offsets.c               |  4 ++
 arch/powerpc/kernel/entry_64.S                  | 22 ++++++-
 arch/powerpc/kernel/exceptions-64s.S            |  3 +
 arch/powerpc/kernel/idle_book3s.S               | 39 ++++++++++++
 arch/powerpc/kernel/setup_64.c                  | 10 ++++
 arch/powerpc/lib/checksum_wrappers.c            |  4 ++
 arch/powerpc/lib/code-patching.c                |  4 +-
 arch/powerpc/mm/fault.c                         | 28 ++++++---
 arch/powerpc/mm/init-common.c                   | 26 ++++++++
 arch/powerpc/mm/init_32.c                       |  3 +
 arch/powerpc/mm/pgtable-radix.c                 | 31 +++++++++-
 arch/powerpc/mm/pkeys.c                         |  1 +
 arch/powerpc/platforms/Kconfig.cputype          | 33 +++++++++++
 23 files changed, 384 insertions(+), 29 deletions(-)
 create mode 100644 arch/powerpc/include/asm/book3s/64/kup-radix.h
 create mode 100644 arch/powerpc/include/asm/kup.h

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 858b6c0b9a15..0a76dbb39011 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2808,11 +2808,11 @@
 			noexec=on: enable non-executable mappings (default)
 			noexec=off: disable non-executable mappings
 
-	nosmap		[X86]
+	nosmap		[X86,PPC]
 			Disable SMAP (Supervisor Mode Access Prevention)
 			even if it is supported by processor.
 
-	nosmep		[X86]
+	nosmep		[X86,PPC]
 			Disable SMEP (Supervisor Mode Execution Prevention)
 			even if it is supported by processor.
 
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h
new file mode 100644
index 000000000000..87f2af26764c
--- /dev/null
+++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H
+#define _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H
+
+#ifdef __ASSEMBLY__
+
+.macro kuap_restore_amr	gpr
+#ifdef CONFIG_PPC_KUAP
+	BEGIN_MMU_FTR_SECTION_NESTED(67)
+	ld	\gpr, STACK_REGS_KUAP(r1)
+	mtspr	SPRN_AMR, \gpr
+	END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67)
+#endif
+.endm
+
+.macro kuap_check_amr gpr
+#ifdef CONFIG_PPC_KUAP_DEBUG
+	BEGIN_MMU_FTR_SECTION_NESTED(67)
+	mfspr	\gpr, SPRN_AMR
+	sradi	\gpr, \gpr, 48
+999:	tdnei	\gpr, RADIX_AMR_LOCKED@...hest
+	EMIT_BUG_ENTRY 999b,__FILE__,__LINE__, \
+		(BUGFLAG_WARNING|BUGFLAG_ONCE)
+	END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67)
+#endif
+.endm
+
+.macro kuap_save_amr_and_lock gpr, msr_pr_cr
+#ifdef CONFIG_PPC_KUAP
+	BEGIN_MMU_FTR_SECTION_NESTED(67)
+	.ifnb \msr_pr_cr
+	bne	\msr_pr_cr, 99f
+	.endif
+	mfspr	\gpr, SPRN_AMR
+	std	\gpr, STACK_REGS_KUAP(r1)
+	li	\gpr, (RADIX_AMR_LOCKED)@highest
+	sldi	\gpr, \gpr, 48
+	mtspr	SPRN_AMR,\gpr
+99:
+	END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_RADIX_KUAP, 67)
+#endif
+.endm
+
+#else /* !__ASSEMBLY__ */
+
+#ifdef CONFIG_PPC_KUAP
+
+#include <asm/reg.h>
+/*
+ * We do have the ability to individually lock/unlock reads and writes rather
+ * than both at once, however it's a significant performance hit due to needing
+ * to do a read-modify-write, which adds a mfspr, which is slow.  As a result,
+ * locking/unlocking both at once is preferred.
+ */
+static inline void allow_user_access(void __user *to, const void __user *from,
+				     unsigned long size)
+{
+	if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+		return;
+
+	mtspr(SPRN_AMR, 0);
+	isync();
+}
+
+static inline void prevent_user_access(void __user *to, const void __user *from,
+				       unsigned long size)
+{
+	if (!mmu_has_feature(MMU_FTR_RADIX_KUAP))
+		return;
+
+	mtspr(SPRN_AMR, RADIX_AMR_LOCKED);
+	isync();
+}
+
+#endif /* CONFIG_PPC_KUAP */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H */
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 937bb630093f..df7cbfc45952 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -497,6 +497,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 	RESTORE_CTR(r1, area);						   \
 	b	bad_stack;						   \
 3:	EXCEPTION_PROLOG_COMMON_1();					   \
+	kuap_save_amr_and_lock r9, cr0;					   \
 	beq	4f;			/* if from kernel mode		*/ \
 	ACCOUNT_CPU_USER_ENTRY(r13, r9, r10);				   \
 	SAVE_PPR(area, r9);						   \
@@ -691,6 +692,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
  */
 #define EXCEPTION_COMMON_NORET_STACK(area, trap, label, hdlr, additions) \
 	EXCEPTION_PROLOG_COMMON_1();				\
+	kuap_save_amr_and_lock r9;				\
 	EXCEPTION_PROLOG_COMMON_2(area);			\
 	EXCEPTION_PROLOG_COMMON_3(trap);			\
 	/* Volatile regs are potentially clobbered here */	\
diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index 40a6c9261a6b..f6fc31f8baff 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/arch/powerpc/include/asm/feature-fixups.h
@@ -100,6 +100,9 @@ label##5:							\
 #define END_MMU_FTR_SECTION(msk, val)		\
 	END_MMU_FTR_SECTION_NESTED(msk, val, 97)
 
+#define END_MMU_FTR_SECTION_NESTED_IFSET(msk, label)	\
+	END_MMU_FTR_SECTION_NESTED((msk), (msk), label)
+
 #define END_MMU_FTR_SECTION_IFSET(msk)	END_MMU_FTR_SECTION((msk), (msk))
 #define END_MMU_FTR_SECTION_IFCLR(msk)	END_MMU_FTR_SECTION((msk), 0)
 
diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h
index 88b38b37c21b..3a6aa57b9d90 100644
--- a/arch/powerpc/include/asm/futex.h
+++ b/arch/powerpc/include/asm/futex.h
@@ -35,6 +35,7 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
+	allow_write_to_user(uaddr, sizeof(*uaddr));
 	pagefault_disable();
 
 	switch (op) {
@@ -62,6 +63,7 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	if (!ret)
 		*oval = oldval;
 
+	prevent_write_to_user(uaddr, sizeof(*uaddr));
 	return ret;
 }
 
@@ -75,6 +77,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 	if (!access_ok(uaddr, sizeof(u32)))
 		return -EFAULT;
 
+	allow_write_to_user(uaddr, sizeof(*uaddr));
         __asm__ __volatile__ (
         PPC_ATOMIC_ENTRY_BARRIER
 "1:     lwarx   %1,0,%3         # futex_atomic_cmpxchg_inatomic\n\
@@ -95,6 +98,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
         : "cc", "memory");
 
 	*uval = prev;
+	prevent_write_to_user(uaddr, sizeof(*uaddr));
         return ret;
 }
 
diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
new file mode 100644
index 000000000000..082f50ad41a7
--- /dev/null
+++ b/arch/powerpc/include/asm/kup.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_KUP_H_
+#define _ASM_POWERPC_KUP_H_
+
+#ifdef CONFIG_PPC_BOOK3S_64
+#include <asm/book3s/64/kup-radix.h>
+#endif
+
+#ifndef __ASSEMBLY__
+
+#include <asm/pgtable.h>
+
+void setup_kup(void);
+
+#ifdef CONFIG_PPC_KUEP
+void setup_kuep(bool disabled);
+#else
+static inline void setup_kuep(bool disabled) { }
+#endif /* CONFIG_PPC_KUEP */
+
+#ifdef CONFIG_PPC_KUAP
+void setup_kuap(bool disabled);
+#else
+static inline void setup_kuap(bool disabled) { }
+static inline void allow_user_access(void __user *to, const void __user *from,
+				     unsigned long size) { }
+static inline void prevent_user_access(void __user *to, const void __user *from,
+				       unsigned long size) { }
+#endif /* CONFIG_PPC_KUAP */
+
+static inline void allow_read_from_user(const void __user *from, unsigned long size)
+{
+	allow_user_access(NULL, from, size);
+}
+
+static inline void allow_write_to_user(void __user *to, unsigned long size)
+{
+	allow_user_access(to, NULL, size);
+}
+
+static inline void prevent_read_from_user(const void __user *from, unsigned long size)
+{
+	prevent_user_access(NULL, from, size);
+}
+
+static inline void prevent_write_to_user(void __user *to, unsigned long size)
+{
+	prevent_user_access(to, NULL, size);
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* _ASM_POWERPC_KUP_H_ */
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index d34ad1657d7b..59acb4418164 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -107,6 +107,11 @@
  */
 #define MMU_FTR_1T_SEGMENT		ASM_CONST(0x40000000)
 
+/*
+ * Supports KUAP (key 0 controlling userspace addresses) on radix
+ */
+#define MMU_FTR_RADIX_KUAP		ASM_CONST(0x80000000)
+
 /* MMU feature bit sets for various CPUs */
 #define MMU_FTRS_DEFAULT_HPTE_ARCH_V2	\
 	MMU_FTR_HPTE_TABLE | MMU_FTR_PPCAS_ARCH_V2
@@ -164,7 +169,10 @@ enum {
 #endif
 #ifdef CONFIG_PPC_RADIX_MMU
 		MMU_FTR_TYPE_RADIX |
-#endif
+#ifdef CONFIG_PPC_KUAP
+		MMU_FTR_RADIX_KUAP |
+#endif /* CONFIG_PPC_KUAP */
+#endif /* CONFIG_PPC_RADIX_MMU */
 		0,
 };
 
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 64271e562fed..6f047730e642 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -52,10 +52,17 @@ struct pt_regs
 		};
 	};
 
+	union {
+		struct {
 #ifdef CONFIG_PPC64
-	unsigned long ppr;
-	unsigned long __pad;	/* Maintain 16 byte interrupt stack alignment */
+			unsigned long ppr;
+#endif
+#ifdef CONFIG_PPC_KUAP
+			unsigned long kuap;
 #endif
+		};
+		unsigned long __pad[2];	/* Maintain 16 byte interrupt stack alignment */
+	};
 };
 #endif
 
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index c5b2aff0ce8e..6350873af4bc 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -246,6 +246,7 @@
 #define SPRN_DSCR	0x11
 #define SPRN_CFAR	0x1c	/* Come From Address Register */
 #define SPRN_AMR	0x1d	/* Authority Mask Register */
+#define   RADIX_AMR_LOCKED	0xC000000000000000UL /* Read & Write disabled */
 #define SPRN_UAMOR	0x9d	/* User Authority Mask Override Register */
 #define SPRN_AMOR	0x15d	/* Authority Mask Override Register */
 #define SPRN_ACOP	0x1F	/* Available Coprocessor Register */
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index e3a731793ea2..fb7651a5488b 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -6,6 +6,7 @@
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/extable.h>
+#include <asm/kup.h>
 
 /*
  * The fs value determines whether argument validity checking should be
@@ -141,6 +142,7 @@ extern long __put_user_bad(void);
 #define __put_user_size(x, ptr, size, retval)			\
 do {								\
 	retval = 0;						\
+	allow_write_to_user(ptr, size);				\
 	switch (size) {						\
 	  case 1: __put_user_asm(x, ptr, retval, "stb"); break;	\
 	  case 2: __put_user_asm(x, ptr, retval, "sth"); break;	\
@@ -148,6 +150,7 @@ do {								\
 	  case 8: __put_user_asm2(x, ptr, retval); break;	\
 	  default: __put_user_bad();				\
 	}							\
+	prevent_write_to_user(ptr, size);			\
 } while (0)
 
 #define __put_user_nocheck(x, ptr, size)			\
@@ -240,6 +243,7 @@ do {								\
 	__chk_user_ptr(ptr);					\
 	if (size > sizeof(x))					\
 		(x) = __get_user_bad();				\
+	allow_read_from_user(ptr, size);			\
 	switch (size) {						\
 	case 1: __get_user_asm(x, ptr, retval, "lbz"); break;	\
 	case 2: __get_user_asm(x, ptr, retval, "lhz"); break;	\
@@ -247,6 +251,7 @@ do {								\
 	case 8: __get_user_asm2(x, ptr, retval);  break;	\
 	default: (x) = __get_user_bad();			\
 	}							\
+	prevent_read_from_user(ptr, size);			\
 } while (0)
 
 /*
@@ -306,15 +311,21 @@ extern unsigned long __copy_tofrom_user(void __user *to,
 static inline unsigned long
 raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 {
-	return __copy_tofrom_user(to, from, n);
+	unsigned long ret;
+
+	allow_user_access(to, from, n);
+	ret = __copy_tofrom_user(to, from, n);
+	prevent_user_access(to, from, n);
+	return ret;
 }
 #endif /* __powerpc64__ */
 
 static inline unsigned long raw_copy_from_user(void *to,
 		const void __user *from, unsigned long n)
 {
+	unsigned long ret;
 	if (__builtin_constant_p(n) && (n <= 8)) {
-		unsigned long ret = 1;
+		ret = 1;
 
 		switch (n) {
 		case 1:
@@ -339,14 +350,18 @@ static inline unsigned long raw_copy_from_user(void *to,
 	}
 
 	barrier_nospec();
-	return __copy_tofrom_user((__force void __user *)to, from, n);
+	allow_read_from_user(from, n);
+	ret = __copy_tofrom_user((__force void __user *)to, from, n);
+	prevent_read_from_user(from, n);
+	return ret;
 }
 
 static inline unsigned long raw_copy_to_user(void __user *to,
 		const void *from, unsigned long n)
 {
+	unsigned long ret;
 	if (__builtin_constant_p(n) && (n <= 8)) {
-		unsigned long ret = 1;
+		ret = 1;
 
 		switch (n) {
 		case 1:
@@ -366,17 +381,24 @@ static inline unsigned long raw_copy_to_user(void __user *to,
 			return 0;
 	}
 
-	return __copy_tofrom_user(to, (__force const void __user *)from, n);
+	allow_write_to_user(to, n);
+	ret = __copy_tofrom_user(to, (__force const void __user *)from, n);
+	prevent_write_to_user(to, n);
+	return ret;
 }
 
 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 
 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 {
+	unsigned long ret = size;
 	might_fault();
-	if (likely(access_ok(addr, size)))
-		return __clear_user(addr, size);
-	return size;
+	if (likely(access_ok(addr, size))) {
+		allow_write_to_user(addr, size);
+		ret = __clear_user(addr, size);
+		prevent_write_to_user(addr, size);
+	}
+	return ret;
 }
 
 extern long strncpy_from_user(char *dst, const char __user *src, long count);
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 86a61e5f8285..66202e02fee2 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -332,6 +332,10 @@ int main(void)
 	STACK_PT_REGS_OFFSET(_PPR, ppr);
 #endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_PPC_KUAP
+	STACK_PT_REGS_OFFSET(STACK_REGS_KUAP, kuap);
+#endif
+
 #if defined(CONFIG_PPC32)
 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
 	DEFINE(EXC_LVL_SIZE, STACK_EXC_LVL_FRAME_SIZE);
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 15c67d2c0534..612cfa4bffd7 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -46,6 +46,7 @@
 #include <asm/exception-64e.h>
 #endif
 #include <asm/feature-fixups.h>
+#include <asm/kup.h>
 
 /*
  * System calls.
@@ -275,6 +276,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	andi.	r6,r8,MSR_PR
 	ld	r4,_LINK(r1)
 
+	kuap_check_amr r11
+
 #ifdef CONFIG_PPC_BOOK3S
 	/*
 	 * Clear MSR_RI, MSR_EE is already and remains disabled. We could do
@@ -296,6 +299,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	std	r8, PACATMSCRATCH(r13)
 #endif
 
+	/*
+	 * We don't need to restore AMR on the way back to userspace for KUAP.
+	 * The value of AMR only matters while we're in the kernel.
+	 */
 	ld	r13,GPR13(r1)	/* only restore r13 if returning to usermode */
 	ld	r2,GPR2(r1)
 	ld	r1,GPR1(r1)
@@ -306,8 +313,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	RFI_TO_USER
 	b	.	/* prevent speculative execution */
 
-	/* exit to kernel */
-1:	ld	r2,GPR2(r1)
+1:	/* exit to kernel */
+	kuap_restore_amr r2
+
+	ld	r2,GPR2(r1)
 	ld	r1,GPR1(r1)
 	mtlr	r4
 	mtcr	r5
@@ -594,6 +603,8 @@ _GLOBAL(_switch)
 	std	r23,_CCR(r1)
 	std	r1,KSP(r3)	/* Set old stack pointer */
 
+	kuap_check_amr r6
+
 	FLUSH_COUNT_CACHE
 
 	/*
@@ -974,6 +985,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
 	REST_GPR(13, r1)
 
+	/*
+	 * We don't need to restore AMR on the way back to userspace for KUAP.
+	 * The value of AMR only matters while we're in the kernel.
+	 */
 	mtspr	SPRN_SRR1,r3
 
 	ld	r2,_CCR(r1)
@@ -1006,6 +1021,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ld	r0,GPR0(r1)
 	ld	r2,GPR2(r1)
 	ld	r3,GPR3(r1)
+
+	kuap_restore_amr r4
+
 	ld	r4,GPR4(r1)
 	ld	r1,GPR1(r1)
 	RFI_TO_KERNEL
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index a5b8fbae56a0..dd73f4ae6cb7 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -19,6 +19,7 @@
 #include <asm/cpuidle.h>
 #include <asm/head-64.h>
 #include <asm/feature-fixups.h>
+#include <asm/kup.h>
 
 /*
  * There are a few constraints to be concerned with.
@@ -309,6 +310,7 @@ TRAMP_REAL_BEGIN(machine_check_common_early)
 	mfspr	r11,SPRN_DSISR		/* Save DSISR */
 	std	r11,_DSISR(r1)
 	std	r9,_CCR(r1)		/* Save CR in stackframe */
+	kuap_save_amr_and_lock r9
 	/* Save r9 through r13 from EXMC save area to stack frame. */
 	EXCEPTION_PROLOG_COMMON_2(PACA_EXMC)
 	mfmsr	r11			/* get MSR value */
@@ -1097,6 +1099,7 @@ TRAMP_REAL_BEGIN(hmi_exception_early)
 	mfspr	r11,SPRN_HSRR0		/* Save HSRR0 */
 	mfspr	r12,SPRN_HSRR1		/* Save HSRR1 */
 	EXCEPTION_PROLOG_COMMON_1()
+	kuap_save_amr_and_lock r9
 	EXCEPTION_PROLOG_COMMON_2(PACA_EXGEN)
 	EXCEPTION_PROLOG_COMMON_3(0xe60)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 7f5ac2e8581b..4a860d3b9229 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -170,6 +170,12 @@ core_idle_lock_held:
 	bne-	core_idle_lock_held
 	blr
 
+/* Reuse some unused pt_regs slots for AMR/IAMR/UAMOR/UAMOR */
+#define PNV_POWERSAVE_AMR	_TRAP
+#define PNV_POWERSAVE_IAMR	_DAR
+#define PNV_POWERSAVE_UAMOR	_DSISR
+#define PNV_POWERSAVE_AMOR	RESULT
+
 /*
  * Pass requested state in r3:
  *	r3 - PNV_THREAD_NAP/SLEEP/WINKLE in POWER8
@@ -200,6 +206,20 @@ pnv_powersave_common:
 	/* Continue saving state */
 	SAVE_GPR(2, r1)
 	SAVE_NVGPRS(r1)
+
+BEGIN_FTR_SECTION
+	mfspr	r4, SPRN_AMR
+	mfspr	r5, SPRN_IAMR
+	mfspr	r6, SPRN_UAMOR
+	std	r4, PNV_POWERSAVE_AMR(r1)
+	std	r5, PNV_POWERSAVE_IAMR(r1)
+	std	r6, PNV_POWERSAVE_UAMOR(r1)
+BEGIN_FTR_SECTION_NESTED(42)
+	mfspr	r7, SPRN_AMOR
+	std	r7, PNV_POWERSAVE_AMOR(r1)
+END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
+
 	mfcr	r5
 	std	r5,_CCR(r1)
 	std	r1,PACAR1(r13)
@@ -924,6 +944,25 @@ BEGIN_FTR_SECTION
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
 	REST_NVGPRS(r1)
 	REST_GPR(2, r1)
+
+BEGIN_FTR_SECTION
+	/* These regs were saved in pnv_powersave_common() */
+	ld	r4, PNV_POWERSAVE_AMR(r1)
+	ld	r5, PNV_POWERSAVE_IAMR(r1)
+	ld	r6, PNV_POWERSAVE_UAMOR(r1)
+	mtspr	SPRN_AMR, r4
+	mtspr	SPRN_IAMR, r5
+	mtspr	SPRN_UAMOR, r6
+BEGIN_FTR_SECTION_NESTED(42)
+	ld	r7, PNV_POWERSAVE_AMOR(r1)
+	mtspr	SPRN_AMOR, r7
+END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
+	/*
+	 * We don't need an isync here after restoring IAMR because the upcoming
+	 * mtmsrd is execution synchronizing.
+	 */
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
+
 	ld	r4,PACAKMSR(r13)
 	ld	r5,_LINK(r1)
 	ld	r6,_CCR(r1)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index daa361fc6a24..72358a5022fe 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -68,6 +68,7 @@
 #include <asm/cputhreads.h>
 #include <asm/hw_irq.h>
 #include <asm/feature-fixups.h>
+#include <asm/kup.h>
 
 #include "setup.h"
 
@@ -331,6 +332,12 @@ void __init early_setup(unsigned long dt_ptr)
 	 */
 	configure_exceptions();
 
+	/*
+	 * Configure Kernel Userspace Protection. This needs to happen before
+	 * feature fixups for platforms that implement this using features.
+	 */
+	setup_kup();
+
 	/* Apply all the dynamic patching */
 	apply_feature_fixups();
 	setup_feature_keys();
@@ -383,6 +390,9 @@ void early_setup_secondary(void)
 	/* Initialize the hash table or TLB handling */
 	early_init_mmu_secondary();
 
+	/* Perform any KUP setup that is per-cpu */
+	setup_kup();
+
 	/*
 	 * At this point, we can let interrupts switch to virtual mode
 	 * (the MMU has been setup), so adjust the MSR in the PACA to
diff --git a/arch/powerpc/lib/checksum_wrappers.c b/arch/powerpc/lib/checksum_wrappers.c
index 890d4ddd91d6..bb9307ce2440 100644
--- a/arch/powerpc/lib/checksum_wrappers.c
+++ b/arch/powerpc/lib/checksum_wrappers.c
@@ -29,6 +29,7 @@ __wsum csum_and_copy_from_user(const void __user *src, void *dst,
 	unsigned int csum;
 
 	might_sleep();
+	allow_read_from_user(src, len);
 
 	*err_ptr = 0;
 
@@ -60,6 +61,7 @@ __wsum csum_and_copy_from_user(const void __user *src, void *dst,
 	}
 
 out:
+	prevent_read_from_user(src, len);
 	return (__force __wsum)csum;
 }
 EXPORT_SYMBOL(csum_and_copy_from_user);
@@ -70,6 +72,7 @@ __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
 	unsigned int csum;
 
 	might_sleep();
+	allow_write_to_user(dst, len);
 
 	*err_ptr = 0;
 
@@ -97,6 +100,7 @@ __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
 	}
 
 out:
+	prevent_write_to_user(dst, len);
 	return (__force __wsum)csum;
 }
 EXPORT_SYMBOL(csum_and_copy_to_user);
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 506413a2c25e..42fdadac6587 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -26,9 +26,9 @@
 static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
 			       unsigned int *patch_addr)
 {
-	int err;
+	int err = 0;
 
-	__put_user_size(instr, patch_addr, 4, err);
+	__put_user_asm(instr, patch_addr, err, "stw");
 	if (err)
 		return err;
 
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 887f11bcf330..463d1e9d026e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -223,19 +223,28 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
 }
 
 /* Is this a bad kernel fault ? */
-static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
+static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
 			     unsigned long address)
 {
+	int is_exec = TRAP(regs) == 0x400;
+
 	/* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
 	if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
 				      DSISR_PROTFAULT))) {
-		printk_ratelimited(KERN_CRIT "kernel tried to execute"
-				   " exec-protected page (%lx) -"
-				   "exploit attempt? (uid: %d)\n",
-				   address, from_kuid(&init_user_ns,
-						      current_uid()));
+		pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
+				    address >= TASK_SIZE ? "exec-protected" : "user",
+				    address,
+				    from_kuid(&init_user_ns, current_uid()));
+	}
+
+	if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) &&
+	    !search_exception_tables(regs->nip)) {
+		pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
+				    address,
+				    from_kuid(&init_user_ns, current_uid()));
 	}
-	return is_exec || (address >= TASK_SIZE);
+
+	return is_exec || (address >= TASK_SIZE) || !search_exception_tables(regs->nip);
 }
 
 static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address,
@@ -455,9 +464,10 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
 
 	/*
 	 * The kernel should never take an execute fault nor should it
-	 * take a page fault to a kernel address.
+	 * take a page fault to a kernel address or a page fault to a user
+	 * address outside of dedicated places
 	 */
-	if (unlikely(!is_user && bad_kernel_fault(is_exec, error_code, address)))
+	if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address)))
 		return SIGSEGV;
 
 	/*
diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index 1e6910eb70ed..ecaedfff9992 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -24,6 +24,32 @@
 #include <linux/string.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include <asm/kup.h>
+
+static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
+static bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
+
+static int __init parse_nosmep(char *p)
+{
+	disable_kuep = true;
+	pr_warn("Disabling Kernel Userspace Execution Prevention\n");
+	return 0;
+}
+early_param("nosmep", parse_nosmep);
+
+static int __init parse_nosmap(char *p)
+{
+	disable_kuap = true;
+	pr_warn("Disabling Kernel Userspace Access Protection\n");
+	return 0;
+}
+early_param("nosmap", parse_nosmap);
+
+void __init setup_kup(void)
+{
+	setup_kuep(disable_kuep);
+	setup_kuap(disable_kuap);
+}
 
 #define CTOR(shift) static void ctor_##shift(void *addr) \
 {							\
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 41a3513cadc9..80cc97cd8878 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -45,6 +45,7 @@
 #include <asm/tlb.h>
 #include <asm/sections.h>
 #include <asm/hugetlb.h>
+#include <asm/kup.h>
 
 #include "mmu_decl.h"
 
@@ -178,6 +179,8 @@ void __init MMU_init(void)
 	btext_unmap();
 #endif
 
+	setup_kup();
+
 	/* Shortly after that, the entire linear mapping will be available */
 	memblock_set_current_limit(lowmem_end_addr);
 }
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index 931156069a81..aa7d9de3ba3f 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -29,6 +29,7 @@
 #include <asm/powernv.h>
 #include <asm/sections.h>
 #include <asm/trace.h>
+#include <asm/uaccess.h>
 
 #include <trace/events/thp.h>
 
@@ -535,8 +536,15 @@ static void radix_init_amor(void)
 	mtspr(SPRN_AMOR, (3ul << 62));
 }
 
-static void radix_init_iamr(void)
+#ifdef CONFIG_PPC_KUEP
+void __init setup_kuep(bool disabled)
 {
+	if (disabled || !early_radix_enabled())
+		return;
+
+	if (smp_processor_id() == boot_cpuid)
+		pr_info("Activating Kernel Userspace Execution Prevention\n");
+
 	/*
 	 * Radix always uses key0 of the IAMR to determine if an access is
 	 * allowed. We set bit 0 (IBM bit 1) of key0, to prevent instruction
@@ -544,6 +552,25 @@ static void radix_init_iamr(void)
 	 */
 	mtspr(SPRN_IAMR, (1ul << 62));
 }
+#endif
+
+#ifdef CONFIG_PPC_KUAP
+void __init setup_kuap(bool disabled)
+{
+	if (disabled || !early_radix_enabled())
+		return;
+
+	if (smp_processor_id() == boot_cpuid) {
+		pr_info("Activating Kernel Userspace Access Prevention\n");
+		cur_cpu_spec->mmu_features |= MMU_FTR_RADIX_KUAP;
+	}
+
+	/* Make sure userspace can't change the AMR */
+	mtspr(SPRN_UAMOR, 0);
+
+	mtspr(SPRN_AMR, RADIX_AMR_LOCKED);
+}
+#endif
 
 void __init radix__early_init_mmu(void)
 {
@@ -605,7 +632,6 @@ void __init radix__early_init_mmu(void)
 
 	memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
 
-	radix_init_iamr();
 	radix_init_pgtable();
 	/* Switch to the guard PID before turning on MMU */
 	radix__switch_mmu_context(NULL, &init_mm);
@@ -627,7 +653,6 @@ void radix__early_init_mmu_secondary(void)
 		      __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
 		radix_init_amor();
 	}
-	radix_init_iamr();
 
 	radix__switch_mmu_context(NULL, &init_mm);
 	if (cpu_has_feature(CPU_FTR_HVMODE))
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 587807763737..ae7fca40e5b3 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -7,6 +7,7 @@
 
 #include <asm/mman.h>
 #include <asm/mmu_context.h>
+#include <asm/mmu.h>
 #include <asm/setup.h>
 #include <linux/pkeys.h>
 #include <linux/of_device.h>
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 842b2c7e156a..5e53b9fd62aa 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -326,6 +326,8 @@ config PPC_RADIX_MMU
 	bool "Radix MMU Support"
 	depends on PPC_BOOK3S_64
 	select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
+	select PPC_HAVE_KUEP
+	select PPC_HAVE_KUAP
 	default y
 	help
 	  Enable support for the Power ISA 3.0 Radix style MMU. Currently this
@@ -345,6 +347,37 @@ config PPC_RADIX_MMU_DEFAULT
 
 	  If you're unsure, say Y.
 
+config PPC_HAVE_KUEP
+	bool
+
+config PPC_KUEP
+	bool "Kernel Userspace Execution Prevention"
+	depends on PPC_HAVE_KUEP
+	default y
+	help
+	  Enable support for Kernel Userspace Execution Prevention (KUEP)
+
+	  If you're unsure, say Y.
+
+config PPC_HAVE_KUAP
+	bool
+
+config PPC_KUAP
+	bool "Kernel Userspace Access Protection"
+	depends on PPC_HAVE_KUAP
+	default y
+	help
+	  Enable support for Kernel Userspace Access Protection (KUAP)
+
+	  If you're unsure, say Y.
+
+config PPC_KUAP_DEBUG
+	bool "Extra debugging for Kernel Userspace Access Protection"
+	depends on PPC_HAVE_KUAP && PPC_RADIX_MMU
+	help
+	  Add extra debugging for Kernel Userspace Access Protection (KUAP)
+	  If you're unsure, say N.
+
 config ARCH_ENABLE_HUGEPAGE_MIGRATION
 	def_bool y
 	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
-- 
2.13.3

Powered by blists - more mailing lists