Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull rseq fixes from Ingo Molnar:
 "Various rseq ABI fixes and cleanups: use get_user()/put_user(),
  validate parameters and use proper uapi types, etc"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq/selftests: cleanup: Update comment above rseq_prepare_unload
  rseq: Remove unused types_32_64.h uapi header
  rseq: uapi: Declare rseq_cs field as union, update includes
  rseq: uapi: Update uapi comments
  rseq: Use get_user/put_user rather than __get_user/__put_user
  rseq: Use __u64 for rseq_cs fields, validate user inputs

include/uapi/linux/rseq.h

@@ -10,13 +10,8 @@
  * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
-#ifdef __KERNEL__
-# include <linux/types.h>
-#else
-# include <stdint.h>
-#endif
-
-#include <linux/types_32_64.h>
+#include <linux/types.h>
+#include <asm/byteorder.h>
 
 enum rseq_cpu_id_state {
 	RSEQ_CPU_ID_UNINITIALIZED		= -1,
@@ -52,10 +47,10 @@ struct rseq_cs {
 	__u32 version;
 	/* enum rseq_cs_flags */
 	__u32 flags;
-	LINUX_FIELD_u32_u64(start_ip);
+	__u64 start_ip;
 	/* Offset from start_ip. */
-	LINUX_FIELD_u32_u64(post_commit_offset);
-	LINUX_FIELD_u32_u64(abort_ip);
+	__u64 post_commit_offset;
+	__u64 abort_ip;
 } __attribute__((aligned(4 * sizeof(__u64))));
 
 /*
@@ -67,28 +62,30 @@ struct rseq_cs {
 struct rseq {
 	/*
 	 * Restartable sequences cpu_id_start field. Updated by the
-	 * kernel, and read by user-space with single-copy atomicity
-	 * semantics. Aligned on 32-bit. Always contains a value in the
-	 * range of possible CPUs, although the value may not be the
-	 * actual current CPU (e.g. if rseq is not initialized). This
-	 * CPU number value should always be compared against the value
-	 * of the cpu_id field before performing a rseq commit or
-	 * returning a value read from a data structure indexed using
-	 * the cpu_id_start value.
+	 * kernel. Read by user-space with single-copy atomicity
+	 * semantics. This field should only be read by the thread which
+	 * registered this data structure. Aligned on 32-bit. Always
+	 * contains a value in the range of possible CPUs, although the
+	 * value may not be the actual current CPU (e.g. if rseq is not
+	 * initialized). This CPU number value should always be compared
+	 * against the value of the cpu_id field before performing a rseq
+	 * commit or returning a value read from a data structure indexed
+	 * using the cpu_id_start value.
 	 */
 	__u32 cpu_id_start;
 	/*
-	 * Restartable sequences cpu_id field. Updated by the kernel,
-	 * and read by user-space with single-copy atomicity semantics.
-	 * Aligned on 32-bit. Values RSEQ_CPU_ID_UNINITIALIZED and
-	 * RSEQ_CPU_ID_REGISTRATION_FAILED have a special semantic: the
-	 * former means "rseq uninitialized", and latter means "rseq
-	 * initialization failed". This value is meant to be read within
-	 * rseq critical sections and compared with the cpu_id_start
-	 * value previously read, before performing the commit instruction,
-	 * or read and compared with the cpu_id_start value before returning
-	 * a value loaded from a data structure indexed using the
-	 * cpu_id_start value.
+	 * Restartable sequences cpu_id field. Updated by the kernel.
+	 * Read by user-space with single-copy atomicity semantics. This
+	 * field should only be read by the thread which registered this
+	 * data structure. Aligned on 32-bit. Values
+	 * RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
+	 * have a special semantic: the former means "rseq uninitialized",
+	 * and latter means "rseq initialization failed". This value is
+	 * meant to be read within rseq critical sections and compared
+	 * with the cpu_id_start value previously read, before performing
+	 * the commit instruction, or read and compared with the
+	 * cpu_id_start value before returning a value loaded from a data
+	 * structure indexed using the cpu_id_start value.
 	 */
 	__u32 cpu_id;
 	/*
@@ -105,27 +102,44 @@ struct rseq {
 	 * targeted by the rseq_cs. Also needs to be set to NULL by user-space
 	 * before reclaiming memory that contains the targeted struct rseq_cs.
 	 *
-	 * Read and set by the kernel with single-copy atomicity semantics.
-	 * Set by user-space with single-copy atomicity semantics. Aligned
-	 * on 64-bit.
+	 * Read and set by the kernel. Set by user-space with single-copy
+	 * atomicity semantics. This field should only be updated by the
+	 * thread which registered this data structure. Aligned on 64-bit.
 	 */
-	LINUX_FIELD_u32_u64(rseq_cs);
+	union {
+		__u64 ptr64;
+#ifdef __LP64__
+		__u64 ptr;
+#else
+		struct {
+#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN)
+			__u32 padding;		/* Initialized to zero. */
+			__u32 ptr32;
+#else /* LITTLE */
+			__u32 ptr32;
+			__u32 padding;		/* Initialized to zero. */
+#endif /* ENDIAN */
+		} ptr;
+#endif
+	} rseq_cs;
+
 	/*
-	 * - RSEQ_DISABLE flag:
+	 * Restartable sequences flags field.
+	 *
+	 * This field should only be updated by the thread which
+	 * registered this data structure. Read by the kernel.
+	 * Mainly used for single-stepping through rseq critical sections
+	 * with debuggers.
 	 *
-	 * Fallback fast-track flag for single-stepping.
-	 * Set by user-space if lack of progress is detected.
-	 * Cleared by user-space after rseq finish.
-	 * Read by the kernel.
 	 * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
-	 *     Inhibit instruction sequence block restart and event
-	 *     counter increment on preemption for this thread.
+	 *     Inhibit instruction sequence block restart on preemption
+	 *     for this thread.
 	 * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
-	 *     Inhibit instruction sequence block restart and event
-	 *     counter increment on signal delivery for this thread.
+	 *     Inhibit instruction sequence block restart on signal
+	 *     delivery for this thread.
 	 * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
-	 *     Inhibit instruction sequence block restart and event
-	 *     counter increment on migration for this thread.
+	 *     Inhibit instruction sequence block restart on migration for
+	 *     this thread.
 	 */
 	__u32 flags;
 } __attribute__((aligned(4 * sizeof(__u64))));

include/uapi/linux/types_32_64.h

-/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
-#ifndef _UAPI_LINUX_TYPES_32_64_H
-#define _UAPI_LINUX_TYPES_32_64_H
-
-/*
- * linux/types_32_64.h
- *
- * Integer type declaration for pointers across 32-bit and 64-bit systems.
- *
- * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- */
-
-#ifdef __KERNEL__
-# include <linux/types.h>
-#else
-# include <stdint.h>
-#endif
-
-#include <asm/byteorder.h>
-
-#ifdef __BYTE_ORDER
-# if (__BYTE_ORDER == __BIG_ENDIAN)
-#  define LINUX_BYTE_ORDER_BIG_ENDIAN
-# else
-#  define LINUX_BYTE_ORDER_LITTLE_ENDIAN
-# endif
-#else
-# ifdef __BIG_ENDIAN
-#  define LINUX_BYTE_ORDER_BIG_ENDIAN
-# else
-#  define LINUX_BYTE_ORDER_LITTLE_ENDIAN
-# endif
-#endif
-
-#ifdef __LP64__
-# define LINUX_FIELD_u32_u64(field)			__u64 field
-# define LINUX_FIELD_u32_u64_INIT_ONSTACK(field, v)	field = (intptr_t)v
-#else
-# ifdef LINUX_BYTE_ORDER_BIG_ENDIAN
-#  define LINUX_FIELD_u32_u64(field)	__u32 field ## _padding, field
-#  define LINUX_FIELD_u32_u64_INIT_ONSTACK(field, v)	\
-	field ## _padding = 0, field = (intptr_t)v
-# else
-#  define LINUX_FIELD_u32_u64(field)	__u32 field, field ## _padding
-#  define LINUX_FIELD_u32_u64_INIT_ONSTACK(field, v)	\
-	field = (intptr_t)v, field ## _padding = 0
-# endif
-#endif
-
-#endif /* _UAPI_LINUX_TYPES_32_64_H */

kernel/rseq.c

@@ -85,9 +85,9 @@ static int rseq_update_cpu_id(struct task_struct *t)
 {
 	u32 cpu_id = raw_smp_processor_id();
 
-	if (__put_user(cpu_id, &t->rseq->cpu_id_start))
+	if (put_user(cpu_id, &t->rseq->cpu_id_start))
 		return -EFAULT;
-	if (__put_user(cpu_id, &t->rseq->cpu_id))
+	if (put_user(cpu_id, &t->rseq->cpu_id))
 		return -EFAULT;
 	trace_rseq_update(t);
 	return 0;
@@ -100,14 +100,14 @@ static int rseq_reset_rseq_cpu_id(struct task_struct *t)
 	/*
 	 * Reset cpu_id_start to its initial state (0).
 	 */
-	if (__put_user(cpu_id_start, &t->rseq->cpu_id_start))
+	if (put_user(cpu_id_start, &t->rseq->cpu_id_start))
 		return -EFAULT;
 	/*
 	 * Reset cpu_id to RSEQ_CPU_ID_UNINITIALIZED, so any user coming
 	 * in after unregistration can figure out that rseq needs to be
 	 * registered again.
 	 */
-	if (__put_user(cpu_id, &t->rseq->cpu_id))
+	if (put_user(cpu_id, &t->rseq->cpu_id))
 		return -EFAULT;
 	return 0;
 }
@@ -115,29 +115,36 @@ static int rseq_reset_rseq_cpu_id(struct task_struct *t)
 static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
 {
 	struct rseq_cs __user *urseq_cs;
-	unsigned long ptr;
+	u64 ptr;
 	u32 __user *usig;
 	u32 sig;
 	int ret;
 
-	ret = __get_user(ptr, &t->rseq->rseq_cs);
-	if (ret)
-		return ret;
+	if (copy_from_user(&ptr, &t->rseq->rseq_cs.ptr64, sizeof(ptr)))
+		return -EFAULT;
 	if (!ptr) {
 		memset(rseq_cs, 0, sizeof(*rseq_cs));
 		return 0;
 	}
-	urseq_cs = (struct rseq_cs __user *)ptr;
+	if (ptr >= TASK_SIZE)
+		return -EINVAL;
+	urseq_cs = (struct rseq_cs __user *)(unsigned long)ptr;
 	if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)))
 		return -EFAULT;
-	if (rseq_cs->version > 0)
-		return -EINVAL;
 
+	if (rseq_cs->start_ip >= TASK_SIZE ||
+	    rseq_cs->start_ip + rseq_cs->post_commit_offset >= TASK_SIZE ||
+	    rseq_cs->abort_ip >= TASK_SIZE ||
+	    rseq_cs->version > 0)
+		return -EINVAL;
+	/* Check for overflow. */
+	if (rseq_cs->start_ip + rseq_cs->post_commit_offset < rseq_cs->start_ip)
+		return -EINVAL;
 	/* Ensure that abort_ip is not in the critical section. */
 	if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset)
 		return -EINVAL;
 
-	usig = (u32 __user *)(rseq_cs->abort_ip - sizeof(u32));
+	usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32));
 	ret = get_user(sig, usig);
 	if (ret)
 		return ret;
@@ -146,7 +153,7 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
 		printk_ratelimited(KERN_WARNING
 			"Possible attack attempt. Unexpected rseq signature 0x%x, expecting 0x%x (pid=%d, addr=%p).\n",
 			sig, current->rseq_sig, current->pid, usig);
-		return -EPERM;
+		return -EINVAL;
 	}
 	return 0;
 }
@@ -157,7 +164,7 @@ static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
 	int ret;
 
 	/* Get thread flags. */
-	ret = __get_user(flags, &t->rseq->flags);
+	ret = get_user(flags, &t->rseq->flags);
 	if (ret)
 		return ret;
 
@@ -195,9 +202,11 @@ static int clear_rseq_cs(struct task_struct *t)
 	 * of code outside of the rseq assembly block. This performs
 	 * a lazy clear of the rseq_cs field.
 	 *
-	 * Set rseq_cs to NULL with single-copy atomicity.
+	 * Set rseq_cs to NULL.
 	 */
-	return __put_user(0UL, &t->rseq->rseq_cs);
+	if (clear_user(&t->rseq->rseq_cs.ptr64, sizeof(t->rseq->rseq_cs.ptr64)))
+		return -EFAULT;
+	return 0;
 }
 
 /*

tools/testing/selftests/rseq/rseq.h

@@ -133,17 +133,27 @@ static inline uint32_t rseq_current_cpu(void)
 	return cpu;
 }
 
+static inline void rseq_clear_rseq_cs(void)
+{
+#ifdef __LP64__
+	__rseq_abi.rseq_cs.ptr = 0;
+#else
+	__rseq_abi.rseq_cs.ptr.ptr32 = 0;
+#endif
+}
+
 /*
- * rseq_prepare_unload() should be invoked by each thread using rseq_finish*()
- * at least once between their last rseq_finish*() and library unload of the
- * library defining the rseq critical section (struct rseq_cs). This also
- * applies to use of rseq in code generated by JIT: rseq_prepare_unload()
- * should be invoked at least once by each thread using rseq_finish*() before
- * reclaim of the memory holding the struct rseq_cs.
+ * rseq_prepare_unload() should be invoked by each thread executing a rseq
+ * critical section at least once between their last critical section and
+ * library unload of the library defining the rseq critical section
+ * (struct rseq_cs). This also applies to use of rseq in code generated by
+ * JIT: rseq_prepare_unload() should be invoked at least once by each
+ * thread executing a rseq critical section before reclaim of the memory
+ * holding the struct rseq_cs.
  */
 static inline void rseq_prepare_unload(void)
 {
-	__rseq_abi.rseq_cs = 0;
+	rseq_clear_rseq_cs();
 }
 
 #endif  /* RSEQ_H_ */