Linux-parisc archive on lore.kernel.org
 help / color / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: x86@kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-parisc@vger.kernel.org, linux-um@lists.infradead.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 10/23] maccess: unify the probe kernel arch hooks
Date: Thu, 21 May 2020 17:22:48 +0200
Message-ID: <20200521152301.2587579-11-hch@lst.de> (raw)
In-Reply-To: <20200521152301.2587579-1-hch@lst.de>

Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants.  Just provide a single arch hooks instead to
make sure all architectures cover all the cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/parisc/lib/memcpy.c | 12 ++++------
 arch/um/kernel/maccess.c | 10 ++++----
 arch/x86/mm/maccess.c    | 33 ++++++++++-----------------
 include/linux/uaccess.h  |  6 +++--
 mm/maccess.c             | 49 ++++++++++++++++++++++++++++++----------
 5 files changed, 61 insertions(+), 49 deletions(-)

diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c
index beceaab34ecb7..5b75c35d1da0d 100644
--- a/arch/parisc/lib/memcpy.c
+++ b/arch/parisc/lib/memcpy.c
@@ -57,14 +57,10 @@ void * memcpy(void * dst,const void *src, size_t count)
 EXPORT_SYMBOL(raw_copy_in_user);
 EXPORT_SYMBOL(memcpy);
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
 {
-	unsigned long addr = (unsigned long)src;
-
-	if (addr < PAGE_SIZE)
-		return -EFAULT;
-
+	if ((unsigned long)unsafe_src < PAGE_SIZE)
+		return false;
 	/* check for I/O space F_EXTEND(0xfff00000) access as well? */
-
-	return __probe_kernel_read(dst, src, size);
+	return true;
 }
diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c
index 67b2e0fa92bba..ad2c538ce497c 100644
--- a/arch/um/kernel/maccess.c
+++ b/arch/um/kernel/maccess.c
@@ -7,15 +7,13 @@
 #include <linux/kernel.h>
 #include <os.h>
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+bool probe_kernel_read_allowed(const void *src, size_t size, bool strict)
 {
 	void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
 
 	if ((unsigned long)src < PAGE_SIZE || size <= 0)
-		return -EFAULT;
-
+		return false;
 	if (os_mincore(psrc, size + src - psrc) <= 0)
-		return -EFAULT;
-
-	return __probe_kernel_read(dst, src, size);
+		return false;
+	return true;
 }
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
index 62c4017a2473d..a96a56ff16109 100644
--- a/arch/x86/mm/maccess.c
+++ b/arch/x86/mm/maccess.c
@@ -9,35 +9,26 @@ static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
 	return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
 }
 
-static __always_inline bool invalid_probe_range(u64 vaddr)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
 {
+	unsigned long vaddr = (unsigned long)unsafe_src;
+
+	if (!strict)
+		return true;
+
 	/*
 	 * Range covering the highest possible canonical userspace address
 	 * as well as non-canonical address range. For the canonical range
 	 * we also need to include the userspace guard page.
 	 */
-	return vaddr < TASK_SIZE_MAX + PAGE_SIZE ||
-	       canonical_address(vaddr, boot_cpu_data.x86_virt_bits) != vaddr;
+	return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
+	       canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
 }
 #else
-static __always_inline bool invalid_probe_range(u64 vaddr)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
 {
-	return vaddr < TASK_SIZE_MAX;
+	if (!strict)
+		return true;
+	return (unsigned long)vaddr >= TASK_SIZE_MAX;
 }
 #endif
-
-long probe_kernel_read_strict(void *dst, const void *src, size_t size)
-{
-	if (unlikely(invalid_probe_range((unsigned long)src)))
-		return -EFAULT;
-
-	return __probe_kernel_read(dst, src, size);
-}
-
-long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
-{
-	if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))
-		return -EFAULT;
-
-	return __strncpy_from_unsafe(dst, unsafe_addr, count);
-}
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index d8366f8468664..65a37ae3b8871 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -301,9 +301,11 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
 	return 0;
 }
 
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size,
+		bool strict);
+
 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 extern long probe_kernel_read_strict(void *dst, const void *src, size_t size);
-extern long __probe_kernel_read(void *dst, const void *src, size_t size);
 extern long probe_user_read(void *dst, const void __user *src, size_t size);
 
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
@@ -312,7 +314,7 @@ extern long notrace probe_user_write(void __user *dst, const void *src, size_t s
 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 		long count);
-extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
+
 long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 		long count);
 long strnlen_user_nofault(const void __user *unsafe_addr, long count);
diff --git a/mm/maccess.c b/mm/maccess.c
index 31cf6604e7fff..6116742608217 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -6,6 +6,17 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
+static long __probe_kernel_read(void *dst, const void *src, size_t size,
+		bool strict);
+static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
+		long count, bool strict);
+
+bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size,
+		bool strict)
+{
+	return true;
+}
+
 /**
  * probe_kernel_read(): safely attempt to read from any location
  * @dst: pointer to the buffer that shall take the data
@@ -19,8 +30,11 @@
  * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
  * separate kernel and user address spaces, and also a bad idea otherwise.
  */
-long __weak probe_kernel_read(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_read")));
+long probe_kernel_read(void *dst, const void *src, size_t size)
+{
+	return __probe_kernel_read(dst, src, size, false);
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
 
 /**
  * probe_kernel_read_strict(): safely attempt to read from kernel-space
@@ -36,14 +50,20 @@ long __weak probe_kernel_read(void *dst, const void *src, size_t size)
  * probe_kernel_read() suitable for use within regions where the caller
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  */
-long __weak probe_kernel_read_strict(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_read")));
+long probe_kernel_read_strict(void *dst, const void *src, size_t size)
+{
+	return __probe_kernel_read(dst, src, size, true);
+}
 
-long __probe_kernel_read(void *dst, const void *src, size_t size)
+static long __probe_kernel_read(void *dst, const void *src, size_t size,
+		bool strict)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
 
+	if (!probe_kernel_read_allowed(src, size, strict))
+		return -EFAULT;
+
 	set_fs(KERNEL_DS);
 	pagefault_disable();
 	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
@@ -55,7 +75,6 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_read);
 
 /**
  * probe_user_read(): safely attempt to read from a user-space location
@@ -161,8 +180,10 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
  * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
  * separate kernel and user address spaces, and also a bad idea otherwise.
  */
-long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
-    __attribute__((alias("__strncpy_from_unsafe")));
+long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+{
+	return __strncpy_from_unsafe(dst, unsafe_addr, count, false);
+}
 
 /**
  * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
@@ -182,11 +203,13 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  */
-long __weak strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
-				       long count)
-    __attribute__((alias("__strncpy_from_unsafe")));
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
+{
+	return __strncpy_from_unsafe(dst, unsafe_addr, count, true);
+}
 
-long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
+		long count, bool strict)
 {
 	mm_segment_t old_fs = get_fs();
 	const void *src = unsafe_addr;
@@ -194,6 +217,8 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
 
 	if (unlikely(count <= 0))
 		return 0;
+	if (!probe_kernel_read_allowed(unsafe_addr, count, strict))
+		return -EFAULT;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
-- 
2.26.2


  parent reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-21 15:22 clean up and streamline probe_kernel_* and friends v4 Christoph Hellwig
2020-05-21 15:22 ` [PATCH 01/23] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
2020-05-21 15:22 ` [PATCH 02/23] maccess: remove various unused weak aliases Christoph Hellwig
2020-05-21 15:22 ` [PATCH 03/23] maccess: remove duplicate kerneldoc comments Christoph Hellwig
2020-05-21 15:22 ` [PATCH 04/23] maccess: clarify " Christoph Hellwig
2020-05-21 15:22 ` [PATCH 05/23] maccess: update the top of file comment Christoph Hellwig
2020-05-21 15:22 ` [PATCH 06/23] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig
2020-05-21 15:22 ` [PATCH 07/23] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig
2020-05-21 15:22 ` [PATCH 08/23] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig
2020-05-21 15:22 ` [PATCH 09/23] maccess: remove probe_read_common and probe_write_common Christoph Hellwig
2020-05-21 15:22 ` Christoph Hellwig [this message]
2020-05-28  0:55   ` [PATCH 10/23] maccess: unify the probe kernel arch hooks Andrew Morton
2020-05-21 15:22 ` [PATCH 11/23] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig
2020-05-21 22:10   ` Andrii Nakryiko
2020-05-21 15:22 ` [PATCH 12/23] bpf: handle the compat string in bpf_trace_copy_string better Christoph Hellwig
2020-05-21 22:10   ` Andrii Nakryiko
2020-05-28  2:04   ` Andrew Morton
2020-05-28  2:26     ` Yonghong Song
2020-05-28  4:39       ` Christoph Hellwig
2020-05-28 17:06         ` Yonghong Song
2020-05-21 15:22 ` [PATCH 13/23] bpf: rework the compat kernel probe handling Christoph Hellwig
2020-05-21 22:10   ` Andrii Nakryiko
2020-05-21 15:22 ` [PATCH 14/23] tracing/kprobes: handle mixed kernel/userspace probes better Christoph Hellwig
2020-05-22  0:04   ` Masami Hiramatsu
2020-05-21 15:22 ` [PATCH 15/23] maccess: remove strncpy_from_unsafe Christoph Hellwig
2020-05-21 15:22 ` [PATCH 16/23] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
2020-05-21 15:22 ` [PATCH 17/23] maccess: move user access routines together Christoph Hellwig
2020-05-21 15:22 ` [PATCH 18/23] maccess: allow architectures to provide kernel probing directly Christoph Hellwig
2020-05-21 15:22 ` [PATCH 19/23] x86: use non-set_fs based maccess routines Christoph Hellwig
2020-05-21 15:22 ` [PATCH 20/23] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig
2020-05-21 15:22 ` [PATCH 21/23] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig
2020-05-21 15:23 ` [PATCH 22/23] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig
2020-05-21 15:23 ` [PATCH 23/23] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig
2020-05-21 18:03 ` clean up and streamline probe_kernel_* and friends v4 Linus Torvalds
2020-05-22  0:22 ` Masami Hiramatsu
2020-05-25 22:19 ` Andrew Morton
2020-05-26  6:13   ` Christoph Hellwig
2020-05-28  0:36     ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200521152301.2587579-11-hch@lst.de \
    --to=hch@lst.de \
    --cc=akpm@linux-foundation.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-um@lists.infradead.org \
    --cc=mhiramat@kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-parisc archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-parisc/0 linux-parisc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-parisc linux-parisc/ https://lore.kernel.org/linux-parisc \
		linux-parisc@vger.kernel.org
	public-inbox-index linux-parisc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-parisc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git