The patch titled
Subject: maccess: always use strict semantics for probe_kernel_read
has been removed from the -mm tree. Its filename was
maccess-always-use-strict-semantics-for-probe_kernel_read.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: maccess: always use strict semantics for probe_kernel_read
Except for historical confusion in the kprobes/uprobes and bpf tracers,
which has been fixed now, there is no good reason to ever allow user
memory accesses from probe_kernel_read. Switch probe_kernel_read to only
read from kernel memory.
[akpm@xxxxxxxxxxxxxxxxxxxx: update it for "mm, dump_page(): do not crash with invalid mapping pointer"]
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/parisc/lib/memcpy.c | 2 -
arch/um/kernel/maccess.c | 2 -
arch/x86/mm/maccess.c | 9 +------
include/linux/uaccess.h | 4 ---
kernel/trace/bpf_trace.c | 2 -
kernel/trace/trace_kprobe.c | 4 +--
mm/debug.c | 10 ++++----
mm/maccess.c | 40 +++++-----------------------------
8 files changed, 19 insertions(+), 54 deletions(-)
--- a/arch/parisc/lib/memcpy.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/arch/parisc/lib/memcpy.c
@@ -57,7 +57,7 @@ void * memcpy(void * dst,const void *src
EXPORT_SYMBOL(raw_copy_in_user);
EXPORT_SYMBOL(memcpy);
-bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size)
{
if ((unsigned long)unsafe_src < PAGE_SIZE)
return false;
--- a/arch/um/kernel/maccess.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/arch/um/kernel/maccess.c
@@ -7,7 +7,7 @@
#include <linux/kernel.h>
#include <os.h>
-bool probe_kernel_read_allowed(const void *src, size_t size, bool strict)
+bool probe_kernel_read_allowed(const void *src, size_t size)
{
void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
--- a/arch/x86/mm/maccess.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/arch/x86/mm/maccess.c
@@ -9,13 +9,10 @@ static __always_inline u64 canonical_add
return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
}
-bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size)
{
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
@@ -25,10 +22,8 @@ bool probe_kernel_read_allowed(const voi
canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
}
#else
-bool probe_kernel_read_allowed(const void *unsafe_src, size_t size, bool strict)
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size)
{
- if (!strict)
- return true;
return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
}
#endif
--- a/include/linux/uaccess.h~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/include/linux/uaccess.h
@@ -301,11 +301,9 @@ copy_struct_from_user(void *dst, size_t
return 0;
}
-bool probe_kernel_read_allowed(const void *unsafe_src, size_t size,
- bool strict);
+bool probe_kernel_read_allowed(const void *unsafe_src, size_t size);
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_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);
--- a/kernel/trace/bpf_trace.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/kernel/trace/bpf_trace.c
@@ -196,7 +196,7 @@ bpf_probe_read_kernel_common(void *dst,
if (unlikely(ret < 0))
goto fail;
- ret = probe_kernel_read_strict(dst, unsafe_ptr, size);
+ ret = probe_kernel_read(dst, unsafe_ptr, size);
if (unlikely(ret < 0))
goto fail;
return ret;
--- a/kernel/trace/trace_kprobe.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/kernel/trace/trace_kprobe.c
@@ -1222,7 +1222,7 @@ fetch_store_strlen(unsigned long addr)
#endif
do {
- ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1);
+ ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
@@ -1300,7 +1300,7 @@ probe_mem_read(void *dest, void *src, si
if ((unsigned long)src < TASK_SIZE)
return probe_mem_read_user(dest, src, size);
#endif
- return probe_kernel_read_strict(dest, src, size);
+ return probe_kernel_read(dest, src, size);
}
/* Note that we don't verify it, since the code does not come from user space */
--- a/mm/debug.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/mm/debug.c
@@ -120,9 +120,9 @@ void __dump_page(struct page *page, cons
* mapping can be invalid pointer and we don't want to crash
* accessing it, so probe everything depending on it carefully
*/
- if (probe_kernel_read_strict(&host, &mapping->host,
- sizeof(struct inode *)) ||
- probe_kernel_read_strict(&a_ops, &mapping->a_ops,
+ if (probe_kernel_read(&host, &mapping->host,
+ sizeof(struct inode *)) ||
+ probe_kernel_read(&a_ops, &mapping->a_ops,
sizeof(struct address_space_operations *))) {
pr_warn("failed to read mapping->host or a_ops, mapping not a valid kernel address?\n");
goto out_mapping;
@@ -133,7 +133,7 @@ void __dump_page(struct page *page, cons
goto out_mapping;
}
- if (probe_kernel_read_strict(&dentry_first,
+ if (probe_kernel_read(&dentry_first,
&host->i_dentry.first, sizeof(struct hlist_node *))) {
pr_warn("mapping->a_ops:%ps with invalid mapping->host inode address %px\n",
a_ops, host);
@@ -146,7 +146,7 @@ void __dump_page(struct page *page, cons
}
dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
- if (probe_kernel_read_strict(&dentry, dentry_ptr,
+ if (probe_kernel_read(&dentry, dentry_ptr,
sizeof(struct dentry))) {
pr_warn("mapping->aops:%ps with invalid mapping->host->i_dentry.first %px\n",
a_ops, dentry_ptr);
--- a/mm/maccess.c~maccess-always-use-strict-semantics-for-probe_kernel_read
+++ a/mm/maccess.c
@@ -6,36 +6,13 @@
#include <linux/mm.h>
#include <linux/uaccess.h>
-static long __probe_kernel_read(void *dst, const void *src, size_t size,
- bool strict);
-
-bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size,
- bool strict)
+bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size)
{
return true;
}
/**
- * probe_kernel_read(): safely attempt to read from any location
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from
- * @size: size of the data chunk
- *
- * Same as probe_kernel_read_strict() except that for architectures with
- * not fully separated user and kernel address spaces this function also works
- * for user address tanges.
- *
- * 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 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
+ * probe_kernel_read(): safely attempt to read from kernel-space
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
* @size: size of the data chunk
@@ -48,18 +25,12 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
* probe_kernel_read() suitable for use within regions where the caller
* already holds mmap_lock, or other locks which nest inside mmap_lock.
*/
-long probe_kernel_read_strict(void *dst, const void *src, size_t size)
-{
- return __probe_kernel_read(dst, src, size, true);
-}
-
-static long __probe_kernel_read(void *dst, const void *src, size_t size,
- bool strict)
+long probe_kernel_read(void *dst, const void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
- if (!probe_kernel_read_allowed(src, size, strict))
+ if (!probe_kernel_read_allowed(src, size))
return -EFAULT;
set_fs(KERNEL_DS);
@@ -73,6 +44,7 @@ static long __probe_kernel_read(void *ds
return -EFAULT;
return 0;
}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
/**
* probe_user_read(): safely attempt to read from a user-space location
@@ -181,7 +153,7 @@ long strncpy_from_kernel_nofault(char *d
if (unlikely(count <= 0))
return 0;
- if (!probe_kernel_read_allowed(unsafe_addr, count, true))
+ if (!probe_kernel_read_allowed(unsafe_addr, count))
return -EFAULT;
set_fs(KERNEL_DS);
_
Patches currently in -mm which might be from hch@xxxxxx are
amdgpu-a-null-mm-does-not-mean-a-thread-is-a-kthread.patch
kernel-move-use_mm-unuse_mm-to-kthreadc.patch
kernel-move-use_mm-unuse_mm-to-kthreadc-v2.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract.patch
kernel-better-document-the-use_mm-unuse_mm-api-contract-v2.patch
kernel-set-user_ds-in-kthread_use_mm.patch
