summaryrefslogtreecommitdiff
path: root/include/linux/uaccess.h
diff options
context:
space:
mode:
authorDaniel Borkmann <daniel@iogearbox.net>2019-11-02 00:17:57 +0100
committerAlexei Starovoitov <ast@kernel.org>2019-11-02 12:39:12 -0700
commit75a1a607bb7e6d918be3aca11ec2214a275392f4 (patch)
treed6efb41d43ae96ded0960f19eac6f49a2aabf7b5 /include/linux/uaccess.h
parent1d1585ca0f48fe7ed95c3571f3e4a82b2b5045dc (diff)
uaccess: Add strict non-pagefault kernel-space read function
Add two new probe_kernel_read_strict() and strncpy_from_unsafe_strict() helpers which by default alias to the __probe_kernel_read() and the __strncpy_from_unsafe(), respectively, but can be overridden by archs which have non-overlapping address ranges for kernel space and user space in order to bail out with -EFAULT when attempting to probe user memory including non-canonical user access addresses [0]: 4-level page tables: user-space mem: 0x0000000000000000 - 0x00007fffffffffff non-canonical: 0x0000800000000000 - 0xffff7fffffffffff 5-level page tables: user-space mem: 0x0000000000000000 - 0x00ffffffffffffff non-canonical: 0x0100000000000000 - 0xfeffffffffffffff The idea is that these helpers are complementary to the probe_user_read() and strncpy_from_unsafe_user() which probe user-only memory. Both added helpers here do the same, but for kernel-only addresses. Both set of helpers are going to be used for BPF tracing. They also explicitly avoid throwing the splat for non-canonical user addresses from 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences"). For compat, the current probe_kernel_read() and strncpy_from_unsafe() are left as-is. [0] Documentation/x86/x86_64/mm.txt Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: x86@kernel.org Link: https://lore.kernel.org/bpf/eefeefd769aa5a013531f491a71f0936779e916b.1572649915.git.daniel@iogearbox.net
Diffstat (limited to 'include/linux/uaccess.h')
-rw-r--r--include/linux/uaccess.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 38555435a64a..67f016010aad 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -311,6 +311,7 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
* happens, handle that and return -EFAULT.
*/
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);
/*
@@ -350,6 +351,9 @@ extern long notrace probe_user_write(void __user *dst, const void *src, size_t s
extern long notrace __probe_user_write(void __user *dst, const void *src, size_t size);
extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
+extern long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
+ long count);
+extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
extern long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr,
long count);
extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count);