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authorMasami Hiramatsu <mhiramat@kernel.org>2019-05-15 14:38:18 +0900
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-05-25 23:04:42 -0400
commit3d7081822f7f9eab867d9bcc8fd635208ec438e0 (patch)
tree8afb5e61c1f23305996d4a8e03dedd7c048de01d /include/linux/uaccess.h
parent2d8d8fac3b4eab035dcd0068e1f5a746a697fbb3 (diff)
uaccess: Add non-pagefault user-space read functions
Add probe_user_read(), strncpy_from_unsafe_user() and strnlen_unsafe_user() which allows caller to access user-space in IRQ context. Current probe_kernel_read() and strncpy_from_unsafe() are not available for user-space memory, because it sets KERNEL_DS while accessing data. On some arch, user address space and kernel address space can be co-exist, but others can not. In that case, setting KERNEL_DS means given address is treated as a kernel address space. Also strnlen_user() is only available from user context since it can sleep if pagefault is enabled. To access user-space memory without pagefault, we need these new functions which sets USER_DS while accessing the data. Link: http://lkml.kernel.org/r/155789869802.26965.4940338412595759063.stgit@devnote2 Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/uaccess.h')
-rw-r--r--include/linux/uaccess.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 5a43ef7db492..9c435c3f2105 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -243,6 +243,17 @@ extern long probe_kernel_read(void *dst, const void *src, size_t size);
extern long __probe_kernel_read(void *dst, const void *src, size_t size);
/*
+ * probe_user_read(): safely attempt to read from a location in user space
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_user_read(void *dst, const void __user *src, size_t size);
+
+/*
* probe_kernel_write(): safely attempt to write to a location
* @dst: address to write to
* @src: pointer to the data that shall be written
@@ -255,6 +266,9 @@ extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
extern long notrace __probe_kernel_write(void *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_user(char *dst, const void __user *unsafe_addr,
+ long count);
+extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count);
/**
* probe_kernel_address(): safely attempt to read from a location