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| author |   Masami Hiramatsu <mhiramat@kernel.org> | 2019-05-15 14:38:18 +0900 |
|---|---|---|
| committer |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-05-25 23:04:42 -0400 |
| commit | 3d7081822f7f9eab867d9bcc8fd635208ec438e0 (patch) | |
| tree | 8afb5e61c1f23305996d4a8e03dedd7c048de01d /include/linux/uaccess.h | |
| parent | x86/uaccess: Allow access_ok() in irq context if pagefault_disabled (diff) | |
| download | linux-dev-3d7081822f7f9eab867d9bcc8fd635208ec438e0.tar.xz linux-dev-3d7081822f7f9eab867d9bcc8fd635208ec438e0.zip | |
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.h | 14 |
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 |