Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753698AbbHaP51 (ORCPT ); Mon, 31 Aug 2015 11:57:27 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:33544 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752877AbbHaP50 (ORCPT ); Mon, 31 Aug 2015 11:57:26 -0400 From: Alexei Starovoitov To: "David S. Miller" Cc: Fengguang Wu , Guenter Roeck , Steven Rostedt , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next] lib: move strncpy_from_unsafe() into mm/maccess.c Date: Mon, 31 Aug 2015 08:57:10 -0700 Message-Id: <1441036630-10124-1-git-send-email-ast@plumgrid.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4474 Lines: 131 To fix build errors: kernel/built-in.o: In function `bpf_trace_printk': bpf_trace.c:(.text+0x11a254): undefined reference to `strncpy_from_unsafe' kernel/built-in.o: In function `fetch_memory_string': trace_kprobe.c:(.text+0x11acf8): undefined reference to `strncpy_from_unsafe' move strncpy_from_unsafe() next to probe_kernel_read/write() which use the same memory access style. Reported-by: Fengguang Wu Reported-by: Guenter Roeck Fixes: 1a6877b9c0c2 ("lib: introduce strncpy_from_unsafe()") Signed-off-by: Alexei Starovoitov --- For configs without kprobes and bpf the cost of this unused function is ~200 bytes which I think is a better trade off vs creating new Kconfig selector just for this single function. Another alternative is to move it to kernel/trace/trace_kprobe.c, but then it will lose generality and probably should be removed from include/linux/uaccess.h, so mm/maccess.c looks the best. lib/strncpy_from_user.c | 41 ----------------------------------------- mm/maccess.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 41 deletions(-) diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index ead8c4a068d1..e0af6ff73d14 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -112,44 +112,3 @@ long strncpy_from_user(char *dst, const char __user *src, long count) return -EFAULT; } EXPORT_SYMBOL(strncpy_from_user); - -/** - * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address. - * @dst: Destination address, in kernel space. This buffer must be at - * least @count bytes long. - * @src: Unsafe address. - * @count: Maximum number of bytes to copy, including the trailing NUL. - * - * Copies a NUL-terminated string from unsafe address to kernel buffer. - * - * On success, returns the length of the string INCLUDING the trailing NUL. - * - * If access fails, returns -EFAULT (some data may have been copied - * and the trailing NUL added). - * - * 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 strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) -{ - mm_segment_t old_fs = get_fs(); - const void *src = unsafe_addr; - long ret; - - if (unlikely(count <= 0)) - return 0; - - set_fs(KERNEL_DS); - pagefault_disable(); - - do { - ret = __copy_from_user_inatomic(dst++, - (const void __user __force *)src++, 1); - } while (dst[-1] && ret == 0 && src - unsafe_addr < count); - - dst[-1] = '\0'; - pagefault_enable(); - set_fs(old_fs); - - return ret < 0 ? ret : src - unsafe_addr; -} diff --git a/mm/maccess.c b/mm/maccess.c index d53adf9ba84b..34fe24759ed1 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -60,3 +60,44 @@ long __probe_kernel_write(void *dst, const void *src, size_t size) return ret ? -EFAULT : 0; } EXPORT_SYMBOL_GPL(probe_kernel_write); + +/** + * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address. + * @dst: Destination address, in kernel space. This buffer must be at + * least @count bytes long. + * @src: Unsafe address. + * @count: Maximum number of bytes to copy, including the trailing NUL. + * + * Copies a NUL-terminated string from unsafe address to kernel buffer. + * + * On success, returns the length of the string INCLUDING the trailing NUL. + * + * If access fails, returns -EFAULT (some data may have been copied + * and the trailing NUL added). + * + * 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 strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) +{ + mm_segment_t old_fs = get_fs(); + const void *src = unsafe_addr; + long ret; + + if (unlikely(count <= 0)) + return 0; + + set_fs(KERNEL_DS); + pagefault_disable(); + + do { + ret = __copy_from_user_inatomic(dst++, + (const void __user __force *)src++, 1); + } while (dst[-1] && ret == 0 && src - unsafe_addr < count); + + dst[-1] = '\0'; + pagefault_enable(); + set_fs(old_fs); + + return ret < 0 ? ret : src - unsafe_addr; +} -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/