Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422878AbWBNXsA (ORCPT ); Tue, 14 Feb 2006 18:48:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422874AbWBNXsA (ORCPT ); Tue, 14 Feb 2006 18:48:00 -0500 Received: from xproxy.gmail.com ([66.249.82.202]:38591 "EHLO xproxy.gmail.com") by vger.kernel.org with ESMTP id S1422875AbWBNXr6 (ORCPT ); Tue, 14 Feb 2006 18:47:58 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:date:from:to:cc:subject:message-id:x-mailer:mime-version:content-type:content-transfer-encoding; b=IwtLwizRFI4VFvKPc4a9P0zYo+4HP1r7KvWO+YH0LUEpfQQLQb7e6LQ1QDko5s0HDTfL99BIIUekv6r62dr8JmTB9wxJJ3sCmdIkcntUuF8sNmU+RhTPMMFwzYcP2FsJTODGjsBjr6rKWuiBbQwr/O376J3gyAUiln/G/vfXnko= Date: Tue, 14 Feb 2006 21:47:47 -0300 From: Davi Arnaut To: akpm@osdl.org Cc: davi.arnaut@gmail.com, linux-kernel@vger.kernel.org Subject: [PATH 0/2] strndup_user, description Message-Id: <20060214214747.ef05e4d8.davi.arnaut@gmail.com> X-Mailer: Sylpheed Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2240 Lines: 86 This patch series creates a strndup_user() function in order to avoid duplicated and error-prone (userspace modifying the string after the strlen_user()) code. The diffstat: include/linux/string.h | 3 + kernel/module.c | 19 +------- mm/util.c | 37 +++++++++++++++ security/keys/keyctl.c | 116 ++++++++++--------------------------------------- 4 files changed, 68 insertions(+), 107 deletions(-) Signed-off-by: Davi Arnaut -- diff --git a/include/linux/string.h b/include/linux/string.h index 369be32..2cb2dc8 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -18,6 +18,9 @@ extern char * strsep(char **,const char extern __kernel_size_t strspn(const char *,const char *); extern __kernel_size_t strcspn(const char *,const char *); +#define strdup_user(s) strndup_user(s, PAGE_SIZE) +extern char *strndup_user(const char __user *, long); + /* * Include machine specific inline routines */ diff --git a/mm/util.c b/mm/util.c index 5f4bb59..09c2c3b 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1,6 +1,8 @@ #include #include #include +#include +#include /** * kzalloc - allocate memory. The memory is set to zero. @@ -37,3 +39,38 @@ char *kstrdup(const char *s, gfp_t gfp) return buf; } EXPORT_SYMBOL(kstrdup); + +/* + * strndup_user - duplicate an existing string from user space + * + * @s: The string to duplicate + * @n: Maximum number of bytes to copy, including the trailing NUL. + */ +char *strndup_user(const char __user *s, long n) +{ + char *p; + long length; + + length = strlen_user(s); + + if (!length) + return ERR_PTR(-EFAULT); + + if (length > n) + length = n; + + p = kmalloc(length, GFP_KERNEL); + + if (!p) + return ERR_PTR(-ENOMEM); + + if (strncpy_from_user(p, s, length) < 0) { + kfree(p); + return ERR_PTR(-EFAULT); + } + + p[length - 1] = '\0'; + + return p; +} +EXPORT_SYMBOL(strndup_user); - 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/