Messages in this thread Patch in this message | | | Date | Tue, 14 Feb 2006 21:47:47 -0300 | From | Davi Arnaut <> | Subject | [PATH 0/2] strndup_user, description |
| |
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 <davi.arnaut@gmail.com> --
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 <linux/slab.h> #include <linux/string.h> #include <linux/module.h> +#include <linux/err.h> +#include <asm/uaccess.h> /** * 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/
| |