[PATCH] docs: networking: Replace strncpy() with strscpy()

[PATCH] docs: networking: Replace strncpy() with strscpy()

[Kees Cook]

Replace example code's use of strncpy() with strscpy() functions. Using
strncpy() is considered deprecated:
https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 Documentation/input/joydev/joystick-api.rst | 2 +-
 Documentation/networking/packet_mmap.rst    | 2 +-
 Documentation/networking/tuntap.rst         | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/input/joydev/joystick-api.rst b/Documentation/input/joydev/joystick-api.rst
index af5934c10c1c..5db6dc6fe1c5 100644
--- a/Documentation/input/joydev/joystick-api.rst
+++ b/Documentation/input/joydev/joystick-api.rst
@@ -263,7 +263,7 @@ possible overrun should the name be too long::
 
 	char name[128];
 	if (ioctl(fd, JSIOCGNAME(sizeof(name)), name) < 0)
-		strncpy(name, "Unknown", sizeof(name));
+		strscpy(name, "Unknown", sizeof(name));
 	printf("Name: %s\n", name);
 
 
diff --git a/Documentation/networking/packet_mmap.rst b/Documentation/networking/packet_mmap.rst
index 500ef60b1b82..c5da1a5d93de 100644
--- a/Documentation/networking/packet_mmap.rst
+++ b/Documentation/networking/packet_mmap.rst
@@ -153,7 +153,7 @@ As capture, each frame contains two parts::
     struct ifreq s_ifr;
     ...
 
-    strncpy (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
+    strscpy_pad (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
 
     /* get interface index of eth0 */
     ioctl(this->socket, SIOCGIFINDEX, &s_ifr);
diff --git a/Documentation/networking/tuntap.rst b/Documentation/networking/tuntap.rst
index a59d1dd6fdcc..4d7087f727be 100644
--- a/Documentation/networking/tuntap.rst
+++ b/Documentation/networking/tuntap.rst
@@ -107,7 +107,7 @@ Note that the character pointer becomes overwritten with the real device name
        */
       ifr.ifr_flags = IFF_TUN;
       if( *dev )
-	 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
+	 strscpy_pad(ifr.ifr_name, dev, IFNAMSIZ);
 
       if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
 	 close(fd);
-- 
2.25.1

Re: [PATCH] docs: networking: Replace strncpy() with strscpy()

[Dmitry Torokhov]

On Wed, Jun 02, 2021 at 01:29:14PM -0700, Kees Cook wrote:
> Replace example code's use of strncpy() with strscpy() functions. Using
> strncpy() is considered deprecated:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  Documentation/input/joydev/joystick-api.rst | 2 +-

FWIW:

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

>  Documentation/networking/packet_mmap.rst    | 2 +-
>  Documentation/networking/tuntap.rst         | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/input/joydev/joystick-api.rst b/Documentation/input/joydev/joystick-api.rst
> index af5934c10c1c..5db6dc6fe1c5 100644
> --- a/Documentation/input/joydev/joystick-api.rst
> +++ b/Documentation/input/joydev/joystick-api.rst
> @@ -263,7 +263,7 @@ possible overrun should the name be too long::
>  
>  	char name[128];
>  	if (ioctl(fd, JSIOCGNAME(sizeof(name)), name) < 0)
> -		strncpy(name, "Unknown", sizeof(name));
> +		strscpy(name, "Unknown", sizeof(name));
>  	printf("Name: %s\n", name);
>  
>  
> diff --git a/Documentation/networking/packet_mmap.rst b/Documentation/networking/packet_mmap.rst
> index 500ef60b1b82..c5da1a5d93de 100644
> --- a/Documentation/networking/packet_mmap.rst
> +++ b/Documentation/networking/packet_mmap.rst
> @@ -153,7 +153,7 @@ As capture, each frame contains two parts::
>      struct ifreq s_ifr;
>      ...
>  
> -    strncpy (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
> +    strscpy_pad (s_ifr.ifr_name, "eth0", sizeof(s_ifr.ifr_name));
>  
>      /* get interface index of eth0 */
>      ioctl(this->socket, SIOCGIFINDEX, &s_ifr);
> diff --git a/Documentation/networking/tuntap.rst b/Documentation/networking/tuntap.rst
> index a59d1dd6fdcc..4d7087f727be 100644
> --- a/Documentation/networking/tuntap.rst
> +++ b/Documentation/networking/tuntap.rst
> @@ -107,7 +107,7 @@ Note that the character pointer becomes overwritten with the real device name
>         */
>        ifr.ifr_flags = IFF_TUN;
>        if( *dev )
> -	 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
> +	 strscpy_pad(ifr.ifr_name, dev, IFNAMSIZ);
>  
>        if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
>  	 close(fd);
> -- 
> 2.25.1
> 

Thanks.

-- 
Dmitry

Re: [PATCH] docs: networking: Replace strncpy() with strscpy()

[Jonathan Corbet]

Kees Cook <keescook@chromium.org> writes:

> Replace example code's use of strncpy() with strscpy() functions. Using
> strncpy() is considered deprecated:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  Documentation/input/joydev/joystick-api.rst | 2 +-
>  Documentation/networking/packet_mmap.rst    | 2 +-
>  Documentation/networking/tuntap.rst         | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)

Applied, thanks.

jon