[v2] Added warnings in checkpatch.pl script to :
diff mbox series

Message ID 20190709054055.21984-1-nitin.r.gote@intel.com
State New
Headers show
Series
  • [v2] Added warnings in checkpatch.pl script to :
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Commit Message

NitinGote July 9, 2019, 5:40 a.m. UTC
From: Nitin Gote <nitin.r.gote@intel.com>

1. Deprecate strcpy() in favor of strscpy().
2. Deprecate strlcpy() in favor of strscpy().
3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().

Updated strncpy() section in Documentation/process/deprecated.rst
to cover strscpy_pad() case.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
---
 Change log:
 v1->v2
 - For string related apis, created different %deprecated_string_api
   and these will get emitted at CHECK Level using command line option
   -f/--file to avoid bad patched from novice script users.

 This patch is already reviewed by mailing list
 kernel-hardening@lists.openwall.com. Refer below link
 <https://www.openwall.com/lists/kernel-hardening/2019/07/03/4>
Acked-by: Kees Cook <keescook@chromium.org>

 Documentation/process/deprecated.rst |  6 +++---
 scripts/checkpatch.pl                | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

--
2.17.1

Comments

Joe Perches July 9, 2019, 5:57 a.m. UTC | #1
On Tue, 2019-07-09 at 11:10 +0530, NitinGote wrote:
> From: Nitin Gote <nitin.r.gote@intel.com>
> 
> 1. Deprecate strcpy() in favor of strscpy().
> 2. Deprecate strlcpy() in favor of strscpy().
> 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
> 
> Updated strncpy() section in Documentation/process/deprecated.rst
> to cover strscpy_pad() case.
> 
> Acked-by: Kees Cook <keescook@chromium.org>

Kees, I think the concept is fine, but perhaps your
acked-by here isn't great.  There are a few clear
defects in the checkpatch code that you also might
have overlooked.

>  Change log:
>  v1->v2
>  - For string related apis, created different %deprecated_string_api
>    and these will get emitted at CHECK Level using command line option
>    -f/--file to avoid bad patched from novice script users.
> 

[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl

[]
> @@ -605,6 +605,21 @@ foreach my $entry (keys %deprecated_apis) {
>  }
>  $deprecated_apis_search = "(?:${deprecated_apis_search})";
> 
> +our %deprecated_string_apis = (
> +        "strcpy"                                => "strscpy",
> +        "strlcpy"                               => "strscpy",
> +        "strncpy"                               => "strscpy, strscpy_pad or for non-NUL-terminated strings,
> +         strncpy() can still be used, but destinations should be marked with the __nonstring",

This last strncpy line should not be on multiple lines.
checkpatch output is single line.

[]

> @@ -6446,6 +6461,16 @@ sub process {
>  			     "Deprecated use of '$deprecated_api', prefer '$new_api' instead\n" . $herecurr);
>  		}
> 
> +# check for string deprecated apis
> +                if ($line =~ /\b($deprecated_string_apis_search)\b\s*\(/) {
> +                        my $deprecated_string_api = $1;
> +                        my $new_api = $deprecated_string_apis{$deprecated_string_api};
> +			$check = 1;
> +                        CHK("DEPRECATED_API",
> +                             "Deprecated use of '$deprecated_string_api', prefer '$new_api' instead\n" . $herecurr);
> +			$check = 0;

nack.

Please use consistent tab indentation and no,
do not set and unset $check.

Please use the same style as the rest of the script
when emitting at different levels for -f uses

			my $msg_level = \&WARN;
			$msg_level = \&CHK if ($file);
			&{$msg_level}("DEPRECATED_API", etc...

Patch
diff mbox series

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 49e0f64a3427..f564de3caf76 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -93,9 +93,9 @@  will be NUL terminated. This can lead to various linear read overflows
 and other misbehavior due to the missing termination. It also NUL-pads the
 destination buffer if the source contents are shorter than the destination
 buffer size, which may be a needless performance penalty for callers using
-only NUL-terminated strings. The safe replacement is :c:func:`strscpy`.
-(Users of :c:func:`strscpy` still needing NUL-padding will need an
-explicit :c:func:`memset` added.)
+only NUL-terminated strings. In this case, the safe replacement is
+:c:func:`strscpy`. If, however, the destination buffer still needs
+NUL-padding, the safe replacement is :c:func:`strscpy_pad`.

 If a caller is using non-NUL-terminated strings, :c:func:`strncpy()` can
 still be used, but destinations should be marked with the `__nonstring
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index bb28b178d929..10bd72e99dc8 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -605,6 +605,21 @@  foreach my $entry (keys %deprecated_apis) {
 }
 $deprecated_apis_search = "(?:${deprecated_apis_search})";

+our %deprecated_string_apis = (
+        "strcpy"                                => "strscpy",
+        "strlcpy"                               => "strscpy",
+        "strncpy"                               => "strscpy, strscpy_pad or for non-NUL-terminated strings,
+         strncpy() can still be used, but destinations should be marked with the __nonstring",
+);
+
+#Create a search pattern for all these strings apis to speed up a loop below
+our $deprecated_string_apis_search = "";
+foreach my $entry (keys %deprecated_string_apis) {
+        $deprecated_string_apis_search .= '|' if ($deprecated_string_apis_search ne "");
+        $deprecated_string_apis_search .= $entry;
+}
+$deprecated_string_apis_search = "(?:${deprecated_string_apis_search})";
+
 our $mode_perms_world_writable = qr{
 	S_IWUGO		|
 	S_IWOTH		|
@@ -6446,6 +6461,16 @@  sub process {
 			     "Deprecated use of '$deprecated_api', prefer '$new_api' instead\n" . $herecurr);
 		}

+# check for string deprecated apis
+                if ($line =~ /\b($deprecated_string_apis_search)\b\s*\(/) {
+                        my $deprecated_string_api = $1;
+                        my $new_api = $deprecated_string_apis{$deprecated_string_api};
+			$check = 1;
+                        CHK("DEPRECATED_API",
+                             "Deprecated use of '$deprecated_string_api', prefer '$new_api' instead\n" . $herecurr);
+			$check = 0;
+                }
+
 # check for various structs that are normally const (ops, kgdb, device_tree)
 # and avoid what seem like struct definitions 'struct foo {'
 		if ($line !~ /\bconst\b/ &&