* [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
@ 2019-07-17 4:30 NitinGote
2019-07-22 17:30 ` Kees Cook
0 siblings, 1 reply; 7+ messages in thread
From: NitinGote @ 2019-07-17 4:30 UTC (permalink / raw)
To: joe, corbet; +Cc: akpm, apw, keescook, linux-doc, kernel-hardening, Nitin Gote
From: Nitin Gote <nitin.r.gote@intel.com>
Added check in checkpatch.pl to
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.
Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
---
Documentation/process/deprecated.rst | 6 +++---
scripts/checkpatch.pl | 24 ++++++++++++++++++++++++
2 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 49e0f64a3427..c348ef9d44f5 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
+strscpy(). If, however, the destination buffer still needs NUL-padding,
+the safe replacement is 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..1bb12127115d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -605,6 +605,20 @@ 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 __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 $mode_perms_world_writable = qr{
S_IWUGO |
S_IWOTH |
@@ -6446,6 +6460,16 @@ sub process {
"Deprecated use of '$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};
+ my $msg_level = \&WARN;
+ $msg_level = \&CHK if ($file);
+ &{$msg_level}("DEPRECATED_API",
+ "Deprecated use of '$deprecated_string_api', prefer '$new_api' instead\n" . $herecurr);
+ }
+
# check for various structs that are normally const (ops, kgdb, device_tree)
# and avoid what seem like struct definitions 'struct foo {'
if ($line !~ /\bconst\b/ &&
--
2.17.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-17 4:30 [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy NitinGote
@ 2019-07-22 17:30 ` Kees Cook
2019-07-22 17:40 ` Joe Perches
0 siblings, 1 reply; 7+ messages in thread
From: Kees Cook @ 2019-07-22 17:30 UTC (permalink / raw)
To: NitinGote; +Cc: joe, corbet, akpm, apw, linux-doc, kernel-hardening
On Wed, Jul 17, 2019 at 10:00:05AM +0530, NitinGote wrote:
> From: Nitin Gote <nitin.r.gote@intel.com>
>
> Added check in checkpatch.pl to
> 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.
>
> Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Joe, does this address your checkpatch concerns?
-Kees
> ---
> Documentation/process/deprecated.rst | 6 +++---
> scripts/checkpatch.pl | 24 ++++++++++++++++++++++++
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> index 49e0f64a3427..c348ef9d44f5 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
> +strscpy(). If, however, the destination buffer still needs NUL-padding,
> +the safe replacement is 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..1bb12127115d 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -605,6 +605,20 @@ 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 __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 $mode_perms_world_writable = qr{
> S_IWUGO |
> S_IWOTH |
> @@ -6446,6 +6460,16 @@ sub process {
> "Deprecated use of '$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};
> + my $msg_level = \&WARN;
> + $msg_level = \&CHK if ($file);
> + &{$msg_level}("DEPRECATED_API",
> + "Deprecated use of '$deprecated_string_api', prefer '$new_api' instead\n" . $herecurr);
> + }
> +
> # check for various structs that are normally const (ops, kgdb, device_tree)
> # and avoid what seem like struct definitions 'struct foo {'
> if ($line !~ /\bconst\b/ &&
> --
> 2.17.1
>
--
Kees Cook
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-22 17:30 ` Kees Cook
@ 2019-07-22 17:40 ` Joe Perches
2019-07-23 9:26 ` Gote, Nitin R
0 siblings, 1 reply; 7+ messages in thread
From: Joe Perches @ 2019-07-22 17:40 UTC (permalink / raw)
To: Kees Cook, NitinGote; +Cc: corbet, akpm, apw, linux-doc, kernel-hardening
On Mon, 2019-07-22 at 10:30 -0700, Kees Cook wrote:
> On Wed, Jul 17, 2019 at 10:00:05AM +0530, NitinGote wrote:
> > From: Nitin Gote <nitin.r.gote@intel.com>
> >
> > Added check in checkpatch.pl to
> > 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.
> >
> > Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> Joe, does this address your checkpatch concerns?
Well, kinda.
strscpy_pad isn't used anywhere in the kernel.
And
+ "strncpy" => "strscpy, strscpy_pad or for non-NUL-terminated strings, strncpy() can still be used, but destinations should be marked with __nonstring",
is a bit verbose. This could be simply:
+ "strncpy" => "strscpy - for non-NUL-terminated uses, strncpy() dst should be __nonstring",
And I still prefer adding stracpy as it
reduces code verbosity and eliminates defects.
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-22 17:40 ` Joe Perches
@ 2019-07-23 9:26 ` Gote, Nitin R
2019-07-24 18:17 ` Gote, Nitin R
0 siblings, 1 reply; 7+ messages in thread
From: Gote, Nitin R @ 2019-07-23 9:26 UTC (permalink / raw)
To: Joe Perches, Kees Cook; +Cc: corbet, akpm, apw, linux-doc, kernel-hardening
> -----Original Message-----
> From: Joe Perches [mailto:joe@perches.com]
> Sent: Monday, July 22, 2019 11:11 PM
> To: Kees Cook <keescook@chromium.org>; Gote, Nitin R
> <nitin.r.gote@intel.com>
> Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> Subject: Re: [PATCH v5] Documentation/checkpatch: Prefer
> strscpy/strscpy_pad over strcpy/strlcpy/strncpy
>
> On Mon, 2019-07-22 at 10:30 -0700, Kees Cook wrote:
> > On Wed, Jul 17, 2019 at 10:00:05AM +0530, NitinGote wrote:
> > > From: Nitin Gote <nitin.r.gote@intel.com>
> > >
> > > Added check in checkpatch.pl to
> > > 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.
> > >
> > > Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
> >
> > Reviewed-by: Kees Cook <keescook@chromium.org>
> >
> > Joe, does this address your checkpatch concerns?
>
> Well, kinda.
>
> strscpy_pad isn't used anywhere in the kernel.
>
> And
>
> + "strncpy" => "strscpy, strscpy_pad or for non-
> NUL-terminated strings, strncpy() can still be used, but destinations should
> be marked with __nonstring",
>
> is a bit verbose. This could be simply:
>
> + "strncpy" => "strscpy - for non-NUL-terminated uses, strncpy() dst
> should be __nonstring",
>
But, if the destination buffer needs extra NUL-padding for remaining size of destination,
then safe replacement is strscpy_pad(). Right? If yes, then what is your opinion on below change :
"strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated uses, strncpy() dst
should be __nonstring",
> And I still prefer adding stracpy as it
> reduces code verbosity and eliminates defects.
>
-Nitin
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-23 9:26 ` Gote, Nitin R
@ 2019-07-24 18:17 ` Gote, Nitin R
2019-07-24 18:29 ` Joe Perches
0 siblings, 1 reply; 7+ messages in thread
From: Gote, Nitin R @ 2019-07-24 18:17 UTC (permalink / raw)
To: Joe Perches, Kees Cook; +Cc: corbet, akpm, apw, linux-doc, kernel-hardening
Hi,
> -----Original Message-----
> From: Gote, Nitin R [mailto:nitin.r.gote@intel.com]
> Sent: Tuesday, July 23, 2019 2:56 PM
> To: Joe Perches <joe@perches.com>; Kees Cook <keescook@chromium.org>
> Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> Subject: RE: [PATCH v5] Documentation/checkpatch: Prefer
> strscpy/strscpy_pad over strcpy/strlcpy/strncpy
>
>
> > -----Original Message-----
> > From: Joe Perches [mailto:joe@perches.com]
> > Sent: Monday, July 22, 2019 11:11 PM
> > To: Kees Cook <keescook@chromium.org>; Gote, Nitin R
> > <nitin.r.gote@intel.com>
> > Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> > linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> > Subject: Re: [PATCH v5] Documentation/checkpatch: Prefer
> > strscpy/strscpy_pad over strcpy/strlcpy/strncpy
> >
> > On Mon, 2019-07-22 at 10:30 -0700, Kees Cook wrote:
> > > On Wed, Jul 17, 2019 at 10:00:05AM +0530, NitinGote wrote:
> > > > From: Nitin Gote <nitin.r.gote@intel.com>
> > > >
> > > > Added check in checkpatch.pl to
> > > > 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.
> > > >
> > > > Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
> > >
> > > Reviewed-by: Kees Cook <keescook@chromium.org>
> > >
> > > Joe, does this address your checkpatch concerns?
> >
> > Well, kinda.
> >
> > strscpy_pad isn't used anywhere in the kernel.
> >
> > And
> >
> > + "strncpy" => "strscpy, strscpy_pad or
> for non-
> > NUL-terminated strings, strncpy() can still be used, but destinations
> > should be marked with __nonstring",
> >
> > is a bit verbose. This could be simply:
> >
> > + "strncpy" => "strscpy - for non-NUL-terminated uses,
> > + strncpy() dst
> > should be __nonstring",
> >
>
Could you please give your opinion on below comment.
> But, if the destination buffer needs extra NUL-padding for remaining size of
> destination, then safe replacement is strscpy_pad(). Right? If yes, then what
> is your opinion on below change :
>
> "strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated uses,
> strncpy() dst should be __nonstring",
>
>
If you agree on this, then I will include this change in next patch version.
> -Nitin
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-24 18:17 ` Gote, Nitin R
@ 2019-07-24 18:29 ` Joe Perches
2019-07-25 7:26 ` Gote, Nitin R
0 siblings, 1 reply; 7+ messages in thread
From: Joe Perches @ 2019-07-24 18:29 UTC (permalink / raw)
To: Gote, Nitin R, Kees Cook; +Cc: corbet, akpm, apw, linux-doc, kernel-hardening
On Wed, 2019-07-24 at 18:17 +0000, Gote, Nitin R wrote:
> Hi,
Hi again.
[]
> > > > > 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
Please remember there does not exist a single actual use
of strscpy_pad in the kernel sources and no apparent real
need for it. I don't find one anyway.
> Could you please give your opinion on below comment.
>
> > But, if the destination buffer needs extra NUL-padding for remaining size of
> > destination, then safe replacement is strscpy_pad(). Right? If yes, then what
> > is your opinion on below change :
> >
> > "strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated uses,
> > strncpy() dst should be __nonstring",
> >
> If you agree on this, then I will include this change in next patch version.
Two things:
The kernel-doc documentation uses dest not dst.
I think stracpy should be preferred over strscpy.
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy
2019-07-24 18:29 ` Joe Perches
@ 2019-07-25 7:26 ` Gote, Nitin R
0 siblings, 0 replies; 7+ messages in thread
From: Gote, Nitin R @ 2019-07-25 7:26 UTC (permalink / raw)
To: Joe Perches, Kees Cook; +Cc: corbet, akpm, apw, linux-doc, kernel-hardening
> -----Original Message-----
> From: Joe Perches [mailto:joe@perches.com]
> Sent: Wednesday, July 24, 2019 11:59 PM
> To: Gote, Nitin R <nitin.r.gote@intel.com>; Kees Cook
> <keescook@chromium.org>
> Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> Subject: Re: [PATCH v5] Documentation/checkpatch: Prefer
> strscpy/strscpy_pad over strcpy/strlcpy/strncpy
>
> On Wed, 2019-07-24 at 18:17 +0000, Gote, Nitin R wrote:
> > Hi,
>
> Hi again.
>
> []
> > > > > > 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
>
> Please remember there does not exist a single actual use of strscpy_pad in
> the kernel sources and no apparent real need for it. I don't find one anyway.
>
Thanks for clarification. I will remove strscpy_pad() from patch.
> > Could you please give your opinion on below comment.
> >
> > > But, if the destination buffer needs extra NUL-padding for remaining
> > > size of destination, then safe replacement is strscpy_pad(). Right?
> > > If yes, then what is your opinion on below change :
> > >
> > > "strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated
> > > uses,
> > > strncpy() dst should be __nonstring",
> > >
> > If you agree on this, then I will include this change in next patch version.
>
> Two things:
>
> The kernel-doc documentation uses dest not dst.
Noted. I will correct this.
> I think stracpy should be preferred over strscpy.
>
Agreed.
I will use stracpy() instead of strscpy().
Thanks,
Nitin
^ permalink raw reply [flat|nested] 7+ messages in thread
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2019-07-17 4:30 [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy NitinGote
2019-07-22 17:30 ` Kees Cook
2019-07-22 17:40 ` Joe Perches
2019-07-23 9:26 ` Gote, Nitin R
2019-07-24 18:17 ` Gote, Nitin R
2019-07-24 18:29 ` Joe Perches
2019-07-25 7:26 ` Gote, Nitin R
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