| Message ID | 20190717043005.19627-1-nitin.r.gote@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy | expand |
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 >
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.
> -----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
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
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.
> -----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
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/ &&