| Message ID | 153779152340.28003.6461494237075964365.stgit@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KEYS: Revert and replace incorrect UAPI fix | expand |
On Mon, 2018-09-24 at 13:18 +0100, David Howells wrote: > The keyctl_dh_params struct in uapi/linux/keyctl.h contains the > symbol > "private" which means that the header file will cause compilation > failure > if #included in to a C++ program. Further, the patch that added the > same > struct to the keyutils package named the symbol "priv", not > "private". > > The previous attempt to fix this (commit 8a2336e549d3) did so by > simply > renaming the kernel's copy of the field to dh_private, but this then > breaks > existing userspace and as such has to be reverted (which is done by > the > preceding patch). > > [And note, to those who think that wrapping the struct in extern "C" > {} > will work: it won't; that only changes how symbol names are > presented to > the assembler and linker.]. > > Instead, insert an anonymous union around the "private" member and > add a > second member in there with the name "priv" to match the one in the > keyutils package. The "private" member is then wrapped in > !__cplusplus > cpp-conditionals to hide it from C++. > > Fixes: ddbb41148724 ("KEYS: Add KEYCTL_DH_COMPUTE command") > Fixes: 8a2336e549d3 ("uapi/linux/keyctl.h: don't use C++ reserved > keyword as a struct member name") > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Randy Dunlap <rdunlap@infradead.org> > cc: Lubomir Rintel <lkundrak@v3.sk> > cc: James Morris <jmorris@namei.org> > cc: Mat Martineau <mathew.j.martineau@linux.intel.com> > cc: Stephan Mueller <smueller@chronox.de> > cc: Andrew Morton <akpm@linux-foundation.org> > cc: Linus Torvalds <torvalds@linux-foundation.org> > cc: stable@vger.kernel.org > --- > > include/uapi/linux/keyctl.h | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/keyctl.h > b/include/uapi/linux/keyctl.h > index 7b8c9e19bad1..0f3cb13db8e9 100644 > --- a/include/uapi/linux/keyctl.h > +++ b/include/uapi/linux/keyctl.h > @@ -65,7 +65,12 @@ > > /* keyctl structures */ > struct keyctl_dh_params { > - __s32 private; > + union { > +#ifndef __cplusplus > + __s32 private; > +#endif > + __s32 priv; > + }; > __s32 prime; > __s32 base; > }; > Thank you, checked that this works fine for libell build. Tested-by: Lubomir Rintel <lkundrak@v3.sk> Perhaps you may want to call the C++ friendly field "dh_private", because there might be C++ users that utilize it already. (The chance might be negligible though.). Lubo
On Mon, 24 Sep 2018, David Howells wrote: > The keyctl_dh_params struct in uapi/linux/keyctl.h contains the symbol > "private" which means that the header file will cause compilation failure > if #included in to a C++ program. Further, the patch that added the same > struct to the keyutils package named the symbol "priv", not "private". > > The previous attempt to fix this (commit 8a2336e549d3) did so by simply > renaming the kernel's copy of the field to dh_private, but this then breaks > existing userspace and as such has to be reverted (which is done by the > preceding patch). > > [And note, to those who think that wrapping the struct in extern "C" {} > will work: it won't; that only changes how symbol names are presented to > the assembler and linker.]. > > Instead, insert an anonymous union around the "private" member and add a > second member in there with the name "priv" to match the one in the > keyutils package. The "private" member is then wrapped in !__cplusplus > cpp-conditionals to hide it from C++. > > Fixes: ddbb41148724 ("KEYS: Add KEYCTL_DH_COMPUTE command") > Fixes: 8a2336e549d3 ("uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name") > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Randy Dunlap <rdunlap@infradead.org> > cc: Lubomir Rintel <lkundrak@v3.sk> > cc: James Morris <jmorris@namei.org> > cc: Mat Martineau <mathew.j.martineau@linux.intel.com> > cc: Stephan Mueller <smueller@chronox.de> > cc: Andrew Morton <akpm@linux-foundation.org> > cc: Linus Torvalds <torvalds@linux-foundation.org> > cc: stable@vger.kernel.org > --- > > include/uapi/linux/keyctl.h | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h > index 7b8c9e19bad1..0f3cb13db8e9 100644 > --- a/include/uapi/linux/keyctl.h > +++ b/include/uapi/linux/keyctl.h > @@ -65,7 +65,12 @@ > > /* keyctl structures */ > struct keyctl_dh_params { > - __s32 private; > + union { > +#ifndef __cplusplus > + __s32 private; > +#endif > + __s32 priv; > + }; > __s32 prime; > __s32 base; > }; > > Thanks David. This is an important fix for existing C userspace code, it would create a headache now and in to the future if the keyctl.h change introduced in v4.19-rc3 made it in to an official release. Please merge, James! Reviewed-By: Mat Martineau <mathew.j.martineau@linux.intel.com> -- Mat Martineau Intel OTC
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h index 7b8c9e19bad1..0f3cb13db8e9 100644 --- a/include/uapi/linux/keyctl.h +++ b/include/uapi/linux/keyctl.h @@ -65,7 +65,12 @@ /* keyctl structures */ struct keyctl_dh_params { - __s32 private; + union { +#ifndef __cplusplus + __s32 private; +#endif + __s32 priv; + }; __s32 prime; __s32 base; };
The keyctl_dh_params struct in uapi/linux/keyctl.h contains the symbol "private" which means that the header file will cause compilation failure if #included in to a C++ program. Further, the patch that added the same struct to the keyutils package named the symbol "priv", not "private". The previous attempt to fix this (commit 8a2336e549d3) did so by simply renaming the kernel's copy of the field to dh_private, but this then breaks existing userspace and as such has to be reverted (which is done by the preceding patch). [And note, to those who think that wrapping the struct in extern "C" {} will work: it won't; that only changes how symbol names are presented to the assembler and linker.]. Instead, insert an anonymous union around the "private" member and add a second member in there with the name "priv" to match the one in the keyutils package. The "private" member is then wrapped in !__cplusplus cpp-conditionals to hide it from C++. Fixes: ddbb41148724 ("KEYS: Add KEYCTL_DH_COMPUTE command") Fixes: 8a2336e549d3 ("uapi/linux/keyctl.h: don't use C++ reserved keyword as a struct member name") Signed-off-by: David Howells <dhowells@redhat.com> cc: Randy Dunlap <rdunlap@infradead.org> cc: Lubomir Rintel <lkundrak@v3.sk> cc: James Morris <jmorris@namei.org> cc: Mat Martineau <mathew.j.martineau@linux.intel.com> cc: Stephan Mueller <smueller@chronox.de> cc: Andrew Morton <akpm@linux-foundation.org> cc: Linus Torvalds <torvalds@linux-foundation.org> cc: stable@vger.kernel.org --- include/uapi/linux/keyctl.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)