[libvirt] [PATCH v1 05/21] virfile: Introduce ACL helpers

[Michal Privoznik]

On 05.12.2016 15:00, Daniel P. Berrange wrote:
> On Thu, Nov 24, 2016 at 03:47:54PM +0100, Michal Privoznik wrote:
>> Namely, virFileGetACLs, virFileSetACLs, virFileFreeACLs and
>> virFileCopyACLs. These functions are going to be required when we
>> are creating /dev for qemu. We have copy anything that's in
>> host's /dev exactly as is. Including ACLs.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  configure.ac             | 10 +++++-
>>  src/Makefile.am          |  4 +--
>>  src/libvirt_private.syms |  4 +++
>>  src/util/virfile.c       | 81 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  src/util/virfile.h       | 11 +++++++
>>  5 files changed, 107 insertions(+), 3 deletions(-)
>>
>> diff --git a/configure.ac b/configure.ac
>> index 5661752..972b399 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -332,11 +332,19 @@ dnl Availability of various common headers (non-fatal if missing).
>>  AC_CHECK_HEADERS([pwd.h regex.h sys/un.h \
>>    sys/poll.h syslog.h mntent.h net/ethernet.h linux/magic.h \
>>    sys/un.h sys/syscall.h sys/sysctl.h netinet/tcp.h ifaddrs.h \
>> -  libtasn1.h sys/ucred.h sys/mount.h])
>> +  libtasn1.h sys/ucred.h sys/mount.h sys/acl.h])
>>  dnl Check whether endian provides handy macros.
>>  AC_CHECK_DECLS([htole64], [], [], [[#include <endian.h>]])
>>  AC_CHECK_FUNCS([stat stat64 __xstat __xstat64 lstat lstat64 __lxstat __lxstat64])
>>  
>> +ACL_CFLAGS=""
>> +ACL_LIBS=""
>> +if test "x$ac_cv_header_sys_acl_h" = "xyes" ; then
>> +    ACL_LIBS="-lacl"
>> +fi
>> +AC_SUBST([ACL_CFLAGS])
>> +AC_SUBST([ACL_LIBS])
>> +
>>  dnl We need to decide at configure time if libvirt will use real atomic
>>  dnl operations ("lock free") or emulated ones with a mutex.
>>  
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index b358e0e..c08a350 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -1125,12 +1125,12 @@ libvirt_util_la_SOURCES =					\
>>  libvirt_util_la_CFLAGS = $(CAPNG_CFLAGS) $(YAJL_CFLAGS) $(LIBNL_CFLAGS) \
>>  		$(AM_CFLAGS) $(AUDIT_CFLAGS) $(DEVMAPPER_CFLAGS) \
>>  		$(DBUS_CFLAGS) $(LDEXP_LIBM) $(NUMACTL_CFLAGS)	\
>> -		$(POLKIT_CFLAGS) $(GNUTLS_CFLAGS) \
>> +		$(POLKIT_CFLAGS) $(GNUTLS_CFLAGS) $(ACL_CFLAGS) \
>>  		-I$(srcdir)/conf
>>  libvirt_util_la_LIBADD = $(CAPNG_LIBS) $(YAJL_LIBS) $(LIBNL_LIBS) \
>>  		$(THREAD_LIBS) $(AUDIT_LIBS) $(DEVMAPPER_LIBS) \
>>  		$(LIB_CLOCK_GETTIME) $(DBUS_LIBS) $(MSCOM_LIBS) $(LIBXML_LIBS) \
>> -		$(SECDRIVER_LIBS) $(NUMACTL_LIBS) \
>> +		$(SECDRIVER_LIBS) $(NUMACTL_LIBS) $(ACL_LIBS) \
>>  		$(POLKIT_LIBS)
>>  
>>  
>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>> index ae563eb..5f560bf 100644
>> --- a/src/libvirt_private.syms
>> +++ b/src/libvirt_private.syms
>> @@ -1559,6 +1559,7 @@ virFileActivateDirOverride;
>>  virFileBindMountDevice;
>>  virFileBuildPath;
>>  virFileClose;
>> +virFileCopyACLs;
>>  virFileDeleteTree;
>>  virFileDirectFdFlag;
>>  virFileExists;
>> @@ -1568,6 +1569,8 @@ virFileFindHugeTLBFS;
>>  virFileFindMountPoint;
>>  virFileFindResource;
>>  virFileFindResourceFull;
>> +virFileFreeACLs;
>> +virFileGetACLs;
>>  virFileGetHugepageSize;
>>  virFileGetMountReverseSubtree;
>>  virFileGetMountSubtree;
>> @@ -1602,6 +1605,7 @@ virFileResolveAllLinks;
>>  virFileResolveLink;
>>  virFileRewrite;
>>  virFileSanitizePath;
>> +virFileSetACLs;
>>  virFileSetupDev;
>>  virFileSkipRoot;
>>  virFileStripSuffix;
>> diff --git a/src/util/virfile.c b/src/util/virfile.c
>> index 6200004..c777025 100644
>> --- a/src/util/virfile.c
>> +++ b/src/util/virfile.c
>> @@ -48,6 +48,9 @@
>>  #if HAVE_SYS_SYSCALL_H
>>  # include <sys/syscall.h>
>>  #endif
>> +#if HAVE_SYS_ACL_H
>> +# include <sys/acl.h>
>> +#endif
>>  
>>  #ifdef __linux__
>>  # if HAVE_LINUX_MAGIC_H
>> @@ -3573,3 +3576,81 @@ virFileBindMountDevice(const char *src ATTRIBUTE_UNUSED,
>>      return -1;
>>  }
>>  #endif /* !defined(HAVE_SYS_MOUNT_H) */
>> +
>> +
>> +#if defined(HAVE_SYS_ACL_H) && !defined(LIBVIRT_NSS) && !defined(LIBVIRT_SETUID_RPC_CLIENT)
> 
> You can simplify this by just adding #undef HAVE_SYS_ACL_H to config-post.h
> for both the NSS + SETUID blocks

Ah, will do.

> 
>> +int
>> +virFileGetACLs(const char *file,
>> +               void **acl)
>> +{
>> +    if (!(*acl = acl_get_file(file, ACL_TYPE_ACCESS)))
>> +        return -1;
>> +
>> +    return 0;
>> +}
>> +
>> +
>> +int
>> +virFileSetACLs(const char *file,
>> +               void *acl)
>> +{
>> +    if (acl_set_file(file, ACL_TYPE_ACCESS, acl) < 0)
>> +        return -1;
>> +
>> +    return 0;
>> +}
> 
> Should we consider doing virReportSystemError in these methods
> rather than letting the caller report the error, or is there
> a need for the caller to ignore errors in some cases ?

I'd rather not. If a filesystem is mounted with ACLs disabled, we can
avoid spurious errors in the logs ("Hey, I couldn't copy ACLs on
/dev/blaah") even if the error is properly ignored later in the code.
And then if GetACLs() doesn't report the error, no other *ACL() function
should.

Michal