[Ocfs2-devel] [PATCH 23/30] ocfs2: Handles missing export should_remove_suid()

[Sunil Mushran]

Commits 01de85e057328ecbef36e108673b1e81059d54c1 and
d23a147bb6e8d467e8df73b6589888717da3b9ce in mainline added and exported
symbol should_remove_suid(). This patch allows one to build ocfs2 with
kernels having/not having these changes.

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
Signed-off-by: Joel Becker <joel.becker at oracle.com>
---
 Config.make.in                           |    1 +
 Makefile                                 |    3 +-
 configure.in                             |    6 +++++
 fs/ocfs2/Makefile                        |    4 +++
 kapi-compat/include/should_remove_suid.h |   37 ++++++++++++++++++++++++++++++
 5 files changed, 50 insertions(+), 1 deletions(-)
 create mode 100644 kapi-compat/include/should_remove_suid.h

diff --git a/Config.make.in b/Config.make.in
index a912f40..53792d0 100644
--- a/Config.make.in
+++ b/Config.make.in
@@ -68,6 +68,7 @@ NO_SU_MUTEX_IN_STRUCT_CONFIGFS_SUBSYSTEM = @NO_SU_MUTEX_IN_STRUCT_CONFIGFS_SUBSY
 STRUCT_SUBSYSTEM_DEFINED = @STRUCT_SUBSYSTEM_DEFINED@
 NO_FALLOCATE = @NO_FALLOCATE@
 NO_SPLICE_HEADER = @NO_SPLICE_HEADER@
+NO_SHOULD_REMOVE_SUID = @NO_SHOULD_REMOVE_SUID@
 
 OCFS_DEBUG = @OCFS_DEBUG@
 
diff --git a/Makefile b/Makefile
index b3998b4..5daa098 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,8 @@ KAPI_COMPAT_FILES = \
 	kapi-compat/include/su_mutex.h \
 	kapi-compat/include/kobject.h \
 	kapi-compat/include/cap.h \
-	kapi-compat/include/relatime.h
+	kapi-compat/include/relatime.h \
+	kapi-compat/include/should_remove_suid.h
 
 PATCH_FILES =
 
diff --git a/configure.in b/configure.in
index 9cef1f8..c2356da 100644
--- a/configure.in
+++ b/configure.in
@@ -263,6 +263,12 @@ OCFS2_CHECK_KERNEL([MNT_RELATIME in mount.h], mount.h,
   , relatime_compat_header="relatime.h", [^#define MNT_RELATIME])
 KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS $relatime_compat_header"
 
+NO_SHOULD_REMOVE_SUID=
+OCFS2_CHECK_KERNEL([should_remove_suid() in fs.h], fs.h,
+  , NO_SHOULD_REMOVE_SUID=yes, [should_remove_suid()])
+AC_SUBST(NO_SHOULD_REMOVE_SUID)
+KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS should_remove_suid.h"
+
 # using -include has two advantages:
 #  the source doesn't need to know to include compat headers
 #  the compat header file names don't go through the search path
diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index 58be004..cecd610 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -57,6 +57,10 @@ ifdef NO_SPLICE_HEADER
 EXTRA_CFLAGS += -DNO_SPLICE_HEADER
 endif
 
+ifdef NO_SHOULD_REMOVE_SUID
+CFLAGS_file.o += -DNO_SHOULD_REMOVE_SUID
+endif
+
 #
 # Since SUBDIRS means something to kbuild, define them safely.  Do not
 # include trailing slashes.
diff --git a/kapi-compat/include/should_remove_suid.h b/kapi-compat/include/should_remove_suid.h
new file mode 100644
index 0000000..4c9e598
--- /dev/null
+++ b/kapi-compat/include/should_remove_suid.h
@@ -0,0 +1,37 @@
+#ifndef KAP_SHOULD_REMOVE_SUID_H
+#define KAP_SHOULD_REMOVE_SUID_H
+
+#ifdef NO_SHOULD_REMOVE_SUID
+
+#include <linux/fs.h>
+
+/*
+ * The logic we want is
+ *
+ *	if suid or (sgid and xgrp)
+ *		remove privs
+ */
+int should_remove_suid(struct dentry *dentry)
+{
+	mode_t mode = dentry->d_inode->i_mode;
+	int kill = 0;
+
+	/* suid always must be killed */
+	if (unlikely(mode & S_ISUID))
+		kill = ATTR_KILL_SUID;
+
+	/*
+	 * sgid without any exec bits is just a mandatory locking mark; leave
+	 * it alone.  If some exec bits are set, it's a real sgid; kill it.
+	 */
+	if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
+		kill |= ATTR_KILL_SGID;
+
+	if (unlikely(kill && !capable(CAP_FSETID)))
+		return kill;
+
+	return 0;
+}
+#endif
+
+#endif
-- 
1.5.3.4