[RFC PATCH] Keep 3 high personality bytes across exec

!MAILaRCHIVE_VOTE_RePLACE
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To: <linuxppc-dev@...>
Cc: <linux-kernel@...>
Date: Wednesday, June 18, 2008 - 2:06 am

Currently when a 32 bit process is exec'd on a powerpc 64 bit host the valu=
es
of the top three bytes of the personality are clobbered.  This patch adds a
check in the SET_PERSONALITY macro that will carry all the values in the top
three bytes across the exec.

Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>

---

Based on 2.6.26-rc6

 include/asm-powerpc/elf.h   |    3 ++-
 include/linux/personality.h |    6 ++++++
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h
index 9080d85..2f11a0e 100644
--- a/include/asm-powerpc/elf.h
+++ b/include/asm-powerpc/elf.h
@@ -257,7 +257,8 @@ do {								\
 	else							\
 		clear_thread_flag(TIF_ABI_PENDING);		\
 	if (personality(current->personality) !=3D PER_LINUX32)	\
-		set_personality(PER_LINUX);			\
+		set_personality(PER_LINUX |			\
+			(current->personality & PER_INHERIT));	\
 } while (0)
 /*
  * An executable for which elf_read_implies_exec() returns TRUE will
diff --git a/include/linux/personality.h b/include/linux/personality.h
index a84e9ff..362eb90 100644
--- a/include/linux/personality.h
+++ b/include/linux/personality.h
@@ -36,6 +36,12 @@ enum {
 	ADDR_LIMIT_3GB =3D 	0x8000000,
 };
=20
+/* Mask for the above personality values */
+#define PER_INHERIT (ADDR_NO_RANDOMIZE|FDPIC_FUNCPTRS|MMAP_PAGE_ZERO| \
+			ADDR_COMPAT_LAYOUT|READ_IMPLIES_EXEC|ADDR_LIMIT_32BIT| \
+			SHORT_INODE|WHOLE_SECONDS|STICKY_TIMEOUTS| \
+			ADDR_LIMIT_3GB)
+
 /*
  * Security-relevant compatibility flags that must be
  * cleared upon setuid or setgid exec:
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Messages in current thread:
[RFC PATCH] Keep 3 high personality bytes across exec, Eric B Munson, (Wed Jun 18, 2:06 am)
[RFC PATCH V2] Keep 3 high personality bytes across exec, Eric B Munson, (Wed Jun 18, 5:15 pm)
Re: [RFC PATCH] Keep 3 high personality bytes across exec, Paul Mackerras, (Wed Jun 18, 2:12 am)