lkml.org 
[lkml]   [2018]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/1 v2] powerpc: pkey-mprotect must allow pkey-0
Date
Once an address range is associated with an allocated pkey, it cannot be
reverted back to key-0. There is no valid reason for the above behavior. On
the contrary applications need the ability to do so.

The patch relaxes the restriction.

Tested on powerpc.

cc: Dave Hansen <dave.hansen@intel.com>
cc: Michael Ellermen <mpe@ellerman.id.au>
cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/pkeys.h | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 0409c80..3c1deec 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -101,10 +101,18 @@ static inline u16 pte_to_pkey_bits(u64 pteflags)

static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey)
{
- /* A reserved key is never considered as 'explicitly allocated' */
- return ((pkey < arch_max_pkey()) &&
- !__mm_pkey_is_reserved(pkey) &&
- __mm_pkey_is_allocated(mm, pkey));
+ /* pkey 0 is allocated by default. */
+ if (!pkey)
+ return true;
+
+ if (pkey < 0 || pkey >= arch_max_pkey())
+ return false;
+
+ /* Reserved keys are never allocated. */
+ if (__mm_pkey_is_reserved(pkey))
+ return false;
+
+ return __mm_pkey_is_allocated(mm, pkey);
}

extern void __arch_activate_pkey(int pkey);
@@ -150,7 +158,8 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
if (static_branch_likely(&pkey_disabled))
return -1;

- if (!mm_pkey_is_allocated(mm, pkey))
+ /* pkey 0 cannot be freed */
+ if (!pkey || !mm_pkey_is_allocated(mm, pkey))
return -EINVAL;

/*
--
1.8.3.1
\
 
 \ /
  Last update: 2018-03-14 08:45    [W:0.027 / U:0.596 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site