Messages in this thread Patch in this message | | | From | Ram Pai <> | Subject | [PATCH] x86, powerpc : pkey-mprotect must allow pkey-0 | Date | Fri, 9 Mar 2018 00:12:41 -0800 |
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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 and x86_64.
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 ++++++++++++++----- arch/x86/include/asm/pkeys.h | 5 +++-- 2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 0409c80..3e8abe4 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; /* diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h index a0ba1ff..6ea7486 100644 --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -52,7 +52,7 @@ bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) * from pkey_alloc(). pkey 0 is special, and never * returned from pkey_alloc(). */ - if (pkey <= 0) + if (pkey < 0) return false; if (pkey >= arch_max_pkey()) return false; @@ -92,7 +92,8 @@ int mm_pkey_alloc(struct mm_struct *mm) static inline int mm_pkey_free(struct mm_struct *mm, int pkey) { - if (!mm_pkey_is_allocated(mm, pkey)) + /* pkey 0 is special and can never be freed */ + if (!pkey || !mm_pkey_is_allocated(mm, pkey)) return -EINVAL; mm_set_pkey_free(mm, pkey); -- 1.8.3.1
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