| Message ID | 1504910713-7094-20-git-send-email-linuxram@us.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc: Free up RPAGE_RSV bits | expand |
On Fri, 8 Sep 2017 15:44:59 -0700 Ram Pai <linuxram@us.ibm.com> wrote: > This patch provides the implementation of execute-only pkey. > The architecture-independent layer expects the arch-dependent > layer, to support the ability to create and enable a special > key which has execute-only permission. > > Signed-off-by: Ram Pai <linuxram@us.ibm.com> > --- > arch/powerpc/include/asm/book3s/64/mmu.h | 1 + > arch/powerpc/include/asm/pkeys.h | 9 ++++- > arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ > 3 files changed, 66 insertions(+), 1 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h > index 55950f4..ee18ba0 100644 > --- a/arch/powerpc/include/asm/book3s/64/mmu.h > +++ b/arch/powerpc/include/asm/book3s/64/mmu.h > @@ -115,6 +115,7 @@ struct patb_entry { > * bit unset -> key available for allocation > */ > u32 pkey_allocation_map; > + s16 execute_only_pkey; /* key holding execute-only protection */ > #endif > } mm_context_t; > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > index 78c5362..0cf115f 100644 > --- a/arch/powerpc/include/asm/pkeys.h > +++ b/arch/powerpc/include/asm/pkeys.h > @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) > * Try to dedicate one of the protection keys to be used as an > * execute-only protection key. > */ > +extern int __execute_only_pkey(struct mm_struct *mm); > static inline int execute_only_pkey(struct mm_struct *mm) > { > - return 0; > + if (!pkey_inited || !pkey_execute_disable_support) > + return -1; > + > + return __execute_only_pkey(mm); > } > > + > static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, > int prot, int pkey) > { > @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) > if (!pkey_inited) > return; > mm_pkey_allocation_map(mm) = initial_allocation_mask; > + /* -1 means unallocated or invalid */ > + mm->context.execute_only_pkey = -1; > } > > extern void thread_pkey_regs_save(struct thread_struct *thread); > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > index 7cd1be4..8a24983 100644 > --- a/arch/powerpc/mm/pkeys.c > +++ b/arch/powerpc/mm/pkeys.c > @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) > write_iamr(0x0ul); > write_uamor(0x0ul); > } > + > +static inline bool pkey_allows_readwrite(int pkey) > +{ > + int pkey_shift = pkeyshift(pkey); > + > + if (!(read_uamor() & (0x3UL << pkey_shift))) > + return true; If uamor for key 0 is 0x10 for example or 0x01 it's a bug. The above check might miss it. > + > + return !(read_amr() & ((AMR_RD_BIT|AMR_WR_BIT) << pkey_shift)); > +} > + > +int __execute_only_pkey(struct mm_struct *mm) > +{ > + bool need_to_set_mm_pkey = false; > + int execute_only_pkey = mm->context.execute_only_pkey; > + int ret; > + > + /* Do we need to assign a pkey for mm's execute-only maps? */ > + if (execute_only_pkey == -1) { > + /* Go allocate one to use, which might fail */ > + execute_only_pkey = mm_pkey_alloc(mm); > + if (execute_only_pkey < 0) > + return -1; > + need_to_set_mm_pkey = true; > + } > + > + /* > + * We do not want to go through the relatively costly > + * dance to set AMR if we do not need to. Check it > + * first and assume that if the execute-only pkey is > + * readwrite-disabled than we do not have to set it > + * ourselves. > + */ > + if (!need_to_set_mm_pkey && > + !pkey_allows_readwrite(execute_only_pkey)) > + return execute_only_pkey; > + > + /* > + * Set up AMR so that it denies access for everything > + * other than execution. > + */ > + ret = __arch_set_user_pkey_access(current, execute_only_pkey, > + (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)); > + /* > + * If the AMR-set operation failed somehow, just return > + * 0 and effectively disable execute-only support. > + */ > + if (ret) { > + mm_set_pkey_free(mm, execute_only_pkey); > + return -1; > + } > + > + /* We got one, store it and use it from here on out */ > + if (need_to_set_mm_pkey) > + mm->context.execute_only_pkey = execute_only_pkey; > + return execute_only_pkey; > +} Looks good otherwise Acked-by: Balbir Singh <bsingharora@gmail.com>
On Wed, Oct 18, 2017 at 03:15:22PM +1100, Balbir Singh wrote: > On Fri, 8 Sep 2017 15:44:59 -0700 > Ram Pai <linuxram@us.ibm.com> wrote: > > > This patch provides the implementation of execute-only pkey. > > The architecture-independent layer expects the arch-dependent > > layer, to support the ability to create and enable a special > > key which has execute-only permission. > > > > Signed-off-by: Ram Pai <linuxram@us.ibm.com> > > --- > > arch/powerpc/include/asm/book3s/64/mmu.h | 1 + > > arch/powerpc/include/asm/pkeys.h | 9 ++++- > > arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ > > 3 files changed, 66 insertions(+), 1 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h > > index 55950f4..ee18ba0 100644 > > --- a/arch/powerpc/include/asm/book3s/64/mmu.h > > +++ b/arch/powerpc/include/asm/book3s/64/mmu.h > > @@ -115,6 +115,7 @@ struct patb_entry { > > * bit unset -> key available for allocation > > */ > > u32 pkey_allocation_map; > > + s16 execute_only_pkey; /* key holding execute-only protection */ > > #endif > > } mm_context_t; > > > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > > index 78c5362..0cf115f 100644 > > --- a/arch/powerpc/include/asm/pkeys.h > > +++ b/arch/powerpc/include/asm/pkeys.h > > @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) > > * Try to dedicate one of the protection keys to be used as an > > * execute-only protection key. > > */ > > +extern int __execute_only_pkey(struct mm_struct *mm); > > static inline int execute_only_pkey(struct mm_struct *mm) > > { > > - return 0; > > + if (!pkey_inited || !pkey_execute_disable_support) > > + return -1; > > + > > + return __execute_only_pkey(mm); > > } > > > > + > > static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, > > int prot, int pkey) > > { > > @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) > > if (!pkey_inited) > > return; > > mm_pkey_allocation_map(mm) = initial_allocation_mask; > > + /* -1 means unallocated or invalid */ > > + mm->context.execute_only_pkey = -1; > > } > > > > extern void thread_pkey_regs_save(struct thread_struct *thread); > > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > > index 7cd1be4..8a24983 100644 > > --- a/arch/powerpc/mm/pkeys.c > > +++ b/arch/powerpc/mm/pkeys.c > > @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) > > write_iamr(0x0ul); > > write_uamor(0x0ul); > > } > > + > > +static inline bool pkey_allows_readwrite(int pkey) > > +{ > > + int pkey_shift = pkeyshift(pkey); > > + > > + if (!(read_uamor() & (0x3UL << pkey_shift))) > > + return true; > > If uamor for key 0 is 0x10 for example or 0x01 it's a bug. > The above check might miss it. The specs says both the bits corresponding to a key are set or reset, cannot be anything else. cut-n-paste from the ISA... ---------------------------------------------------- Software must ensure that both bits of each even/odd bit pair of the AMOR contain the same value. -- i.e., the contents of register RS for mtspr specifying the AMOR must be such that (RS)2n = (RS)2n+1 for every n in the range 0:31 - and like for the UAMOR. --------------------------------------------------------- > > > + > > + return !(read_amr() & ((AMR_RD_BIT|AMR_WR_BIT) << pkey_shift)); > > +} > > + > > +int __execute_only_pkey(struct mm_struct *mm) > > +{ > > + bool need_to_set_mm_pkey = false; > > + int execute_only_pkey = mm->context.execute_only_pkey; > > + int ret; > > + > > + /* Do we need to assign a pkey for mm's execute-only maps? */ > > + if (execute_only_pkey == -1) { > > + /* Go allocate one to use, which might fail */ > > + execute_only_pkey = mm_pkey_alloc(mm); > > + if (execute_only_pkey < 0) > > + return -1; > > + need_to_set_mm_pkey = true; > > + } > > + > > + /* > > + * We do not want to go through the relatively costly > > + * dance to set AMR if we do not need to. Check it > > + * first and assume that if the execute-only pkey is > > + * readwrite-disabled than we do not have to set it > > + * ourselves. > > + */ > > + if (!need_to_set_mm_pkey && > > + !pkey_allows_readwrite(execute_only_pkey)) > > + return execute_only_pkey; > > + > > + /* > > + * Set up AMR so that it denies access for everything > > + * other than execution. > > + */ > > + ret = __arch_set_user_pkey_access(current, execute_only_pkey, > > + (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)); > > + /* > > + * If the AMR-set operation failed somehow, just return > > + * 0 and effectively disable execute-only support. > > + */ > > + if (ret) { > > + mm_set_pkey_free(mm, execute_only_pkey); > > + return -1; > > + } > > + > > + /* We got one, store it and use it from here on out */ > > + if (need_to_set_mm_pkey) > > + mm->context.execute_only_pkey = execute_only_pkey; > > + return execute_only_pkey; > > +} > > Looks good otherwise > > Acked-by: Balbir Singh <bsingharora@gmail.com> thanks.
On Wed, 18 Oct 2017 13:57:39 -0700 Ram Pai <linuxram@us.ibm.com> wrote: > On Wed, Oct 18, 2017 at 03:15:22PM +1100, Balbir Singh wrote: > > On Fri, 8 Sep 2017 15:44:59 -0700 > > Ram Pai <linuxram@us.ibm.com> wrote: > > > > > This patch provides the implementation of execute-only pkey. > > > The architecture-independent layer expects the arch-dependent > > > layer, to support the ability to create and enable a special > > > key which has execute-only permission. > > > > > > Signed-off-by: Ram Pai <linuxram@us.ibm.com> > > > --- > > > arch/powerpc/include/asm/book3s/64/mmu.h | 1 + > > > arch/powerpc/include/asm/pkeys.h | 9 ++++- > > > arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ > > > 3 files changed, 66 insertions(+), 1 deletions(-) > > > > > > diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h > > > index 55950f4..ee18ba0 100644 > > > --- a/arch/powerpc/include/asm/book3s/64/mmu.h > > > +++ b/arch/powerpc/include/asm/book3s/64/mmu.h > > > @@ -115,6 +115,7 @@ struct patb_entry { > > > * bit unset -> key available for allocation > > > */ > > > u32 pkey_allocation_map; > > > + s16 execute_only_pkey; /* key holding execute-only protection */ > > > #endif > > > } mm_context_t; > > > > > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > > > index 78c5362..0cf115f 100644 > > > --- a/arch/powerpc/include/asm/pkeys.h > > > +++ b/arch/powerpc/include/asm/pkeys.h > > > @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) > > > * Try to dedicate one of the protection keys to be used as an > > > * execute-only protection key. > > > */ > > > +extern int __execute_only_pkey(struct mm_struct *mm); > > > static inline int execute_only_pkey(struct mm_struct *mm) > > > { > > > - return 0; > > > + if (!pkey_inited || !pkey_execute_disable_support) > > > + return -1; > > > + > > > + return __execute_only_pkey(mm); > > > } > > > > > > + > > > static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, > > > int prot, int pkey) > > > { > > > @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) > > > if (!pkey_inited) > > > return; > > > mm_pkey_allocation_map(mm) = initial_allocation_mask; > > > + /* -1 means unallocated or invalid */ > > > + mm->context.execute_only_pkey = -1; > > > } > > > > > > extern void thread_pkey_regs_save(struct thread_struct *thread); > > > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > > > index 7cd1be4..8a24983 100644 > > > --- a/arch/powerpc/mm/pkeys.c > > > +++ b/arch/powerpc/mm/pkeys.c > > > @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) > > > write_iamr(0x0ul); > > > write_uamor(0x0ul); > > > } > > > + > > > +static inline bool pkey_allows_readwrite(int pkey) > > > +{ > > > + int pkey_shift = pkeyshift(pkey); > > > + > > > + if (!(read_uamor() & (0x3UL << pkey_shift))) > > > + return true; > > > > If uamor for key 0 is 0x10 for example or 0x01 it's a bug. > > The above check might miss it. > > > The specs says both the bits corresponding to a key are set or > reset, cannot be anything else. > I agree, thats why I said it's a bug if the values are such. Do we care to validate that both bits are the same? Balbir Singh.
On Thu, Oct 19, 2017 at 10:02:13AM +1100, Balbir Singh wrote: > On Wed, 18 Oct 2017 13:57:39 -0700 > Ram Pai <linuxram@us.ibm.com> wrote: > > > On Wed, Oct 18, 2017 at 03:15:22PM +1100, Balbir Singh wrote: > > > On Fri, 8 Sep 2017 15:44:59 -0700 > > > Ram Pai <linuxram@us.ibm.com> wrote: > > > > > > > This patch provides the implementation of execute-only pkey. > > > > The architecture-independent layer expects the arch-dependent > > > > layer, to support the ability to create and enable a special > > > > key which has execute-only permission. > > > > > > > > Signed-off-by: Ram Pai <linuxram@us.ibm.com> > > > > --- > > > > arch/powerpc/include/asm/book3s/64/mmu.h | 1 + > > > > arch/powerpc/include/asm/pkeys.h | 9 ++++- > > > > arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ > > > > 3 files changed, 66 insertions(+), 1 deletions(-) > > > > > > > > diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h > > > > index 55950f4..ee18ba0 100644 > > > > --- a/arch/powerpc/include/asm/book3s/64/mmu.h > > > > +++ b/arch/powerpc/include/asm/book3s/64/mmu.h > > > > @@ -115,6 +115,7 @@ struct patb_entry { > > > > * bit unset -> key available for allocation > > > > */ > > > > u32 pkey_allocation_map; > > > > + s16 execute_only_pkey; /* key holding execute-only protection */ > > > > #endif > > > > } mm_context_t; > > > > > > > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > > > > index 78c5362..0cf115f 100644 > > > > --- a/arch/powerpc/include/asm/pkeys.h > > > > +++ b/arch/powerpc/include/asm/pkeys.h > > > > @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) > > > > * Try to dedicate one of the protection keys to be used as an > > > > * execute-only protection key. > > > > */ > > > > +extern int __execute_only_pkey(struct mm_struct *mm); > > > > static inline int execute_only_pkey(struct mm_struct *mm) > > > > { > > > > - return 0; > > > > + if (!pkey_inited || !pkey_execute_disable_support) > > > > + return -1; > > > > + > > > > + return __execute_only_pkey(mm); > > > > } > > > > > > > > + > > > > static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, > > > > int prot, int pkey) > > > > { > > > > @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) > > > > if (!pkey_inited) > > > > return; > > > > mm_pkey_allocation_map(mm) = initial_allocation_mask; > > > > + /* -1 means unallocated or invalid */ > > > > + mm->context.execute_only_pkey = -1; > > > > } > > > > > > > > extern void thread_pkey_regs_save(struct thread_struct *thread); > > > > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > > > > index 7cd1be4..8a24983 100644 > > > > --- a/arch/powerpc/mm/pkeys.c > > > > +++ b/arch/powerpc/mm/pkeys.c > > > > @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) > > > > write_iamr(0x0ul); > > > > write_uamor(0x0ul); > > > > } > > > > + > > > > +static inline bool pkey_allows_readwrite(int pkey) > > > > +{ > > > > + int pkey_shift = pkeyshift(pkey); > > > > + > > > > + if (!(read_uamor() & (0x3UL << pkey_shift))) > > > > + return true; > > > > > > If uamor for key 0 is 0x10 for example or 0x01 it's a bug. > > > The above check might miss it. > > > > > > The specs says both the bits corresponding to a key are set or > > reset, cannot be anything else. > > > > I agree, thats why I said it's a bug if the values are such. > Do we care to validate that both bits are the same? I will put in a assert. Will that work? RP > > Balbir Singh.
diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h index 55950f4..ee18ba0 100644 --- a/arch/powerpc/include/asm/book3s/64/mmu.h +++ b/arch/powerpc/include/asm/book3s/64/mmu.h @@ -115,6 +115,7 @@ struct patb_entry { * bit unset -> key available for allocation */ u32 pkey_allocation_map; + s16 execute_only_pkey; /* key holding execute-only protection */ #endif } mm_context_t; diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 78c5362..0cf115f 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) * Try to dedicate one of the protection keys to be used as an * execute-only protection key. */ +extern int __execute_only_pkey(struct mm_struct *mm); static inline int execute_only_pkey(struct mm_struct *mm) { - return 0; + if (!pkey_inited || !pkey_execute_disable_support) + return -1; + + return __execute_only_pkey(mm); } + static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, int pkey) { @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) if (!pkey_inited) return; mm_pkey_allocation_map(mm) = initial_allocation_mask; + /* -1 means unallocated or invalid */ + mm->context.execute_only_pkey = -1; } extern void thread_pkey_regs_save(struct thread_struct *thread); diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 7cd1be4..8a24983 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) write_iamr(0x0ul); write_uamor(0x0ul); } + +static inline bool pkey_allows_readwrite(int pkey) +{ + int pkey_shift = pkeyshift(pkey); + + if (!(read_uamor() & (0x3UL << pkey_shift))) + return true; + + return !(read_amr() & ((AMR_RD_BIT|AMR_WR_BIT) << pkey_shift)); +} + +int __execute_only_pkey(struct mm_struct *mm) +{ + bool need_to_set_mm_pkey = false; + int execute_only_pkey = mm->context.execute_only_pkey; + int ret; + + /* Do we need to assign a pkey for mm's execute-only maps? */ + if (execute_only_pkey == -1) { + /* Go allocate one to use, which might fail */ + execute_only_pkey = mm_pkey_alloc(mm); + if (execute_only_pkey < 0) + return -1; + need_to_set_mm_pkey = true; + } + + /* + * We do not want to go through the relatively costly + * dance to set AMR if we do not need to. Check it + * first and assume that if the execute-only pkey is + * readwrite-disabled than we do not have to set it + * ourselves. + */ + if (!need_to_set_mm_pkey && + !pkey_allows_readwrite(execute_only_pkey)) + return execute_only_pkey; + + /* + * Set up AMR so that it denies access for everything + * other than execution. + */ + ret = __arch_set_user_pkey_access(current, execute_only_pkey, + (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)); + /* + * If the AMR-set operation failed somehow, just return + * 0 and effectively disable execute-only support. + */ + if (ret) { + mm_set_pkey_free(mm, execute_only_pkey); + return -1; + } + + /* We got one, store it and use it from here on out */ + if (need_to_set_mm_pkey) + mm->context.execute_only_pkey = execute_only_pkey; + return execute_only_pkey; +}
This patch provides the implementation of execute-only pkey. The architecture-independent layer expects the arch-dependent layer, to support the ability to create and enable a special key which has execute-only permission. Signed-off-by: Ram Pai <linuxram@us.ibm.com> --- arch/powerpc/include/asm/book3s/64/mmu.h | 1 + arch/powerpc/include/asm/pkeys.h | 9 ++++- arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 1 deletions(-)