From: Dave Hansen <dave@sr71.net> To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, luto@kernel.org, mgorman@techsingularity.net, Dave Hansen <dave@sr71.net>, dave.hansen@linux.intel.com, arnd@arndb.de Subject: [PATCH 03/10] x86, pkeys: make mprotect_key() mask off additional vm_flags Date: Fri, 29 Jul 2016 09:30:13 -0700 [thread overview] Message-ID: <20160729163013.E48D6981@viggo.jf.intel.com> (raw) In-Reply-To: <20160729163009.5EC1D38C@viggo.jf.intel.com> From: Dave Hansen <dave.hansen@linux.intel.com> Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. Three of those bits: READ/WRITE/EXEC get translated directly in to vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags during the mprotect() call. We do this clearing today by first calculating the VMA flags we want set, then clearing the ones we do not want to inherit from the original VMA: vm_flags = calc_vm_prot_bits(prot, key); ... newflags = vm_flags; newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); However, we *also* want to mask off the original VMA's vm_flags in which we store the protection key. To do that, this patch adds a new macro: ARCH_VM_PKEY_FLAGS which allows the architecture to specify additional bits that it would like cleared. We use that to ensure that the VM_PKEY_BIT* bits get cleared. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Cc: x86@kernel.org Cc: torvalds@linux-foundation.org Cc: akpm@linux-foundation.org Cc: Arnd Bergmann <arnd@arndb.de> --- b/arch/x86/include/asm/pkeys.h | 2 ++ b/include/linux/pkeys.h | 1 + b/mm/mprotect.c | 11 ++++++++++- 3 files changed, 13 insertions(+), 1 deletion(-) diff -puN arch/x86/include/asm/pkeys.h~pkeys-112-mask-off-correct-vm_flags arch/x86/include/asm/pkeys.h --- a/arch/x86/include/asm/pkeys.h~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.818489664 -0700 +++ b/arch/x86/include/asm/pkeys.h 2016-07-29 09:18:56.824489935 -0700 @@ -38,4 +38,6 @@ static inline int arch_override_mprotect extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val); +#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3) + #endif /*_ASM_X86_PKEYS_H */ diff -puN include/linux/pkeys.h~pkeys-112-mask-off-correct-vm_flags include/linux/pkeys.h --- a/include/linux/pkeys.h~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.820489755 -0700 +++ b/include/linux/pkeys.h 2016-07-29 09:18:56.825489981 -0700 @@ -16,6 +16,7 @@ #define execute_only_pkey(mm) (0) #define arch_override_mprotect_pkey(vma, prot, pkey) (0) #define PKEY_DEDICATED_EXECUTE_ONLY 0 +#define ARCH_VM_PKEY_FLAGS 0 #endif /* ! CONFIG_ARCH_HAS_PKEYS */ #endif /* _LINUX_PKEYS_H */ diff -puN mm/mprotect.c~pkeys-112-mask-off-correct-vm_flags mm/mprotect.c --- a/mm/mprotect.c~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.821489800 -0700 +++ b/mm/mprotect.c 2016-07-29 09:18:56.825489981 -0700 @@ -417,6 +417,7 @@ static int do_mprotect_pkey(unsigned lon prev = vma; for (nstart = start ; ; ) { + unsigned long mask_off_old_flags; unsigned long newflags; int new_vma_pkey; @@ -426,9 +427,17 @@ static int do_mprotect_pkey(unsigned lon if (rier && (vma->vm_flags & VM_MAYEXEC)) prot |= PROT_EXEC; + /* + * Each mprotect() call explicitly passes r/w/x permissions. + * If a permission is not passed to mprotect(), it must be + * cleared from the VMA. + */ + mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC | + ARCH_VM_PKEY_FLAGS; + new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); newflags = calc_vm_prot_bits(prot, new_vma_pkey); - newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); + newflags |= (vma->vm_flags & ~mask_off_old_flags); /* newflags >> 4 shift VM_MAY% in place of VM_% */ if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { _
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@sr71.net> To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, luto@kernel.org, mgorman@techsingularity.net, Dave Hansen <dave@sr71.net>, dave.hansen@linux.intel.com, arnd@arndb.de Subject: [PATCH 03/10] x86, pkeys: make mprotect_key() mask off additional vm_flags Date: Fri, 29 Jul 2016 09:30:13 -0700 [thread overview] Message-ID: <20160729163013.E48D6981@viggo.jf.intel.com> (raw) In-Reply-To: <20160729163009.5EC1D38C@viggo.jf.intel.com> From: Dave Hansen <dave.hansen@linux.intel.com> Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. Three of those bits: READ/WRITE/EXEC get translated directly in to vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags during the mprotect() call. We do this clearing today by first calculating the VMA flags we want set, then clearing the ones we do not want to inherit from the original VMA: vm_flags = calc_vm_prot_bits(prot, key); ... newflags = vm_flags; newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); However, we *also* want to mask off the original VMA's vm_flags in which we store the protection key. To do that, this patch adds a new macro: ARCH_VM_PKEY_FLAGS which allows the architecture to specify additional bits that it would like cleared. We use that to ensure that the VM_PKEY_BIT* bits get cleared. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Cc: x86@kernel.org Cc: torvalds@linux-foundation.org Cc: akpm@linux-foundation.org Cc: Arnd Bergmann <arnd@arndb.de> --- b/arch/x86/include/asm/pkeys.h | 2 ++ b/include/linux/pkeys.h | 1 + b/mm/mprotect.c | 11 ++++++++++- 3 files changed, 13 insertions(+), 1 deletion(-) diff -puN arch/x86/include/asm/pkeys.h~pkeys-112-mask-off-correct-vm_flags arch/x86/include/asm/pkeys.h --- a/arch/x86/include/asm/pkeys.h~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.818489664 -0700 +++ b/arch/x86/include/asm/pkeys.h 2016-07-29 09:18:56.824489935 -0700 @@ -38,4 +38,6 @@ static inline int arch_override_mprotect extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val); +#define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | VM_PKEY_BIT3) + #endif /*_ASM_X86_PKEYS_H */ diff -puN include/linux/pkeys.h~pkeys-112-mask-off-correct-vm_flags include/linux/pkeys.h --- a/include/linux/pkeys.h~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.820489755 -0700 +++ b/include/linux/pkeys.h 2016-07-29 09:18:56.825489981 -0700 @@ -16,6 +16,7 @@ #define execute_only_pkey(mm) (0) #define arch_override_mprotect_pkey(vma, prot, pkey) (0) #define PKEY_DEDICATED_EXECUTE_ONLY 0 +#define ARCH_VM_PKEY_FLAGS 0 #endif /* ! CONFIG_ARCH_HAS_PKEYS */ #endif /* _LINUX_PKEYS_H */ diff -puN mm/mprotect.c~pkeys-112-mask-off-correct-vm_flags mm/mprotect.c --- a/mm/mprotect.c~pkeys-112-mask-off-correct-vm_flags 2016-07-29 09:18:56.821489800 -0700 +++ b/mm/mprotect.c 2016-07-29 09:18:56.825489981 -0700 @@ -417,6 +417,7 @@ static int do_mprotect_pkey(unsigned lon prev = vma; for (nstart = start ; ; ) { + unsigned long mask_off_old_flags; unsigned long newflags; int new_vma_pkey; @@ -426,9 +427,17 @@ static int do_mprotect_pkey(unsigned lon if (rier && (vma->vm_flags & VM_MAYEXEC)) prot |= PROT_EXEC; + /* + * Each mprotect() call explicitly passes r/w/x permissions. + * If a permission is not passed to mprotect(), it must be + * cleared from the VMA. + */ + mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC | + ARCH_VM_PKEY_FLAGS; + new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); newflags = calc_vm_prot_bits(prot, new_vma_pkey); - newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); + newflags |= (vma->vm_flags & ~mask_off_old_flags); /* newflags >> 4 shift VM_MAY% in place of VM_% */ if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-07-29 16:30 UTC|newest] Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-29 16:30 [PATCH 00/10] [v6] System Calls for Memory Protection Keys Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-07-29 16:30 ` [PATCH 01/10] x86, pkeys: add fault handling for PF_PK page fault bit Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:10 ` [tip:mm/pkeys] x86/pkeys: Add " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 02/10] mm: implement new pkey_mprotect() system call Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:11 ` [tip:mm/pkeys] mm: Implement " tip-bot for Dave Hansen 2016-07-29 16:30 ` Dave Hansen [this message] 2016-07-29 16:30 ` [PATCH 03/10] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen 2016-09-09 11:11 ` [tip:mm/pkeys] x86/pkeys: Make " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 04/10] x86, pkeys: allocation/free syscalls Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:12 ` [tip:mm/pkeys] x86/pkeys: Allocation/free syscalls tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 05/10] x86: wire up protection keys system calls Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:12 ` [tip:mm/pkeys] x86: Wire " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 06/10] generic syscalls: wire up memory protection keys syscalls Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:12 ` [tip:mm/pkeys] generic syscalls: Wire " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 07/10] pkeys: add details of system call use to Documentation/ Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:13 ` [tip:mm/pkeys] pkeys: Add " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 08/10] x86, pkeys: default to a restrictive init PKRU Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-07-29 17:29 ` Andy Lutomirski 2016-07-29 17:29 ` Andy Lutomirski 2016-07-29 17:50 ` Dave Hansen 2016-07-29 17:50 ` Dave Hansen 2016-07-29 19:44 ` Andy Lutomirski 2016-07-29 19:44 ` Andy Lutomirski 2016-08-01 14:42 ` Vlastimil Babka 2016-08-01 14:42 ` Vlastimil Babka 2016-08-01 14:58 ` Dave Hansen 2016-08-01 14:58 ` Dave Hansen 2016-08-02 8:20 ` Vlastimil Babka 2016-08-02 8:20 ` Vlastimil Babka 2016-09-09 11:13 ` [tip:mm/pkeys] x86/pkeys: Default " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 09/10] x86, pkeys: allow configuration of init_pkru Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-08-02 8:28 ` Vlastimil Babka 2016-08-02 8:28 ` Vlastimil Babka 2016-08-02 14:37 ` Dave Hansen 2016-08-02 14:37 ` Dave Hansen 2016-09-09 11:14 ` [tip:mm/pkeys] x86/pkeys: Allow " tip-bot for Dave Hansen 2016-07-29 16:30 ` [PATCH 10/10] x86, pkeys: add self-tests Dave Hansen 2016-07-29 16:30 ` Dave Hansen 2016-09-09 11:14 ` [tip:mm/pkeys] x86/pkeys: Add self-tests tip-bot for Dave Hansen 2016-08-08 23:18 [PATCH 00/10] [v6] System Calls for Memory Protection Keys Dave Hansen 2016-08-08 23:18 ` [PATCH 03/10] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen 2016-08-08 23:18 ` Dave Hansen
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