path: root/kernel
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authorLinus Torvalds <>2016-03-20 19:08:56 -0700
committerLinus Torvalds <>2016-03-20 19:08:56 -0700
commit643ad15d47410d37d43daf3ef1c8ac52c281efa5 (patch)
treea864860cfe04c994c03d7946e12b3351e38a168b /kernel
parent24b5e20f11a75866bbffc46c30a22fa50612a769 (diff)
parent0d47638f80a02b15869f1fe1fc09e5bf996750fd (diff)
Merge branch 'mm-pkeys-for-linus' of git://
Pull x86 protection key support from Ingo Molnar: "This tree adds support for a new memory protection hardware feature that is available in upcoming Intel CPUs: 'protection keys' (pkeys). There's a background article at The gist is that protection keys allow the encoding of user-controllable permission masks in the pte. So instead of having a fixed protection mask in the pte (which needs a system call to change and works on a per page basis), the user can map a (handful of) protection mask variants and can change the masks runtime relatively cheaply, without having to change every single page in the affected virtual memory range. This allows the dynamic switching of the protection bits of large amounts of virtual memory, via user-space instructions. It also allows more precise control of MMU permission bits: for example the executable bit is separate from the read bit (see more about that below). This tree adds the MM infrastructure and low level x86 glue needed for that, plus it adds a high level API to make use of protection keys - if a user-space application calls: mmap(..., PROT_EXEC); or mprotect(ptr, sz, PROT_EXEC); (note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice this special case, and will set a special protection key on this memory range. It also sets the appropriate bits in the Protection Keys User Rights (PKRU) register so that the memory becomes unreadable and unwritable. So using protection keys the kernel is able to implement 'true' PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies PROT_READ as well. Unreadable executable mappings have security advantages: they cannot be read via information leaks to figure out ASLR details, nor can they be scanned for ROP gadgets - and they cannot be used by exploits for data purposes either. We know about no user-space code that relies on pure PROT_EXEC mappings today, but binary loaders could start making use of this new feature to map binaries and libraries in a more secure fashion. There is other pending pkeys work that offers more high level system call APIs to manage protection keys - but those are not part of this pull request. Right now there's a Kconfig that controls this feature (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled (like most x86 CPU feature enablement code that has no runtime overhead), but it's not user-configurable at the moment. If there's any serious problem with this then we can make it configurable and/or flip the default" * 'mm-pkeys-for-linus' of git:// (38 commits) x86/mm/pkeys: Fix mismerge of protection keys CPUID bits mm/pkeys: Fix siginfo ABI breakage caused by new u64 field x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA mm/core, x86/mm/pkeys: Add execute-only protection keys support x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags x86/mm/pkeys: Allow kernel to modify user pkey rights register x86/fpu: Allow setting of XSAVE state x86/mm: Factor out LDT init from context init mm/core, x86/mm/pkeys: Add arch_validate_pkey() mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits() x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU x86/mm/pkeys: Add Kconfig prompt to existing config option x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps x86/mm/pkeys: Dump PKRU with other kernel registers mm/core, x86/mm/pkeys: Differentiate instruction fetches x86/mm/pkeys: Optimize fault handling in access_error() mm/core: Do not enforce PKEY permissions on remote mm access um, pkeys: Add UML arch_*_access_permitted() methods mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys x86/mm/gup: Simplify get_user_pages() PTE bit handling ...
Diffstat (limited to 'kernel')
2 files changed, 12 insertions, 2 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 5f6ce931f1ea..220fc17b9718 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -299,7 +299,7 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
/* Read the page with vaddr into memory */
- ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
+ ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
if (ret <= 0)
return ret;
@@ -1701,7 +1701,13 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
if (likely(result == 0))
goto out;
- result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
+ /*
+ * The NULL 'tsk' here ensures that any faults that occur here
+ * will not be accounted to the task. 'mm' *is* current->mm,
+ * but we treat this as a 'remote' access since it is
+ * essentially a kernel access to the memory.
+ */
+ result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
if (result < 0)
return result;
diff --git a/kernel/signal.c b/kernel/signal.c
index 0508544c8ced..fe8ed298373c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2709,6 +2709,10 @@ int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
err |= __put_user(from->si_upper, &to->si_upper);
+ if (from->si_signo == SIGSEGV && from->si_code == SEGV_PKUERR)
+ err |= __put_user(from->si_pkey, &to->si_pkey);
case __SI_CHLD:
err |= __put_user(from->si_pid, &to->si_pid);