powerpc: add sys_pkey_modify() system call

RFC New Ram Pai 1 participant 1 message Sep 24, 2017 PowerPC

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Ram Pai

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2017-09-24 18:24 UTC #0 lore raw

RFC 1/1 powerpc: add sys_pkey_modify() system call

sys_pkey_modify() is powerpc specific system call. It
enables the ability to modify *any* attribute of a key.

Since powerpc disallows modification of IAMR from user space an application is unable to change a key's execute-attribute.

This system call helps accomplish the above.

Signed-off-by Ram Pai <[email protected]>

---
 arch/powerpc/include/asm/systbl.h      |    1 +
 arch/powerpc/include/asm/unistd.h      |    2 +-
 arch/powerpc/include/uapi/asm/unistd.h |    1 +
 arch/powerpc/kernel/entry_64.S         |    9 +++++++++
 arch/powerpc/mm/pkeys.c                |   29 +++++++++++++++++++++++++++++
 5 files changed, 41 insertions(+), 1 deletions(-)

arch/powerpc/include/asm/systbl.h +1 -0

index b33b551..d6f667e 100644
@@ -391,3 +391,4 @@
 SYSCALL(pkey_alloc)
 SYSCALL(pkey_free)
 SYSCALL(pkey_mprotect)
+PPC64ONLY(pkey_modify)

arch/powerpc/include/asm/unistd.h +1 -1

index daf1ba9..1e97086 100644
@@ -12,7 +12,7 @@
 #include <uapi/asm/unistd.h>
 
 
-#define NR_syscalls		387
+#define NR_syscalls		388
 
 #define __NR__exit __NR_exit

arch/powerpc/include/uapi/asm/unistd.h +1 -0

index 71ae45e..c70b6d3 100644
@@ -397,5 +397,6 @@
 #define __NR_pkey_alloc		384
 #define __NR_pkey_free		385
 #define __NR_pkey_mprotect	386
+#define __NR_pkey_modify	387
 
 #endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */

arch/powerpc/kernel/entry_64.S +9 -0

index 4a0fd4f..5980b9e 100644
@@ -455,6 +455,15 @@ _GLOBAL(ppc_switch_endian)
 	bl	sys_switch_endian
 	b	.Lsyscall_exit
 
+_GLOBAL(ppc_pkey_modify)
+	bl	save_nvgprs
+#ifdef  CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+	bl	sys_pkey_modify
+#else
+	bl	sys_ni_syscall
+#endif
+	b	.Lsyscall_exit
+
 _GLOBAL(ret_from_fork)
 	bl	schedule_tail
 	REST_NVGPRS(r1)

arch/powerpc/mm/pkeys.c +29 -0

index de2e88f..bd16bc4 100644
@@ -364,3 +364,32 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma,
 
 	return pkey_access_permitted(pkey, write, execute);
 }
+
+unsigned int arch_usable_pkeys(void)
+{
+	unsigned int reserved;
+
+	if (!pkey_inited)
+		return 0;
+
+	/* Reserve one more to account for the execute-only pkey. */
+	reserved = hweight32(initial_allocation_mask) + 1;
+
+	return pkeys_total > reserved ? pkeys_total - reserved : 0;
+}
+
+bool arch_supports_pkeys(int cap)
+{
+	if (cap & PKEY_DISABLE_EXECUTE)
+		return pkey_execute_disable_support;
+	return (cap & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+}
+
+long sys_pkey_modify(int pkey, unsigned long new_val)
+{
+	/* check for unsupported init values */
+	if (new_val & ~PKEY_ACCESS_MASK)
+		return -EINVAL;
+
+	return __arch_set_user_pkey_access(current, pkey, new_val);
+}

Signature · 1 line

1.7.1