[RFC] powerpc: add sys_pkey_modify() system call
From: Ram Pai <hidden>
Date: 2017-09-24 18:24:17
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- 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(-)
diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index b33b551..d6f667e 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h@@ -391,3 +391,4 @@ SYSCALL(pkey_alloc) SYSCALL(pkey_free) SYSCALL(pkey_mprotect) +PPC64ONLY(pkey_modify)
diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index daf1ba9..1e97086 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h@@ -12,7 +12,7 @@ #include <uapi/asm/unistd.h> -#define NR_syscalls 387 +#define NR_syscalls 388 #define __NR__exit __NR_exit
diff --git a/arch/powerpc/include/uapi/asm/unistd.h b/arch/powerpc/include/uapi/asm/unistd.h
index 71ae45e..c70b6d3 100644
--- a/arch/powerpc/include/uapi/asm/unistd.h
+++ b/arch/powerpc/include/uapi/asm/unistd.h@@ -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_ */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 4a0fd4f..5980b9e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S@@ -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)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index de2e88f..bd16bc4 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c@@ -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); +}
--
1.7.1