arm64: Ensure execute-only permissions are not allowed without EPAN
authorCatalin Marinas <catalin.marinas@arm.com>
Thu, 3 Mar 2022 18:00:44 +0000 (18:00 +0000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 16 Mar 2022 13:23:43 +0000 (14:23 +0100)
commit61d32defc00f809dc5102a41b541ee38a66c7c59
treed33394b513c212d8880aa34f3dd85baab7c24d08
parent72ea28d88d30cefc5b0184e4666cf4817f2a0fa8
arm64: Ensure execute-only permissions are not allowed without EPAN

commit 6e2edd6371a497a6350bb735534c9bda2a31f43d upstream.

Commit 18107f8a2df6 ("arm64: Support execute-only permissions with
Enhanced PAN") re-introduced execute-only permissions when EPAN is
available. When EPAN is not available, arch_filter_pgprot() is supposed
to change a PAGE_EXECONLY permission into PAGE_READONLY_EXEC. However,
if BTI or MTE are present, such check does not detect the execute-only
pgprot in the presence of PTE_GP (BTI) or MT_NORMAL_TAGGED (MTE),
allowing the user to request PROT_EXEC with PROT_BTI or PROT_MTE.

Remove the arch_filter_pgprot() function, change the default VM_EXEC
permissions to PAGE_READONLY_EXEC and update the protection_map[] array
at core_initcall() if EPAN is detected.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: 18107f8a2df6 ("arm64: Support execute-only permissions with Enhanced PAN")
Cc: <stable@vger.kernel.org> # 5.13.x
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/arm64/Kconfig
arch/arm64/include/asm/pgtable-prot.h
arch/arm64/include/asm/pgtable.h
arch/arm64/mm/mmap.c