arm64: reject prctl(PR_PAC_RESET_KEYS) on compat tasks (4b7a6ce7) · Commits · 戴 / test

It doesn't make sense to issue prctl(PR_PAC_RESET_KEYS) on a compat task because the 32-bit instruction set does not offer PAuth instructions. For consistency with other 64-bit only prctls such as {SET,GET}_TAGGED_ADDR_CTRL, reject the prctl on compat tasks. Although this is a userspace-visible change, maybe it isn't too late to make this change given that the hardware isn't available yet and it's very unlikely that anyone has 32-bit software that actually depends on this succeeding. Signed-off-by:

Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ie885a1ff84ab498cc9f62d6451e9f2cfd4b1d06a Link: https://lore.kernel.org/r/20201014052430.11630-1-pcc@google.com [will: Do the same for the SVE prctl()s] Signed-off-by:

Will Deacon <will@kernel.org>

arch/arm64/kernel/fpsimd.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -678,7 +678,7 @@ int sve_set_current_vl(unsigned long arg)
		vl = arg & PR_SVE_VL_LEN_MASK;
		flags = arg & ~vl;

		if (!system_supports_sve())
		if (!system_supports_sve() \|\| is_compat_task())
		return -EINVAL;

		ret = sve_set_vector_length(current, vl, flags);
		@@ -691,7 +691,7 @@ int sve_set_current_vl(unsigned long arg)
		/* PR_SVE_GET_VL */
		int sve_get_current_vl(void)
		{
		if (!system_supports_sve())
		if (!system_supports_sve() \|\| is_compat_task())
		return -EINVAL;

		return sve_prctl_status(0);

arch/arm64/kernel/pointer_auth.c

+4 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0

		#include <linux/compat.h>
		#include <linux/errno.h>
		#include <linux/prctl.h>
		#include <linux/random.h>
		@@ -17,6 +18,9 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg)
		if (!system_supports_address_auth() && !system_supports_generic_auth())
		return -EINVAL;

		if (is_compat_thread(task_thread_info(tsk)))
		return -EINVAL;

		if (!arg) {
		ptrauth_keys_init_user(keys);
		return 0;

Admin message