diff options
| author |   Catalin Marinas <catalin.marinas@arm.com> | 2019-08-15 16:44:01 +0100 |
|---|---|---|
| committer |   Will Deacon <will@kernel.org> | 2019-08-20 18:18:10 +0100 |
| commit | 413235fcedc7f61e925fe9818bc3f5eff8ad2494 (patch) | |
| tree | 0c863fbe6a6cdb9cee727f52e5ae8cee565751ef /arch/arm64 | |
| parent | arm64: Tighten the PR_{SET, GET}_TAGGED_ADDR_CTRL prctl() unused arguments (diff) | |
| download | linux-dev-413235fcedc7f61e925fe9818bc3f5eff8ad2494.tar.xz linux-dev-413235fcedc7f61e925fe9818bc3f5eff8ad2494.zip | |
arm64: Change the tagged_addr sysctl control semantics to only prevent the opt-in
First rename the sysctl control to abi.tagged_addr_disabled and make it
default off (zero). When abi.tagged_addr_disabled == 1, only block the
enabling of the TBI ABI via prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE).
Getting the status of the ABI or disabling it is still allowed.
Acked-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kernel/process.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 76b7c55026aa..03689c0beb34 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -579,17 +579,22 @@ void arch_setup_new_exec(void) /* * Control the relaxed ABI allowing tagged user addresses into the kernel. */ -static unsigned int tagged_addr_prctl_allowed = 1; +static unsigned int tagged_addr_disabled; long set_tagged_addr_ctrl(unsigned long arg) { - if (!tagged_addr_prctl_allowed) - return -EINVAL; if (is_compat_task()) return -EINVAL; if (arg & ~PR_TAGGED_ADDR_ENABLE) return -EINVAL; + /* + * Do not allow the enabling of the tagged address ABI if globally + * disabled via sysctl abi.tagged_addr_disabled. + */ + if (arg & PR_TAGGED_ADDR_ENABLE && tagged_addr_disabled) + return -EINVAL; + update_thread_flag(TIF_TAGGED_ADDR, arg & PR_TAGGED_ADDR_ENABLE); return 0; @@ -597,8 +602,6 @@ long set_tagged_addr_ctrl(unsigned long arg) long get_tagged_addr_ctrl(void) { - if (!tagged_addr_prctl_allowed) - return -EINVAL; if (is_compat_task()) return -EINVAL; @@ -618,9 +621,9 @@ static int one = 1; static struct ctl_table tagged_addr_sysctl_table[] = { { - .procname = "tagged_addr", + .procname = "tagged_addr_disabled", .mode = 0644, - .data = &tagged_addr_prctl_allowed, + .data = &tagged_addr_disabled, .maxlen = sizeof(int), .proc_handler = proc_dointvec_minmax, .extra1 = &zero, |