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authorKees Cook <keescook@chromium.org>2018-05-01 15:19:04 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 16:58:01 +0200
commit4272f528da381673a8e7845c93daa88b8aa4f4e9 (patch)
tree06df42ad4350a7041883a4e76100e85ca54726e6 /arch/x86/kernel
parenta078e3e81964c31079627dd32c3ea714d5b1531e (diff)
nospec: Allow getting/setting on non-current task
commit 7bbf1373e228840bb0295a2ca26d548ef37f448e upstream Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than current. This is needed both for /proc/$pid/status queries and for seccomp (since thread-syncing can trigger seccomp in non-current threads). Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/bugs.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index b7d9adf22585..3760931cd40a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -529,31 +529,35 @@ static void ssb_select_mitigation()
#undef pr_fmt
-static int ssb_prctl_set(unsigned long ctrl)
+static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
{
- bool rds = !!test_tsk_thread_flag(current, TIF_RDS);
+ bool rds = !!test_tsk_thread_flag(task, TIF_RDS);
if (ssb_mode != SPEC_STORE_BYPASS_PRCTL)
return -ENXIO;
if (ctrl == PR_SPEC_ENABLE)
- clear_tsk_thread_flag(current, TIF_RDS);
+ clear_tsk_thread_flag(task, TIF_RDS);
else
- set_tsk_thread_flag(current, TIF_RDS);
+ set_tsk_thread_flag(task, TIF_RDS);
- if (rds != !!test_tsk_thread_flag(current, TIF_RDS))
+ /*
+ * If being set on non-current task, delay setting the CPU
+ * mitigation until it is next scheduled.
+ */
+ if (task == current && rds != !!test_tsk_thread_flag(task, TIF_RDS))
speculative_store_bypass_update();
return 0;
}
-static int ssb_prctl_get(void)
+static int ssb_prctl_get(struct task_struct *task)
{
switch (ssb_mode) {
case SPEC_STORE_BYPASS_DISABLE:
return PR_SPEC_DISABLE;
case SPEC_STORE_BYPASS_PRCTL:
- if (test_tsk_thread_flag(current, TIF_RDS))
+ if (test_tsk_thread_flag(task, TIF_RDS))
return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
default:
@@ -563,24 +567,25 @@ static int ssb_prctl_get(void)
}
}
-int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
+ unsigned long ctrl)
{
if (ctrl != PR_SPEC_ENABLE && ctrl != PR_SPEC_DISABLE)
return -ERANGE;
switch (which) {
case PR_SPEC_STORE_BYPASS:
- return ssb_prctl_set(ctrl);
+ return ssb_prctl_set(task, ctrl);
default:
return -ENODEV;
}
}
-int arch_prctl_spec_ctrl_get(unsigned long which)
+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
{
switch (which) {
case PR_SPEC_STORE_BYPASS:
- return ssb_prctl_get();
+ return ssb_prctl_get(task);
default:
return -ENODEV;
}