155 lines
4.5 KiB
Diff
155 lines
4.5 KiB
Diff
From foo@baz Mon May 21 21:56:07 CEST 2018
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From: Kees Cook <keescook@chromium.org>
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Date: Tue, 1 May 2018 15:19:04 -0700
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Subject: nospec: Allow getting/setting on non-current task
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From: Kees Cook <keescook@chromium.org>
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commit 7bbf1373e228840bb0295a2ca26d548ef37f448e upstream
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Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than
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current.
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This is needed both for /proc/$pid/status queries and for seccomp (since
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thread-syncing can trigger seccomp in non-current threads).
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Signed-off-by: Kees Cook <keescook@chromium.org>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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arch/x86/kernel/cpu/bugs.c | 27 ++++++++++++++++-----------
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include/linux/nospec.h | 7 +++++--
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kernel/sys.c | 9 +++++----
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3 files changed, 26 insertions(+), 17 deletions(-)
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -530,31 +530,35 @@ static void ssb_select_mitigation()
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#undef pr_fmt
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-static int ssb_prctl_set(unsigned long ctrl)
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+static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl)
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{
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- bool rds = !!test_tsk_thread_flag(current, TIF_RDS);
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+ bool rds = !!test_tsk_thread_flag(task, TIF_RDS);
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if (ssb_mode != SPEC_STORE_BYPASS_PRCTL)
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return -ENXIO;
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if (ctrl == PR_SPEC_ENABLE)
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- clear_tsk_thread_flag(current, TIF_RDS);
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+ clear_tsk_thread_flag(task, TIF_RDS);
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else
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- set_tsk_thread_flag(current, TIF_RDS);
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+ set_tsk_thread_flag(task, TIF_RDS);
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- if (rds != !!test_tsk_thread_flag(current, TIF_RDS))
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+ /*
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+ * If being set on non-current task, delay setting the CPU
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+ * mitigation until it is next scheduled.
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+ */
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+ if (task == current && rds != !!test_tsk_thread_flag(task, TIF_RDS))
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speculative_store_bypass_update();
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return 0;
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}
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-static int ssb_prctl_get(void)
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+static int ssb_prctl_get(struct task_struct *task)
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{
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switch (ssb_mode) {
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case SPEC_STORE_BYPASS_DISABLE:
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return PR_SPEC_DISABLE;
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case SPEC_STORE_BYPASS_PRCTL:
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- if (test_tsk_thread_flag(current, TIF_RDS))
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+ if (test_tsk_thread_flag(task, TIF_RDS))
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return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
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return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
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default:
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@@ -564,24 +568,25 @@ static int ssb_prctl_get(void)
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}
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}
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-int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
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+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
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+ unsigned long ctrl)
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{
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if (ctrl != PR_SPEC_ENABLE && ctrl != PR_SPEC_DISABLE)
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return -ERANGE;
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switch (which) {
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case PR_SPEC_STORE_BYPASS:
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- return ssb_prctl_set(ctrl);
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+ return ssb_prctl_set(task, ctrl);
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default:
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return -ENODEV;
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}
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}
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-int arch_prctl_spec_ctrl_get(unsigned long which)
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+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
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{
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switch (which) {
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case PR_SPEC_STORE_BYPASS:
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- return ssb_prctl_get();
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+ return ssb_prctl_get(task);
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default:
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return -ENODEV;
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}
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--- a/include/linux/nospec.h
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+++ b/include/linux/nospec.h
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@@ -7,6 +7,8 @@
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#define _LINUX_NOSPEC_H
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#include <asm/barrier.h>
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+struct task_struct;
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+
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/**
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* array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise
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* @index: array element index
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@@ -57,7 +59,8 @@ static inline unsigned long array_index_
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})
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/* Speculation control prctl */
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-int arch_prctl_spec_ctrl_get(unsigned long which);
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-int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl);
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+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which);
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+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
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+ unsigned long ctrl);
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#endif /* _LINUX_NOSPEC_H */
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--- a/kernel/sys.c
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+++ b/kernel/sys.c
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@@ -2192,12 +2192,13 @@ static int propagate_has_child_subreaper
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return 1;
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}
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-int __weak arch_prctl_spec_ctrl_get(unsigned long which)
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+int __weak arch_prctl_spec_ctrl_get(struct task_struct *t, unsigned long which)
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{
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return -EINVAL;
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}
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-int __weak arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
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+int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
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+ unsigned long ctrl)
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{
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return -EINVAL;
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}
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@@ -2413,12 +2414,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
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case PR_GET_SPECULATION_CTRL:
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if (arg3 || arg4 || arg5)
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return -EINVAL;
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- error = arch_prctl_spec_ctrl_get(arg2);
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+ error = arch_prctl_spec_ctrl_get(me, arg2);
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break;
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case PR_SET_SPECULATION_CTRL:
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if (arg4 || arg5)
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return -EINVAL;
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- error = arch_prctl_spec_ctrl_set(arg2, arg3);
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+ error = arch_prctl_spec_ctrl_set(me, arg2, arg3);
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break;
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default:
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error = -EINVAL;
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