From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Tony Luck <tony.luck@intel.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Rik van Riel <riel@surriel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Fenghua Yu <fenghua.yu@intel.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v3 06/10] x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates
Date: Thu, 7 May 2020 08:55:16 -0700 [thread overview]
Message-ID: <20200507155516.25972-1-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20200328164307.17497-7-yu-cheng.yu@intel.com>
The function sanitize_restored_xstate() sanitizes user xstates of an XSAVE
buffer by clearing bits not in the input 'xfeatures' from the buffer's
header->xfeatures, effectively resetting those features back to the init
state.
When supervisor xstates are introduced, it is necessary to make sure only
user xstates are sanitized. Ensure supervisor bits in header->xfeatures
stay set and supervisor states are not modified.
To make names clear, also:
- Rename the function to sanitize_restored_user_xstate().
- Rename input parameter 'xfeatures' to 'user_xfeatures'.
- In __fpu__restore_sig(), rename 'xfeatures' to 'user_xfeatures'.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
---
v3:
- Change xfeatures_user to user_xfeatures.
arch/x86/kernel/fpu/signal.c | 37 +++++++++++++++++++++++-------------
1 file changed, 24 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index cd6eafba12da..d09d72334a12 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -211,9 +211,9 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
}
static inline void
-sanitize_restored_xstate(union fpregs_state *state,
- struct user_i387_ia32_struct *ia32_env,
- u64 xfeatures, int fx_only)
+sanitize_restored_user_xstate(union fpregs_state *state,
+ struct user_i387_ia32_struct *ia32_env,
+ u64 user_xfeatures, int fx_only)
{
struct xregs_state *xsave = &state->xsave;
struct xstate_header *header = &xsave->header;
@@ -226,13 +226,22 @@ sanitize_restored_xstate(union fpregs_state *state,
*/
/*
- * Init the state that is not present in the memory
- * layout and not enabled by the OS.
+ * 'user_xfeatures' might have bits clear which are
+ * set in header->xfeatures. This represents features that
+ * were in init state prior to a signal delivery, and need
+ * to be reset back to the init state. Clear any user
+ * feature bits which are set in the kernel buffer to get
+ * them back to the init state.
+ *
+ * Supervisor state is unchanged by input from userspace.
+ * Ensure supervisor state bits stay set and supervisor
+ * state is not modified.
*/
if (fx_only)
header->xfeatures = XFEATURE_MASK_FPSSE;
else
- header->xfeatures &= xfeatures;
+ header->xfeatures &= user_xfeatures |
+ xfeatures_mask_supervisor();
}
if (use_fxsr()) {
@@ -281,7 +290,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
struct task_struct *tsk = current;
struct fpu *fpu = &tsk->thread.fpu;
struct user_i387_ia32_struct env;
- u64 xfeatures = 0;
+ u64 user_xfeatures = 0;
int fx_only = 0;
int ret = 0;
@@ -314,7 +323,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
trace_x86_fpu_xstate_check_failed(fpu);
} else {
state_size = fx_sw_user.xstate_size;
- xfeatures = fx_sw_user.xfeatures;
+ user_xfeatures = fx_sw_user.xfeatures;
}
}
@@ -349,7 +358,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
*/
fpregs_lock();
pagefault_disable();
- ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only);
+ ret = copy_user_to_fpregs_zeroing(buf_fx, user_xfeatures, fx_only);
pagefault_enable();
if (!ret) {
fpregs_mark_activate();
@@ -362,7 +371,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
if (use_xsave() && !fx_only) {
- u64 init_bv = xfeatures_mask_user() & ~xfeatures;
+ u64 init_bv = xfeatures_mask_user() & ~user_xfeatures;
if (using_compacted_format()) {
ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
@@ -375,12 +384,13 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
if (ret)
goto err_out;
- sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+ sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
+ fx_only);
fpregs_lock();
if (unlikely(init_bv))
copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
- ret = copy_kernel_to_xregs_err(&fpu->state.xsave, xfeatures);
+ ret = copy_kernel_to_xregs_err(&fpu->state.xsave, user_xfeatures);
} else if (use_fxsr()) {
ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
@@ -389,7 +399,8 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
goto err_out;
}
- sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
+ sanitize_restored_user_xstate(&fpu->state, envp,
+ user_xfeatures, fx_only);
fpregs_lock();
if (use_xsave()) {
--
2.21.0
next prev parent reply other threads:[~2020-05-07 15:56 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-28 16:42 [PATCH v3 00/10] Support XSAVES supervisor states Yu-cheng Yu
2020-03-28 16:42 ` [PATCH v3 01/10] x86/fpu/xstate: Rename validate_xstate_header() to validate_user_xstate_header() Yu-cheng Yu
2020-04-28 17:11 ` Borislav Petkov
2020-04-28 17:15 ` Yu-cheng Yu
2020-03-28 16:42 ` [PATCH v3 02/10] x86/fpu/xstate: Define new macros for supervisor and user xstates Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 03/10] x86/fpu/xstate: Separate user and supervisor xfeatures mask Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 04/10] x86/fpu/xstate: Introduce XSAVES supervisor states Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 05/10] x86/fpu/xstate: Define new functions for clearing fpregs and xstates Yu-cheng Yu
2020-04-29 9:27 ` Borislav Petkov
2020-04-29 16:09 ` Yu-cheng Yu
2020-04-29 16:06 ` Yu-cheng Yu
2020-04-29 16:39 ` Borislav Petkov
2020-04-29 17:02 ` Yu-cheng Yu
2020-04-29 17:32 ` Borislav Petkov
2020-04-29 17:42 ` Yu-cheng Yu
2020-04-29 19:10 ` Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 06/10] x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates Yu-cheng Yu
2020-05-07 13:11 ` Borislav Petkov
2020-05-07 15:55 ` Yu-cheng Yu [this message]
2020-03-28 16:43 ` [PATCH v3 07/10] x86/fpu/xstate: Update copy_kernel_to_xregs_err() for XSAVES supervisor states Yu-cheng Yu
2020-05-07 13:28 ` Borislav Petkov
2020-05-07 15:58 ` Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 08/10] x86/fpu: Introduce copy_supervisor_to_kernel() Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 09/10] x86/fpu/xstate: Preserve supervisor states for slow path of __fpu__restore_sig() Yu-cheng Yu
2020-05-10 8:46 ` Borislav Petkov
2020-05-11 20:16 ` Yu-cheng Yu
2020-03-28 16:43 ` [PATCH v3 10/10] x86/fpu/xstate: Restore supervisor states for signal return Yu-cheng Yu
2020-05-10 8:49 ` Borislav Petkov
2020-05-11 20:20 ` Yu-cheng Yu
2020-05-11 20:27 ` [PATCH v3 00/10] Support XSAVES supervisor states Borislav Petkov
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