diff options
-rw-r--r-- | arch/x86/kernel/fpu/signal.c | 10 | ||||
-rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 13 | ||||
-rw-r--r-- | arch/x86/kernel/fpu/xstate.h | 2 | ||||
-rw-r--r-- | arch/x86/kernel/signal.c | 18 |
4 files changed, 43 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 2b3b9e140dd4..931c5469d7f3 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -64,6 +64,16 @@ setfx: } /* + * Update the value of PKRU register that was already pushed onto the signal frame. + */ +static inline int update_pkru_in_sigframe(struct xregs_state __user *buf, u32 pkru) +{ + if (unlikely(!cpu_feature_enabled(X86_FEATURE_OSPKE))) + return 0; + return __put_user(pkru, (unsigned int __user *)get_xsave_addr_user(buf, XFEATURE_PKRU)); +} + +/* * Signal frame handlers. */ static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index c5a026fee5e0..fa7628bb541b 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -993,6 +993,19 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) } EXPORT_SYMBOL_GPL(get_xsave_addr); +/* + * Given an xstate feature nr, calculate where in the xsave buffer the state is. + * The xsave buffer should be in standard format, not compacted (e.g. user mode + * signal frames). + */ +void __user *get_xsave_addr_user(struct xregs_state __user *xsave, int xfeature_nr) +{ + if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr))) + return NULL; + + return (void __user *)xsave + xstate_offsets[xfeature_nr]; +} + #ifdef CONFIG_ARCH_HAS_PKEYS /* diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h index 2ee0b9c53dcc..5f057e50df81 100644 --- a/arch/x86/kernel/fpu/xstate.h +++ b/arch/x86/kernel/fpu/xstate.h @@ -54,6 +54,8 @@ extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void extern void fpu__init_cpu_xstate(void); extern void fpu__init_system_xstate(unsigned int legacy_size); +extern void __user *get_xsave_addr_user(struct xregs_state __user *xsave, int xfeature_nr); + static inline u64 xfeatures_mask_supervisor(void) { return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 1f1e8e0ac5a3..9dc77ad03a0e 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -61,6 +61,24 @@ static inline int is_x32_frame(struct ksignal *ksig) } /* + * Enable all pkeys temporarily, so as to ensure that both the current + * execution stack as well as the alternate signal stack are writeable. + * The application can use any of the available pkeys to protect the + * alternate signal stack, and we don't know which one it is, so enable + * all. The PKRU register will be reset to init_pkru later in the flow, + * in fpu__clear_user_states(), and it is the application's responsibility + * to enable the appropriate pkey as the first step in the signal handler + * so that the handler does not segfault. + */ +static inline u32 sig_prepare_pkru(void) +{ + u32 orig_pkru = read_pkru(); + + write_pkru(0); + return orig_pkru; +} + +/* * Set up a signal frame. */ |