diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h index 163a8bb85d02b..71cff6d6bf3a8 100644 --- a/arch/powerpc/include/asm/vas.h +++ b/arch/powerpc/include/asm/vas.h @@ -5,6 +5,9 @@ #ifndef _ASM_POWERPC_VAS_H #define _ASM_POWERPC_VAS_H +#include +#include +#include #include struct vas_window; @@ -49,6 +52,17 @@ enum vas_cop_type { VAS_COP_TYPE_MAX, }; +/* + * User space VAS windows are opened by tasks and take references + * to pid and mm until windows are closed. + * Stores pid, mm, and tgid for each window. + */ +struct vas_user_win_ref { + struct pid *pid; /* PID of owner */ + struct pid *tgid; /* Thread group ID of owner */ + struct mm_struct *mm; /* Linux process mm_struct */ +}; + /* * User space window operations used for powernv and powerVM */ @@ -59,6 +73,31 @@ struct vas_user_win_ops { int (*close_win)(struct vas_window *); }; +static inline void put_vas_user_win_ref(struct vas_user_win_ref *ref) +{ + /* Drop references to pid, tgid, and mm */ + put_pid(ref->pid); + put_pid(ref->tgid); + if (ref->mm) + mmdrop(ref->mm); +} + +static inline void vas_user_win_add_mm_context(struct vas_user_win_ref *ref) +{ + mm_context_add_vas_window(ref->mm); + /* + * Even a process that has no foreign real address mapping can + * use an unpaired COPY instruction (to no real effect). Issue + * CP_ABORT to clear any pending COPY and prevent a covert + * channel. + * + * __switch_to() will issue CP_ABORT on future context switches + * if process / thread has any open VAS window (Use + * current->mm->context.vas_windows). + */ + asm volatile(PPC_CP_ABORT); +} + /* * Receive window attributes specified by the (in-kernel) owner of window. */ @@ -190,4 +229,5 @@ int vas_register_coproc_api(struct module *mod, enum vas_cop_type cop_type, const struct vas_user_win_ops *vops); void vas_unregister_coproc_api(void); +int get_vas_user_win_ref(struct vas_user_win_ref *task_ref); #endif /* __ASM_POWERPC_VAS_H */ diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c index ad566464b55b9..4ce82500f4c54 100644 --- a/arch/powerpc/platforms/book3s/vas-api.c +++ b/arch/powerpc/platforms/book3s/vas-api.c @@ -55,6 +55,45 @@ static char *coproc_devnode(struct device *dev, umode_t *mode) return kasprintf(GFP_KERNEL, "crypto/%s", dev_name(dev)); } +/* + * Take reference to pid and mm + */ +int get_vas_user_win_ref(struct vas_user_win_ref *task_ref) +{ + /* + * Window opened by a child thread may not be closed when + * it exits. So take reference to its pid and release it + * when the window is free by parent thread. + * Acquire a reference to the task's pid to make sure + * pid will not be re-used - needed only for multithread + * applications. + */ + task_ref->pid = get_task_pid(current, PIDTYPE_PID); + /* + * Acquire a reference to the task's mm. + */ + task_ref->mm = get_task_mm(current); + if (!task_ref->mm) { + put_pid(task_ref->pid); + pr_err("VAS: pid(%d): mm_struct is not found\n", + current->pid); + return -EPERM; + } + + mmgrab(task_ref->mm); + mmput(task_ref->mm); + /* + * Process closes window during exit. In the case of + * multithread application, the child thread can open + * window and can exit without closing it. So takes tgid + * reference until window closed to make sure tgid is not + * reused. + */ + task_ref->tgid = find_get_pid(task_tgid_vnr(current)); + + return 0; +} + static int coproc_open(struct inode *inode, struct file *fp) { struct coproc_instance *cp_inst; diff --git a/arch/powerpc/platforms/powernv/vas-fault.c b/arch/powerpc/platforms/powernv/vas-fault.c index 3d21fce254b74..ac3a71ec3bd5e 100644 --- a/arch/powerpc/platforms/powernv/vas-fault.c +++ b/arch/powerpc/platforms/powernv/vas-fault.c @@ -73,7 +73,7 @@ static void update_csb(struct vas_window *window, * NX user space windows can not be opened for task->mm=NULL * and faults will not be generated for kernel requests. */ - if (WARN_ON_ONCE(!window->mm || !window->user_win)) + if (WARN_ON_ONCE(!window->task_ref.mm || !window->user_win)) return; csb_addr = (void __user *)be64_to_cpu(crb->csb_addr); @@ -92,7 +92,7 @@ static void update_csb(struct vas_window *window, csb.address = crb->stamp.nx.fault_storage_addr; csb.flags = 0; - pid = window->pid; + pid = window->task_ref.pid; tsk = get_pid_task(pid, PIDTYPE_PID); /* * Process closes send window after all pending NX requests are @@ -111,7 +111,7 @@ static void update_csb(struct vas_window *window, * a window and exits without closing it. */ if (!tsk) { - pid = window->tgid; + pid = window->task_ref.tgid; tsk = get_pid_task(pid, PIDTYPE_PID); /* * Parent thread (tgid) will be closing window when it @@ -127,7 +127,7 @@ static void update_csb(struct vas_window *window, return; } - kthread_use_mm(window->mm); + kthread_use_mm(window->task_ref.mm); rc = copy_to_user(csb_addr, &csb, sizeof(csb)); /* * User space polls on csb.flags (first byte). So add barrier @@ -139,7 +139,7 @@ static void update_csb(struct vas_window *window, smp_mb(); rc = copy_to_user(csb_addr, &csb, sizeof(u8)); } - kthread_unuse_mm(window->mm); + kthread_unuse_mm(window->task_ref.mm); put_task_struct(tsk); /* Success */ diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c index 26440da4fc6a0..6489e29085be5 100644 --- a/arch/powerpc/platforms/powernv/vas-window.c +++ b/arch/powerpc/platforms/powernv/vas-window.c @@ -1065,51 +1065,11 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop, rc = -ENODEV; goto free_window; } - - /* - * Window opened by a child thread may not be closed when - * it exits. So take reference to its pid and release it - * when the window is free by parent thread. - * Acquire a reference to the task's pid to make sure - * pid will not be re-used - needed only for multithread - * applications. - */ - txwin->pid = get_task_pid(current, PIDTYPE_PID); - /* - * Acquire a reference to the task's mm. - */ - txwin->mm = get_task_mm(current); - - if (!txwin->mm) { - put_pid(txwin->pid); - pr_err("VAS: pid(%d): mm_struct is not found\n", - current->pid); - rc = -EPERM; + rc = get_vas_user_win_ref(&txwin->task_ref); + if (rc) goto free_window; - } - mmgrab(txwin->mm); - mmput(txwin->mm); - mm_context_add_vas_window(txwin->mm); - /* - * Process closes window during exit. In the case of - * multithread application, the child thread can open - * window and can exit without closing it. so takes tgid - * reference until window closed to make sure tgid is not - * reused. - */ - txwin->tgid = find_get_pid(task_tgid_vnr(current)); - /* - * Even a process that has no foreign real address mapping can - * use an unpaired COPY instruction (to no real effect). Issue - * CP_ABORT to clear any pending COPY and prevent a covert - * channel. - * - * __switch_to() will issue CP_ABORT on future context switches - * if process / thread has any open VAS window (Use - * current->mm->context.vas_windows). - */ - asm volatile(PPC_CP_ABORT); + vas_user_win_add_mm_context(&txwin->task_ref); } set_vinst_win(vinst, txwin); @@ -1340,13 +1300,8 @@ int vas_win_close(struct vas_window *window) /* if send window, drop reference to matching receive window */ if (window->tx_win) { if (window->user_win) { - /* Drop references to pid. tgid and mm */ - put_pid(window->pid); - put_pid(window->tgid); - if (window->mm) { - mm_context_remove_vas_window(window->mm); - mmdrop(window->mm); - } + put_vas_user_win_ref(&window->task_ref); + mm_context_remove_vas_window(window->task_ref.mm); } put_rx_win(window->rxwin); } diff --git a/arch/powerpc/platforms/powernv/vas.h b/arch/powerpc/platforms/powernv/vas.h index c2b1e12efca54..614db6a80c67c 100644 --- a/arch/powerpc/platforms/powernv/vas.h +++ b/arch/powerpc/platforms/powernv/vas.h @@ -357,11 +357,9 @@ struct vas_window { bool user_win; /* True if user space window */ void *hvwc_map; /* HV window context */ void *uwc_map; /* OS/User window context */ - struct pid *pid; /* Linux process id of owner */ - struct pid *tgid; /* Thread group ID of owner */ - struct mm_struct *mm; /* Linux process mm_struct */ int wcreds_max; /* Window credits */ + struct vas_user_win_ref task_ref; char *dbgname; struct dentry *dbgdir; @@ -443,7 +441,7 @@ extern void vas_win_paste_addr(struct vas_window *window, u64 *addr, static inline int vas_window_pid(struct vas_window *window) { - return pid_vnr(window->pid); + return pid_vnr(window->task_ref.pid); } static inline void vas_log_write(struct vas_window *win, char *name,