// SPDX-License-Identifier: GPL-2.0 #include "trace.h" /** * trace_find_filtered_pid - check if a pid exists in a filtered_pid list * @filtered_pids: The list of pids to check * @search_pid: The PID to find in @filtered_pids * * Returns true if @search_pid is found in @filtered_pids, and false otherwise. */ bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid) { return trace_pid_list_is_set(filtered_pids, search_pid); } /** * trace_ignore_this_task - should a task be ignored for tracing * @filtered_pids: The list of pids to check * @filtered_no_pids: The list of pids not to be traced * @task: The task that should be ignored if not filtered * * Checks if @task should be traced or not from @filtered_pids. * Returns true if @task should *NOT* be traced. * Returns false if @task should be traced. */ bool trace_ignore_this_task(struct trace_pid_list *filtered_pids, struct trace_pid_list *filtered_no_pids, struct task_struct *task) { /* * If filtered_no_pids is not empty, and the task's pid is listed * in filtered_no_pids, then return true. * Otherwise, if filtered_pids is empty, that means we can * trace all tasks. If it has content, then only trace pids * within filtered_pids. */ return (filtered_pids && !trace_find_filtered_pid(filtered_pids, task->pid)) || (filtered_no_pids && trace_find_filtered_pid(filtered_no_pids, task->pid)); } /** * trace_filter_add_remove_task - Add or remove a task from a pid_list * @pid_list: The list to modify * @self: The current task for fork or NULL for exit * @task: The task to add or remove * * If adding a task, if @self is defined, the task is only added if @self * is also included in @pid_list. This happens on fork and tasks should * only be added when the parent is listed. If @self is NULL, then the * @task pid will be removed from the list, which would happen on exit * of a task. */ void trace_filter_add_remove_task(struct trace_pid_list *pid_list, struct task_struct *self, struct task_struct *task) { if (!pid_list) return; /* For forks, we only add if the forking task is listed */ if (self) { if (!trace_find_filtered_pid(pid_list, self->pid)) return; } /* "self" is set for forks, and NULL for exits */ if (self) trace_pid_list_set(pid_list, task->pid); else trace_pid_list_clear(pid_list, task->pid); } /** * trace_pid_next - Used for seq_file to get to the next pid of a pid_list * @pid_list: The pid list to show * @v: The last pid that was shown (+1 the actual pid to let zero be displayed) * @pos: The position of the file * * This is used by the seq_file "next" operation to iterate the pids * listed in a trace_pid_list structure. * * Returns the pid+1 as we want to display pid of zero, but NULL would * stop the iteration. */ void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos) { long pid = (unsigned long)v; unsigned int next; (*pos)++; /* pid already is +1 of the actual previous bit */ if (trace_pid_list_next(pid_list, pid, &next) < 0) return NULL; pid = next; /* Return pid + 1 to allow zero to be represented */ return (void *)(pid + 1); } /** * trace_pid_start - Used for seq_file to start reading pid lists * @pid_list: The pid list to show * @pos: The position of the file * * This is used by seq_file "start" operation to start the iteration * of listing pids. * * Returns the pid+1 as we want to display pid of zero, but NULL would * stop the iteration. */ void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos) { unsigned long pid; unsigned int first; loff_t l = 0; if (trace_pid_list_first(pid_list, &first) < 0) return NULL; pid = first; /* Return pid + 1 so that zero can be the exit value */ for (pid++; pid && l < *pos; pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l)) ; return (void *)pid; } /** * trace_pid_show - show the current pid in seq_file processing * @m: The seq_file structure to write into * @v: A void pointer of the pid (+1) value to display * * Can be directly used by seq_file operations to display the current * pid value. */ int trace_pid_show(struct seq_file *m, void *v) { unsigned long pid = (unsigned long)v - 1; seq_printf(m, "%lu\n", pid); return 0; } /* 128 should be much more than enough */ #define PID_BUF_SIZE 127 int trace_pid_write(struct trace_pid_list *filtered_pids, struct trace_pid_list **new_pid_list, const char __user *ubuf, size_t cnt) { struct trace_pid_list *pid_list; struct trace_parser parser; unsigned long val; int nr_pids = 0; ssize_t read = 0; ssize_t ret; loff_t pos; pid_t pid; if (trace_parser_get_init(&parser, PID_BUF_SIZE + 1)) return -ENOMEM; /* * Always recreate a new array. The write is an all or nothing * operation. Always create a new array when adding new pids by * the user. If the operation fails, then the current list is * not modified. */ pid_list = trace_pid_list_alloc(); if (!pid_list) { trace_parser_put(&parser); return -ENOMEM; } if (filtered_pids) { /* copy the current bits to the new max */ ret = trace_pid_list_first(filtered_pids, &pid); while (!ret) { ret = trace_pid_list_set(pid_list, pid); if (ret < 0) goto out; ret = trace_pid_list_next(filtered_pids, pid + 1, &pid); nr_pids++; } } ret = 0; while (cnt > 0) { pos = 0; ret = trace_get_user(&parser, ubuf, cnt, &pos); if (ret < 0) break; read += ret; ubuf += ret; cnt -= ret; if (!trace_parser_loaded(&parser)) break; ret = -EINVAL; if (kstrtoul(parser.buffer, 0, &val)) break; pid = (pid_t)val; if (trace_pid_list_set(pid_list, pid) < 0) { ret = -1; break; } nr_pids++; trace_parser_clear(&parser); ret = 0; } out: trace_parser_put(&parser); if (ret < 0) { trace_pid_list_free(pid_list); return ret; } if (!nr_pids) { /* Cleared the list of pids */ trace_pid_list_free(pid_list); pid_list = NULL; } *new_pid_list = pid_list; return read; }
