// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (c) 2021, Microsoft Corporation. * * Authors: * Beau Belgrave */ #include #include #include #include #include #include #include #include #include #include #include #include #include /* Reminder to move to uapi when everything works */ #ifdef CONFIG_COMPILE_TEST #include #else #include #endif #include "trace.h" #include "trace_dynevent.h" #define USER_EVENTS_PREFIX_LEN (sizeof(USER_EVENTS_PREFIX)-1) #define FIELD_DEPTH_TYPE 0 #define FIELD_DEPTH_NAME 1 #define FIELD_DEPTH_SIZE 2 /* * Limits how many trace_event calls user processes can create: * Must be a power of two of PAGE_SIZE. */ #define MAX_PAGE_ORDER 0 #define MAX_PAGES (1 << MAX_PAGE_ORDER) #define MAX_BYTES (MAX_PAGES * PAGE_SIZE) #define MAX_EVENTS (MAX_BYTES * 8) /* Limit how long of an event name plus args within the subsystem. */ #define MAX_EVENT_DESC 512 #define EVENT_NAME(user_event) ((user_event)->tracepoint.name) #define MAX_FIELD_ARRAY_SIZE 1024 /* * The MAP_STATUS_* macros are used for taking a index and determining the * appropriate byte and the bit in the byte to set/reset for an event. * * The lower 3 bits of the index decide which bit to set. * The remaining upper bits of the index decide which byte to use for the bit. * * This is used when an event has a probe attached/removed to reflect live * status of the event wanting tracing or not to user-programs via shared * memory maps. */ #define MAP_STATUS_BYTE(index) ((index) >> 3) #define MAP_STATUS_MASK(index) BIT((index) & 7) /* * Internal bits (kernel side only) to keep track of connected probes: * These are used when status is requested in text form about an event. These * bits are compared against an internal byte on the event to determine which * probes to print out to the user. * * These do not reflect the mapped bytes between the user and kernel space. */ #define EVENT_STATUS_FTRACE BIT(0) #define EVENT_STATUS_PERF BIT(1) #define EVENT_STATUS_OTHER BIT(7) /* * Stores the pages, tables, and locks for a group of events. * Each logical grouping of events has its own group, with a * matching page for status checks within user programs. This * allows for isolation of events to user programs by various * means. */ struct user_event_group { struct page *pages; char *register_page_data; char *system_name; struct hlist_node node; struct mutex reg_mutex; DECLARE_HASHTABLE(register_table, 8); DECLARE_BITMAP(page_bitmap, MAX_EVENTS); }; /* Group for init_user_ns mapping, top-most group */ static struct user_event_group *init_group; /* * Stores per-event properties, as users register events * within a file a user_event might be created if it does not * already exist. These are globally used and their lifetime * is tied to the refcnt member. These cannot go away until the * refcnt reaches one. */ struct user_event { struct user_event_group *group; struct tracepoint tracepoint; struct trace_event_call call; struct trace_event_class class; struct dyn_event devent; struct hlist_node node; struct list_head fields; struct list_head validators; refcount_t refcnt; int index; int flags; int min_size; char status; }; /* * Stores per-file events references, as users register events * within a file this structure is modified and freed via RCU. * The lifetime of this struct is tied to the lifetime of the file. * These are not shared and only accessible by the file that created it. */ struct user_event_refs { struct rcu_head rcu; int count; struct user_event *events[]; }; struct user_event_file_info { struct user_event_group *group; struct user_event_refs *refs; }; #define VALIDATOR_ENSURE_NULL (1 << 0) #define VALIDATOR_REL (1 << 1) struct user_event_validator { struct list_head link; int offset; int flags; }; typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted); static int user_event_parse(struct user_event_group *group, char *name, char *args, char *flags, struct user_event **newuser); static u32 user_event_key(char *name) { return jhash(name, strlen(name), 0); } static void set_page_reservations(char *pages, bool set) { int page; for (page = 0; page < MAX_PAGES; ++page) { void *addr = pages + (PAGE_SIZE * page); if (set) SetPageReserved(virt_to_page(addr)); else ClearPageReserved(virt_to_page(addr)); } } static void user_event_group_destroy(struct user_event_group *group) { if (group->register_page_data) set_page_reservations(group->register_page_data, false); if (group->pages) __free_pages(group->pages, MAX_PAGE_ORDER); kfree(group->system_name); kfree(group); } static char *user_event_group_system_name(struct user_namespace *user_ns) { char *system_name; int len = sizeof(USER_EVENTS_SYSTEM) + 1; if (user_ns != &init_user_ns) { /* * Unexpected at this point: * We only currently support init_user_ns. * When we enable more, this will trigger a failure so log. */ pr_warn("user_events: Namespace other than init_user_ns!\n"); return NULL; } system_name = kmalloc(len, GFP_KERNEL); if (!system_name) return NULL; snprintf(system_name, len, "%s", USER_EVENTS_SYSTEM); return system_name; } static inline struct user_event_group *user_event_group_from_user_ns(struct user_namespace *user_ns) { if (user_ns == &init_user_ns) return init_group; return NULL; } static struct user_event_group *current_user_event_group(void) { struct user_namespace *user_ns = current_user_ns(); struct user_event_group *group = NULL; while (user_ns) { group = user_event_group_from_user_ns(user_ns); if (group) break; user_ns = user_ns->parent; } return group; } static struct user_event_group *user_event_group_create(struct user_namespace *user_ns) { struct user_event_group *group; group = kzalloc(sizeof(*group), GFP_KERNEL); if (!group) return NULL; group->system_name = user_event_group_system_name(user_ns); if (!group->system_name) goto error; group->pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER); if (!group->pages) goto error; group->register_page_data = page_address(group->pages); set_page_reservations(group->register_page_data, true); /* Zero all bits beside 0 (which is reserved for failures) */ bitmap_zero(group->page_bitmap, MAX_EVENTS); set_bit(0, group->page_bitmap); mutex_init(&group->reg_mutex); hash_init(group->register_table); return group; error: if (group) user_event_group_destroy(group); return NULL; }; static __always_inline void user_event_register_set(struct user_event *user) { int i = user->index; user->group->register_page_data[MAP_STATUS_BYTE(i)] |= MAP_STATUS_MASK(i); } static __always_inline void user_event_register_clear(struct user_event *user) { int i = user->index; user->group->register_page_data[MAP_STATUS_BYTE(i)] &= ~MAP_STATUS_MASK(i); } static __always_inline __must_check bool user_event_last_ref(struct user_event *user) { return refcount_read(&user->refcnt) == 1; } static __always_inline __must_check size_t copy_nofault(void *addr, size_t bytes, struct iov_iter *i) { size_t ret; pagefault_disable(); ret = copy_from_iter_nocache(addr, bytes, i); pagefault_enable(); return ret; } static struct list_head *user_event_get_fields(struct trace_event_call *call) { struct user_event *user = (struct user_event *)call->data; return &user->fields; } /* * Parses a register command for user_events * Format: event_name[:FLAG1[,FLAG2...]] [field1[;field2...]] * * Example event named 'test' with a 20 char 'msg' field with an unsigned int * 'id' field after: * test char[20] msg;unsigned int id * * NOTE: Offsets are from the user data perspective, they are not from the * trace_entry/buffer perspective. We automatically add the common properties * sizes to the offset for the user. * * Upon success user_event has its ref count increased by 1. */ static int user_event_parse_cmd(struct user_event_group *group, char *raw_command, struct user_event **newuser) { char *name = raw_command; char *args = strpbrk(name, " "); char *flags; if (args) *args++ = '\0'; flags = strpbrk(name, ":"); if (flags) *flags++ = '\0'; return user_event_parse(group, name, args, flags, newuser); } static int user_field_array_size(const char *type) { const char *start = strchr(type, '['); char val[8]; char *bracket; int size = 0; if (start == NULL) return -EINVAL; if (strscpy(val, start + 1, sizeof(val)) <= 0) return -EINVAL; bracket = strchr(val, ']'); if (!bracket) return -EINVAL; *bracket = '\0'; if (kstrtouint(val, 0, &size)) return -EINVAL; if (size > MAX_FIELD_ARRAY_SIZE) return -EINVAL; return size; } static int user_field_size(const char *type) { /* long is not allowed from a user, since it's ambigious in size */ if (strcmp(type, "s64") == 0) return sizeof(s64); if (strcmp(type, "u64") == 0) return sizeof(u64); if (strcmp(type, "s32") == 0) return sizeof(s32); if (strcmp(type, "u32") == 0) return sizeof(u32); if (strcmp(type, "int") == 0) return sizeof(int); if (strcmp(type, "unsigned int") == 0) return sizeof(unsigned int); if (strcmp(type, "s16") == 0) return sizeof(s16); if (strcmp(type, "u16") == 0) return sizeof(u16); if (strcmp(type, "short") == 0) return sizeof(short); if (strcmp(type, "unsigned short") == 0) return sizeof(unsigned short); if (strcmp(type, "s8") == 0) return sizeof(s8); if (strcmp(type, "u8") == 0) return sizeof(u8); if (strcmp(type, "char") == 0) return sizeof(char); if (strcmp(type, "unsigned char") == 0) return sizeof(unsigned char); if (str_has_prefix(type, "char[")) return user_field_array_size(type); if (str_has_prefix(type, "unsigned char[")) return user_field_array_size(type); if (str_has_prefix(type, "__data_loc ")) return sizeof(u32); if (str_has_prefix(type, "__rel_loc ")) return sizeof(u32); /* Uknown basic type, error */ return -EINVAL; } static void user_event_destroy_validators(struct user_event *user) { struct user_event_validator *validator, *next; struct list_head *head = &user->validators; list_for_each_entry_safe(validator, next, head, link) { list_del(&validator->link); kfree(validator); } } static void user_event_destroy_fields(struct user_event *user) { struct ftrace_event_field *field, *next; struct list_head *head = &user->fields; list_for_each_entry_safe(field, next, head, link) { list_del(&field->link); kfree(field); } } static int user_event_add_field(struct user_event *user, const char *type, const char *name, int offset, int size, int is_signed, int filter_type) { struct user_event_validator *validator; struct ftrace_event_field *field; int validator_flags = 0; field = kmalloc(sizeof(*field), GFP_KERNEL); if (!field) return -ENOMEM; if (str_has_prefix(type, "__data_loc ")) goto add_validator; if (str_has_prefix(type, "__rel_loc ")) { validator_flags |= VALIDATOR_REL; goto add_validator; } goto add_field; add_validator: if (strstr(type, "char") != NULL) validator_flags |= VALIDATOR_ENSURE_NULL; validator = kmalloc(sizeof(*validator), GFP_KERNEL); if (!validator) { kfree(field); return -ENOMEM; } validator->flags = validator_flags; validator->offset = offset; /* Want sequential access when validating */ list_add_tail(&validator->link, &user->validators); add_field: field->type = type; field->name = name; field->offset = offset; field->size = size; field->is_signed = is_signed; field->filter_type = filter_type; list_add(&field->link, &user->fields); /* * Min size from user writes that are required, this does not include * the size of trace_entry (common fields). */ user->min_size = (offset + size) - sizeof(struct trace_entry); return 0; } /* * Parses the values of a field within the description * Format: type name [size] */ static int user_event_parse_field(char *field, struct user_event *user, u32 *offset) { char *part, *type, *name; u32 depth = 0, saved_offset = *offset; int len, size = -EINVAL; bool is_struct = false; field = skip_spaces(field); if (*field == '\0') return 0; /* Handle types that have a space within */ len = str_has_prefix(field, "unsigned "); if (len) goto skip_next; len = str_has_prefix(field, "struct "); if (len) { is_struct = true; goto skip_next; } len = str_has_prefix(field, "__data_loc unsigned "); if (len) goto skip_next; len = str_has_prefix(field, "__data_loc "); if (len) goto skip_next; len = str_has_prefix(field, "__rel_loc unsigned "); if (len) goto skip_next; len = str_has_prefix(field, "__rel_loc "); if (len) goto skip_next; goto parse; skip_next: type = field; field = strpbrk(field + len, " "); if (field == NULL) return -EINVAL; *field++ = '\0'; depth++; parse: name = NULL; while ((part = strsep(&field, " ")) != NULL) { switch (depth++) { case FIELD_DEPTH_TYPE: type = part; break; case FIELD_DEPTH_NAME: name = part; break; case FIELD_DEPTH_SIZE: if (!is_struct) return -EINVAL; if (kstrtou32(part, 10, &size)) return -EINVAL; break; default: return -EINVAL; } } if (depth < FIELD_DEPTH_SIZE || !name) return -EINVAL; if (depth == FIELD_DEPTH_SIZE) size = user_field_size(type); if (size == 0) return -EINVAL; if (size < 0) return size; *offset = saved_offset + size; return user_event_add_field(user, type, name, saved_offset, size, type[0] != 'u', FILTER_OTHER); } static int user_event_parse_fields(struct user_event *user, char *args) { char *field; u32 offset = sizeof(struct trace_entry); int ret = -EINVAL; if (args == NULL) return 0; while ((field = strsep(&args, ";")) != NULL) { ret = user_event_parse_field(field, user, &offset); if (ret) break; } return ret; } static struct trace_event_fields user_event_fields_array[1]; static const char *user_field_format(const char *type) { if (strcmp(type, "s64") == 0) return "%lld"; if (strcmp(type, "u64") == 0) return "%llu"; if (strcmp(type, "s32") == 0) return "%d"; if (strcmp(type, "u32") == 0) return "%u"; if (strcmp(type, "int") == 0) return "%d"; if (strcmp(type, "unsigned int") == 0) return "%u"; if (strcmp(type, "s16") == 0) return "%d"; if (strcmp(type, "u16") == 0) return "%u"; if (strcmp(type, "short") == 0) return "%d"; if (strcmp(type, "unsigned short") == 0) return "%u"; if (strcmp(type, "s8") == 0) return "%d"; if (strcmp(type, "u8") == 0) return "%u"; if (strcmp(type, "char") == 0) return "%d"; if (strcmp(type, "unsigned char") == 0) return "%u"; if (strstr(type, "char[") != NULL) return "%s"; /* Unknown, likely struct, allowed treat as 64-bit */ return "%llu"; } static bool user_field_is_dyn_string(const char *type, const char **str_func) { if (str_has_prefix(type, "__data_loc ")) { *str_func = "__get_str"; goto check; } if (str_has_prefix(type, "__rel_loc ")) { *str_func = "__get_rel_str"; goto check; } return false; check: return strstr(type, "char") != NULL; } #define LEN_OR_ZERO (len ? len - pos : 0) static int user_dyn_field_set_string(int argc, const char **argv, int *iout, char *buf, int len, bool *colon) { int pos = 0, i = *iout; *colon = false; for (; i < argc; ++i) { if (i != *iout) pos += snprintf(buf + pos, LEN_OR_ZERO, " "); pos += snprintf(buf + pos, LEN_OR_ZERO, "%s", argv[i]); if (strchr(argv[i], ';')) { ++i; *colon = true; break; } } /* Actual set, advance i */ if (len != 0) *iout = i; return pos + 1; } static int user_field_set_string(struct ftrace_event_field *field, char *buf, int len, bool colon) { int pos = 0; pos += snprintf(buf + pos, LEN_OR_ZERO, "%s", field->type); pos += snprintf(buf + pos, LEN_OR_ZERO, " "); pos += snprintf(buf + pos, LEN_OR_ZERO, "%s", field->name); if (colon) pos += snprintf(buf + pos, LEN_OR_ZERO, ";"); return pos + 1; } static int user_event_set_print_fmt(struct user_event *user, char *buf, int len) { struct ftrace_event_field *field, *next; struct list_head *head = &user->fields; int pos = 0, depth = 0; const char *str_func; pos += snprintf(buf + pos, LEN_OR_ZERO, "\""); list_for_each_entry_safe_reverse(field, next, head, link) { if (depth != 0) pos += snprintf(buf + pos, LEN_OR_ZERO, " "); pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s", field->name, user_field_format(field->type)); depth++; } pos += snprintf(buf + pos, LEN_OR_ZERO, "\""); list_for_each_entry_safe_reverse(field, next, head, link) { if (user_field_is_dyn_string(field->type, &str_func)) pos += snprintf(buf + pos, LEN_OR_ZERO, ", %s(%s)", str_func, field->name); else pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s", field->name); } return pos + 1; } #undef LEN_OR_ZERO static int user_event_create_print_fmt(struct user_event *user) { char *print_fmt; int len; len = user_event_set_print_fmt(user, NULL, 0); print_fmt = kmalloc(len, GFP_KERNEL); if (!print_fmt) return -ENOMEM; user_event_set_print_fmt(user, print_fmt, len); user->call.print_fmt = print_fmt; return 0; } static enum print_line_t user_event_print_trace(struct trace_iterator *iter, int flags, struct trace_event *event) { /* Unsafe to try to decode user provided print_fmt, use hex */ trace_print_hex_dump_seq(&iter->seq, "", DUMP_PREFIX_OFFSET, 16, 1, iter->ent, iter->ent_size, true); return trace_handle_return(&iter->seq); } static struct trace_event_functions user_event_funcs = { .trace = user_event_print_trace, }; static int user_event_set_call_visible(struct user_event *user, bool visible) { int ret; const struct cred *old_cred; struct cred *cred; cred = prepare_creds(); if (!cred) return -ENOMEM; /* * While by default tracefs is locked down, systems can be configured * to allow user_event files to be less locked down. The extreme case * being "other" has read/write access to user_events_data/status. * * When not locked down, processes may not have permissions to * add/remove calls themselves to tracefs. We need to temporarily * switch to root file permission to allow for this scenario. */ cred->fsuid = GLOBAL_ROOT_UID; old_cred = override_creds(cred); if (visible) ret = trace_add_event_call(&user->call); else ret = trace_remove_event_call(&user->call); revert_creds(old_cred); put_cred(cred); return ret; } static int destroy_user_event(struct user_event *user) { int ret = 0; /* Must destroy fields before call removal */ user_event_destroy_fields(user); ret = user_event_set_call_visible(user, false); if (ret) return ret; dyn_event_remove(&user->devent); user_event_register_clear(user); clear_bit(user->index, user->group->page_bitmap); hash_del(&user->node); user_event_destroy_validators(user); kfree(user->call.print_fmt); kfree(EVENT_NAME(user)); kfree(user); return ret; } static struct user_event *find_user_event(struct user_event_group *group, char *name, u32 *outkey) { struct user_event *user; u32 key = user_event_key(name); *outkey = key; hash_for_each_possible(group->register_table, user, node, key) if (!strcmp(EVENT_NAME(user), name)) { refcount_inc(&user->refcnt); return user; } return NULL; } static int user_event_validate(struct user_event *user, void *data, int len) { struct list_head *head = &user->validators; struct user_event_validator *validator; void *pos, *end = data + len; u32 loc, offset, size; list_for_each_entry(validator, head, link) { pos = data + validator->offset; /* Already done min_size check, no bounds check here */ loc = *(u32 *)pos; offset = loc & 0xffff; size = loc >> 16; if (likely(validator->flags & VALIDATOR_REL)) pos += offset + sizeof(loc); else pos = data + offset; pos += size; if (unlikely(pos > end)) return -EFAULT; if (likely(validator->flags & VALIDATOR_ENSURE_NULL)) if (unlikely(*(char *)(pos - 1) != '\0')) return -EFAULT; } return 0; } /* * Writes the user supplied payload out to a trace file. */ static void user_event_ftrace(struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted) { struct trace_event_file *file; struct trace_entry *entry; struct trace_event_buffer event_buffer; size_t size = sizeof(*entry) + i->count; file = (struct trace_event_file *)tpdata; if (!file || !(file->flags & EVENT_FILE_FL_ENABLED) || trace_trigger_soft_disabled(file)) return; /* Allocates and fills trace_entry, + 1 of this is data payload */ entry = trace_event_buffer_reserve(&event_buffer, file, size); if (unlikely(!entry)) return; if (unlikely(!copy_nofault(entry + 1, i->count, i))) goto discard; if (!list_empty(&user->validators) && unlikely(user_event_validate(user, entry, size))) goto discard; trace_event_buffer_commit(&event_buffer); return; discard: *faulted = true; __trace_event_discard_commit(event_buffer.buffer, event_buffer.event); } #ifdef CONFIG_PERF_EVENTS /* * Writes the user supplied payload out to perf ring buffer. */ static void user_event_perf(struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted) { struct hlist_head *perf_head; perf_head = this_cpu_ptr(user->call.perf_events); if (perf_head && !hlist_empty(perf_head)) { struct trace_entry *perf_entry; struct pt_regs *regs; size_t size = sizeof(*perf_entry) + i->count; int context; perf_entry = perf_trace_buf_alloc(ALIGN(size, 8), ®s, &context); if (unlikely(!perf_entry)) return; perf_fetch_caller_regs(regs); if (unlikely(!copy_nofault(perf_entry + 1, i->count, i))) goto discard; if (!list_empty(&user->validators) && unlikely(user_event_validate(user, perf_entry, size))) goto discard; perf_trace_buf_submit(perf_entry, size, context, user->call.event.type, 1, regs, perf_head, NULL); return; discard: *faulted = true; perf_swevent_put_recursion_context(context); } } #endif /* * Update the register page that is shared between user processes. */ static void update_reg_page_for(struct user_event *user) { struct tracepoint *tp = &user->tracepoint; char status = 0; if (atomic_read(&tp->key.enabled) > 0) { struct tracepoint_func *probe_func_ptr; user_event_func_t probe_func; rcu_read_lock_sched(); probe_func_ptr = rcu_dereference_sched(tp->funcs); if (probe_func_ptr) { do { probe_func = probe_func_ptr->func; if (probe_func == user_event_ftrace) status |= EVENT_STATUS_FTRACE; #ifdef CONFIG_PERF_EVENTS else if (probe_func == user_event_perf) status |= EVENT_STATUS_PERF; #endif else status |= EVENT_STATUS_OTHER; } while ((++probe_func_ptr)->func); } rcu_read_unlock_sched(); } if (status) user_event_register_set(user); else user_event_register_clear(user); user->status = status; } /* * Register callback for our events from tracing sub-systems. */ static int user_event_reg(struct trace_event_call *call, enum trace_reg type, void *data) { struct user_event *user = (struct user_event *)call->data; int ret = 0; if (!user) return -ENOENT; switch (type) { case TRACE_REG_REGISTER: ret = tracepoint_probe_register(call->tp, call->class->probe, data); if (!ret) goto inc; break; case TRACE_REG_UNREGISTER: tracepoint_probe_unregister(call->tp, call->class->probe, data); goto dec; #ifdef CONFIG_PERF_EVENTS case TRACE_REG_PERF_REGISTER: ret = tracepoint_probe_register(call->tp, call->class->perf_probe, data); if (!ret) goto inc; break; case TRACE_REG_PERF_UNREGISTER: tracepoint_probe_unregister(call->tp, call->class->perf_probe, data); goto dec; case TRACE_REG_PERF_OPEN: case TRACE_REG_PERF_CLOSE: case TRACE_REG_PERF_ADD: case TRACE_REG_PERF_DEL: break; #endif } return ret; inc: refcount_inc(&user->refcnt); update_reg_page_for(user); return 0; dec: update_reg_page_for(user); refcount_dec(&user->refcnt); return 0; } static int user_event_create(const char *raw_command) { struct user_event_group *group; struct user_event *user; char *name; int ret; if (!str_has_prefix(raw_command, USER_EVENTS_PREFIX)) return -ECANCELED; raw_command += USER_EVENTS_PREFIX_LEN; raw_command = skip_spaces(raw_command); name = kstrdup(raw_command, GFP_KERNEL); if (!name) return -ENOMEM; group = current_user_event_group(); if (!group) { kfree(name); return -ENOENT; } mutex_lock(&group->reg_mutex); ret = user_event_parse_cmd(group, name, &user); if (!ret) refcount_dec(&user->refcnt); mutex_unlock(&group->reg_mutex); if (ret) kfree(name); return ret; } static int user_event_show(struct seq_file *m, struct dyn_event *ev) { struct user_event *user = container_of(ev, struct user_event, devent); struct ftrace_event_field *field, *next; struct list_head *head; int depth = 0; seq_printf(m, "%s%s", USER_EVENTS_PREFIX, EVENT_NAME(user)); head = trace_get_fields(&user->call); list_for_each_entry_safe_reverse(field, next, head, link) { if (depth == 0) seq_puts(m, " "); else seq_puts(m, "; "); seq_printf(m, "%s %s", field->type, field->name); if (str_has_prefix(field->type, "struct ")) seq_printf(m, " %d", field->size); depth++; } seq_puts(m, "\n"); return 0; } static bool user_event_is_busy(struct dyn_event *ev) { struct user_event *user = container_of(ev, struct user_event, devent); return !user_event_last_ref(user); } static int user_event_free(struct dyn_event *ev) { struct user_event *user = container_of(ev, struct user_event, devent); if (!user_event_last_ref(user)) return -EBUSY; return destroy_user_event(user); } static bool user_field_match(struct ftrace_event_field *field, int argc, const char **argv, int *iout) { char *field_name = NULL, *dyn_field_name = NULL; bool colon = false, match = false; int dyn_len, len; if (*iout >= argc) return false; dyn_len = user_dyn_field_set_string(argc, argv, iout, dyn_field_name, 0, &colon); len = user_field_set_string(field, field_name, 0, colon); if (dyn_len != len) return false; dyn_field_name = kmalloc(dyn_len, GFP_KERNEL); field_name = kmalloc(len, GFP_KERNEL); if (!dyn_field_name || !field_name) goto out; user_dyn_field_set_string(argc, argv, iout, dyn_field_name, dyn_len, &colon); user_field_set_string(field, field_name, len, colon); match = strcmp(dyn_field_name, field_name) == 0; out: kfree(dyn_field_name); kfree(field_name); return match; } static bool user_fields_match(struct user_event *user, int argc, const char **argv) { struct ftrace_event_field *field, *next; struct list_head *head = &user->fields; int i = 0; list_for_each_entry_safe_reverse(field, next, head, link) if (!user_field_match(field, argc, argv, &i)) return false; if (i != argc) return false; return true; } static bool user_event_match(const char *system, const char *event, int argc, const char **argv, struct dyn_event *ev) { struct user_event *user = container_of(ev, struct user_event, devent); bool match; match = strcmp(EVENT_NAME(user), event) == 0 && (!system || strcmp(system, USER_EVENTS_SYSTEM) == 0); if (match && argc > 0) match = user_fields_match(user, argc, argv); return match; } static struct dyn_event_operations user_event_dops = { .create = user_event_create, .show = user_event_show, .is_busy = user_event_is_busy, .free = user_event_free, .match = user_event_match, }; static int user_event_trace_register(struct user_event *user) { int ret; ret = register_trace_event(&user->call.event); if (!ret) return -ENODEV; ret = user_event_set_call_visible(user, true); if (ret) unregister_trace_event(&user->call.event); return ret; } /* * Parses the event name, arguments and flags then registers if successful. * The name buffer lifetime is owned by this method for success cases only. * Upon success the returned user_event has its ref count increased by 1. */ static int user_event_parse(struct user_event_group *group, char *name, char *args, char *flags, struct user_event **newuser) { int ret; int index; u32 key; struct user_event *user; /* Prevent dyn_event from racing */ mutex_lock(&event_mutex); user = find_user_event(group, name, &key); mutex_unlock(&event_mutex); if (user) { *newuser = user; /* * Name is allocated by caller, free it since it already exists. * Caller only worries about failure cases for freeing. */ kfree(name); return 0; } index = find_first_zero_bit(group->page_bitmap, MAX_EVENTS); if (index == MAX_EVENTS) return -EMFILE; user = kzalloc(sizeof(*user), GFP_KERNEL); if (!user) return -ENOMEM; INIT_LIST_HEAD(&user->class.fields); INIT_LIST_HEAD(&user->fields); INIT_LIST_HEAD(&user->validators); user->group = group; user->tracepoint.name = name; ret = user_event_parse_fields(user, args); if (ret) goto put_user; ret = user_event_create_print_fmt(user); if (ret) goto put_user; user->call.data = user; user->call.class = &user->class; user->call.name = name; user->call.flags = TRACE_EVENT_FL_TRACEPOINT; user->call.tp = &user->tracepoint; user->call.event.funcs = &user_event_funcs; user->class.system = group->system_name; user->class.fields_array = user_event_fields_array; user->class.get_fields = user_event_get_fields; user->class.reg = user_event_reg; user->class.probe = user_event_ftrace; #ifdef CONFIG_PERF_EVENTS user->class.perf_probe = user_event_perf; #endif mutex_lock(&event_mutex); ret = user_event_trace_register(user); if (ret) goto put_user_lock; user->index = index; /* Ensure we track self ref and caller ref (2) */ refcount_set(&user->refcnt, 2); dyn_event_init(&user->devent, &user_event_dops); dyn_event_add(&user->devent, &user->call); set_bit(user->index, group->page_bitmap); hash_add(group->register_table, &user->node, key); mutex_unlock(&event_mutex); *newuser = user; return 0; put_user_lock: mutex_unlock(&event_mutex); put_user: user_event_destroy_fields(user); user_event_destroy_validators(user); kfree(user->call.print_fmt); kfree(user); return ret; } /* * Deletes a previously created event if it is no longer being used. */ static int delete_user_event(struct user_event_group *group, char *name) { u32 key; struct user_event *user = find_user_event(group, name, &key); if (!user) return -ENOENT; refcount_dec(&user->refcnt); if (!user_event_last_ref(user)) return -EBUSY; return destroy_user_event(user); } /* * Validates the user payload and writes via iterator. */ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) { struct user_event_file_info *info = file->private_data; struct user_event_refs *refs; struct user_event *user = NULL; struct tracepoint *tp; ssize_t ret = i->count; int idx; if (unlikely(copy_from_iter(&idx, sizeof(idx), i) != sizeof(idx))) return -EFAULT; if (idx < 0) return -EINVAL; rcu_read_lock_sched(); refs = rcu_dereference_sched(info->refs); /* * The refs->events array is protected by RCU, and new items may be * added. But the user retrieved from indexing into the events array * shall be immutable while the file is opened. */ if (likely(refs && idx < refs->count)) user = refs->events[idx]; rcu_read_unlock_sched(); if (unlikely(user == NULL)) return -ENOENT; if (unlikely(i->count < user->min_size)) return -EINVAL; tp = &user->tracepoint; /* * It's possible key.enabled disables after this check, however * we don't mind if a few events are included in this condition. */ if (likely(atomic_read(&tp->key.enabled) > 0)) { struct tracepoint_func *probe_func_ptr; user_event_func_t probe_func; struct iov_iter copy; void *tpdata; bool faulted; if (unlikely(fault_in_iov_iter_readable(i, i->count))) return -EFAULT; faulted = false; rcu_read_lock_sched(); probe_func_ptr = rcu_dereference_sched(tp->funcs); if (probe_func_ptr) { do { copy = *i; probe_func = probe_func_ptr->func; tpdata = probe_func_ptr->data; probe_func(user, ©, tpdata, &faulted); } while ((++probe_func_ptr)->func); } rcu_read_unlock_sched(); if (unlikely(faulted)) return -EFAULT; } return ret; } static int user_events_open(struct inode *node, struct file *file) { struct user_event_group *group; struct user_event_file_info *info; group = current_user_event_group(); if (!group) return -ENOENT; info = kzalloc(sizeof(*info), GFP_KERNEL); if (!info) return -ENOMEM; info->group = group; file->private_data = info; return 0; } static ssize_t user_events_write(struct file *file, const char __user *ubuf, size_t count, loff_t *ppos) { struct iovec iov; struct iov_iter i; if (unlikely(*ppos != 0)) return -EFAULT; if (unlikely(import_single_range(ITER_SOURCE, (char __user *)ubuf, count, &iov, &i))) return -EFAULT; return user_events_write_core(file, &i); } static ssize_t user_events_write_iter(struct kiocb *kp, struct iov_iter *i) { return user_events_write_core(kp->ki_filp, i); } static int user_events_ref_add(struct user_event_file_info *info, struct user_event *user) { struct user_event_group *group = info->group; struct user_event_refs *refs, *new_refs; int i, size, count = 0; refs = rcu_dereference_protected(info->refs, lockdep_is_held(&group->reg_mutex)); if (refs) { count = refs->count; for (i = 0; i < count; ++i) if (refs->events[i] == user) return i; } size = struct_size(refs, events, count + 1); new_refs = kzalloc(size, GFP_KERNEL); if (!new_refs) return -ENOMEM; new_refs->count = count + 1; for (i = 0; i < count; ++i) new_refs->events[i] = refs->events[i]; new_refs->events[i] = user; refcount_inc(&user->refcnt); rcu_assign_pointer(info->refs, new_refs); if (refs) kfree_rcu(refs, rcu); return i; } static long user_reg_get(struct user_reg __user *ureg, struct user_reg *kreg) { u32 size; long ret; ret = get_user(size, &ureg->size); if (ret) return ret; if (size > PAGE_SIZE) return -E2BIG; if (size < offsetofend(struct user_reg, write_index)) return -EINVAL; ret = copy_struct_from_user(kreg, sizeof(*kreg), ureg, size); if (ret) return ret; kreg->size = size; return 0; } /* * Registers a user_event on behalf of a user process. */ static long user_events_ioctl_reg(struct user_event_file_info *info, unsigned long uarg) { struct user_reg __user *ureg = (struct user_reg __user *)uarg; struct user_reg reg; struct user_event *user; char *name; long ret; ret = user_reg_get(ureg, ®); if (ret) return ret; name = strndup_user((const char __user *)(uintptr_t)reg.name_args, MAX_EVENT_DESC); if (IS_ERR(name)) { ret = PTR_ERR(name); return ret; } ret = user_event_parse_cmd(info->group, name, &user); if (ret) { kfree(name); return ret; } ret = user_events_ref_add(info, user); /* No longer need parse ref, ref_add either worked or not */ refcount_dec(&user->refcnt); /* Positive number is index and valid */ if (ret < 0) return ret; put_user((u32)ret, &ureg->write_index); put_user(user->index, &ureg->status_bit); return 0; } /* * Deletes a user_event on behalf of a user process. */ static long user_events_ioctl_del(struct user_event_file_info *info, unsigned long uarg) { void __user *ubuf = (void __user *)uarg; char *name; long ret; name = strndup_user(ubuf, MAX_EVENT_DESC); if (IS_ERR(name)) return PTR_ERR(name); /* event_mutex prevents dyn_event from racing */ mutex_lock(&event_mutex); ret = delete_user_event(info->group, name); mutex_unlock(&event_mutex); kfree(name); return ret; } /* * Handles the ioctl from user mode to register or alter operations. */ static long user_events_ioctl(struct file *file, unsigned int cmd, unsigned long uarg) { struct user_event_file_info *info = file->private_data; struct user_event_group *group = info->group; long ret = -ENOTTY; switch (cmd) { case DIAG_IOCSREG: mutex_lock(&group->reg_mutex); ret = user_events_ioctl_reg(info, uarg); mutex_unlock(&group->reg_mutex); break; case DIAG_IOCSDEL: mutex_lock(&group->reg_mutex); ret = user_events_ioctl_del(info, uarg); mutex_unlock(&group->reg_mutex); break; } return ret; } /* * Handles the final close of the file from user mode. */ static int user_events_release(struct inode *node, struct file *file) { struct user_event_file_info *info = file->private_data; struct user_event_group *group; struct user_event_refs *refs; struct user_event *user; int i; if (!info) return -EINVAL; group = info->group; /* * Ensure refs cannot change under any situation by taking the * register mutex during the final freeing of the references. */ mutex_lock(&group->reg_mutex); refs = info->refs; if (!refs) goto out; /* * The lifetime of refs has reached an end, it's tied to this file. * The underlying user_events are ref counted, and cannot be freed. * After this decrement, the user_events may be freed elsewhere. */ for (i = 0; i < refs->count; ++i) { user = refs->events[i]; if (user) refcount_dec(&user->refcnt); } out: file->private_data = NULL; mutex_unlock(&group->reg_mutex); kfree(refs); kfree(info); return 0; } static const struct file_operations user_data_fops = { .open = user_events_open, .write = user_events_write, .write_iter = user_events_write_iter, .unlocked_ioctl = user_events_ioctl, .release = user_events_release, }; static struct user_event_group *user_status_group(struct file *file) { struct seq_file *m = file->private_data; if (!m) return NULL; return m->private; } /* * Maps the shared page into the user process for checking if event is enabled. */ static int user_status_mmap(struct file *file, struct vm_area_struct *vma) { char *pages; struct user_event_group *group = user_status_group(file); unsigned long size = vma->vm_end - vma->vm_start; if (size != MAX_BYTES) return -EINVAL; if (!group) return -EINVAL; pages = group->register_page_data; return remap_pfn_range(vma, vma->vm_start, virt_to_phys(pages) >> PAGE_SHIFT, size, vm_get_page_prot(VM_READ)); } static void *user_seq_start(struct seq_file *m, loff_t *pos) { if (*pos) return NULL; return (void *)1; } static void *user_seq_next(struct seq_file *m, void *p, loff_t *pos) { ++*pos; return NULL; } static void user_seq_stop(struct seq_file *m, void *p) { } static int user_seq_show(struct seq_file *m, void *p) { struct user_event_group *group = m->private; struct user_event *user; char status; int i, active = 0, busy = 0, flags; if (!group) return -EINVAL; mutex_lock(&group->reg_mutex); hash_for_each(group->register_table, i, user, node) { status = user->status; flags = user->flags; seq_printf(m, "%d:%s", user->index, EVENT_NAME(user)); if (flags != 0 || status != 0) seq_puts(m, " #"); if (status != 0) { seq_puts(m, " Used by"); if (status & EVENT_STATUS_FTRACE) seq_puts(m, " ftrace"); if (status & EVENT_STATUS_PERF) seq_puts(m, " perf"); if (status & EVENT_STATUS_OTHER) seq_puts(m, " other"); busy++; } seq_puts(m, "\n"); active++; } mutex_unlock(&group->reg_mutex); seq_puts(m, "\n"); seq_printf(m, "Active: %d\n", active); seq_printf(m, "Busy: %d\n", busy); seq_printf(m, "Max: %ld\n", MAX_EVENTS); return 0; } static const struct seq_operations user_seq_ops = { .start = user_seq_start, .next = user_seq_next, .stop = user_seq_stop, .show = user_seq_show, }; static int user_status_open(struct inode *node, struct file *file) { struct user_event_group *group; int ret; group = current_user_event_group(); if (!group) return -ENOENT; ret = seq_open(file, &user_seq_ops); if (!ret) { /* Chain group to seq_file */ struct seq_file *m = file->private_data; m->private = group; } return ret; } static const struct file_operations user_status_fops = { .open = user_status_open, .mmap = user_status_mmap, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; /* * Creates a set of tracefs files to allow user mode interactions. */ static int create_user_tracefs(void) { struct dentry *edata, *emmap; edata = tracefs_create_file("user_events_data", TRACE_MODE_WRITE, NULL, NULL, &user_data_fops); if (!edata) { pr_warn("Could not create tracefs 'user_events_data' entry\n"); goto err; } /* mmap with MAP_SHARED requires writable fd */ emmap = tracefs_create_file("user_events_status", TRACE_MODE_WRITE, NULL, NULL, &user_status_fops); if (!emmap) { tracefs_remove(edata); pr_warn("Could not create tracefs 'user_events_mmap' entry\n"); goto err; } return 0; err: return -ENODEV; } static int __init trace_events_user_init(void) { int ret; init_group = user_event_group_create(&init_user_ns); if (!init_group) return -ENOMEM; ret = create_user_tracefs(); if (ret) { pr_warn("user_events could not register with tracefs\n"); user_event_group_destroy(init_group); init_group = NULL; return ret; } if (dyn_event_register(&user_event_dops)) pr_warn("user_events could not register with dyn_events\n"); return 0; } fs_initcall(trace_events_user_init);