diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 409385b25ecb371655460d780cb5d357b4143bf1..e100efa2536ee997b6201aaa86123dc55dc9d504 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -376,6 +376,7 @@ enum { EVENT_FILE_FL_TRIGGER_COND_BIT, EVENT_FILE_FL_PID_FILTER_BIT, EVENT_FILE_FL_WAS_ENABLED_BIT, + EVENT_FILE_FL_FREED_BIT, }; extern struct trace_event_file *trace_get_event_file(const char *instance, @@ -514,6 +515,7 @@ extern int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...); * TRIGGER_COND - When set, one or more triggers has an associated filter * PID_FILTER - When set, the event is filtered based on pid * WAS_ENABLED - Set when enabled to know to clear trace on module removal + * FREED - File descriptor is freed, all fields should be considered invalid */ enum { EVENT_FILE_FL_ENABLED = (1 << EVENT_FILE_FL_ENABLED_BIT), @@ -527,6 +529,7 @@ enum { EVENT_FILE_FL_TRIGGER_COND = (1 << EVENT_FILE_FL_TRIGGER_COND_BIT), EVENT_FILE_FL_PID_FILTER = (1 << EVENT_FILE_FL_PID_FILTER_BIT), EVENT_FILE_FL_WAS_ENABLED = (1 << EVENT_FILE_FL_WAS_ENABLED_BIT), + EVENT_FILE_FL_FREED = (1 << EVENT_FILE_FL_FREED_BIT), }; struct trace_event_file { @@ -555,6 +558,7 @@ struct trace_event_file { * caching and such. Which is mostly OK ;-) */ unsigned long flags; + atomic_t ref; /* ref count for opened files */ atomic_t sm_ref; /* soft-mode reference counter */ atomic_t tm_ref; /* trigger-mode reference counter */ }; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c2bd3285c641512cf7ef40e2643b263b55c82bbd..26e682ba85d6f4f7ce5306b5f8555a8b802fc8bc 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4513,6 +4513,54 @@ int tracing_open_generic_tr(struct inode *inode, struct file *filp) return 0; } +/* + * The private pointer of the inode is the trace_event_file. + * Update the tr ref count associated to it. + */ +int tracing_open_file_tr(struct inode *inode, struct file *filp) +{ + struct trace_event_file *file = inode->i_private; + int ret; + + ret = tracing_check_open_get_tr(file->tr); + if (ret) + return ret; + + mutex_lock(&event_mutex); + + /* Fail if the file is marked for removal */ + if (file->flags & EVENT_FILE_FL_FREED) { + trace_array_put(file->tr); + ret = -ENODEV; + } else { + event_file_get(file); + } + + mutex_unlock(&event_mutex); + if (ret) + return ret; + + filp->private_data = inode->i_private; + + return 0; +} + +int tracing_release_file_tr(struct inode *inode, struct file *filp) +{ + struct trace_event_file *file = inode->i_private; + + trace_array_put(file->tr); + event_file_put(file); + + return 0; +} + +int tracing_single_release_file_tr(struct inode *inode, struct file *filp) +{ + tracing_release_file_tr(inode, filp); + return single_release(inode, filp); +} + static int tracing_release(struct inode *inode, struct file *file) { struct trace_array *tr = inode->i_private; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 6a8a638a2601e0a942b3efeb59c6fb839be09375..ae3411a6c3b5343f11960a5c74d7f18d80b489f9 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -736,6 +736,9 @@ void tracing_reset_all_online_cpus(void); void tracing_reset_all_online_cpus_unlocked(void); int tracing_open_generic(struct inode *inode, struct file *filp); int tracing_open_generic_tr(struct inode *inode, struct file *filp); +int tracing_open_file_tr(struct inode *inode, struct file *filp); +int tracing_release_file_tr(struct inode *inode, struct file *filp); +int tracing_single_release_file_tr(struct inode *inode, struct file *filp); bool tracing_is_disabled(void); bool tracer_tracing_is_on(struct trace_array *tr); void tracer_tracing_on(struct trace_array *tr); @@ -1780,6 +1783,9 @@ extern int register_event_command(struct event_command *cmd); extern int unregister_event_command(struct event_command *cmd); extern int register_trigger_hist_enable_disable_cmds(void); +extern void event_file_get(struct trace_event_file *file); +extern void event_file_put(struct trace_event_file *file); + /** * struct event_trigger_ops - callbacks for trace event triggers * diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 866d58301add82df4a3338cf3eb988271bef3aca..6bd2c5d8b5ac0c96b482cb1137bcdd8dc9e54673 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -743,26 +743,38 @@ static void remove_subsystem(struct trace_subsystem_dir *dir) } } -static void remove_event_file_dir(struct trace_event_file *file) +void event_file_get(struct trace_event_file *file) { - struct dentry *dir = file->dir; - struct dentry *child; + atomic_inc(&file->ref); +} - if (dir) { - spin_lock(&dir->d_lock); /* probably unneeded */ - list_for_each_entry(child, &dir->d_subdirs, d_child) { - if (d_really_is_positive(child)) /* probably unneeded */ - d_inode(child)->i_private = NULL; - } - spin_unlock(&dir->d_lock); +void event_file_put(struct trace_event_file *file) +{ + if (WARN_ON_ONCE(!atomic_read(&file->ref))) { + if (file->flags & EVENT_FILE_FL_FREED) + kmem_cache_free(file_cachep, file); + return; + } - tracefs_remove(dir); + if (atomic_dec_and_test(&file->ref)) { + /* Count should only go to zero when it is freed */ + if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED))) + return; + kmem_cache_free(file_cachep, file); } +} + +static void remove_event_file_dir(struct trace_event_file *file) +{ + struct dentry *dir = file->dir; + + tracefs_remove(dir); list_del(&file->list); remove_subsystem(file->system); free_event_filter(file->filter); - kmem_cache_free(file_cachep, file); + file->flags |= EVENT_FILE_FL_FREED; + event_file_put(file); } /* @@ -1135,7 +1147,7 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt, flags = file->flags; mutex_unlock(&event_mutex); - if (!file) + if (!file || flags & EVENT_FILE_FL_FREED) return -ENODEV; if (flags & EVENT_FILE_FL_ENABLED && @@ -1173,7 +1185,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, ret = -ENODEV; mutex_lock(&event_mutex); file = event_file_data(filp); - if (likely(file)) + if (likely(file && !(file->flags & EVENT_FILE_FL_FREED))) ret = ftrace_event_enable_disable(file, val); mutex_unlock(&event_mutex); break; @@ -1442,7 +1454,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt, mutex_lock(&event_mutex); file = event_file_data(filp); - if (file) + if (file && !(file->flags & EVENT_FILE_FL_FREED)) print_event_filter(file, s); mutex_unlock(&event_mutex); @@ -1852,9 +1864,10 @@ static const struct file_operations ftrace_set_event_notrace_pid_fops = { }; static const struct file_operations ftrace_enable_fops = { - .open = tracing_open_generic, + .open = tracing_open_file_tr, .read = event_enable_read, .write = event_enable_write, + .release = tracing_release_file_tr, .llseek = default_llseek, }; @@ -1871,9 +1884,10 @@ static const struct file_operations ftrace_event_id_fops = { }; static const struct file_operations ftrace_event_filter_fops = { - .open = tracing_open_generic, + .open = tracing_open_file_tr, .read = event_filter_read, .write = event_filter_write, + .release = tracing_release_file_tr, .llseek = default_llseek, }; @@ -2476,6 +2490,7 @@ trace_create_new_event(struct trace_event_call *call, atomic_set(&file->tm_ref, 0); INIT_LIST_HEAD(&file->triggers); list_add(&file->list, &tr->events); + event_file_get(file); return file; } diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index a255ffbe342f3a519a75fcbd1ffe69503db10767..c1db5b62d8114d91085716ef2e9893396f8e2fed 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1893,6 +1893,9 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) struct event_filter *filter = NULL; int err; + if (file->flags & EVENT_FILE_FL_FREED) + return -ENODEV; + if (!strcmp(strstrip(filter_string), "0")) { filter_disable(file); filter = event_filter(file); diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 059a106e62bec568138ad7c4cf8ec568afaeb630..920588dfdeb46994b0fa3c65dfe33b4797a725ed 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -4823,10 +4823,12 @@ static int event_hist_open(struct inode *inode, struct file *file) { int ret; - ret = security_locked_down(LOCKDOWN_TRACEFS); + ret = tracing_open_file_tr(inode, file); if (ret) return ret; + /* Clear private_data to avoid warning in single_open() */ + file->private_data = NULL; return single_open(file, hist_show, file); } @@ -4834,7 +4836,7 @@ const struct file_operations event_hist_fops = { .open = event_hist_open, .read = seq_read, .llseek = seq_lseek, - .release = single_release, + .release = tracing_single_release_file_tr, }; #ifdef CONFIG_HIST_TRIGGERS_DEBUG @@ -5095,10 +5097,12 @@ static int event_hist_debug_open(struct inode *inode, struct file *file) { int ret; - ret = security_locked_down(LOCKDOWN_TRACEFS); + ret = tracing_open_file_tr(inode, file); if (ret) return ret; + /* Clear private_data to avoid warning in single_open() */ + file->private_data = NULL; return single_open(file, hist_debug_show, file); } @@ -5106,7 +5110,7 @@ const struct file_operations event_hist_debug_fops = { .open = event_hist_debug_open, .read = seq_read, .llseek = seq_lseek, - .release = single_release, + .release = tracing_single_release_file_tr, }; #endif diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c index c188045c5f976cc35d20e6c72d108f934f0c27d6..b1fce64e126c0ab66ab03427ef1d4c363c74cf37 100644 --- a/kernel/trace/trace_events_inject.c +++ b/kernel/trace/trace_events_inject.c @@ -321,7 +321,8 @@ event_inject_read(struct file *file, char __user *buf, size_t size, } const struct file_operations event_inject_fops = { - .open = tracing_open_generic, + .open = tracing_open_file_tr, .read = event_inject_read, .write = event_inject_write, + .release = tracing_release_file_tr, };