Merge tag 'trace-v4.7-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[linux-2.6-block.git] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 0d163a84082dbddc846a871a46cfd75aa1eddfb8..a11eb7196ec8b814ce1e9ed098253e0f6cfd24a5 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1820,12 +1820,17 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 
        child = d_hash_and_lookup(dir, &qname);
        if (!child) {
-               child = d_alloc(dir, &qname);
-               if (!child)
-                       goto end_instantiate;
-               if (instantiate(d_inode(dir), child, task, ptr) < 0) {
-                       dput(child);
+               DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+               child = d_alloc_parallel(dir, &qname, &wq);
+               if (IS_ERR(child))
                        goto end_instantiate;
+               if (d_in_lookup(child)) {
+                       int err = instantiate(d_inode(dir), child, task, ptr);
+                       d_lookup_done(child);
+                       if (err < 0) {
+                               dput(child);
+                               goto end_instantiate;
+                       }
                }
        }
        inode = d_inode(child);
@@ -2155,8 +2160,8 @@ out:
 
 static const struct file_operations proc_map_files_operations = {
        .read           = generic_read_dir,
-       .iterate        = proc_map_files_readdir,
-       .llseek         = default_llseek,
+       .iterate_shared = proc_map_files_readdir,
+       .llseek         = generic_file_llseek,
 };
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -2503,8 +2508,8 @@ static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
 
 static const struct file_operations proc_attr_dir_operations = {
        .read           = generic_read_dir,
-       .iterate        = proc_attr_dir_readdir,
-       .llseek         = default_llseek,
+       .iterate_shared = proc_attr_dir_readdir,
+       .llseek         = generic_file_llseek,
 };
 
 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
@@ -2911,8 +2916,8 @@ static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
 
 static const struct file_operations proc_tgid_base_operations = {
        .read           = generic_read_dir,
-       .iterate        = proc_tgid_base_readdir,
-       .llseek         = default_llseek,
+       .iterate_shared = proc_tgid_base_readdir,
+       .llseek         = generic_file_llseek,
 };
 
 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
@@ -3157,6 +3162,44 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
        return 0;
 }
 
+/*
+ * proc_tid_comm_permission is a special permission function exclusively
+ * used for the node /proc/<pid>/task/<tid>/comm.
+ * It bypasses generic permission checks in the case where a task of the same
+ * task group attempts to access the node.
+ * The rationale behind this is that glibc and bionic access this node for
+ * cross thread naming (pthread_set/getname_np(!self)). However, if
+ * PR_SET_DUMPABLE gets set to 0 this node among others becomes uid=0 gid=0,
+ * which locks out the cross thread naming implementation.
+ * This function makes sure that the node is always accessible for members of
+ * same thread group.
+ */
+static int proc_tid_comm_permission(struct inode *inode, int mask)
+{
+       bool is_same_tgroup;
+       struct task_struct *task;
+
+       task = get_proc_task(inode);
+       if (!task)
+               return -ESRCH;
+       is_same_tgroup = same_thread_group(current, task);
+       put_task_struct(task);
+
+       if (likely(is_same_tgroup && !(mask & MAY_EXEC))) {
+               /* This file (/proc/<pid>/task/<tid>/comm) can always be
+                * read or written by the members of the corresponding
+                * thread group.
+                */
+               return 0;
+       }
+
+       return generic_permission(inode, mask);
+}
+
+static const struct inode_operations proc_tid_comm_inode_operations = {
+               .permission = proc_tid_comm_permission,
+};
+
 /*
  * Tasks
  */
@@ -3175,7 +3218,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_SCHED_DEBUG
        REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
 #endif
-       REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
+       NOD("comm",      S_IFREG|S_IRUGO|S_IWUSR,
+                        &proc_tid_comm_inode_operations,
+                        &proc_pid_set_comm_operations, {}),
 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
        ONE("syscall",   S_IRUSR, proc_pid_syscall),
 #endif
@@ -3259,8 +3304,8 @@ static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *den
 
 static const struct file_operations proc_tid_base_operations = {
        .read           = generic_read_dir,
-       .iterate        = proc_tid_base_readdir,
-       .llseek         = default_llseek,
+       .iterate_shared = proc_tid_base_readdir,
+       .llseek         = generic_file_llseek,
 };
 
 static const struct inode_operations proc_tid_base_inode_operations = {
@@ -3470,6 +3515,6 @@ static const struct inode_operations proc_task_inode_operations = {
 
 static const struct file_operations proc_task_operations = {
        .read           = generic_read_dir,
-       .iterate        = proc_task_readdir,
-       .llseek         = default_llseek,
+       .iterate_shared = proc_task_readdir,
+       .llseek         = generic_file_llseek,
 };