proc: convert the return type of proc_fd_access_allowed() to be boolean

Convert return type of proc_fd_access_allowed() and the 'allowed' in it
to be boolean since the return type of ptrace_may_access() is boolean.

Link: https://lkml.kernel.org/r/20211219024404.29779-1-zhengqi.arch@bytedance.comSigned-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

@@ -670,10 +670,10 @@ static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
 /************************************************************************/
 
 /* permission checks */
-static int proc_fd_access_allowed(struct inode *inode)
+static bool proc_fd_access_allowed(struct inode *inode)
 {
 	struct task_struct *task;
-	int allowed = 0;
+	bool allowed = false;
 	/* Allow access to a task's file descriptors if it is us or we
 	 * may use ptrace attach to the process and find out that
 	 * information.