Messages in this thread Patch in this message | | | Date | Fri, 6 Dec 2019 13:23:11 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH] ptrace: add PTRACE_GETFD request |
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> On Thu, Dec 05, 2019 at 11:44:53PM +0000, Sargun Dhillon wrote: > > > +static int ptrace_getfd(struct task_struct *child, unsigned long fd) > > +{ > > + struct files_struct *files; > > + struct file *file; > > + int ret = 0; > > + > > + files = get_files_struct(child); > > + if (!files) > > + return -ENOENT; > > + > > + spin_lock(&files->file_lock); > > + file = fcheck_files(files, fd); > > + if (!file) > > + ret = -EBADF; > > + else > > + get_file(file); > > + spin_unlock(&files->file_lock); > > + put_files_struct(files);
may be someone can finally create a helper for this, it can have more users. say, struct file *get_task_file(task, fd) { struct file *file = NULL;
task_lock(task); rcu_read_lock(); if (task->files) { file = fcheck_files(task->files, fd); if (file) get_file(file); } rcu_read_unlock(); task_unlock(task);
return file; }
no need to get/put files_struct, no need to take ->file_lock.
> > + > > + if (ret) > > + goto out; > > + > > + ret = get_unused_fd_flags(0); > > + if (ret >= 0) > > + fd_install(ret, file); > > + > > + fput(file);
this looks wrong or I am totally confused...
if (ret >= 0) fd_install(file); else fput(file);
?
> > @@ -1265,7 +1299,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, > > } > > > > ret = ptrace_check_attach(child, request == PTRACE_KILL || > > - request == PTRACE_INTERRUPT); > > + request == PTRACE_INTERRUPT || > > + request == PTRACE_GETFD);
Hmm. not sure why do you want this... But OK, we do not need to stop the tracee.
Oleg.
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