On Sep 10, 2015 5:22 PM, "Tycho Andersen" <tycho.ander...@canonical.com> wrote: > > This patch adds a way for a process that is "real root" to access the > seccomp filters of another process. The process first does a > PTRACE_SECCOMP_GET_FILTER_FD to get an fd with that process' seccomp filter > attached, and then iterates on this with PTRACE_SECCOMP_NEXT_FILTER using > bpf(BPF_PROG_DUMP) to dump the actual program at each step. >
> + > + fd = bpf_new_fd(filter->prog, O_RDONLY); > + if (fd > 0) > + atomic_inc(&filter->prog->aux->refcnt); Why isn't this folded into bpf_new_fd? > + > + return fd; > +} > + > +long seccomp_next_filter(struct task_struct *child, u32 fd) > +{ > + struct seccomp_filter *cur; > + struct bpf_prog *prog; > + long ret = -ESRCH; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EACCES; > + > + if (child->seccomp.mode != SECCOMP_MODE_FILTER) > + return -EINVAL; > + > + prog = bpf_prog_get(fd); > + if (IS_ERR(prog)) { > + ret = PTR_ERR(prog); > + goto out; > + } > + > + for (cur = child->seccomp.filter; cur; cur = cur->prev) { > + if (cur->prog == prog) { > + if (!cur->prev) > + ret = -ENOENT; > + else > + ret = bpf_prog_set(fd, cur->prev->prog); This lets you take an fd pointing to one prog and point it elsewhere. I'm not sure that's a good idea. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/