Re: [PATCH v6 08/12] tools/bpf/bpftool/skeleton: make it adopt to task comm size change
From: Kees Cook <hidden>
Date: 2021-10-25 21:24:39
Also in:
bpf, linux-fsdevel, linux-mm, linux-perf-users, lkml, netdev
On Mon, Oct 25, 2021 at 08:33:11AM +0000, Yafang Shao wrote:
bpf_probe_read_kernel_str() will add a nul terminator to the dst, then we don't care about if the dst size is big enough. Signed-off-by: Yafang Shao <redacted> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Arnaldo Carvalho de Melo <redacted> Cc: Andrii Nakryiko <redacted> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <redacted> Cc: Petr Mladek <pmladek@suse.com>
So, if we're ever going to copying these buffers out of the kernel (I don't know what the object lifetime here in bpf is for "e", etc), we should be zero-padding (as get_task_comm() does). Should this, instead, be using a bounce buffer? get_task_comm(comm, task->group_leader); bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm), comm); -Kees
quoted hunk ↗ jump to hunk
--- tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c index d9b420972934..f70702fcb224 100644 --- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c +++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c@@ -71,8 +71,8 @@ int iter(struct bpf_iter__task_file *ctx) e.pid = task->tgid; e.id = get_obj_id(file->private_data, obj_type); - bpf_probe_read_kernel(&e.comm, sizeof(e.comm), - task->group_leader->comm); + bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm), + task->group_leader->comm); bpf_seq_write(ctx->meta->seq, &e, sizeof(e)); return 0;-- 2.17.1
-- Kees Cook