From 42f298c06b30bfe0a8cbee5d38644e618699e26e Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Mon, 25 Mar 2024 13:24:13 -0700 Subject: af_unix: Link struct unix_edge when queuing skb. Just before queuing skb with inflight fds, we call scm_stat_add(), which is a good place to set up the preallocated struct unix_vertex and struct unix_edge in UNIXCB(skb).fp. Then, we call unix_add_edges() and construct the directed graph as follows: 1. Set the inflight socket's unix_sock to unix_edge.predecessor. 2. Set the receiver's unix_sock to unix_edge.successor. 3. Set the preallocated vertex to inflight socket's unix_sock.vertex. 4. Link inflight socket's unix_vertex.entry to unix_unvisited_vertices. 5. Link unix_edge.vertex_entry to the inflight socket's unix_vertex.edges. Let's say we pass the fd of AF_UNIX socket A to B and the fd of B to C. The graph looks like this: +-------------------------+ | unix_unvisited_vertices | <-------------------------. +-------------------------+ | + | | +--------------+ +--------------+ | +--------------+ | | unix_sock A | <---. .---> | unix_sock B | <-|-. .---> | unix_sock C | | +--------------+ | | +--------------+ | | | +--------------+ | .-+ | vertex | | | .-+ | vertex | | | | | vertex | | | +--------------+ | | | +--------------+ | | | +--------------+ | | | | | | | | | | +--------------+ | | | +--------------+ | | | | '-> | unix_vertex | | | '-> | unix_vertex | | | | | +--------------+ | | +--------------+ | | | `---> | entry | +---------> | entry | +-' | | |--------------| | | |--------------| | | | edges | <-. | | | edges | <-. | | +--------------+ | | | +--------------+ | | | | | | | | | .----------------------' | | .----------------------' | | | | | | | | | +--------------+ | | | +--------------+ | | | | unix_edge | | | | | unix_edge | | | | +--------------+ | | | +--------------+ | | `-> | vertex_entry | | | `-> | vertex_entry | | | |--------------| | | |--------------| | | | predecessor | +---' | | predecessor | +---' | |--------------| | |--------------| | | successor | +-----' | successor | +-----' +--------------+ +--------------+ Henceforth, we denote such a graph as A -> B (-> C). Now, we can express all inflight fd graphs that do not contain embryo sockets. We will support the particular case later. Signed-off-by: Kuniyuki Iwashima Acked-by: Paolo Abeni Link: https://lore.kernel.org/r/20240325202425.60930-4-kuniyu@amazon.com Signed-off-by: Jakub Kicinski --- net/unix/garbage.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 89 insertions(+), 1 deletion(-) (limited to 'net/unix/garbage.c') diff --git a/net/unix/garbage.c b/net/unix/garbage.c index f31917683288..36d665936096 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -101,6 +101,38 @@ struct unix_sock *unix_get_socket(struct file *filp) return NULL; } +static LIST_HEAD(unix_unvisited_vertices); + +static void unix_add_edge(struct scm_fp_list *fpl, struct unix_edge *edge) +{ + struct unix_vertex *vertex = edge->predecessor->vertex; + + if (!vertex) { + vertex = list_first_entry(&fpl->vertices, typeof(*vertex), entry); + vertex->out_degree = 0; + INIT_LIST_HEAD(&vertex->edges); + + list_move_tail(&vertex->entry, &unix_unvisited_vertices); + edge->predecessor->vertex = vertex; + } + + vertex->out_degree++; + list_add_tail(&edge->vertex_entry, &vertex->edges); +} + +static void unix_del_edge(struct scm_fp_list *fpl, struct unix_edge *edge) +{ + struct unix_vertex *vertex = edge->predecessor->vertex; + + list_del(&edge->vertex_entry); + vertex->out_degree--; + + if (!vertex->out_degree) { + edge->predecessor->vertex = NULL; + list_move_tail(&vertex->entry, &fpl->vertices); + } +} + static void unix_free_vertices(struct scm_fp_list *fpl) { struct unix_vertex *vertex, *next_vertex; @@ -111,6 +143,60 @@ static void unix_free_vertices(struct scm_fp_list *fpl) } } +DEFINE_SPINLOCK(unix_gc_lock); + +void unix_add_edges(struct scm_fp_list *fpl, struct unix_sock *receiver) +{ + int i = 0, j = 0; + + spin_lock(&unix_gc_lock); + + if (!fpl->count_unix) + goto out; + + do { + struct unix_sock *inflight = unix_get_socket(fpl->fp[j++]); + struct unix_edge *edge; + + if (!inflight) + continue; + + edge = fpl->edges + i++; + edge->predecessor = inflight; + edge->successor = receiver; + + unix_add_edge(fpl, edge); + } while (i < fpl->count_unix); + +out: + spin_unlock(&unix_gc_lock); + + fpl->inflight = true; + + unix_free_vertices(fpl); +} + +void unix_del_edges(struct scm_fp_list *fpl) +{ + int i = 0; + + spin_lock(&unix_gc_lock); + + if (!fpl->count_unix) + goto out; + + do { + struct unix_edge *edge = fpl->edges + i++; + + unix_del_edge(fpl, edge); + } while (i < fpl->count_unix); + +out: + spin_unlock(&unix_gc_lock); + + fpl->inflight = false; +} + int unix_prepare_fpl(struct scm_fp_list *fpl) { struct unix_vertex *vertex; @@ -141,11 +227,13 @@ err: void unix_destroy_fpl(struct scm_fp_list *fpl) { + if (fpl->inflight) + unix_del_edges(fpl); + kvfree(fpl->edges); unix_free_vertices(fpl); } -DEFINE_SPINLOCK(unix_gc_lock); unsigned int unix_tot_inflight; static LIST_HEAD(gc_candidates); static LIST_HEAD(gc_inflight_list); -- cgit v1.2.3