From 9e8acd9c44a0dd52b2922eeb82398c04e356c058 Mon Sep 17 00:00:00 2001 From: Jiri Benc Date: Wed, 9 Oct 2019 10:31:24 +0200 Subject: [PATCH 1/7] bpf: lwtunnel: Fix reroute supplying invalid dst The dst in bpf_input() has lwtstate field set. As it is of the LWTUNNEL_ENCAP_BPF type, lwtstate->data is struct bpf_lwt. When the bpf program returns BPF_LWT_REROUTE, ip_route_input_noref is directly called on this skb. This causes invalid memory access, as ip_route_input_slow calls skb_tunnel_info(skb) that expects the dst->lwstate->data to be struct ip_tunnel_info. This results to struct bpf_lwt being accessed as struct ip_tunnel_info. Drop the dst before calling the IP route input functions (both for IPv4 and IPv6). Reported by KASAN. Fixes: 3bd0b15281af ("bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c") Signed-off-by: Jiri Benc Signed-off-by: Alexei Starovoitov Acked-by: Peter Oskolkov Link: https://lore.kernel.org/bpf/111664d58fe4e9dd9c8014bb3d0b2dab93086a9e.1570609794.git.jbenc@redhat.com --- net/core/lwt_bpf.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index f93785e5833c..74cfb8b5ab33 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -88,11 +88,16 @@ static int bpf_lwt_input_reroute(struct sk_buff *skb) int err = -EINVAL; if (skb->protocol == htons(ETH_P_IP)) { + struct net_device *dev = skb_dst(skb)->dev; struct iphdr *iph = ip_hdr(skb); + dev_hold(dev); + skb_dst_drop(skb); err = ip_route_input_noref(skb, iph->daddr, iph->saddr, - iph->tos, skb_dst(skb)->dev); + iph->tos, dev); + dev_put(dev); } else if (skb->protocol == htons(ETH_P_IPV6)) { + skb_dst_drop(skb); err = ipv6_stub->ipv6_route_input(skb); } else { err = -EAFNOSUPPORT; From 11875ba7f251c52effb2b924e04c2ddefa9856ef Mon Sep 17 00:00:00 2001 From: Jiri Benc Date: Fri, 18 Oct 2019 14:00:42 +0200 Subject: [PATCH 2/7] selftests/bpf: More compatible nc options in test_tc_edt Out of the three nc implementations widely in use, at least two (BSD netcat and nmap-ncat) do not support -l combined with -s. Modify the nc invocation to be accepted by all of them. Fixes: 7df5e3db8f63 ("selftests: bpf: tc-bpf flow shaping with EDT") Signed-off-by: Jiri Benc Signed-off-by: Daniel Borkmann Acked-by: Peter Oskolkov Link: https://lore.kernel.org/bpf/f5bf07dccd8b552a76c84d49e80b86c5aa071122.1571400024.git.jbenc@redhat.com --- tools/testing/selftests/bpf/test_tc_edt.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/test_tc_edt.sh b/tools/testing/selftests/bpf/test_tc_edt.sh index f38567ef694b..daa7d1b8d309 100755 --- a/tools/testing/selftests/bpf/test_tc_edt.sh +++ b/tools/testing/selftests/bpf/test_tc_edt.sh @@ -59,7 +59,7 @@ ip netns exec ${NS_SRC} tc filter add dev veth_src egress \ # start the listener ip netns exec ${NS_DST} bash -c \ - "nc -4 -l -s ${IP_DST} -p 9000 >/dev/null &" + "nc -4 -l -p 9000 >/dev/null &" declare -i NC_PID=$! sleep 1 From 05679ca6feebc1ef3bf743563315d9975adcf6fb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Thu, 17 Oct 2019 12:57:02 +0200 Subject: [PATCH 3/7] xdp: Prevent overflow in devmap_hash cost calculation for 32-bit builds MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Tetsuo pointed out that without an explicit cast, the cost calculation for devmap_hash type maps could overflow on 32-bit builds. This adds the missing cast. Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index") Reported-by: Tetsuo Handa Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20191017105702.2807093-1-toke@redhat.com --- kernel/bpf/devmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index d27f3b60ff6d..c0a48f336997 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -128,7 +128,7 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr) if (!dtab->n_buckets) /* Overflow check */ return -EINVAL; - cost += sizeof(struct hlist_head) * dtab->n_buckets; + cost += (u64) sizeof(struct hlist_head) * dtab->n_buckets; } /* if map size is larger than memlock limit, reject it */ From ce197d83a9fc42795c248c90983bf05faf0f013b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Sat, 19 Oct 2019 13:19:31 +0200 Subject: [PATCH 4/7] xdp: Handle device unregister for devmap_hash map type MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It seems I forgot to add handling of devmap_hash type maps to the device unregister hook for devmaps. This omission causes devices to not be properly released, which causes hangs. Fix this by adding the missing handler. Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index") Reported-by: Tetsuo Handa Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20191019111931.2981954-1-toke@redhat.com --- kernel/bpf/devmap.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index c0a48f336997..3867864cdc2f 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -719,6 +719,32 @@ const struct bpf_map_ops dev_map_hash_ops = { .map_check_btf = map_check_no_btf, }; +static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab, + struct net_device *netdev) +{ + unsigned long flags; + u32 i; + + spin_lock_irqsave(&dtab->index_lock, flags); + for (i = 0; i < dtab->n_buckets; i++) { + struct bpf_dtab_netdev *dev; + struct hlist_head *head; + struct hlist_node *next; + + head = dev_map_index_hash(dtab, i); + + hlist_for_each_entry_safe(dev, next, head, index_hlist) { + if (netdev != dev->dev) + continue; + + dtab->items--; + hlist_del_rcu(&dev->index_hlist); + call_rcu(&dev->rcu, __dev_map_entry_free); + } + } + spin_unlock_irqrestore(&dtab->index_lock, flags); +} + static int dev_map_notification(struct notifier_block *notifier, ulong event, void *ptr) { @@ -735,6 +761,11 @@ static int dev_map_notification(struct notifier_block *notifier, */ rcu_read_lock(); list_for_each_entry_rcu(dtab, &dev_map_list, list) { + if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) { + dev_map_hash_remove_netdev(dtab, netdev); + continue; + } + for (i = 0; i < dtab->map.max_entries; i++) { struct bpf_dtab_netdev *dev, *odev; From cd7455f1013ef96d5cbf5c05d2b7c06f273810a6 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 22 Oct 2019 15:57:23 +0200 Subject: [PATCH 5/7] bpf: Fix use after free in subprog's jited symbol removal syzkaller managed to trigger the following crash: [...] BUG: unable to handle page fault for address: ffffc90001923030 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD aa551067 P4D aa551067 PUD aa552067 PMD a572b067 PTE 80000000a1173163 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 7982 Comm: syz-executor912 Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:bpf_jit_binary_hdr include/linux/filter.h:787 [inline] RIP: 0010:bpf_get_prog_addr_region kernel/bpf/core.c:531 [inline] RIP: 0010:bpf_tree_comp kernel/bpf/core.c:600 [inline] RIP: 0010:__lt_find include/linux/rbtree_latch.h:115 [inline] RIP: 0010:latch_tree_find include/linux/rbtree_latch.h:208 [inline] RIP: 0010:bpf_prog_kallsyms_find kernel/bpf/core.c:674 [inline] RIP: 0010:is_bpf_text_address+0x184/0x3b0 kernel/bpf/core.c:709 [...] Call Trace: kernel_text_address kernel/extable.c:147 [inline] __kernel_text_address+0x9a/0x110 kernel/extable.c:102 unwind_get_return_address+0x4c/0x90 arch/x86/kernel/unwind_frame.c:19 arch_stack_walk+0x98/0xe0 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0xb6/0x150 kernel/stacktrace.c:123 save_stack mm/kasan/common.c:69 [inline] set_track mm/kasan/common.c:77 [inline] __kasan_kmalloc+0x11c/0x1b0 mm/kasan/common.c:510 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:518 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc mm/slab.c:3319 [inline] kmem_cache_alloc+0x1f5/0x2e0 mm/slab.c:3483 getname_flags+0xba/0x640 fs/namei.c:138 getname+0x19/0x20 fs/namei.c:209 do_sys_open+0x261/0x560 fs/open.c:1091 __do_sys_open fs/open.c:1115 [inline] __se_sys_open fs/open.c:1110 [inline] __x64_sys_open+0x87/0x90 fs/open.c:1110 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe [...] After further debugging it turns out that we walk kallsyms while in parallel we tear down a BPF program which contains subprograms that have been JITed though the program itself has not been fully exposed and is eventually bailing out with error. The bpf_prog_kallsyms_del_subprogs() in bpf_prog_load()'s error path removes the symbols, however, bpf_prog_free() tears down the JIT memory too early via scheduled work. Instead, it needs to properly respect RCU grace period as the kallsyms walk for BPF is under RCU. Fix it by refactoring __bpf_prog_put()'s tear down and reuse it in our error path where we defer final destruction when we have subprogs in the program. Fixes: 7d1982b4e335 ("bpf: fix panic in prog load calls cleanup") Fixes: 1c2a088a6626 ("bpf: x64: add JIT support for multi-function programs") Reported-by: syzbot+710043c5d1d5b5013bc7@syzkaller.appspotmail.com Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Tested-by: syzbot+710043c5d1d5b5013bc7@syzkaller.appspotmail.com Link: https://lore.kernel.org/bpf/55f6367324c2d7e9583fa9ccf5385dcbba0d7a6e.1571752452.git.daniel@iogearbox.net --- include/linux/filter.h | 1 - kernel/bpf/core.c | 2 +- kernel/bpf/syscall.c | 31 ++++++++++++++++++++----------- 3 files changed, 21 insertions(+), 13 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 2ce57645f3cd..0367a75f873b 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1099,7 +1099,6 @@ static inline void bpf_get_prog_name(const struct bpf_prog *prog, char *sym) #endif /* CONFIG_BPF_JIT */ -void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp); void bpf_prog_kallsyms_del_all(struct bpf_prog *fp); #define BPF_ANC BIT(15) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 66088a9e9b9e..ef0e1e3e66f4 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -502,7 +502,7 @@ int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) return WARN_ON_ONCE(bpf_adj_branches(prog, off, off + cnt, off, false)); } -void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp) +static void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp) { int i; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 82eabd4e38ad..bcfc362de4f2 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1332,18 +1332,26 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) bpf_prog_free(aux->prog); } +static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) +{ + bpf_prog_kallsyms_del_all(prog); + btf_put(prog->aux->btf); + kvfree(prog->aux->func_info); + bpf_prog_free_linfo(prog); + + if (deferred) + call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); + else + __bpf_prog_put_rcu(&prog->aux->rcu); +} + static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock) { if (atomic_dec_and_test(&prog->aux->refcnt)) { perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0); /* bpf_prog_free_id() must be called first */ bpf_prog_free_id(prog, do_idr_lock); - bpf_prog_kallsyms_del_all(prog); - btf_put(prog->aux->btf); - kvfree(prog->aux->func_info); - bpf_prog_free_linfo(prog); - - call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); + __bpf_prog_put_noref(prog, true); } } @@ -1741,11 +1749,12 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) return err; free_used_maps: - bpf_prog_free_linfo(prog); - kvfree(prog->aux->func_info); - btf_put(prog->aux->btf); - bpf_prog_kallsyms_del_subprogs(prog); - free_used_maps(prog->aux); + /* In case we have subprogs, we need to wait for a grace + * period before we can tear down JIT memory since symbols + * are already exposed under kallsyms. + */ + __bpf_prog_put_noref(prog, prog->aux->func_cnt); + return err; free_prog: bpf_prog_uncharge_memlock(prog); free_prog_sec: From 3b4d9eb2ee74dd5ea7fa36cffb0ca7f5bc4924da Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 22 Oct 2019 23:30:38 +0200 Subject: [PATCH 6/7] bpf: Fix use after free in bpf_get_prog_name There is one more problematic case I noticed while recently fixing BPF kallsyms handling in cd7455f1013e ("bpf: Fix use after free in subprog's jited symbol removal") and that is bpf_get_prog_name(). If BTF has been attached to the prog, then we may be able to fetch the function signature type id in kallsyms through prog->aux->func_info[prog->aux->func_idx].type_id. However, while the BTF object itself is torn down via RCU callback, the prog's aux->func_info is immediately freed via kvfree(prog->aux->func_info) once the prog's refcount either hit zero or when subprograms were already exposed via kallsyms and we hit the error path added in 5482e9a93c83 ("bpf: Fix memleak in aux->func_info and aux->btf"). This violates RCU as well since kallsyms could be walked in parallel where we could access aux->func_info. Hence, defer kvfree() to after RCU grace period. Looking at ba64e7d85252 ("bpf: btf: support proper non-jit func info") there is no reason/dependency where we couldn't defer the kvfree(aux->func_info) into the RCU callback. Fixes: 5482e9a93c83 ("bpf: Fix memleak in aux->func_info and aux->btf") Fixes: ba64e7d85252 ("bpf: btf: support proper non-jit func info") Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Cc: Martin KaFai Lau Link: https://lore.kernel.org/bpf/875f2906a7c1a0691f2d567b4d8e4ea2739b1e88.1571779205.git.daniel@iogearbox.net --- kernel/bpf/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index bcfc362de4f2..0937719b87e2 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1326,6 +1326,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) { struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu); + kvfree(aux->func_info); free_used_maps(aux); bpf_prog_uncharge_memlock(aux->prog); security_bpf_prog_free(aux); @@ -1336,7 +1337,6 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) { bpf_prog_kallsyms_del_all(prog); btf_put(prog->aux->btf); - kvfree(prog->aux->func_info); bpf_prog_free_linfo(prog); if (deferred) From 2afd23f78f39da84937006ecd24aa664a4ab052b Mon Sep 17 00:00:00 2001 From: Magnus Karlsson Date: Mon, 21 Oct 2019 10:16:58 +0200 Subject: [PATCH 7/7] xsk: Fix registration of Rx-only sockets Having Rx-only AF_XDP sockets can potentially lead to a crash in the system by a NULL pointer dereference in xsk_umem_consume_tx(). This function iterates through a list of all sockets tied to a umem and checks if there are any packets to send on the Tx ring. Rx-only sockets do not have a Tx ring, so this will cause a NULL pointer dereference. This will happen if you have registered one or more Rx-only sockets to a umem and the driver is checking the Tx ring even on Rx, or if the XDP_SHARED_UMEM mode is used and there is a mix of Rx-only and other sockets tied to the same umem. Fixed by only putting sockets with a Tx component on the list that xsk_umem_consume_tx() iterates over. Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions") Reported-by: Kal Cutter Conley Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov Acked-by: Jonathan Lemon Link: https://lore.kernel.org/bpf/1571645818-16244-1-git-send-email-magnus.karlsson@intel.com --- net/xdp/xdp_umem.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c index 16d5f353163a..3049af269fbf 100644 --- a/net/xdp/xdp_umem.c +++ b/net/xdp/xdp_umem.c @@ -27,6 +27,9 @@ void xdp_add_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) { unsigned long flags; + if (!xs->tx) + return; + spin_lock_irqsave(&umem->xsk_list_lock, flags); list_add_rcu(&xs->list, &umem->xsk_list); spin_unlock_irqrestore(&umem->xsk_list_lock, flags); @@ -36,6 +39,9 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs) { unsigned long flags; + if (!xs->tx) + return; + spin_lock_irqsave(&umem->xsk_list_lock, flags); list_del_rcu(&xs->list); spin_unlock_irqrestore(&umem->xsk_list_lock, flags);