CVE-2024-35895
Jakub Sitnicki (3): bpf, sockmap: Prevent lock inversion deadlock in map delete elem bpf: Allow delete from sockmap/sockhash only if update is allowed Revert "bpf, sockmap: Prevent lock inversion deadlock in map delete elem"
kernel/bpf/verifier.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
From: Jakub Sitnicki jakub@cloudflare.com
stable inclusion from stable-v5.10.215 commit dd54b48db0c822ae7b520bc80751f0a0a173ef75 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QG7M CVE: CVE-2024-35895
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
---------------------------
commit ff91059932401894e6c86341915615c5eb0eca48 upstream.
syzkaller started using corpuses where a BPF tracing program deletes elements from a sockmap/sockhash map. Because BPF tracing programs can be invoked from any interrupt context, locks taken during a map_delete_elem operation must be hardirq-safe. Otherwise a deadlock due to lock inversion is possible, as reported by lockdep:
CPU0 CPU1 ---- ---- lock(&htab->buckets[i].lock); local_irq_disable(); lock(&host->lock); lock(&htab->buckets[i].lock); <Interrupt> lock(&host->lock);
Locks in sockmap are hardirq-unsafe by design. We expects elements to be deleted from sockmap/sockhash only in task (normal) context with interrupts enabled, or in softirq context.
Detect when map_delete_elem operation is invoked from a context which is _not_ hardirq-unsafe, that is interrupts are disabled, and bail out with an error.
Note that map updates are not affected by this issue. BPF verifier does not allow updating sockmap/sockhash from a BPF tracing program today.
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Reported-by: xingwei lee xrivendell7@gmail.com Reported-by: yue sun samsun1006219@gmail.com Reported-by: syzbot+bc922f476bd65abbd466@syzkaller.appspotmail.com Reported-by: syzbot+d4066896495db380182e@syzkaller.appspotmail.com Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: syzbot+d4066896495db380182e@syzkaller.appspotmail.com Acked-by: John Fastabend john.fastabend@gmail.com Closes: https://syzkaller.appspot.com/bug?extid=d4066896495db380182e Closes: https://syzkaller.appspot.com/bug?extid=bc922f476bd65abbd466 Link: https://lore.kernel.org/bpf/20240402104621.1050319-1-jakub@cloudflare.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Liu Jian liujian56@huawei.com --- net/core/sock_map.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 83e3ef655684..e7600cd7c2e8 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -434,6 +434,9 @@ static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test, struct sock *sk; int err = 0;
+ if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + raw_spin_lock_bh(&stab->lock); sk = *psk; if (!sk_test || sk_test == sk) @@ -967,6 +970,9 @@ static int sock_hash_delete_elem(struct bpf_map *map, void *key) struct bpf_shtab_elem *elem; int ret = -ENOENT;
+ if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + hash = sock_hash_bucket_hash(key, key_size); bucket = sock_hash_select_bucket(htab, hash);
From: Jakub Sitnicki jakub@cloudflare.com
mainline inclusion from mainline-v6.10-rc2 commit 98e948fb60d41447fd8d2d0c3b8637fc6b6dc26d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QG7M CVE: CVE-2024-35895
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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We have seen an influx of syzkaller reports where a BPF program attached to a tracepoint triggers a locking rule violation by performing a map_delete on a sockmap/sockhash.
We don't intend to support this artificial use scenario. Extend the existing verifier allowed-program-type check for updating sockmap/sockhash to also cover deleting from a map.
From now on only BPF programs which were previously allowed to update sockmap/sockhash can delete from these map types.
Fixes: ff9105993240 ("bpf, sockmap: Prevent lock inversion deadlock in map delete elem") Reported-by: Tetsuo Handa penguin-kernel@i-love.sakura.ne.jp Reported-by: syzbot+ec941d6e24f633a59172@syzkaller.appspotmail.com Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: syzbot+ec941d6e24f633a59172@syzkaller.appspotmail.com Acked-by: John Fastabend john.fastabend@gmail.com Closes: https://syzkaller.appspot.com/bug?extid=ec941d6e24f633a59172 Link: https://lore.kernel.org/bpf/20240527-sockmap-verify-deletes-v1-1-944b372f210... Signed-off-by: Liu Jian liujian56@huawei.com --- kernel/bpf/verifier.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 946e485a102c..c628fe1d105e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4718,7 +4718,8 @@ static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) enum bpf_attach_type eatype = env->prog->expected_attach_type; enum bpf_prog_type type = resolve_prog_type(env->prog);
- if (func_id != BPF_FUNC_map_update_elem) + if (func_id != BPF_FUNC_map_update_elem && + func_id != BPF_FUNC_map_delete_elem) return false;
/* It's not possible to get access to a locked struct sock in these @@ -4729,6 +4730,11 @@ static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) if (eatype == BPF_TRACE_ITER) return true; break; + case BPF_PROG_TYPE_SOCK_OPS: + /* map_update allowed only via dedicated helpers with event type checks */ + if (func_id == BPF_FUNC_map_delete_elem) + return true; + break; case BPF_PROG_TYPE_SOCKET_FILTER: case BPF_PROG_TYPE_SCHED_CLS: case BPF_PROG_TYPE_SCHED_ACT: @@ -4816,7 +4822,6 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_MAP_TYPE_SOCKMAP: if (func_id != BPF_FUNC_sk_redirect_map && func_id != BPF_FUNC_sock_map_update && - func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_msg_redirect_map && func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem && @@ -4826,7 +4831,6 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_MAP_TYPE_SOCKHASH: if (func_id != BPF_FUNC_sk_redirect_hash && func_id != BPF_FUNC_sock_hash_update && - func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_msg_redirect_hash && func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem &&
From: Jakub Sitnicki jakub@cloudflare.com
mainline inclusion from mainline-v6.10-rc2 commit 3b9ce0491a43e9af7f108b2f1bced7cd35931660 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QG7M CVE: CVE-2024-35895
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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This reverts commit ff91059932401894e6c86341915615c5eb0eca48.
This check is no longer needed. BPF programs attached to tracepoints are now rejected by the verifier when they attempt to delete from a sockmap/sockhash maps.
Signed-off-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/bpf/20240527-sockmap-verify-deletes-v1-2-944b372f210...
Conflicts: net/core/sock_map.c [This is because we did not backport 35d2b7ffffc1.] Signed-off-by: Liu Jian liujian56@huawei.com --- net/core/sock_map.c | 6 ------ 1 file changed, 6 deletions(-)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c index e7600cd7c2e8..83e3ef655684 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -434,9 +434,6 @@ static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test, struct sock *sk; int err = 0;
- if (irqs_disabled()) - return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ - raw_spin_lock_bh(&stab->lock); sk = *psk; if (!sk_test || sk_test == sk) @@ -970,9 +967,6 @@ static int sock_hash_delete_elem(struct bpf_map *map, void *key) struct bpf_shtab_elem *elem; int ret = -ENOENT;
- if (irqs_disabled()) - return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ - hash = sock_hash_bucket_hash(key, key_size); bucket = sock_hash_select_bucket(htab, hash);
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