From 350a5c4dd2452ea999cc5e1d4a8dbf12de2f97ef Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Sun, 7 Mar 2021 14:52:48 -0800 Subject: bpf: Dont allow vmlinux BTF to be used in map_create and prog_load. The syzbot got FD of vmlinux BTF and passed it into map_create which caused crash in btf_type_id_size() when it tried to access resolved_ids. The vmlinux BTF doesn't have 'resolved_ids' and 'resolved_sizes' initialized to save memory. To avoid such issues disallow using vmlinux BTF in prog_load and map_create commands. Fixes: 5329722057d4 ("bpf: Assign ID to vmlinux BTF and return extra info for BTF in GET_OBJ_INFO") Reported-by: syzbot+8bab8ed346746e7540e8@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20210307225248.79031-1-alexei.starovoitov@gmail.com --- kernel/bpf/syscall.c | 5 +++++ kernel/bpf/verifier.c | 4 ++++ 2 files changed, 9 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c859bc46d06c..250503482cda 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -854,6 +854,11 @@ static int map_create(union bpf_attr *attr) err = PTR_ERR(btf); goto free_map; } + if (btf_is_kernel(btf)) { + btf_put(btf); + err = -EACCES; + goto free_map; + } map->btf = btf; if (attr->btf_value_type_id) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c56e3fcb5f1a..4192a9e56654 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9056,6 +9056,10 @@ static int check_btf_info(struct bpf_verifier_env *env, btf = btf_get_by_fd(attr->prog_btf_fd); if (IS_ERR(btf)) return PTR_ERR(btf); + if (btf_is_kernel(btf)) { + btf_put(btf); + return -EACCES; + } env->prog->aux->btf = btf; err = check_btf_func(env, attr, uattr); -- cgit v1.2.3 From 769c18b254ca191b45047e1fcb3b2ce56fada0b6 Mon Sep 17 00:00:00 2001 From: Tal Lossos Date: Sun, 7 Mar 2021 14:09:48 +0200 Subject: bpf: Change inode_storage's lookup_elem return value from NULL to -EBADF bpf_fd_inode_storage_lookup_elem() returned NULL when getting a bad FD, which caused -ENOENT in bpf_map_copy_value. -EBADF error is better than -ENOENT for a bad FD behaviour. The patch was partially contributed by CyberArk Software, Inc. Fixes: 8ea636848aca ("bpf: Implement bpf_local_storage for inodes") Signed-off-by: Tal Lossos Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20210307120948.61414-1-tallossos@gmail.com --- kernel/bpf/bpf_inode_storage.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index 6639640523c0..b58b2efb9b43 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -109,7 +109,7 @@ static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key) fd = *(int *)key; f = fget_raw(fd); if (!f) - return NULL; + return ERR_PTR(-EBADF); sdata = inode_storage_lookup(f->f_inode, map, true); fput(f); -- cgit v1.2.3