From 3cf214f2755bb22bf056e6a155f4314bb6378d50 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 13 Jun 2023 15:35:30 -0700 Subject: [PATCH] bpf: Move unprivileged checks into map_create() and bpf_prog_load() [ Upstream commit 1d28635abcf1914425d6516e641978011984c58a ] Make each bpf() syscall command a bit more self-contained, making it easier to further enhance it. We move sysctl_unprivileged_bpf_disabled handling down to map_create() and bpf_prog_load(), two special commands in this regard. Also swap the order of checks, calling bpf_capable() only if sysctl_unprivileged_bpf_disabled is true, avoiding unnecessary audit messages. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20230613223533.3689589-2-andrii@kernel.org Stable-dep-of: 640a604585aa ("bpf, cpumap: Make sure kthread is running before map update returns") Signed-off-by: Sasha Levin --- kernel/bpf/syscall.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 5524fcf6fb2a..0a7238125e1a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1157,6 +1157,15 @@ static int map_create(union bpf_attr *attr) !node_online(numa_node))) return -EINVAL; + /* Intent here is for unprivileged_bpf_disabled to block BPF map + * creation for unprivileged users; other actions depend + * on fd availability and access to bpffs, so are dependent on + * object creation success. Even with unprivileged BPF disabled, + * capability checks are still carried out. + */ + if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) + return -EPERM; + /* find map type and init map: hashtable vs rbtree vs bloom vs ... */ map = find_and_alloc_map(attr); if (IS_ERR(map)) @@ -2535,6 +2544,16 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size) /* eBPF programs must be GPL compatible to use GPL-ed functions */ is_gpl = license_is_gpl_compatible(license); + /* Intent here is for unprivileged_bpf_disabled to block BPF program + * creation for unprivileged users; other actions depend + * on fd availability and access to bpffs, so are dependent on + * object creation success. Even with unprivileged BPF disabled, + * capability checks are still carried out for these + * and other operations. + */ + if (sysctl_unprivileged_bpf_disabled && !bpf_capable()) + return -EPERM; + if (attr->insn_cnt == 0 || attr->insn_cnt > (bpf_capable() ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) return -E2BIG; @@ -5018,23 +5037,8 @@ out_prog_put: static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size) { union bpf_attr attr; - bool capable; int err; - capable = bpf_capable() || !sysctl_unprivileged_bpf_disabled; - - /* Intent here is for unprivileged_bpf_disabled to block key object - * creation commands for unprivileged users; other actions depend - * of fd availability and access to bpffs, so are dependent on - * object creation success. Capabilities are later verified for - * operations such as load and map create, so even with unprivileged - * BPF disabled, capability checks are still carried out for these - * and other operations. - */ - if (!capable && - (cmd == BPF_MAP_CREATE || cmd == BPF_PROG_LOAD)) - return -EPERM; - err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); if (err) return err;