From 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Tue, 28 Jun 2022 10:43:06 -0700 Subject: bpf: per-cgroup lsm flavor Allow attaching to lsm hooks in the cgroup context. Attaching to per-cgroup LSM works exactly like attaching to other per-cgroup hooks. New BPF_LSM_CGROUP is added to trigger new mode; the actual lsm hook we attach to is signaled via existing attach_btf_id. For the hooks that have 'struct socket' or 'struct sock' as its first argument, we use the cgroup associated with that socket. For the rest, we use 'current' cgroup (this is all on default hierarchy == v2 only). Note that for some hooks that work on 'struct sock' we still take the cgroup from 'current' because some of them work on the socket that hasn't been properly initialized yet. Behind the scenes, we allocate a shim program that is attached to the trampoline and runs cgroup effective BPF programs array. This shim has some rudimentary ref counting and can be shared between several programs attaching to the same lsm hook from different cgroups. Note that this patch bloats cgroup size because we add 211 cgroup_bpf_attach_type(s) for simplicity sake. This will be addressed in the subsequent patch. Also note that we only add non-sleepable flavor for now. To enable sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu, shim programs have to be freed via trace rcu, cgroup_bpf.effective should be also trace-rcu-managed + maybe some other changes that I'm not aware of. Reviewed-by: Martin KaFai Lau Signed-off-by: Stanislav Fomichev Link: https://lore.kernel.org/r/20220628174314.1216643-4-sdf@google.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'kernel/bpf/syscall.c') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7d5af5b99f0d..626b8f7d237b 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3416,6 +3416,8 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type) return BPF_PROG_TYPE_SK_LOOKUP; case BPF_XDP: return BPF_PROG_TYPE_XDP; + case BPF_LSM_CGROUP: + return BPF_PROG_TYPE_LSM; default: return BPF_PROG_TYPE_UNSPEC; } @@ -3469,6 +3471,11 @@ static int bpf_prog_attach(const union bpf_attr *attr) case BPF_PROG_TYPE_CGROUP_SOCKOPT: case BPF_PROG_TYPE_CGROUP_SYSCTL: case BPF_PROG_TYPE_SOCK_OPS: + case BPF_PROG_TYPE_LSM: + if (ptype == BPF_PROG_TYPE_LSM && + prog->expected_attach_type != BPF_LSM_CGROUP) + return -EINVAL; + ret = cgroup_bpf_prog_attach(attr, ptype, prog); break; default: @@ -3506,6 +3513,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) case BPF_PROG_TYPE_CGROUP_SOCKOPT: case BPF_PROG_TYPE_CGROUP_SYSCTL: case BPF_PROG_TYPE_SOCK_OPS: + case BPF_PROG_TYPE_LSM: return cgroup_bpf_prog_detach(attr, ptype); default: return -EINVAL; @@ -4540,6 +4548,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) ret = bpf_raw_tp_link_attach(prog, NULL); else if (prog->expected_attach_type == BPF_TRACE_ITER) ret = bpf_iter_link_attach(attr, uattr, prog); + else if (prog->expected_attach_type == BPF_LSM_CGROUP) + ret = cgroup_bpf_link_attach(attr, prog); else ret = bpf_tracing_prog_attach(prog, attr->link_create.target_fd, -- cgit v1.2.3 From b79c9fc9551b45953a94abf550b7bd3b00e3a0f9 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Tue, 28 Jun 2022 10:43:08 -0700 Subject: bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP We have two options: 1. Treat all BPF_LSM_CGROUP the same, regardless of attach_btf_id 2. Treat BPF_LSM_CGROUP+attach_btf_id as a separate hook point I was doing (2) in the original patch, but switching to (1) here: * bpf_prog_query returns all attached BPF_LSM_CGROUP programs regardless of attach_btf_id * attach_btf_id is exported via bpf_prog_info Reviewed-by: Martin KaFai Lau Signed-off-by: Stanislav Fomichev Link: https://lore.kernel.org/r/20220628174314.1216643-6-sdf@google.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/syscall.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/bpf/syscall.c') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 626b8f7d237b..ab688d85b2c6 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3520,7 +3520,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) } } -#define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt +#define BPF_PROG_QUERY_LAST_FIELD query.prog_attach_flags static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) @@ -3556,6 +3556,7 @@ static int bpf_prog_query(const union bpf_attr *attr, case BPF_CGROUP_SYSCTL: case BPF_CGROUP_GETSOCKOPT: case BPF_CGROUP_SETSOCKOPT: + case BPF_LSM_CGROUP: return cgroup_bpf_prog_query(attr, uattr); case BPF_LIRC_MODE2: return lirc_prog_query(attr, uattr); @@ -4066,6 +4067,11 @@ static int bpf_prog_get_info_by_fd(struct file *file, if (prog->aux->btf) info.btf_id = btf_obj_id(prog->aux->btf); + info.attach_btf_id = prog->aux->attach_btf_id; + if (prog->aux->attach_btf) + info.attach_btf_obj_id = btf_obj_id(prog->aux->attach_btf); + else if (prog->aux->dst_prog) + info.attach_btf_obj_id = btf_obj_id(prog->aux->dst_prog->aux->attach_btf); ulen = info.nr_func_info; info.nr_func_info = prog->aux->func_info_cnt; -- cgit v1.2.3