Merge branch 'bpf-cgroup-multi-prog'

Alexei Starovoitov says:

====================
bpf: muli prog support for cgroup-bpf

v1->v2:
- fixed accidentally swapped two lines which caused static_key not going to zero
- addressed Martin's feedback and changed prog_query to be consistent
  with verifier output: return -enospc and fill supplied buffer instead
  of just returning -enospc when buffer is too small to fit all prog_ids

v1:
cgroup-bpf use cases are getting more advanced and running only
one program per cgroup is no longer enough. Therefore introduce
support for attaching multiple programs per cgroup and running
a set of effective programs.

These patches introduces BPF_F_ALLOW_MULTI flag for BPF_PROG_ATTACH cmd.
The default is still NONE and behavior of BPF_F_ALLOW_OVERRIDE flag
is unchanged.
The difference between three possible flags for BPF_PROG_ATTACH command:
- NONE(default): No further bpf programs allowed in the subtree.
- BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
  the program in this cgroup yields to sub-cgroup program.
- BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
  that cgroup program gets run in addition to the program in this cgroup.

Most of the logic is in patch 1. Even when cgroup doesn't have
any programs attached its set of effective program can be non-empty.
To quickly execute them and avoid penalizing cgroups without
any effective programs introduce 'struct bpf_prog_array'
which has an optimization for cgroups with zero effective programs.

Patch 2 introduces BPF_PROG_QUERY command for introspection
Patch 3 makes verifier more strict for cgroup-bpf program types.
Patch 4+ are tests.

More details in individual patches
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 60 insertions, 11 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b927da66f653..0048cb24ba7b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1168,6 +1168,9 @@ static int sockmap_get_from_fd(const union bpf_attr *attr, bool attach)
 	return 0;
 }
 
+#define BPF_F_ATTACH_MASK \
+	(BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI)
+
 static int bpf_prog_attach(const union bpf_attr *attr)
 {
 	enum bpf_prog_type ptype;
@@ -1181,7 +1184,7 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	if (CHECK_ATTR(BPF_PROG_ATTACH))
 		return -EINVAL;
 
-	if (attr->attach_flags & ~BPF_F_ALLOW_OVERRIDE)
+	if (attr->attach_flags & ~BPF_F_ATTACH_MASK)
 		return -EINVAL;
 
 	switch (attr->attach_type) {
@@ -1212,8 +1215,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 		return PTR_ERR(cgrp);
 	}
 
-	ret = cgroup_bpf_update(cgrp, prog, attr->attach_type,
-				attr->attach_flags & BPF_F_ALLOW_OVERRIDE);
+	ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
+				attr->attach_flags);
 	if (ret)
 		bpf_prog_put(prog);
 	cgroup_put(cgrp);
@@ -1225,6 +1228,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 
 static int bpf_prog_detach(const union bpf_attr *attr)
 {
+	enum bpf_prog_type ptype;
+	struct bpf_prog *prog;
 	struct cgroup *cgrp;
 	int ret;
 
@@ -1237,26 +1242,67 @@ static int bpf_prog_detach(const union bpf_attr *attr)
 	switch (attr->attach_type) {
 	case BPF_CGROUP_INET_INGRESS:
 	case BPF_CGROUP_INET_EGRESS:
+		ptype = BPF_PROG_TYPE_CGROUP_SKB;
+		break;
 	case BPF_CGROUP_INET_SOCK_CREATE:
+		ptype = BPF_PROG_TYPE_CGROUP_SOCK;
+		break;
 	case BPF_CGROUP_SOCK_OPS:
-		cgrp = cgroup_get_from_fd(attr->target_fd);
-		if (IS_ERR(cgrp))
-			return PTR_ERR(cgrp);
-
-		ret = cgroup_bpf_update(cgrp, NULL, attr->attach_type, false);
-		cgroup_put(cgrp);
+		ptype = BPF_PROG_TYPE_SOCK_OPS;
 		break;
 	case BPF_SK_SKB_STREAM_PARSER:
 	case BPF_SK_SKB_STREAM_VERDICT:
-		ret = sockmap_get_from_fd(attr, false);
-		break;
+		return sockmap_get_from_fd(attr, false);
 	default:
 		return -EINVAL;
 	}
 
+	cgrp = cgroup_get_from_fd(attr->target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+
+	prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
+	if (IS_ERR(prog))
+		prog = NULL;
+
+	ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type, 0);
+	if (prog)
+		bpf_prog_put(prog);
+	cgroup_put(cgrp);
 	return ret;
 }
 
+#define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt
+
+static int bpf_prog_query(const union bpf_attr *attr,
+			  union bpf_attr __user *uattr)
+{
+	struct cgroup *cgrp;
+	int ret;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+	if (CHECK_ATTR(BPF_PROG_QUERY))
+		return -EINVAL;
+	if (attr->query.query_flags & ~BPF_F_QUERY_EFFECTIVE)
+		return -EINVAL;
+
+	switch (attr->query.attach_type) {
+	case BPF_CGROUP_INET_INGRESS:
+	case BPF_CGROUP_INET_EGRESS:
+	case BPF_CGROUP_INET_SOCK_CREATE:
+	case BPF_CGROUP_SOCK_OPS:
+		break;
+	default:
+		return -EINVAL;
+	}
+	cgrp = cgroup_get_from_fd(attr->query.target_fd);
+	if (IS_ERR(cgrp))
+		return PTR_ERR(cgrp);
+	ret = cgroup_bpf_query(cgrp, attr, uattr);
+	cgroup_put(cgrp);
+	return ret;
+}
 #endif /* CONFIG_CGROUP_BPF */
 
 #define BPF_PROG_TEST_RUN_LAST_FIELD test.duration
@@ -1553,6 +1599,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_PROG_DETACH:
 		err = bpf_prog_detach(&attr);
 		break;
+	case BPF_PROG_QUERY:
+		err = bpf_prog_query(&attr, uattr);
+		break;
 #endif
 	case BPF_PROG_TEST_RUN:
 		err = bpf_prog_test_run(&attr, uattr);