Cgroup v2 lacks the device controller, provided by cgroup v1.
This patch adds a new eBPF program type, which in combination
of previously added ability to attach multiple eBPF programs
to a cgroup, will provide a similar functionality, but with some
additional flexibility.
This patch introduces a BPF_PROG_TYPE_CGROUP_DEVICE program type.
A program takes major and minor device numbers, device type
(block/character) and access type (mknod/read/write) as parameters
and returns an integer which defines if the operation should be
allowed or terminated with -EPERM.
Signed-off-by: Roman Gushchin <g...@fb.com>
Acked-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: Tejun Heo <t...@kernel.org>
Cc: Daniel Borkmann <dan...@iogearbox.net>
---
include/linux/bpf-cgroup.h | 15 ++++++++++
include/linux/bpf_types.h | 3 ++
include/linux/device_cgroup.h | 8 ++++-
include/uapi/linux/bpf.h | 15 ++++++++++
kernel/bpf/cgroup.c | 67 ++++++++++++++++++++++++++++++++++++++++++
kernel/bpf/syscall.c | 7 +++++
kernel/bpf/verifier.c | 1 +
tools/include/uapi/linux/bpf.h | 15 ++++++++++
8 files changed, 130 insertions(+), 1 deletion(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 359b6f5d3d90..d77cefb3fe99 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -66,6 +66,9 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
struct bpf_sock_ops_kern *sock_ops,
enum bpf_attach_type type);
+int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
+ short access, enum bpf_attach_type type);
+
/* Wrappers for __cgroup_bpf_run_filter_skb() guarded by cgroup_bpf_enabled. */
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb) \
({ \
@@ -111,6 +114,17 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
} \
__ret; \
})
+
+#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled) \
+ __ret = __cgroup_bpf_check_dev_permission(type, major, minor, \
+ access, \
+ BPF_CGROUP_DEVICE); \
+ \
+ __ret; \
+})
#else
struct cgroup_bpf {};
@@ -121,6 +135,7 @@ static inline int cgroup_bpf_inherit(struct cgroup *cgrp) {
return 0; }
#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; })
#define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
#endif /* CONFIG_CGROUP_BPF */
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 36418ad43245..963a97ee4b7c 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -18,6 +18,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint)
BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event)
#endif
+#ifdef CONFIG_CGROUP_BPF
+BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
+#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/linux/device_cgroup.h b/include/linux/device_cgroup.h
index 1e42d33accbf..90245a70d940 100644
--- a/include/linux/device_cgroup.h
+++ b/include/linux/device_cgroup.h
@@ -1,4 +1,5 @@
#include <linux/fs.h>
+#include <linux/bpf-cgroup.h>
#define DEVCG_ACC_MKNOD 1
#define DEVCG_ACC_READ 2
@@ -18,10 +19,15 @@ static inline int __devcgroup_check_permission(short type,
u32 major, u32 minor,
{ return 0; }
#endif
-#ifdef CONFIG_CGROUP_DEVICE
+#if defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF)
static inline int devcgroup_check_permission(short type, u32 major, u32 minor,
short access)
{
+ int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);
+
+ if (rc)
+ return -EPERM;
+
return __devcgroup_check_permission(type, major, minor, access);
}
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0b7b54d898bd..ea905863a033 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -131,6 +131,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LWT_XMIT,
BPF_PROG_TYPE_SOCK_OPS,
BPF_PROG_TYPE_SK_SKB,
+ BPF_PROG_TYPE_CGROUP_DEVICE,
};
enum bpf_attach_type {
@@ -140,6 +141,7 @@ enum bpf_attach_type {
BPF_CGROUP_SOCK_OPS,
BPF_SK_SKB_STREAM_PARSER,
BPF_SK_SKB_STREAM_VERDICT,
+ BPF_CGROUP_DEVICE,
__MAX_BPF_ATTACH_TYPE
};
@@ -984,4 +986,17 @@ struct bpf_perf_event_value {
__u64 running;
};
+#define BPF_DEVCG_ACC_MKNOD (1ULL << 0)
+#define BPF_DEVCG_ACC_READ (1ULL << 1)
+#define BPF_DEVCG_ACC_WRITE (1ULL << 2)
+
+#define BPF_DEVCG_DEV_BLOCK (1ULL << 0)
+#define BPF_DEVCG_DEV_CHAR (1ULL << 1)
+
+struct bpf_cgroup_dev_ctx {
+ __u32 access_type; /* (access << 16) | type */
+ __u32 major;
+ __u32 minor;
+};
+
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 3db5a17fcfe8..b789ab78d28f 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -522,3 +522,70 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);
+
+int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
+ short access, enum bpf_attach_type type)
+{
+ struct cgroup *cgrp;
+ struct bpf_cgroup_dev_ctx ctx = {
+ .access_type = (access << 16) | dev_type,
+ .major = major,
+ .minor = minor,
+ };
+ int allow = 1;
+
+ rcu_read_lock();
+ cgrp = task_dfl_cgroup(current);
+ allow = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx,
+ BPF_PROG_RUN);
+ rcu_read_unlock();
+
+ return !allow;
+}
+EXPORT_SYMBOL(__cgroup_bpf_check_dev_permission);
+
+static const struct bpf_func_proto *
+cgroup_dev_func_proto(enum bpf_func_id func_id)
+{
+ switch (func_id) {
+ case BPF_FUNC_map_lookup_elem:
+ return &bpf_map_lookup_elem_proto;
+ case BPF_FUNC_map_update_elem:
+ return &bpf_map_update_elem_proto;
+ case BPF_FUNC_map_delete_elem:
+ return &bpf_map_delete_elem_proto;
+ case BPF_FUNC_get_current_uid_gid:
+ return &bpf_get_current_uid_gid_proto;
+ case BPF_FUNC_trace_printk:
+ if (capable(CAP_SYS_ADMIN))
+ return bpf_get_trace_printk_proto();
+ default:
+ return NULL;
+ }
+}
+
+static bool cgroup_dev_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ struct bpf_insn_access_aux *info)
+{
+ if (type == BPF_WRITE)
+ return false;
+
+ if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
+ return false;
+ /* The verifier guarantees that size > 0. */
+ if (off % size != 0)
+ return false;
+ if (size != sizeof(__u32))
+ return false;
+
+ return true;
+}
+
+const struct bpf_prog_ops cg_dev_prog_ops = {
+};
+
+const struct bpf_verifier_ops cg_dev_verifier_ops = {
+ .get_func_proto = cgroup_dev_func_proto,
+ .is_valid_access = cgroup_dev_is_valid_access,
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 323be2473c4b..08f7b450828e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1291,6 +1291,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_CGROUP_SOCK_OPS:
ptype = BPF_PROG_TYPE_SOCK_OPS;
break;
+ case BPF_CGROUP_DEVICE:
+ ptype = BPF_PROG_TYPE_CGROUP_DEVICE;
+ break;
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
return sockmap_get_from_fd(attr, true);
@@ -1343,6 +1346,9 @@ static int bpf_prog_detach(const union bpf_attr *attr)
case BPF_CGROUP_SOCK_OPS:
ptype = BPF_PROG_TYPE_SOCK_OPS;
break;
+ case BPF_CGROUP_DEVICE:
+ ptype = BPF_PROG_TYPE_CGROUP_DEVICE;
+ break;
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
return sockmap_get_from_fd(attr, false);
@@ -1385,6 +1391,7 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_CGROUP_INET_EGRESS:
case BPF_CGROUP_INET_SOCK_CREATE:
case BPF_CGROUP_SOCK_OPS:
+ case BPF_CGROUP_DEVICE:
break;
default:
return -EINVAL;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2bb6d6aa7085..811f0582a1cc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3100,6 +3100,7 @@ static int check_return_code(struct bpf_verifier_env *env)
case BPF_PROG_TYPE_CGROUP_SKB:
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_SOCK_OPS:
+ case BPF_PROG_TYPE_CGROUP_DEVICE:
break;
default:
return 0;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4a4b6e78c977..83763a3eb339 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -131,6 +131,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LWT_XMIT,
BPF_PROG_TYPE_SOCK_OPS,
BPF_PROG_TYPE_SK_SKB,
+ BPF_PROG_TYPE_CGROUP_DEVICE,
};
enum bpf_attach_type {
@@ -140,6 +141,7 @@ enum bpf_attach_type {
BPF_CGROUP_SOCK_OPS,
BPF_SK_SKB_STREAM_PARSER,
BPF_SK_SKB_STREAM_VERDICT,
+ BPF_CGROUP_DEVICE,
__MAX_BPF_ATTACH_TYPE
};
@@ -984,4 +986,17 @@ struct bpf_perf_event_value {
__u64 running;
};
+#define BPF_DEVCG_ACC_MKNOD (1ULL << 0)
+#define BPF_DEVCG_ACC_READ (1ULL << 1)
+#define BPF_DEVCG_ACC_WRITE (1ULL << 2)
+
+#define BPF_DEVCG_DEV_BLOCK (1ULL << 0)
+#define BPF_DEVCG_DEV_CHAR (1ULL << 1)
+
+struct bpf_cgroup_dev_ctx {
+ __u32 access_type; /* (access << 16) | type */
+ __u32 major;
+ __u32 minor;
+};
+
#endif /* _UAPI__LINUX_BPF_H__ */
--
2.13.6
