by Sean Young

[permalink] [raw]

Subject: [PATCH v3] bpf: attach type BPF_LIRC_MODE2 should not depend on CONFIG_CGROUP_BPF

If the kernel is compiled with CONFIG_CGROUP_BPF not enabled, it is not
possible to attach, detach or query IR BPF programs to /dev/lircN devices,
making them impossible to use. For embedded devices, it should be possible
to use IR decoding without cgroups or CONFIG_CGROUP_BPF enabled.

This change requires some refactoring, since bpf_prog_{attach,detach,query}
functions are now always compiled, but their code paths for cgroups need
moving out. Rather than a #ifdef CONFIG_CGROUP_BPF in kernel/bpf/syscall.c,
moving them to kernel/bpf/cgroup.c and kernel/bpf/sockmap.c does not
require #ifdefs since that is already conditionally compiled.

Signed-off-by: Sean Young <[email protected]>
---
drivers/media/rc/bpf-lirc.c | 14 +-----
include/linux/bpf-cgroup.h | 26 ++++++++++
include/linux/bpf.h | 8 +++
include/linux/bpf_lirc.h | 5 +-
kernel/bpf/cgroup.c | 52 ++++++++++++++++++++
kernel/bpf/sockmap.c | 18 +++++++
kernel/bpf/syscall.c | 98 ++++++++-----------------------------
7 files changed, 130 insertions(+), 91 deletions(-)

diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c
index 40826bba06b6..fcfab6635f9c 100644
--- a/drivers/media/rc/bpf-lirc.c
+++ b/drivers/media/rc/bpf-lirc.c
@@ -207,29 +207,19 @@ void lirc_bpf_free(struct rc_dev *rcdev)
bpf_prog_array_free(rcdev->raw->progs);
}

-int lirc_prog_attach(const union bpf_attr *attr)
+int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
- struct bpf_prog *prog;
struct rc_dev *rcdev;
int ret;

if (attr->attach_flags)
return -EINVAL;

- prog = bpf_prog_get_type(attr->attach_bpf_fd,
- BPF_PROG_TYPE_LIRC_MODE2);
- if (IS_ERR(prog))
- return PTR_ERR(prog);
-
rcdev = rc_dev_get_from_fd(attr->target_fd);
- if (IS_ERR(rcdev)) {
- bpf_prog_put(prog);
+ if (IS_ERR(rcdev))
return PTR_ERR(rcdev);
- }

ret = lirc_bpf_attach(rcdev, prog);
- if (ret)
- bpf_prog_put(prog);

put_device(&rcdev->dev);

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 975fb4cf1bb7..79795c5fa7c3 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -188,12 +188,38 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
\
__ret; \
})
+int cgroup_bpf_prog_attach(const union bpf_attr *attr,
+ enum bpf_prog_type ptype, struct bpf_prog *prog);
+int cgroup_bpf_prog_detach(const union bpf_attr *attr,
+ enum bpf_prog_type ptype);
+int cgroup_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr);
#else

+struct bpf_prog;
struct cgroup_bpf {};
static inline void cgroup_bpf_put(struct cgroup *cgrp) {}
static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }

+static inline int cgroup_bpf_prog_attach(const union bpf_attr *attr,
+ enum bpf_prog_type ptype,
+ struct bpf_prog *prog)
+{
+ return -EINVAL;
+}
+
+static inline int cgroup_bpf_prog_detach(const union bpf_attr *attr,
+ enum bpf_prog_type ptype)
+{
+ return -EINVAL;
+}
+
+static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ return -EINVAL;
+}
+
#define cgroup_bpf_enabled (0)
#define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 995c3b1e59bf..ac4c73d29f96 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -684,6 +684,8 @@ static inline void bpf_map_offload_map_free(struct bpf_map *map)
struct sock *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
struct sock *__sock_hash_lookup_elem(struct bpf_map *map, void *key);
int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type);
+int sockmap_get_from_fd(const union bpf_attr *attr, int type,
+ struct bpf_prog *prog);
#else
static inline struct sock *__sock_map_lookup_elem(struct bpf_map *map, u32 key)
{
@@ -702,6 +704,12 @@ static inline int sock_map_prog(struct bpf_map *map,
{
return -EOPNOTSUPP;
}
+
+int sockmap_get_from_fd(const union bpf_attr *attr, int type,
+ struct bpf_prog *prog);
+{
+ return -EINVAL;
+}
#endif

#if defined(CONFIG_XDP_SOCKETS)
diff --git a/include/linux/bpf_lirc.h b/include/linux/bpf_lirc.h
index 5f8a4283092d..9d9ff755ec29 100644
--- a/include/linux/bpf_lirc.h
+++ b/include/linux/bpf_lirc.h
@@ -5,11 +5,12 @@
#include <uapi/linux/bpf.h>

#ifdef CONFIG_BPF_LIRC_MODE2
-int lirc_prog_attach(const union bpf_attr *attr);
+int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog);
int lirc_prog_detach(const union bpf_attr *attr);
int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
#else
-static inline int lirc_prog_attach(const union bpf_attr *attr)
+static inline int lirc_prog_attach(const union bpf_attr *attr,
+ struct bpf_prog *prog)
{
return -EINVAL;
}
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index f7c00bd6f8e4..f0ae8a3d01f9 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -428,6 +428,58 @@ int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
return ret;
}

+int cgroup_bpf_prog_attach(const union bpf_attr *attr,
+ enum bpf_prog_type ptype, struct bpf_prog *prog)
+{
+ struct cgroup *cgrp;
+ int ret;
+
+ cgrp = cgroup_get_from_fd(attr->target_fd);
+ if (IS_ERR(cgrp))
+ return PTR_ERR(cgrp);
+
+ ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
+ attr->attach_flags);
+ cgroup_put(cgrp);
+
+ return ret;
+}
+
+int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
+{
+ struct bpf_prog *prog;
+ struct cgroup *cgrp;
+ int ret;
+
+ 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;
+}
+
+int cgroup_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ struct cgroup *cgrp;
+ int ret;
+
+ 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;
+}
+
/**
* __cgroup_bpf_run_filter_skb() - Run a program for packet filtering
* @sk: The socket sending or receiving traffic
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 52a91d816c0e..81d0c55a77aa 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -1915,6 +1915,24 @@ int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type)
return 0;
}

+int sockmap_get_from_fd(const union bpf_attr *attr, int type,
+ struct bpf_prog *prog)
+{
+ int ufd = attr->target_fd;
+ struct bpf_map *map;
+ struct fd f;
+ int err;
+
+ f = fdget(ufd);
+ map = __bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ err = sock_map_prog(map, prog, attr->attach_type);
+ fdput(f);
+ return err;
+}
+
static void *sock_map_lookup(struct bpf_map *map, void *key)
{
return NULL;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0fa20624707f..93993c03c9ac 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1489,8 +1489,6 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
return err;
}

-#ifdef CONFIG_CGROUP_BPF
-
static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
enum bpf_attach_type attach_type)
{
@@ -1505,40 +1503,6 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,

#define BPF_PROG_ATTACH_LAST_FIELD attach_flags

-static int sockmap_get_from_fd(const union bpf_attr *attr,
- int type, bool attach)
-{
- struct bpf_prog *prog = NULL;
- int ufd = attr->target_fd;
- struct bpf_map *map;
- struct fd f;
- int err;
-
- f = fdget(ufd);
- map = __bpf_map_get(f);
- if (IS_ERR(map))
- return PTR_ERR(map);
-
- if (attach) {
- prog = bpf_prog_get_type(attr->attach_bpf_fd, type);
- if (IS_ERR(prog)) {
- fdput(f);
- return PTR_ERR(prog);
- }
- }
-
- err = sock_map_prog(map, prog, attr->attach_type);
- if (err) {
- fdput(f);
- if (prog)
- bpf_prog_put(prog);
- return err;
- }
-
- fdput(f);
- return 0;
-}
-
#define BPF_F_ATTACH_MASK \
(BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI)

@@ -1546,7 +1510,6 @@ static int bpf_prog_attach(const union bpf_attr *attr)
{
enum bpf_prog_type ptype;
struct bpf_prog *prog;
- struct cgroup *cgrp;
int ret;

if (!capable(CAP_NET_ADMIN))
@@ -1583,12 +1546,15 @@ static int bpf_prog_attach(const union bpf_attr *attr)
ptype = BPF_PROG_TYPE_CGROUP_DEVICE;
break;
case BPF_SK_MSG_VERDICT:
- return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_MSG, true);
+ ptype = BPF_PROG_TYPE_SK_MSG;
+ break;
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
- return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true);
+ ptype = BPF_PROG_TYPE_SK_SKB;
+ break;
case BPF_LIRC_MODE2:
- return lirc_prog_attach(attr);
+ ptype = BPF_PROG_TYPE_LIRC_MODE2;
+ break;
default:
return -EINVAL;
}
@@ -1602,17 +1568,20 @@ static int bpf_prog_attach(const union bpf_attr *attr)
return -EINVAL;
}

- cgrp = cgroup_get_from_fd(attr->target_fd);
- if (IS_ERR(cgrp)) {
- bpf_prog_put(prog);
- return PTR_ERR(cgrp);
+ switch (ptype) {
+ case BPF_PROG_TYPE_SK_SKB:
+ case BPF_PROG_TYPE_SK_MSG:
+ ret = sockmap_get_from_fd(attr, ptype, prog);
+ break;
+ case BPF_PROG_TYPE_LIRC_MODE2:
+ ret = lirc_prog_attach(attr, prog);
+ break;
+ default:
+ ret = cgroup_bpf_prog_attach(attr, ptype, prog);
}

- ret = cgroup_bpf_attach(cgrp, prog, attr->attach_type,
- attr->attach_flags);
if (ret)
bpf_prog_put(prog);
- cgroup_put(cgrp);

return ret;
}
@@ -1622,9 +1591,6 @@ 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;

if (!capable(CAP_NET_ADMIN))
return -EPERM;
@@ -1657,29 +1623,17 @@ static int bpf_prog_detach(const union bpf_attr *attr)
ptype = BPF_PROG_TYPE_CGROUP_DEVICE;
break;
case BPF_SK_MSG_VERDICT:
- return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_MSG, false);
+ return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_MSG, NULL);
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
- return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, false);
+ return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, NULL);
case BPF_LIRC_MODE2:
return lirc_prog_detach(attr);
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;
+ return cgroup_bpf_prog_detach(attr, ptype);
}

#define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt
@@ -1687,9 +1641,6 @@ static int bpf_prog_detach(const union bpf_attr *attr)
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))
@@ -1717,14 +1668,9 @@ static int bpf_prog_query(const union bpf_attr *attr,
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;
+
+ return cgroup_bpf_prog_query(attr, uattr);
}
-#endif /* CONFIG_CGROUP_BPF */

#define BPF_PROG_TEST_RUN_LAST_FIELD test.duration

@@ -2371,7 +2317,6 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
case BPF_OBJ_GET:
err = bpf_obj_get(&attr);
break;
-#ifdef CONFIG_CGROUP_BPF
case BPF_PROG_ATTACH:
err = bpf_prog_attach(&attr);
break;
@@ -2381,7 +2326,6 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
case BPF_PROG_QUERY:
err = bpf_prog_query(&attr, uattr);
break;
-#endif
case BPF_PROG_TEST_RUN:
err = bpf_prog_test_run(&attr, uattr);
break;
--
2.17.1

2018-06-18 18:49:41

On 06/19/2018 01:04 AM, Sean Young wrote:
> If the kernel is compiled with CONFIG_CGROUP_BPF not enabled, it is not
> possible to attach, detach or query IR BPF programs to /dev/lircN devices,
> making them impossible to use. For embedded devices, it should be possible
> to use IR decoding without cgroups or CONFIG_CGROUP_BPF enabled.
>
> This change requires some refactoring, since bpf_prog_{attach,detach,query}
> functions are now always compiled, but their code paths for cgroups need
> moving out. Rather than a #ifdef CONFIG_CGROUP_BPF in kernel/bpf/syscall.c,
> moving them to kernel/bpf/cgroup.c and kernel/bpf/sockmap.c does not
> require #ifdefs since that is already conditionally compiled.
>
> Signed-off-by: Sean Young <[email protected]>

Applied to bpf, thanks Sean!