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bpf: fix attach type BPF_LIRC_MODE2 dependency wrt CONFIG_CGROUP_BPF
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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.

Fixes: f4364dc ("media: rc: introduce BPF_PROG_LIRC_MODE2")
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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@seanyoung @borkmann
seanyoung authored and borkmann committed Jun 26, 2018
1 parent 68d676a commit fdb5c45
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Showing 7 changed files with 132 additions and 92 deletions.
14 changes: 2 additions & 12 deletions drivers/media/rc/bpf-lirc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand Down
26 changes: 26 additions & 0 deletions include/linux/bpf-cgroup.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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; })
Expand Down
8 changes: 8 additions & 0 deletions include/linux/bpf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -696,6 +696,8 @@ 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)
{
Expand All @@ -714,6 +716,12 @@ static inline int sock_map_prog(struct bpf_map *map,
{
return -EOPNOTSUPP;
}

static inline int sockmap_get_from_fd(const union bpf_attr *attr, int type,
struct bpf_prog *prog)
{
return -EINVAL;
}
#endif

#if defined(CONFIG_XDP_SOCKETS)
Expand Down
5 changes: 3 additions & 2 deletions include/linux/bpf_lirc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down
54 changes: 54 additions & 0 deletions kernel/bpf/cgroup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -428,6 +428,60 @@ 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
Expand Down
18 changes: 18 additions & 0 deletions kernel/bpf/sockmap.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
99 changes: 21 additions & 78 deletions kernel/bpf/syscall.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1483,8 +1483,6 @@ 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)
{
Expand All @@ -1499,48 +1497,13 @@ 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)

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))
Expand Down Expand Up @@ -1577,12 +1540,15 @@ 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;
}
Expand All @@ -1596,18 +1562,20 @@ 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;
}

Expand All @@ -1616,9 +1584,6 @@ 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;
Expand Down Expand Up @@ -1651,39 +1616,24 @@ 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

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))
Expand Down Expand Up @@ -1711,14 +1661,9 @@ 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

Expand Down Expand Up @@ -2365,7 +2310,6 @@ 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;
Expand All @@ -2375,7 +2319,6 @@ 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;
Expand Down

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