bpf: refactor bpf_prog_get and type check into helper

Since bpf_prog_get() and program type check is used in a couple of places,
refactor this into a small helper function that we can make use of. Since
the non RO prog->aux part is not used in performance critical paths and a
program destruction via RCU is rather very unlikley when doing the put, we
shouldn't have an issue just doing the bpf_prog_get() + prog->type != type
check, but actually not taking the ref at all (due to being in fdget() /
fdput() section of the bpf fd) is even cleaner and makes the diff smaller
as well, so just go for that. Callsites are changed to make use of the new
helper where possible.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 749549888b8670d52709d1cc7f1de38ad99f1ff4..b3336b4f5d04dfbd686012d2cf6d58121d7187ed 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -218,6 +218,7 @@ void bpf_register_prog_type(struct bpf_prog_type_list *tl);
 void bpf_register_map_type(struct bpf_map_type_list *tl);
 
 struct bpf_prog *bpf_prog_get(u32 ufd);
+struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
 struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog);
 void bpf_prog_put(struct bpf_prog *prog);
 
@@ -277,6 +278,12 @@ static inline struct bpf_prog *bpf_prog_get(u32 ufd)
        return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
+                                                enum bpf_prog_type type)
+{
+       return ERR_PTR(-EOPNOTSUPP);
+}
+
 static inline void bpf_prog_put(struct bpf_prog *prog)
 {
 }

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f6806a1d7ed978a250596bf2166d74d373129dee..22863d9872b1eda47349d208005f0ef26e02a0a1 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -657,7 +657,7 @@ int bpf_prog_new_fd(struct bpf_prog *prog)
                                O_RDWR | O_CLOEXEC);
 }
 
-static struct bpf_prog *__bpf_prog_get(struct fd f)
+static struct bpf_prog *____bpf_prog_get(struct fd f)
 {
        if (!f.file)
                return ERR_PTR(-EBADF);
@@ -678,24 +678,35 @@ struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
        return prog;
 }
 
-/* called by sockets/tracing/seccomp before attaching program to an event
- * pairs with bpf_prog_put()
- */
-struct bpf_prog *bpf_prog_get(u32 ufd)
+static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
 {
        struct fd f = fdget(ufd);
        struct bpf_prog *prog;
 
-       prog = __bpf_prog_get(f);
+       prog = ____bpf_prog_get(f);
        if (IS_ERR(prog))
                return prog;
+       if (type && prog->type != *type) {
+               prog = ERR_PTR(-EINVAL);
+               goto out;
+       }
 
        prog = bpf_prog_inc(prog);
+out:
        fdput(f);
-
        return prog;
 }
-EXPORT_SYMBOL_GPL(bpf_prog_get);
+
+struct bpf_prog *bpf_prog_get(u32 ufd)
+{
+       return __bpf_prog_get(ufd, NULL);
+}
+
+struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
+{
+       return __bpf_prog_get(ufd, &type);
+}
+EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
 /* last field in 'union bpf_attr' used by this command */
 #define        BPF_PROG_LOAD_LAST_FIELD kern_version

diff --git a/net/core/filter.c b/net/core/filter.c
index 76f9a4938be4ac1c9e414792d56e022c744e2440..76fee35da244b4ca30e9a22941866a0559d8c39d 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1301,21 +1301,10 @@ int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 
 static struct bpf_prog *__get_bpf(u32 ufd, struct sock *sk)
 {
-       struct bpf_prog *prog;
-
        if (sock_flag(sk, SOCK_FILTER_LOCKED))
                return ERR_PTR(-EPERM);
 
-       prog = bpf_prog_get(ufd);
-       if (IS_ERR(prog))
-               return prog;
-
-       if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-               bpf_prog_put(prog);
-               return ERR_PTR(-EINVAL);
-       }
-
-       return prog;
+       return bpf_prog_get_type(ufd, BPF_PROG_TYPE_SOCKET_FILTER);
 }
 
 int sk_attach_bpf(u32 ufd, struct sock *sk)

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 0b68ba730a067ad4d9be9d75f42034d709a762aa..cb39e05b166cf5eaa0729b775f3ee0b8a140398a 100644 (file)
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1765,18 +1765,12 @@ static int kcm_attach_ioctl(struct socket *sock, struct kcm_attach *info)
        if (!csock)
                return -ENOENT;
 
-       prog = bpf_prog_get(info->bpf_fd);
+       prog = bpf_prog_get_type(info->bpf_fd, BPF_PROG_TYPE_SOCKET_FILTER);
        if (IS_ERR(prog)) {
                err = PTR_ERR(prog);
                goto out;
        }
 
-       if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-               bpf_prog_put(prog);
-               err = -EINVAL;
-               goto out;
-       }
-
        err = kcm_attach(sock, csock, prog);
        if (err) {
                bpf_prog_put(prog);

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d1f3b9e977e57f5a7a6191adbd43bd2fe255ebd9..48b58957adf44623276e570164a96d7b64537dfa 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1588,13 +1588,9 @@ static int fanout_set_data_ebpf(struct packet_sock *po, char __user *data,
        if (copy_from_user(&fd, data, len))
                return -EFAULT;
 
-       new = bpf_prog_get(fd);
+       new = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
        if (IS_ERR(new))
                return PTR_ERR(new);
-       if (new->type != BPF_PROG_TYPE_SOCKET_FILTER) {
-               bpf_prog_put(new);
-               return -EINVAL;
-       }
 
        __fanout_set_data_bpf(po->fanout, new);
        return 0;

diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index f7b6cf49ea6f343f4a169e8766fe4114d0f4b769..ef74bffa610128eb8f55fe9a6ad277cc623a2129 100644 (file)
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -223,15 +223,10 @@ static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
 
        bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
 
-       fp = bpf_prog_get(bpf_fd);
+       fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
        if (IS_ERR(fp))
                return PTR_ERR(fp);
 
-       if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
-               bpf_prog_put(fp);
-               return -EINVAL;
-       }
-
        if (tb[TCA_ACT_BPF_NAME]) {
                name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
                               nla_len(tb[TCA_ACT_BPF_NAME]),

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 7b342c779da7b1f7572f50e6bb45d4b99a1238df..c3002c2c68bbf58cdad92e13bb1b733d9e39c271 100644 (file)
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -272,15 +272,10 @@ static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
 
        bpf_fd = nla_get_u32(tb[TCA_BPF_FD]);
 
-       fp = bpf_prog_get(bpf_fd);
+       fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_CLS);
        if (IS_ERR(fp))
                return PTR_ERR(fp);
 
-       if (fp->type != BPF_PROG_TYPE_SCHED_CLS) {
-               bpf_prog_put(fp);
-               return -EINVAL;
-       }
-
        if (tb[TCA_BPF_NAME]) {
                name = kmemdup(nla_data(tb[TCA_BPF_NAME]),
                               nla_len(tb[TCA_BPF_NAME]),