fix "netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'"

Descriptor table is a shared object; it's not a place where you can
stick temporary references to files, especially when we don't need
an opened file at all.

Cc: stable@vger.kernel.org # v4.14
Fixes: 98589a0998b8 ("netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e55e425..b63a592 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -419,6 +419,8 @@ static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
                attr->numa_node : NUMA_NO_NODE;
 }
 
+struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type);
+
 #else /* !CONFIG_BPF_SYSCALL */
 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 {
@@ -506,6 +508,12 @@ static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
 {
        return 0;
 }
+
+static inline struct bpf_prog *bpf_prog_get_type_path(const char *name,
+                               enum bpf_prog_type type)
+{
+       return ERR_PTR(-EOPNOTSUPP);
+}
 #endif /* CONFIG_BPF_SYSCALL */
 
 static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
@@ -514,6 +522,8 @@ static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
        return bpf_prog_get_type_dev(ufd, type, false);
 }
 
+bool bpf_prog_get_ok(struct bpf_prog *, enum bpf_prog_type *, bool);
+
 int bpf_prog_offload_compile(struct bpf_prog *prog);
 void bpf_prog_offload_destroy(struct bpf_prog *prog);
 

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 01aaef1..5bb5e49 100644 (file)
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -368,7 +368,45 @@ out:
        putname(pname);
        return ret;
 }
-EXPORT_SYMBOL_GPL(bpf_obj_get_user);
+
+static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type type)
+{
+       struct bpf_prog *prog;
+       int ret = inode_permission(inode, MAY_READ | MAY_WRITE);
+       if (ret)
+               return ERR_PTR(ret);
+
+       if (inode->i_op == &bpf_map_iops)
+               return ERR_PTR(-EINVAL);
+       if (inode->i_op != &bpf_prog_iops)
+               return ERR_PTR(-EACCES);
+
+       prog = inode->i_private;
+
+       ret = security_bpf_prog(prog);
+       if (ret < 0)
+               return ERR_PTR(ret);
+
+       if (!bpf_prog_get_ok(prog, &type, false))
+               return ERR_PTR(-EINVAL);
+
+       return bpf_prog_inc(prog);
+}
+
+struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type)
+{
+       struct bpf_prog *prog;
+       struct path path;
+       int ret = kern_path(name, LOOKUP_FOLLOW, &path);
+       if (ret)
+               return ERR_PTR(ret);
+       prog = __get_prog_inode(d_backing_inode(path.dentry), type);
+       if (!IS_ERR(prog))
+               touch_atime(&path);
+       path_put(&path);
+       return prog;
+}
+EXPORT_SYMBOL(bpf_prog_get_type_path);
 
 static void bpf_evict_inode(struct inode *inode)
 {

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2c4cfea..5cb783f 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1057,7 +1057,7 @@ struct bpf_prog *bpf_prog_inc_not_zero(struct bpf_prog *prog)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_inc_not_zero);
 
-static bool bpf_prog_get_ok(struct bpf_prog *prog,
+bool bpf_prog_get_ok(struct bpf_prog *prog,
                            enum bpf_prog_type *attach_type, bool attach_drv)
 {
        /* not an attachment, just a refcount inc, always allow */

diff --git a/net/netfilter/xt_bpf.c b/net/netfilter/xt_bpf.c
index 041da0d..fa2ca0a 100644 (file)
--- a/net/netfilter/xt_bpf.c
+++ b/net/netfilter/xt_bpf.c
@@ -52,18 +52,8 @@ static int __bpf_mt_check_fd(int fd, struct bpf_prog **ret)
 
 static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
 {
-       mm_segment_t oldfs = get_fs();
-       int retval, fd;
-
-       set_fs(KERNEL_DS);
-       fd = bpf_obj_get_user(path, 0);
-       set_fs(oldfs);
-       if (fd < 0)
-               return fd;
-
-       retval = __bpf_mt_check_fd(fd, ret);
-       sys_close(fd);
-       return retval;
+       *ret = bpf_prog_get_type_path(path, BPF_PROG_TYPE_SOCKET_FILTER);
+       return PTR_ERR_OR_ZERO(*ret);
 }
 
 static int bpf_mt_check(const struct xt_mtchk_param *par)