kernel/bpf/bpf_lsm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Copyright (C) 2020 Google LLC.
   5  */
   6
   7 #include <linux/filter.h>
   8 #include <linux/bpf.h>
   9 #include <linux/btf.h>
  10 #include <linux/binfmts.h>
  11 #include <linux/lsm_hooks.h>
  12 #include <linux/bpf_lsm.h>
  13 #include <linux/kallsyms.h>
  14 #include <linux/bpf_verifier.h>
  15 #include <net/bpf_sk_storage.h>
  16 #include <linux/bpf_local_storage.h>
  17 #include <linux/btf_ids.h>
  18 #include <linux/ima.h>
  19
  20 /* For every LSM hook that allows attachment of BPF programs, declare a nop
  21  * function where a BPF program can be attached.
  22  */
  23 #define LSM_HOOK(RET, DEFAULT, NAME, ...)       \
  24 noinline RET bpf_lsm_##NAME(__VA_ARGS__)        \
  25 {                                               \
  26         return DEFAULT;                         \
  27 }
  28
  29 #include <linux/lsm_hook_defs.h>
  30 #undef LSM_HOOK
  31
  32 #define LSM_HOOK(RET, DEFAULT, NAME, ...) BTF_ID(func, bpf_lsm_##NAME)
  33 BTF_SET_START(bpf_lsm_hooks)
  34 #include <linux/lsm_hook_defs.h>
  35 #undef LSM_HOOK
  36 BTF_SET_END(bpf_lsm_hooks)
  37
  38 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
  39                         const struct bpf_prog *prog)
  40 {
  41         if (!prog->gpl_compatible) {
  42                 bpf_log(vlog,
  43                         "LSM programs must have a GPL compatible license\n");
  44                 return -EINVAL;
  45         }
  46
  47         if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) {
  48                 bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
  49                         prog->aux->attach_btf_id, prog->aux->attach_func_name);
  50                 return -EINVAL;
  51         }
  52
  53         return 0;
  54 }
  55
  56 /* Mask for all the currently supported BPRM option flags */
  57 #define BPF_F_BRPM_OPTS_MASK    BPF_F_BPRM_SECUREEXEC
  58
  59 BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags)
  60 {
  61         if (flags & ~BPF_F_BRPM_OPTS_MASK)
  62                 return -EINVAL;
  63
  64         bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC);
  65         return 0;
  66 }
  67
  68 BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm)
  69
  70 const static struct bpf_func_proto bpf_bprm_opts_set_proto = {
  71         .func           = bpf_bprm_opts_set,
  72         .gpl_only       = false,
  73         .ret_type       = RET_INTEGER,
  74         .arg1_type      = ARG_PTR_TO_BTF_ID,
  75         .arg1_btf_id    = &bpf_bprm_opts_set_btf_ids[0],
  76         .arg2_type      = ARG_ANYTHING,
  77 };
  78
  79 BPF_CALL_3(bpf_ima_inode_hash, struct inode *, inode, void *, dst, u32, size)
  80 {
  81         return ima_inode_hash(inode, dst, size);
  82 }
  83
  84 static bool bpf_ima_inode_hash_allowed(const struct bpf_prog *prog)
  85 {
  86         return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id);
  87 }
  88
  89 BTF_ID_LIST_SINGLE(bpf_ima_inode_hash_btf_ids, struct, inode)
  90
  91 const static struct bpf_func_proto bpf_ima_inode_hash_proto = {
  92         .func           = bpf_ima_inode_hash,
  93         .gpl_only       = false,
  94         .ret_type       = RET_INTEGER,
  95         .arg1_type      = ARG_PTR_TO_BTF_ID,
  96         .arg1_btf_id    = &bpf_ima_inode_hash_btf_ids[0],
  97         .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
  98         .arg3_type      = ARG_CONST_SIZE,
  99         .allowed        = bpf_ima_inode_hash_allowed,
 100 };
 101
 102 static const struct bpf_func_proto *
 103 bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 104 {
 105         switch (func_id) {
 106         case BPF_FUNC_inode_storage_get:
 107                 return &bpf_inode_storage_get_proto;
 108         case BPF_FUNC_inode_storage_delete:
 109                 return &bpf_inode_storage_delete_proto;
 110         case BPF_FUNC_sk_storage_get:
 111                 return &bpf_sk_storage_get_proto;
 112         case BPF_FUNC_sk_storage_delete:
 113                 return &bpf_sk_storage_delete_proto;
 114         case BPF_FUNC_spin_lock:
 115                 return &bpf_spin_lock_proto;
 116         case BPF_FUNC_spin_unlock:
 117                 return &bpf_spin_unlock_proto;
 118         case BPF_FUNC_task_storage_get:
 119                 return &bpf_task_storage_get_proto;
 120         case BPF_FUNC_task_storage_delete:
 121                 return &bpf_task_storage_delete_proto;
 122         case BPF_FUNC_bprm_opts_set:
 123                 return &bpf_bprm_opts_set_proto;
 124         case BPF_FUNC_ima_inode_hash:
 125                 return prog->aux->sleepable ? &bpf_ima_inode_hash_proto : NULL;
 126         default:
 127                 return tracing_prog_func_proto(func_id, prog);
 128         }
 129 }
 130
 131 /* The set of hooks which are called without pagefaults disabled and are allowed
 132  * to "sleep" and thus can be used for sleeable BPF programs.
 133  */
 134 BTF_SET_START(sleepable_lsm_hooks)
 135 BTF_ID(func, bpf_lsm_bpf)
 136 BTF_ID(func, bpf_lsm_bpf_map)
 137 BTF_ID(func, bpf_lsm_bpf_map_alloc_security)
 138 BTF_ID(func, bpf_lsm_bpf_map_free_security)
 139 BTF_ID(func, bpf_lsm_bpf_prog)
 140 BTF_ID(func, bpf_lsm_bprm_check_security)
 141 BTF_ID(func, bpf_lsm_bprm_committed_creds)
 142 BTF_ID(func, bpf_lsm_bprm_committing_creds)
 143 BTF_ID(func, bpf_lsm_bprm_creds_for_exec)
 144 BTF_ID(func, bpf_lsm_bprm_creds_from_file)
 145 BTF_ID(func, bpf_lsm_capget)
 146 BTF_ID(func, bpf_lsm_capset)
 147 BTF_ID(func, bpf_lsm_cred_prepare)
 148 BTF_ID(func, bpf_lsm_file_ioctl)
 149 BTF_ID(func, bpf_lsm_file_lock)
 150 BTF_ID(func, bpf_lsm_file_open)
 151 BTF_ID(func, bpf_lsm_file_receive)
 152 BTF_ID(func, bpf_lsm_inet_conn_established)
 153 BTF_ID(func, bpf_lsm_inode_create)
 154 BTF_ID(func, bpf_lsm_inode_free_security)
 155 BTF_ID(func, bpf_lsm_inode_getattr)
 156 BTF_ID(func, bpf_lsm_inode_getxattr)
 157 BTF_ID(func, bpf_lsm_inode_mknod)
 158 BTF_ID(func, bpf_lsm_inode_need_killpriv)
 159 BTF_ID(func, bpf_lsm_inode_post_setxattr)
 160 BTF_ID(func, bpf_lsm_inode_readlink)
 161 BTF_ID(func, bpf_lsm_inode_rename)
 162 BTF_ID(func, bpf_lsm_inode_rmdir)
 163 BTF_ID(func, bpf_lsm_inode_setattr)
 164 BTF_ID(func, bpf_lsm_inode_setxattr)
 165 BTF_ID(func, bpf_lsm_inode_symlink)
 166 BTF_ID(func, bpf_lsm_inode_unlink)
 167 BTF_ID(func, bpf_lsm_kernel_module_request)
 168 BTF_ID(func, bpf_lsm_kernfs_init_security)
 169 BTF_ID(func, bpf_lsm_key_free)
 170 BTF_ID(func, bpf_lsm_mmap_file)
 171 BTF_ID(func, bpf_lsm_netlink_send)
 172 BTF_ID(func, bpf_lsm_path_notify)
 173 BTF_ID(func, bpf_lsm_release_secctx)
 174 BTF_ID(func, bpf_lsm_sb_alloc_security)
 175 BTF_ID(func, bpf_lsm_sb_eat_lsm_opts)
 176 BTF_ID(func, bpf_lsm_sb_kern_mount)
 177 BTF_ID(func, bpf_lsm_sb_mount)
 178 BTF_ID(func, bpf_lsm_sb_remount)
 179 BTF_ID(func, bpf_lsm_sb_set_mnt_opts)
 180 BTF_ID(func, bpf_lsm_sb_show_options)
 181 BTF_ID(func, bpf_lsm_sb_statfs)
 182 BTF_ID(func, bpf_lsm_sb_umount)
 183 BTF_ID(func, bpf_lsm_settime)
 184 BTF_ID(func, bpf_lsm_socket_accept)
 185 BTF_ID(func, bpf_lsm_socket_bind)
 186 BTF_ID(func, bpf_lsm_socket_connect)
 187 BTF_ID(func, bpf_lsm_socket_create)
 188 BTF_ID(func, bpf_lsm_socket_getpeername)
 189 BTF_ID(func, bpf_lsm_socket_getpeersec_dgram)
 190 BTF_ID(func, bpf_lsm_socket_getsockname)
 191 BTF_ID(func, bpf_lsm_socket_getsockopt)
 192 BTF_ID(func, bpf_lsm_socket_listen)
 193 BTF_ID(func, bpf_lsm_socket_post_create)
 194 BTF_ID(func, bpf_lsm_socket_recvmsg)
 195 BTF_ID(func, bpf_lsm_socket_sendmsg)
 196 BTF_ID(func, bpf_lsm_socket_shutdown)
 197 BTF_ID(func, bpf_lsm_socket_socketpair)
 198 BTF_ID(func, bpf_lsm_syslog)
 199 BTF_ID(func, bpf_lsm_task_alloc)
 200 BTF_ID(func, bpf_lsm_task_getsecid)
 201 BTF_ID(func, bpf_lsm_task_prctl)
 202 BTF_ID(func, bpf_lsm_task_setscheduler)
 203 BTF_ID(func, bpf_lsm_task_to_inode)
 204 BTF_SET_END(sleepable_lsm_hooks)
 205
 206 bool bpf_lsm_is_sleepable_hook(u32 btf_id)
 207 {
 208         return btf_id_set_contains(&sleepable_lsm_hooks, btf_id);
 209 }
 210
 211 const struct bpf_prog_ops lsm_prog_ops = {
 212 };
 213
 214 const struct bpf_verifier_ops lsm_verifier_ops = {
 215         .get_func_proto = bpf_lsm_func_proto,
 216         .is_valid_access = btf_ctx_access,
 217 };