kernel/trace/bpf_trace.c:1216:17: warning: no previous declaration for 'bpf_lookup_user_key'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   4853c74bd7ab7fdb83f319bd9ace8a08c031e9b6
commit: f3cf4134c5c6c47b9b5c7aa3cb2d67e107887a7b bpf: Add bpf_lookup_*_key() and bpf_key_put() kfuncs
date:   11 months ago
config: x86_64-randconfig-x012-20230816 (https://download.01.org/0day-ci/archive/20230816/202308162316.PIY9owc8-lkp@xxxxxxxxx/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce: (https://download.01.org/0day-ci/archive/20230816/202308162316.PIY9owc8-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308162316.PIY9owc8-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> kernel/trace/bpf_trace.c:1216:17: warning: no previous declaration for 'bpf_lookup_user_key' [-Wmissing-declarations]
    struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags)
                    ^~~~~~~~~~~~~~~~~~~
>> kernel/trace/bpf_trace.c:1265:17: warning: no previous declaration for 'bpf_lookup_system_key' [-Wmissing-declarations]
    struct bpf_key *bpf_lookup_system_key(u64 id)
                    ^~~~~~~~~~~~~~~~~~~~~
>> kernel/trace/bpf_trace.c:1289:6: warning: no previous declaration for 'bpf_key_put' [-Wmissing-declarations]
    void bpf_key_put(struct bpf_key *bkey)
         ^~~~~~~~~~~


vim +/bpf_lookup_user_key +1216 kernel/trace/bpf_trace.c

  1185	
  1186	#ifdef CONFIG_KEYS
  1187	__diag_push();
  1188	__diag_ignore_all("-Wmissing-prototypes",
  1189			  "kfuncs which will be used in BPF programs");
  1190	
  1191	/**
  1192	 * bpf_lookup_user_key - lookup a key by its serial
  1193	 * @serial: key handle serial number
  1194	 * @flags: lookup-specific flags
  1195	 *
  1196	 * Search a key with a given *serial* and the provided *flags*.
  1197	 * If found, increment the reference count of the key by one, and
  1198	 * return it in the bpf_key structure.
  1199	 *
  1200	 * The bpf_key structure must be passed to bpf_key_put() when done
  1201	 * with it, so that the key reference count is decremented and the
  1202	 * bpf_key structure is freed.
  1203	 *
  1204	 * Permission checks are deferred to the time the key is used by
  1205	 * one of the available key-specific kfuncs.
  1206	 *
  1207	 * Set *flags* with KEY_LOOKUP_CREATE, to attempt creating a requested
  1208	 * special keyring (e.g. session keyring), if it doesn't yet exist.
  1209	 * Set *flags* with KEY_LOOKUP_PARTIAL, to lookup a key without waiting
  1210	 * for the key construction, and to retrieve uninstantiated keys (keys
  1211	 * without data attached to them).
  1212	 *
  1213	 * Return: a bpf_key pointer with a valid key pointer if the key is found, a
  1214	 *         NULL pointer otherwise.
  1215	 */
> 1216	struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags)
  1217	{
  1218		key_ref_t key_ref;
  1219		struct bpf_key *bkey;
  1220	
  1221		if (flags & ~KEY_LOOKUP_ALL)
  1222			return NULL;
  1223	
  1224		/*
  1225		 * Permission check is deferred until the key is used, as the
  1226		 * intent of the caller is unknown here.
  1227		 */
  1228		key_ref = lookup_user_key(serial, flags, KEY_DEFER_PERM_CHECK);
  1229		if (IS_ERR(key_ref))
  1230			return NULL;
  1231	
  1232		bkey = kmalloc(sizeof(*bkey), GFP_KERNEL);
  1233		if (!bkey) {
  1234			key_put(key_ref_to_ptr(key_ref));
  1235			return NULL;
  1236		}
  1237	
  1238		bkey->key = key_ref_to_ptr(key_ref);
  1239		bkey->has_ref = true;
  1240	
  1241		return bkey;
  1242	}
  1243	
  1244	/**
  1245	 * bpf_lookup_system_key - lookup a key by a system-defined ID
  1246	 * @id: key ID
  1247	 *
  1248	 * Obtain a bpf_key structure with a key pointer set to the passed key ID.
  1249	 * The key pointer is marked as invalid, to prevent bpf_key_put() from
  1250	 * attempting to decrement the key reference count on that pointer. The key
  1251	 * pointer set in such way is currently understood only by
  1252	 * verify_pkcs7_signature().
  1253	 *
  1254	 * Set *id* to one of the values defined in include/linux/verification.h:
  1255	 * 0 for the primary keyring (immutable keyring of system keys);
  1256	 * VERIFY_USE_SECONDARY_KEYRING for both the primary and secondary keyring
  1257	 * (where keys can be added only if they are vouched for by existing keys
  1258	 * in those keyrings); VERIFY_USE_PLATFORM_KEYRING for the platform
  1259	 * keyring (primarily used by the integrity subsystem to verify a kexec'ed
  1260	 * kerned image and, possibly, the initramfs signature).
  1261	 *
  1262	 * Return: a bpf_key pointer with an invalid key pointer set from the
  1263	 *         pre-determined ID on success, a NULL pointer otherwise
  1264	 */
> 1265	struct bpf_key *bpf_lookup_system_key(u64 id)
  1266	{
  1267		struct bpf_key *bkey;
  1268	
  1269		if (system_keyring_id_check(id) < 0)
  1270			return NULL;
  1271	
  1272		bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC);
  1273		if (!bkey)
  1274			return NULL;
  1275	
  1276		bkey->key = (struct key *)(unsigned long)id;
  1277		bkey->has_ref = false;
  1278	
  1279		return bkey;
  1280	}
  1281	
  1282	/**
  1283	 * bpf_key_put - decrement key reference count if key is valid and free bpf_key
  1284	 * @bkey: bpf_key structure
  1285	 *
  1286	 * Decrement the reference count of the key inside *bkey*, if the pointer
  1287	 * is valid, and free *bkey*.
  1288	 */
> 1289	void bpf_key_put(struct bpf_key *bkey)
  1290	{
  1291		if (bkey->has_ref)
  1292			key_put(bkey->key);
  1293	
  1294		kfree(bkey);
  1295	}
  1296	

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