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| author | Kevin Easton <kevin@guarana.org> | 2018-04-07 11:40:33 -0400 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2018-04-09 07:06:38 +0200 |
| commit | 4b66af2d6356a00e94bcdea3e7fea324e8b5c6f4 (patch) | |
| tree | 3efe012a7d80247996cbca68eff8aca7894853c5 /net/key | |
| parent | 76327a35caabd1a932e83d6a42b967aa08584e5d (diff) | |
| download | lwn-4b66af2d6356a00e94bcdea3e7fea324e8b5c6f4.tar.gz lwn-4b66af2d6356a00e94bcdea3e7fea324e8b5c6f4.zip | |
af_key: Always verify length of provided sadb_key
Key extensions (struct sadb_key) include a user-specified number of key
bits. The kernel uses that number to determine how much key data to copy
out of the message in pfkey_msg2xfrm_state().
The length of the sadb_key message must be verified to be long enough,
even in the case of SADB_X_AALG_NULL. Furthermore, the sadb_key_len value
must be long enough to include both the key data and the struct sadb_key
itself.
Introduce a helper function verify_key_len(), and call it from
parse_exthdrs() where other exthdr types are similarly checked for
correctness.
Signed-off-by: Kevin Easton <kevin@guarana.org>
Reported-by: syzbot+5022a34ca5a3d49b84223653fab632dfb7b4cf37@syzkaller.appspotmail.com
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/key')
| -rw-r--r-- | net/key/af_key.c | 45 |
1 files changed, 35 insertions, 10 deletions
diff --git a/net/key/af_key.c b/net/key/af_key.c index 7e2e7188e7f4..e62e52e8f141 100644 --- a/net/key/af_key.c +++ b/net/key/af_key.c @@ -437,6 +437,24 @@ static int verify_address_len(const void *p) return 0; } +static inline int sadb_key_len(const struct sadb_key *key) +{ + int key_bytes = DIV_ROUND_UP(key->sadb_key_bits, 8); + + return DIV_ROUND_UP(sizeof(struct sadb_key) + key_bytes, + sizeof(uint64_t)); +} + +static int verify_key_len(const void *p) +{ + const struct sadb_key *key = p; + + if (sadb_key_len(key) > key->sadb_key_len) + return -EINVAL; + + return 0; +} + static inline int pfkey_sec_ctx_len(const struct sadb_x_sec_ctx *sec_ctx) { return DIV_ROUND_UP(sizeof(struct sadb_x_sec_ctx) + @@ -533,16 +551,25 @@ static int parse_exthdrs(struct sk_buff *skb, const struct sadb_msg *hdr, void * return -EINVAL; if (ext_hdrs[ext_type-1] != NULL) return -EINVAL; - if (ext_type == SADB_EXT_ADDRESS_SRC || - ext_type == SADB_EXT_ADDRESS_DST || - ext_type == SADB_EXT_ADDRESS_PROXY || - ext_type == SADB_X_EXT_NAT_T_OA) { + switch (ext_type) { + case SADB_EXT_ADDRESS_SRC: + case SADB_EXT_ADDRESS_DST: + case SADB_EXT_ADDRESS_PROXY: + case SADB_X_EXT_NAT_T_OA: if (verify_address_len(p)) return -EINVAL; - } - if (ext_type == SADB_X_EXT_SEC_CTX) { + break; + case SADB_X_EXT_SEC_CTX: if (verify_sec_ctx_len(p)) return -EINVAL; + break; + case SADB_EXT_KEY_AUTH: + case SADB_EXT_KEY_ENCRYPT: + if (verify_key_len(p)) + return -EINVAL; + break; + default: + break; } ext_hdrs[ext_type-1] = (void *) p; } @@ -1104,14 +1131,12 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net, key = ext_hdrs[SADB_EXT_KEY_AUTH - 1]; if (key != NULL && sa->sadb_sa_auth != SADB_X_AALG_NULL && - ((key->sadb_key_bits+7) / 8 == 0 || - (key->sadb_key_bits+7) / 8 > key->sadb_key_len * sizeof(uint64_t))) + key->sadb_key_bits == 0) return ERR_PTR(-EINVAL); key = ext_hdrs[SADB_EXT_KEY_ENCRYPT-1]; if (key != NULL && sa->sadb_sa_encrypt != SADB_EALG_NULL && - ((key->sadb_key_bits+7) / 8 == 0 || - (key->sadb_key_bits+7) / 8 > key->sadb_key_len * sizeof(uint64_t))) + key->sadb_key_bits == 0) return ERR_PTR(-EINVAL); x = xfrm_state_alloc(net); |