From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit 254ba7e6032d3fc738050d500b0c1d8197af90ca ]
fib_valid_key_len() is called in the beginning of fib_table_insert() or fib_table_delete() to check if the prefix length is valid.
fib_table_insert() and fib_table_delete() are called from 3 paths
- ip_rt_ioctl() - inet_rtm_newroute() / inet_rtm_delroute() - fib_magic()
In the first ioctl() path, rtentry_to_fib_config() checks the prefix length with bad_mask(). Also, fib_magic() always passes the correct prefix: 32 or ifa->ifa_prefixlen, which is already validated.
Let's move fib_valid_key_len() to the rtnetlink path, rtm_to_fib_config().
While at it, 2 direct returns in rtm_to_fib_config() are changed to goto to match other places in the same function
Signed-off-by: Kuniyuki Iwashima kuniyu@amazon.com Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://patch.msgid.link/20250228042328.96624-12-kuniyu@amazon.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/fib_frontend.c | 18 ++++++++++++++++-- net/ipv4/fib_trie.c | 22 ---------------------- 2 files changed, 16 insertions(+), 24 deletions(-)
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 90ce87ffed461..7993ff46de23c 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -829,19 +829,33 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb, } }
+ if (cfg->fc_dst_len > 32) { + NL_SET_ERR_MSG(extack, "Invalid prefix length"); + err = -EINVAL; + goto errout; + } + + if (cfg->fc_dst_len < 32 && (ntohl(cfg->fc_dst) << cfg->fc_dst_len)) { + NL_SET_ERR_MSG(extack, "Invalid prefix for given prefix length"); + err = -EINVAL; + goto errout; + } + if (cfg->fc_nh_id) { if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_encap || cfg->fc_mp) { NL_SET_ERR_MSG(extack, "Nexthop specification and nexthop id are mutually exclusive"); - return -EINVAL; + err = -EINVAL; + goto errout; } }
if (has_gw && has_via) { NL_SET_ERR_MSG(extack, "Nexthop configuration can not contain both GATEWAY and VIA"); - return -EINVAL; + err = -EINVAL; + goto errout; }
if (!cfg->fc_table) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 77b97c48da5ea..fa54b36b241ac 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1192,22 +1192,6 @@ static int fib_insert_alias(struct trie *t, struct key_vector *tp, return 0; }
-static bool fib_valid_key_len(u32 key, u8 plen, struct netlink_ext_ack *extack) -{ - if (plen > KEYLENGTH) { - NL_SET_ERR_MSG(extack, "Invalid prefix length"); - return false; - } - - if ((plen < KEYLENGTH) && (key << plen)) { - NL_SET_ERR_MSG(extack, - "Invalid prefix for given prefix length"); - return false; - } - - return true; -} - static void fib_remove_alias(struct trie *t, struct key_vector *tp, struct key_vector *l, struct fib_alias *old);
@@ -1228,9 +1212,6 @@ int fib_table_insert(struct net *net, struct fib_table *tb,
key = ntohl(cfg->fc_dst);
- if (!fib_valid_key_len(key, plen, extack)) - return -EINVAL; - pr_debug("Insert table=%u %08x/%d\n", tb->tb_id, key, plen);
fi = fib_create_info(cfg, extack); @@ -1723,9 +1704,6 @@ int fib_table_delete(struct net *net, struct fib_table *tb,
key = ntohl(cfg->fc_dst);
- if (!fib_valid_key_len(key, plen, extack)) - return -EINVAL; - l = fib_find_node(t, &tp, key); if (!l) return -ESRCH;