netfilter: complete validation of user input

jira VULN-5223
cve CVE-2024-35962
commit-author Eric Dumazet <[email protected]>
commit 65acf6e

In my recent commit, I missed that do_replace() handlers
use copy_from_sockptr() (which I fixed), followed
by unsafe copy_from_sockptr_offset() calls.

In all functions, we can perform the @optlen validation
before even calling xt_alloc_table_info() with the following
check:

if ((u64)optlen < (u64)tmp.size + sizeof(tmp))
        return -EINVAL;

Fixes: 0c83842 ("netfilter: validate user input for expected length")
	Reported-by: syzbot <[email protected]>
	Signed-off-by: Eric Dumazet <[email protected]>
	Reviewed-by: Pablo Neira Ayuso <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
	Signed-off-by: Jakub Kicinski <[email protected]>
(cherry picked from commit 65acf6e)
	Signed-off-by: Brett Mastbergen <[email protected]>

Author: bmastbergen

net/ipv4/netfilter/arp_tables.c

@@ -965,6 +965,8 @@ static int do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
@@ -1265,6 +1267,8 @@ static int compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;
 

net/ipv4/netfilter/ip_tables.c

@@ -1120,6 +1120,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
@@ -1506,6 +1508,8 @@ compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;
 

net/ipv6/netfilter/ip6_tables.c

@@ -1137,6 +1137,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
@@ -1515,6 +1517,8 @@ compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters == 0)
 		return -EINVAL;
+	if ((u64)len < (u64)tmp.size + sizeof(tmp))
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name)-1] = 0;