Re: [PATCH net v5 1/2] net: netfilter: Limit the number of ftp helper port attempts

From: kernel test robot
Date: Mon Sep 20 2021 - 02:06:30 EST


Hi Cole,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net/master]

url: https://github.com/0day-ci/linux/commits/Cole-Dishington/Fix-port-selection-of-FTP-for-NF_NAT_RANGE_PROTO_SPECIFIED/20210920-090056
base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git e30cd812dffadc58241ae378e48728e6a161becd
config: x86_64-randconfig-a002-20210920 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c8b3d7d6d6de37af68b2f379d0e37304f78e115f)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/b90b875dc5be3c59ec418ce403a8d749690a24ec
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Cole-Dishington/Fix-port-selection-of-FTP-for-NF_NAT_RANGE_PROTO_SPECIFIED/20210920-090056
git checkout b90b875dc5be3c59ec418ce403a8d749690a24ec
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> net/netfilter/nf_nat_ftp.c:117:37: warning: more '%' conversions than data arguments [-Wformat-insufficient-args]
nf_ct_helper_log(skb, ct, "tried %u ports, all were in use");
~^
1 warning generated.


vim +117 net/netfilter/nf_nat_ftp.c

60
61 /* So, this packet has hit the connection tracking matching code.
62 Mangle it, and change the expectation to match the new version. */
63 static unsigned int nf_nat_ftp(struct sk_buff *skb,
64 enum ip_conntrack_info ctinfo,
65 enum nf_ct_ftp_type type,
66 unsigned int protoff,
67 unsigned int matchoff,
68 unsigned int matchlen,
69 struct nf_conntrack_expect *exp)
70 {
71 union nf_inet_addr newaddr;
72 u_int16_t port;
73 int dir = CTINFO2DIR(ctinfo);
74 struct nf_conn *ct = exp->master;
75 unsigned int i, min, max, range_size;
76 static const unsigned int max_attempts = 128;
77 char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
78 unsigned int buflen;
79 int ret;
80
81 pr_debug("type %i, off %u len %u\n", type, matchoff, matchlen);
82
83 /* Connection will come from wherever this packet goes, hence !dir */
84 newaddr = ct->tuplehash[!dir].tuple.dst.u3;
85 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
86 exp->dir = !dir;
87
88 /* When you see the packet, we need to NAT it the same as the
89 * this one. */
90 exp->expectfn = nf_nat_follow_master;
91
92 min = ntohs(exp->saved_proto.tcp.port);
93 max = 65535;
94
95 /* Try to get same port */
96 ret = nf_ct_expect_related(exp, 0);
97
98 /* if same port is not in range or available, try to change it. */
99 if (ret != 0) {
100 range_size = max - min + 1;
101 if (range_size > max_attempts)
102 range_size = max_attempts;
103
104 port = min + prandom_u32_max(max - min);
105 for (i = 0; i < range_size; i++) {
106 exp->tuple.dst.u.tcp.port = htons(port);
107 ret = nf_ct_expect_related(exp, 0);
108 if (ret != -EBUSY)
109 break;
110 port++;
111 if (port > max)
112 port = min;
113 }
114 }
115
116 if (ret != 0) {
> 117 nf_ct_helper_log(skb, ct, "tried %u ports, all were in use");
118 return NF_DROP;
119 }
120
121 buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer),
122 &newaddr, port);
123 if (!buflen)
124 goto out;
125
126 pr_debug("calling nf_nat_mangle_tcp_packet\n");
127
128 if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
129 matchlen, buffer, buflen))
130 goto out;
131
132 return NF_ACCEPT;
133
134 out:
135 nf_ct_helper_log(skb, ct, "cannot mangle packet");
136 nf_ct_unexpect_related(exp);
137 return NF_DROP;
138 }
139

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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