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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0265ab44 JE |
2 | /* |
3 | * Kernel module to match various things tied to sockets associated with | |
4 | * locally generated outgoing packets. | |
5 | * | |
6 | * (C) 2000 Marc Boucher <marc@mbsi.ca> | |
7 | * | |
edc26f7a | 8 | * Copyright © CC Computer Consultants GmbH, 2007 - 2008 |
0265ab44 JE |
9 | */ |
10 | #include <linux/module.h> | |
11 | #include <linux/skbuff.h> | |
12 | #include <linux/file.h> | |
5b825c3a IM |
13 | #include <linux/cred.h> |
14 | ||
0265ab44 | 15 | #include <net/sock.h> |
fdd723e2 | 16 | #include <net/inet_sock.h> |
0265ab44 JE |
17 | #include <linux/netfilter/x_tables.h> |
18 | #include <linux/netfilter/xt_owner.h> | |
0265ab44 | 19 | |
26711a79 EB |
20 | static int owner_check(const struct xt_mtchk_param *par) |
21 | { | |
22 | struct xt_owner_match_info *info = par->matchinfo; | |
9847371a | 23 | struct net *net = par->net; |
26711a79 | 24 | |
9911c113 PNA |
25 | if (info->match & ~XT_OWNER_MASK) |
26 | return -EINVAL; | |
27 | ||
9847371a EB |
28 | /* Only allow the common case where the userns of the writer |
29 | * matches the userns of the network namespace. | |
30 | */ | |
26711a79 | 31 | if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) && |
9847371a | 32 | (current_user_ns() != net->user_ns)) |
26711a79 | 33 | return -EINVAL; |
9847371a EB |
34 | |
35 | /* Ensure the uids are valid */ | |
36 | if (info->match & XT_OWNER_UID) { | |
37 | kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); | |
38 | kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); | |
39 | ||
40 | if (!uid_valid(uid_min) || !uid_valid(uid_max) || | |
41 | (info->uid_max < info->uid_min) || | |
42 | uid_lt(uid_max, uid_min)) { | |
43 | return -EINVAL; | |
44 | } | |
45 | } | |
46 | ||
47 | /* Ensure the gids are valid */ | |
48 | if (info->match & XT_OWNER_GID) { | |
49 | kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); | |
50 | kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); | |
51 | ||
52 | if (!gid_valid(gid_min) || !gid_valid(gid_max) || | |
53 | (info->gid_max < info->gid_min) || | |
54 | gid_lt(gid_max, gid_min)) { | |
55 | return -EINVAL; | |
56 | } | |
57 | } | |
58 | ||
26711a79 EB |
59 | return 0; |
60 | } | |
61 | ||
0265ab44 | 62 | static bool |
62fc8051 | 63 | owner_mt(const struct sk_buff *skb, struct xt_action_param *par) |
0265ab44 | 64 | { |
f7108a20 | 65 | const struct xt_owner_match_info *info = par->matchinfo; |
0265ab44 | 66 | const struct file *filp; |
fdd723e2 | 67 | struct sock *sk = skb_to_full_sk(skb); |
613dbd95 | 68 | struct net *net = xt_net(par); |
0265ab44 | 69 | |
f5646501 | 70 | if (!sk || !sk->sk_socket || !net_eq(net, sock_net(sk))) |
0265ab44 JE |
71 | return (info->match ^ info->invert) == 0; |
72 | else if (info->match & info->invert & XT_OWNER_SOCKET) | |
73 | /* | |
74 | * Socket exists but user wanted ! --socket-exists. | |
75 | * (Single ampersands intended.) | |
76 | */ | |
77 | return false; | |
78 | ||
fdd723e2 | 79 | filp = sk->sk_socket->file; |
0265ab44 JE |
80 | if (filp == NULL) |
81 | return ((info->match ^ info->invert) & | |
82 | (XT_OWNER_UID | XT_OWNER_GID)) == 0; | |
83 | ||
26711a79 | 84 | if (info->match & XT_OWNER_UID) { |
9847371a EB |
85 | kuid_t uid_min = make_kuid(net->user_ns, info->uid_min); |
86 | kuid_t uid_max = make_kuid(net->user_ns, info->uid_max); | |
26711a79 EB |
87 | if ((uid_gte(filp->f_cred->fsuid, uid_min) && |
88 | uid_lte(filp->f_cred->fsuid, uid_max)) ^ | |
edc26f7a | 89 | !(info->invert & XT_OWNER_UID)) |
0265ab44 | 90 | return false; |
26711a79 | 91 | } |
0265ab44 | 92 | |
26711a79 | 93 | if (info->match & XT_OWNER_GID) { |
ea6cc2fd | 94 | unsigned int i, match = false; |
9847371a EB |
95 | kgid_t gid_min = make_kgid(net->user_ns, info->gid_min); |
96 | kgid_t gid_max = make_kgid(net->user_ns, info->gid_max); | |
ea6cc2fd LP |
97 | struct group_info *gi = filp->f_cred->group_info; |
98 | ||
99 | if (gid_gte(filp->f_cred->fsgid, gid_min) && | |
100 | gid_lte(filp->f_cred->fsgid, gid_max)) | |
101 | match = true; | |
102 | ||
103 | if (!match && (info->match & XT_OWNER_SUPPL_GROUPS) && gi) { | |
104 | for (i = 0; i < gi->ngroups; ++i) { | |
105 | kgid_t group = gi->gid[i]; | |
106 | ||
107 | if (gid_gte(group, gid_min) && | |
108 | gid_lte(group, gid_max)) { | |
109 | match = true; | |
110 | break; | |
111 | } | |
112 | } | |
113 | } | |
114 | ||
115 | if (match ^ !(info->invert & XT_OWNER_GID)) | |
0265ab44 | 116 | return false; |
26711a79 | 117 | } |
0265ab44 JE |
118 | |
119 | return true; | |
120 | } | |
121 | ||
6461caed JE |
122 | static struct xt_match owner_mt_reg __read_mostly = { |
123 | .name = "owner", | |
124 | .revision = 1, | |
125 | .family = NFPROTO_UNSPEC, | |
26711a79 | 126 | .checkentry = owner_check, |
6461caed JE |
127 | .match = owner_mt, |
128 | .matchsize = sizeof(struct xt_owner_match_info), | |
129 | .hooks = (1 << NF_INET_LOCAL_OUT) | | |
130 | (1 << NF_INET_POST_ROUTING), | |
131 | .me = THIS_MODULE, | |
0265ab44 JE |
132 | }; |
133 | ||
134 | static int __init owner_mt_init(void) | |
135 | { | |
6461caed | 136 | return xt_register_match(&owner_mt_reg); |
0265ab44 JE |
137 | } |
138 | ||
139 | static void __exit owner_mt_exit(void) | |
140 | { | |
6461caed | 141 | xt_unregister_match(&owner_mt_reg); |
0265ab44 JE |
142 | } |
143 | ||
144 | module_init(owner_mt_init); | |
145 | module_exit(owner_mt_exit); | |
6461caed | 146 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); |
2ae15b64 | 147 | MODULE_DESCRIPTION("Xtables: socket owner matching"); |
0265ab44 JE |
148 | MODULE_LICENSE("GPL"); |
149 | MODULE_ALIAS("ipt_owner"); | |
150 | MODULE_ALIAS("ip6t_owner"); |