Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
30639b6a AD |
2 | /* |
3 | * Supplementary group IDs | |
4 | */ | |
5 | #include <linux/cred.h> | |
9984de1a | 6 | #include <linux/export.h> |
30639b6a AD |
7 | #include <linux/slab.h> |
8 | #include <linux/security.h> | |
b7b2562f | 9 | #include <linux/sort.h> |
30639b6a | 10 | #include <linux/syscalls.h> |
273d2c67 | 11 | #include <linux/user_namespace.h> |
81243eac | 12 | #include <linux/vmalloc.h> |
7c0f6ba6 | 13 | #include <linux/uaccess.h> |
30639b6a | 14 | |
30639b6a AD |
15 | struct group_info *groups_alloc(int gidsetsize) |
16 | { | |
81243eac | 17 | struct group_info *gi; |
e1e01411 | 18 | gi = kvmalloc(struct_size(gi, gid, gidsetsize), GFP_KERNEL_ACCOUNT); |
81243eac | 19 | if (!gi) |
30639b6a | 20 | return NULL; |
30639b6a | 21 | |
81243eac AD |
22 | atomic_set(&gi->usage, 1); |
23 | gi->ngroups = gidsetsize; | |
24 | return gi; | |
30639b6a AD |
25 | } |
26 | ||
27 | EXPORT_SYMBOL(groups_alloc); | |
28 | ||
29 | void groups_free(struct group_info *group_info) | |
30 | { | |
81243eac | 31 | kvfree(group_info); |
30639b6a AD |
32 | } |
33 | ||
34 | EXPORT_SYMBOL(groups_free); | |
35 | ||
36 | /* export the group_info to a user-space array */ | |
37 | static int groups_to_user(gid_t __user *grouplist, | |
38 | const struct group_info *group_info) | |
39 | { | |
ae2975bc | 40 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
41 | int i; |
42 | unsigned int count = group_info->ngroups; | |
43 | ||
ae2975bc EB |
44 | for (i = 0; i < count; i++) { |
45 | gid_t gid; | |
81243eac | 46 | gid = from_kgid_munged(user_ns, group_info->gid[i]); |
ae2975bc | 47 | if (put_user(gid, grouplist+i)) |
30639b6a | 48 | return -EFAULT; |
30639b6a AD |
49 | } |
50 | return 0; | |
51 | } | |
52 | ||
53 | /* fill a group_info from a user-space array - it must be allocated already */ | |
54 | static int groups_from_user(struct group_info *group_info, | |
55 | gid_t __user *grouplist) | |
56 | { | |
ae2975bc | 57 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
58 | int i; |
59 | unsigned int count = group_info->ngroups; | |
60 | ||
ae2975bc EB |
61 | for (i = 0; i < count; i++) { |
62 | gid_t gid; | |
63 | kgid_t kgid; | |
64 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
65 | return -EFAULT; |
66 | ||
ae2975bc EB |
67 | kgid = make_kgid(user_ns, gid); |
68 | if (!gid_valid(kgid)) | |
69 | return -EINVAL; | |
70 | ||
81243eac | 71 | group_info->gid[i] = kgid; |
30639b6a AD |
72 | } |
73 | return 0; | |
74 | } | |
75 | ||
b7b2562f RV |
76 | static int gid_cmp(const void *_a, const void *_b) |
77 | { | |
78 | kgid_t a = *(kgid_t *)_a; | |
79 | kgid_t b = *(kgid_t *)_b; | |
80 | ||
81 | return gid_gt(a, b) - gid_lt(a, b); | |
82 | } | |
83 | ||
bdcf0a42 | 84 | void groups_sort(struct group_info *group_info) |
30639b6a | 85 | { |
b7b2562f RV |
86 | sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid), |
87 | gid_cmp, NULL); | |
30639b6a | 88 | } |
bdcf0a42 | 89 | EXPORT_SYMBOL(groups_sort); |
30639b6a AD |
90 | |
91 | /* a simple bsearch */ | |
ae2975bc | 92 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
93 | { |
94 | unsigned int left, right; | |
95 | ||
96 | if (!group_info) | |
97 | return 0; | |
98 | ||
99 | left = 0; | |
100 | right = group_info->ngroups; | |
101 | while (left < right) { | |
102 | unsigned int mid = (left+right)/2; | |
81243eac | 103 | if (gid_gt(grp, group_info->gid[mid])) |
30639b6a | 104 | left = mid + 1; |
81243eac | 105 | else if (gid_lt(grp, group_info->gid[mid])) |
30639b6a AD |
106 | right = mid; |
107 | else | |
108 | return 1; | |
109 | } | |
110 | return 0; | |
111 | } | |
112 | ||
113 | /** | |
114 | * set_groups - Change a group subscription in a set of credentials | |
115 | * @new: The newly prepared set of credentials to alter | |
116 | * @group_info: The group list to install | |
30639b6a | 117 | */ |
8f6c5ffc | 118 | void set_groups(struct cred *new, struct group_info *group_info) |
30639b6a | 119 | { |
30639b6a | 120 | put_group_info(new->group_info); |
30639b6a AD |
121 | get_group_info(group_info); |
122 | new->group_info = group_info; | |
30639b6a AD |
123 | } |
124 | ||
125 | EXPORT_SYMBOL(set_groups); | |
126 | ||
127 | /** | |
128 | * set_current_groups - Change current's group subscription | |
129 | * @group_info: The group list to impose | |
130 | * | |
131 | * Validate a group subscription and, if valid, impose it upon current's task | |
132 | * security record. | |
133 | */ | |
134 | int set_current_groups(struct group_info *group_info) | |
135 | { | |
136 | struct cred *new; | |
30639b6a AD |
137 | |
138 | new = prepare_creds(); | |
139 | if (!new) | |
140 | return -ENOMEM; | |
141 | ||
8f6c5ffc | 142 | set_groups(new, group_info); |
30639b6a AD |
143 | return commit_creds(new); |
144 | } | |
145 | ||
146 | EXPORT_SYMBOL(set_current_groups); | |
147 | ||
148 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
149 | { | |
150 | const struct cred *cred = current_cred(); | |
151 | int i; | |
152 | ||
153 | if (gidsetsize < 0) | |
154 | return -EINVAL; | |
155 | ||
156 | /* no need to grab task_lock here; it cannot change */ | |
157 | i = cred->group_info->ngroups; | |
158 | if (gidsetsize) { | |
159 | if (i > gidsetsize) { | |
160 | i = -EINVAL; | |
161 | goto out; | |
162 | } | |
163 | if (groups_to_user(grouplist, cred->group_info)) { | |
164 | i = -EFAULT; | |
165 | goto out; | |
166 | } | |
167 | } | |
168 | out: | |
169 | return i; | |
170 | } | |
171 | ||
7ff4d90b EB |
172 | bool may_setgroups(void) |
173 | { | |
174 | struct user_namespace *user_ns = current_user_ns(); | |
175 | ||
111767c1 | 176 | return ns_capable_setid(user_ns, CAP_SETGID) && |
273d2c67 | 177 | userns_may_setgroups(user_ns); |
7ff4d90b EB |
178 | } |
179 | ||
30639b6a AD |
180 | /* |
181 | * SMP: Our groups are copy-on-write. We can set them safely | |
182 | * without another task interfering. | |
183 | */ | |
184 | ||
185 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
186 | { | |
187 | struct group_info *group_info; | |
188 | int retval; | |
189 | ||
7ff4d90b | 190 | if (!may_setgroups()) |
30639b6a AD |
191 | return -EPERM; |
192 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
193 | return -EINVAL; | |
194 | ||
195 | group_info = groups_alloc(gidsetsize); | |
196 | if (!group_info) | |
197 | return -ENOMEM; | |
198 | retval = groups_from_user(group_info, grouplist); | |
199 | if (retval) { | |
200 | put_group_info(group_info); | |
201 | return retval; | |
202 | } | |
203 | ||
bdcf0a42 | 204 | groups_sort(group_info); |
30639b6a AD |
205 | retval = set_current_groups(group_info); |
206 | put_group_info(group_info); | |
207 | ||
208 | return retval; | |
209 | } | |
210 | ||
211 | /* | |
212 | * Check whether we're fsgid/egid or in the supplemental group.. | |
213 | */ | |
72cda3d1 | 214 | int in_group_p(kgid_t grp) |
30639b6a AD |
215 | { |
216 | const struct cred *cred = current_cred(); | |
217 | int retval = 1; | |
218 | ||
72cda3d1 EB |
219 | if (!gid_eq(grp, cred->fsgid)) |
220 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
221 | return retval; |
222 | } | |
223 | ||
224 | EXPORT_SYMBOL(in_group_p); | |
225 | ||
72cda3d1 | 226 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
227 | { |
228 | const struct cred *cred = current_cred(); | |
229 | int retval = 1; | |
230 | ||
72cda3d1 EB |
231 | if (!gid_eq(grp, cred->egid)) |
232 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
233 | return retval; |
234 | } | |
235 | ||
236 | EXPORT_SYMBOL(in_egroup_p); |