Commit | Line | Data |
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30639b6a AD |
1 | /* |
2 | * Supplementary group IDs | |
3 | */ | |
4 | #include <linux/cred.h> | |
9984de1a | 5 | #include <linux/export.h> |
30639b6a AD |
6 | #include <linux/slab.h> |
7 | #include <linux/security.h> | |
8 | #include <linux/syscalls.h> | |
fc9b65e3 | 9 | #include <linux/user_namespace.h> |
30639b6a AD |
10 | #include <asm/uaccess.h> |
11 | ||
12 | /* init to 2 - one for init_task, one to ensure it is never freed */ | |
13 | struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; | |
14 | ||
15 | struct group_info *groups_alloc(int gidsetsize) | |
16 | { | |
17 | struct group_info *group_info; | |
18 | int nblocks; | |
19 | int i; | |
20 | ||
21 | nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; | |
22 | /* Make sure we always allocate at least one indirect block pointer */ | |
23 | nblocks = nblocks ? : 1; | |
24 | group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); | |
25 | if (!group_info) | |
26 | return NULL; | |
27 | group_info->ngroups = gidsetsize; | |
28 | group_info->nblocks = nblocks; | |
29 | atomic_set(&group_info->usage, 1); | |
30 | ||
31 | if (gidsetsize <= NGROUPS_SMALL) | |
32 | group_info->blocks[0] = group_info->small_block; | |
33 | else { | |
34 | for (i = 0; i < nblocks; i++) { | |
ae2975bc | 35 | kgid_t *b; |
30639b6a AD |
36 | b = (void *)__get_free_page(GFP_USER); |
37 | if (!b) | |
38 | goto out_undo_partial_alloc; | |
39 | group_info->blocks[i] = b; | |
40 | } | |
41 | } | |
42 | return group_info; | |
43 | ||
44 | out_undo_partial_alloc: | |
45 | while (--i >= 0) { | |
46 | free_page((unsigned long)group_info->blocks[i]); | |
47 | } | |
48 | kfree(group_info); | |
49 | return NULL; | |
50 | } | |
51 | ||
52 | EXPORT_SYMBOL(groups_alloc); | |
53 | ||
54 | void groups_free(struct group_info *group_info) | |
55 | { | |
56 | if (group_info->blocks[0] != group_info->small_block) { | |
57 | int i; | |
58 | for (i = 0; i < group_info->nblocks; i++) | |
59 | free_page((unsigned long)group_info->blocks[i]); | |
60 | } | |
61 | kfree(group_info); | |
62 | } | |
63 | ||
64 | EXPORT_SYMBOL(groups_free); | |
65 | ||
66 | /* export the group_info to a user-space array */ | |
67 | static int groups_to_user(gid_t __user *grouplist, | |
68 | const struct group_info *group_info) | |
69 | { | |
ae2975bc | 70 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
71 | int i; |
72 | unsigned int count = group_info->ngroups; | |
73 | ||
ae2975bc EB |
74 | for (i = 0; i < count; i++) { |
75 | gid_t gid; | |
76 | gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i)); | |
77 | if (put_user(gid, grouplist+i)) | |
30639b6a | 78 | return -EFAULT; |
30639b6a AD |
79 | } |
80 | return 0; | |
81 | } | |
82 | ||
83 | /* fill a group_info from a user-space array - it must be allocated already */ | |
84 | static int groups_from_user(struct group_info *group_info, | |
85 | gid_t __user *grouplist) | |
86 | { | |
ae2975bc | 87 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
88 | int i; |
89 | unsigned int count = group_info->ngroups; | |
90 | ||
ae2975bc EB |
91 | for (i = 0; i < count; i++) { |
92 | gid_t gid; | |
93 | kgid_t kgid; | |
94 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
95 | return -EFAULT; |
96 | ||
ae2975bc EB |
97 | kgid = make_kgid(user_ns, gid); |
98 | if (!gid_valid(kgid)) | |
99 | return -EINVAL; | |
100 | ||
101 | GROUP_AT(group_info, i) = kgid; | |
30639b6a AD |
102 | } |
103 | return 0; | |
104 | } | |
105 | ||
106 | /* a simple Shell sort */ | |
107 | static void groups_sort(struct group_info *group_info) | |
108 | { | |
109 | int base, max, stride; | |
110 | int gidsetsize = group_info->ngroups; | |
111 | ||
112 | for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) | |
113 | ; /* nothing */ | |
114 | stride /= 3; | |
115 | ||
116 | while (stride) { | |
117 | max = gidsetsize - stride; | |
118 | for (base = 0; base < max; base++) { | |
119 | int left = base; | |
120 | int right = left + stride; | |
ae2975bc | 121 | kgid_t tmp = GROUP_AT(group_info, right); |
30639b6a | 122 | |
ae2975bc | 123 | while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) { |
30639b6a AD |
124 | GROUP_AT(group_info, right) = |
125 | GROUP_AT(group_info, left); | |
126 | right = left; | |
127 | left -= stride; | |
128 | } | |
129 | GROUP_AT(group_info, right) = tmp; | |
130 | } | |
131 | stride /= 3; | |
132 | } | |
133 | } | |
134 | ||
135 | /* a simple bsearch */ | |
ae2975bc | 136 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
137 | { |
138 | unsigned int left, right; | |
139 | ||
140 | if (!group_info) | |
141 | return 0; | |
142 | ||
143 | left = 0; | |
144 | right = group_info->ngroups; | |
145 | while (left < right) { | |
146 | unsigned int mid = (left+right)/2; | |
ae2975bc | 147 | if (gid_gt(grp, GROUP_AT(group_info, mid))) |
30639b6a | 148 | left = mid + 1; |
ae2975bc | 149 | else if (gid_lt(grp, GROUP_AT(group_info, mid))) |
30639b6a AD |
150 | right = mid; |
151 | else | |
152 | return 1; | |
153 | } | |
154 | return 0; | |
155 | } | |
156 | ||
157 | /** | |
158 | * set_groups - Change a group subscription in a set of credentials | |
159 | * @new: The newly prepared set of credentials to alter | |
160 | * @group_info: The group list to install | |
161 | * | |
162 | * Validate a group subscription and, if valid, insert it into a set | |
163 | * of credentials. | |
164 | */ | |
165 | int set_groups(struct cred *new, struct group_info *group_info) | |
166 | { | |
30639b6a AD |
167 | put_group_info(new->group_info); |
168 | groups_sort(group_info); | |
169 | get_group_info(group_info); | |
170 | new->group_info = group_info; | |
171 | return 0; | |
172 | } | |
173 | ||
174 | EXPORT_SYMBOL(set_groups); | |
175 | ||
176 | /** | |
177 | * set_current_groups - Change current's group subscription | |
178 | * @group_info: The group list to impose | |
179 | * | |
180 | * Validate a group subscription and, if valid, impose it upon current's task | |
181 | * security record. | |
182 | */ | |
183 | int set_current_groups(struct group_info *group_info) | |
184 | { | |
185 | struct cred *new; | |
186 | int ret; | |
187 | ||
188 | new = prepare_creds(); | |
189 | if (!new) | |
190 | return -ENOMEM; | |
191 | ||
192 | ret = set_groups(new, group_info); | |
193 | if (ret < 0) { | |
194 | abort_creds(new); | |
195 | return ret; | |
196 | } | |
197 | ||
198 | return commit_creds(new); | |
199 | } | |
200 | ||
201 | EXPORT_SYMBOL(set_current_groups); | |
202 | ||
203 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
204 | { | |
205 | const struct cred *cred = current_cred(); | |
206 | int i; | |
207 | ||
208 | if (gidsetsize < 0) | |
209 | return -EINVAL; | |
210 | ||
211 | /* no need to grab task_lock here; it cannot change */ | |
212 | i = cred->group_info->ngroups; | |
213 | if (gidsetsize) { | |
214 | if (i > gidsetsize) { | |
215 | i = -EINVAL; | |
216 | goto out; | |
217 | } | |
218 | if (groups_to_user(grouplist, cred->group_info)) { | |
219 | i = -EFAULT; | |
220 | goto out; | |
221 | } | |
222 | } | |
223 | out: | |
224 | return i; | |
225 | } | |
226 | ||
4accc8c8 EB |
227 | bool may_setgroups(void) |
228 | { | |
229 | struct user_namespace *user_ns = current_user_ns(); | |
230 | ||
fc9b65e3 EB |
231 | return ns_capable(user_ns, CAP_SETGID) && |
232 | userns_may_setgroups(user_ns); | |
4accc8c8 EB |
233 | } |
234 | ||
30639b6a AD |
235 | /* |
236 | * SMP: Our groups are copy-on-write. We can set them safely | |
237 | * without another task interfering. | |
238 | */ | |
239 | ||
240 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
241 | { | |
242 | struct group_info *group_info; | |
243 | int retval; | |
244 | ||
4accc8c8 | 245 | if (!may_setgroups()) |
30639b6a AD |
246 | return -EPERM; |
247 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
248 | return -EINVAL; | |
249 | ||
250 | group_info = groups_alloc(gidsetsize); | |
251 | if (!group_info) | |
252 | return -ENOMEM; | |
253 | retval = groups_from_user(group_info, grouplist); | |
254 | if (retval) { | |
255 | put_group_info(group_info); | |
256 | return retval; | |
257 | } | |
258 | ||
259 | retval = set_current_groups(group_info); | |
260 | put_group_info(group_info); | |
261 | ||
262 | return retval; | |
263 | } | |
264 | ||
265 | /* | |
266 | * Check whether we're fsgid/egid or in the supplemental group.. | |
267 | */ | |
72cda3d1 | 268 | int in_group_p(kgid_t grp) |
30639b6a AD |
269 | { |
270 | const struct cred *cred = current_cred(); | |
271 | int retval = 1; | |
272 | ||
72cda3d1 EB |
273 | if (!gid_eq(grp, cred->fsgid)) |
274 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
275 | return retval; |
276 | } | |
277 | ||
278 | EXPORT_SYMBOL(in_group_p); | |
279 | ||
72cda3d1 | 280 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
281 | { |
282 | const struct cred *cred = current_cred(); | |
283 | int retval = 1; | |
284 | ||
72cda3d1 EB |
285 | if (!gid_eq(grp, cred->egid)) |
286 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
287 | return retval; |
288 | } | |
289 | ||
290 | EXPORT_SYMBOL(in_egroup_p); |