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> | |
9 | #include <asm/uaccess.h> | |
10 | ||
11 | /* init to 2 - one for init_task, one to ensure it is never freed */ | |
12 | struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; | |
13 | ||
14 | struct group_info *groups_alloc(int gidsetsize) | |
15 | { | |
16 | struct group_info *group_info; | |
17 | int nblocks; | |
18 | int i; | |
19 | ||
20 | nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; | |
21 | /* Make sure we always allocate at least one indirect block pointer */ | |
22 | nblocks = nblocks ? : 1; | |
23 | group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); | |
24 | if (!group_info) | |
25 | return NULL; | |
26 | group_info->ngroups = gidsetsize; | |
27 | group_info->nblocks = nblocks; | |
28 | atomic_set(&group_info->usage, 1); | |
29 | ||
30 | if (gidsetsize <= NGROUPS_SMALL) | |
31 | group_info->blocks[0] = group_info->small_block; | |
32 | else { | |
33 | for (i = 0; i < nblocks; i++) { | |
ae2975bc | 34 | kgid_t *b; |
30639b6a AD |
35 | b = (void *)__get_free_page(GFP_USER); |
36 | if (!b) | |
37 | goto out_undo_partial_alloc; | |
38 | group_info->blocks[i] = b; | |
39 | } | |
40 | } | |
41 | return group_info; | |
42 | ||
43 | out_undo_partial_alloc: | |
44 | while (--i >= 0) { | |
45 | free_page((unsigned long)group_info->blocks[i]); | |
46 | } | |
47 | kfree(group_info); | |
48 | return NULL; | |
49 | } | |
50 | ||
51 | EXPORT_SYMBOL(groups_alloc); | |
52 | ||
53 | void groups_free(struct group_info *group_info) | |
54 | { | |
55 | if (group_info->blocks[0] != group_info->small_block) { | |
56 | int i; | |
57 | for (i = 0; i < group_info->nblocks; i++) | |
58 | free_page((unsigned long)group_info->blocks[i]); | |
59 | } | |
60 | kfree(group_info); | |
61 | } | |
62 | ||
63 | EXPORT_SYMBOL(groups_free); | |
64 | ||
65 | /* export the group_info to a user-space array */ | |
66 | static int groups_to_user(gid_t __user *grouplist, | |
67 | const struct group_info *group_info) | |
68 | { | |
ae2975bc | 69 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
70 | int i; |
71 | unsigned int count = group_info->ngroups; | |
72 | ||
ae2975bc EB |
73 | for (i = 0; i < count; i++) { |
74 | gid_t gid; | |
75 | gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i)); | |
76 | if (put_user(gid, grouplist+i)) | |
30639b6a | 77 | return -EFAULT; |
30639b6a AD |
78 | } |
79 | return 0; | |
80 | } | |
81 | ||
82 | /* fill a group_info from a user-space array - it must be allocated already */ | |
83 | static int groups_from_user(struct group_info *group_info, | |
84 | gid_t __user *grouplist) | |
85 | { | |
ae2975bc | 86 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
87 | int i; |
88 | unsigned int count = group_info->ngroups; | |
89 | ||
ae2975bc EB |
90 | for (i = 0; i < count; i++) { |
91 | gid_t gid; | |
92 | kgid_t kgid; | |
93 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
94 | return -EFAULT; |
95 | ||
ae2975bc EB |
96 | kgid = make_kgid(user_ns, gid); |
97 | if (!gid_valid(kgid)) | |
98 | return -EINVAL; | |
99 | ||
100 | GROUP_AT(group_info, i) = kgid; | |
30639b6a AD |
101 | } |
102 | return 0; | |
103 | } | |
104 | ||
105 | /* a simple Shell sort */ | |
106 | static void groups_sort(struct group_info *group_info) | |
107 | { | |
108 | int base, max, stride; | |
109 | int gidsetsize = group_info->ngroups; | |
110 | ||
111 | for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) | |
112 | ; /* nothing */ | |
113 | stride /= 3; | |
114 | ||
115 | while (stride) { | |
116 | max = gidsetsize - stride; | |
117 | for (base = 0; base < max; base++) { | |
118 | int left = base; | |
119 | int right = left + stride; | |
ae2975bc | 120 | kgid_t tmp = GROUP_AT(group_info, right); |
30639b6a | 121 | |
ae2975bc | 122 | while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) { |
30639b6a AD |
123 | GROUP_AT(group_info, right) = |
124 | GROUP_AT(group_info, left); | |
125 | right = left; | |
126 | left -= stride; | |
127 | } | |
128 | GROUP_AT(group_info, right) = tmp; | |
129 | } | |
130 | stride /= 3; | |
131 | } | |
132 | } | |
133 | ||
134 | /* a simple bsearch */ | |
ae2975bc | 135 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
136 | { |
137 | unsigned int left, right; | |
138 | ||
139 | if (!group_info) | |
140 | return 0; | |
141 | ||
142 | left = 0; | |
143 | right = group_info->ngroups; | |
144 | while (left < right) { | |
145 | unsigned int mid = (left+right)/2; | |
ae2975bc | 146 | if (gid_gt(grp, GROUP_AT(group_info, mid))) |
30639b6a | 147 | left = mid + 1; |
ae2975bc | 148 | else if (gid_lt(grp, GROUP_AT(group_info, mid))) |
30639b6a AD |
149 | right = mid; |
150 | else | |
151 | return 1; | |
152 | } | |
153 | return 0; | |
154 | } | |
155 | ||
156 | /** | |
157 | * set_groups - Change a group subscription in a set of credentials | |
158 | * @new: The newly prepared set of credentials to alter | |
159 | * @group_info: The group list to install | |
30639b6a | 160 | */ |
8f6c5ffc | 161 | void set_groups(struct cred *new, struct group_info *group_info) |
30639b6a | 162 | { |
30639b6a AD |
163 | put_group_info(new->group_info); |
164 | groups_sort(group_info); | |
165 | get_group_info(group_info); | |
166 | new->group_info = group_info; | |
30639b6a AD |
167 | } |
168 | ||
169 | EXPORT_SYMBOL(set_groups); | |
170 | ||
171 | /** | |
172 | * set_current_groups - Change current's group subscription | |
173 | * @group_info: The group list to impose | |
174 | * | |
175 | * Validate a group subscription and, if valid, impose it upon current's task | |
176 | * security record. | |
177 | */ | |
178 | int set_current_groups(struct group_info *group_info) | |
179 | { | |
180 | struct cred *new; | |
30639b6a AD |
181 | |
182 | new = prepare_creds(); | |
183 | if (!new) | |
184 | return -ENOMEM; | |
185 | ||
8f6c5ffc | 186 | set_groups(new, group_info); |
30639b6a AD |
187 | return commit_creds(new); |
188 | } | |
189 | ||
190 | EXPORT_SYMBOL(set_current_groups); | |
191 | ||
192 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
193 | { | |
194 | const struct cred *cred = current_cred(); | |
195 | int i; | |
196 | ||
197 | if (gidsetsize < 0) | |
198 | return -EINVAL; | |
199 | ||
200 | /* no need to grab task_lock here; it cannot change */ | |
201 | i = cred->group_info->ngroups; | |
202 | if (gidsetsize) { | |
203 | if (i > gidsetsize) { | |
204 | i = -EINVAL; | |
205 | goto out; | |
206 | } | |
207 | if (groups_to_user(grouplist, cred->group_info)) { | |
208 | i = -EFAULT; | |
209 | goto out; | |
210 | } | |
211 | } | |
212 | out: | |
213 | return i; | |
214 | } | |
215 | ||
216 | /* | |
217 | * SMP: Our groups are copy-on-write. We can set them safely | |
218 | * without another task interfering. | |
219 | */ | |
220 | ||
221 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
222 | { | |
223 | struct group_info *group_info; | |
224 | int retval; | |
225 | ||
c7b96acf | 226 | if (!ns_capable(current_user_ns(), CAP_SETGID)) |
30639b6a AD |
227 | return -EPERM; |
228 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
229 | return -EINVAL; | |
230 | ||
231 | group_info = groups_alloc(gidsetsize); | |
232 | if (!group_info) | |
233 | return -ENOMEM; | |
234 | retval = groups_from_user(group_info, grouplist); | |
235 | if (retval) { | |
236 | put_group_info(group_info); | |
237 | return retval; | |
238 | } | |
239 | ||
240 | retval = set_current_groups(group_info); | |
241 | put_group_info(group_info); | |
242 | ||
243 | return retval; | |
244 | } | |
245 | ||
246 | /* | |
247 | * Check whether we're fsgid/egid or in the supplemental group.. | |
248 | */ | |
72cda3d1 | 249 | int in_group_p(kgid_t grp) |
30639b6a AD |
250 | { |
251 | const struct cred *cred = current_cred(); | |
252 | int retval = 1; | |
253 | ||
72cda3d1 EB |
254 | if (!gid_eq(grp, cred->fsgid)) |
255 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
256 | return retval; |
257 | } | |
258 | ||
259 | EXPORT_SYMBOL(in_group_p); | |
260 | ||
72cda3d1 | 261 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
262 | { |
263 | const struct cred *cred = current_cred(); | |
264 | int retval = 1; | |
265 | ||
72cda3d1 EB |
266 | if (!gid_eq(grp, cred->egid)) |
267 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
268 | return retval; |
269 | } | |
270 | ||
271 | EXPORT_SYMBOL(in_egroup_p); |