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> | |
273d2c67 | 9 | #include <linux/user_namespace.h> |
30639b6a AD |
10 | #include <asm/uaccess.h> |
11 | ||
30639b6a AD |
12 | struct group_info *groups_alloc(int gidsetsize) |
13 | { | |
14 | struct group_info *group_info; | |
15 | int nblocks; | |
16 | int i; | |
17 | ||
18 | nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; | |
19 | /* Make sure we always allocate at least one indirect block pointer */ | |
20 | nblocks = nblocks ? : 1; | |
21 | group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); | |
22 | if (!group_info) | |
23 | return NULL; | |
24 | group_info->ngroups = gidsetsize; | |
25 | group_info->nblocks = nblocks; | |
26 | atomic_set(&group_info->usage, 1); | |
27 | ||
28 | if (gidsetsize <= NGROUPS_SMALL) | |
29 | group_info->blocks[0] = group_info->small_block; | |
30 | else { | |
31 | for (i = 0; i < nblocks; i++) { | |
ae2975bc | 32 | kgid_t *b; |
30639b6a AD |
33 | b = (void *)__get_free_page(GFP_USER); |
34 | if (!b) | |
35 | goto out_undo_partial_alloc; | |
36 | group_info->blocks[i] = b; | |
37 | } | |
38 | } | |
39 | return group_info; | |
40 | ||
41 | out_undo_partial_alloc: | |
42 | while (--i >= 0) { | |
43 | free_page((unsigned long)group_info->blocks[i]); | |
44 | } | |
45 | kfree(group_info); | |
46 | return NULL; | |
47 | } | |
48 | ||
49 | EXPORT_SYMBOL(groups_alloc); | |
50 | ||
51 | void groups_free(struct group_info *group_info) | |
52 | { | |
53 | if (group_info->blocks[0] != group_info->small_block) { | |
54 | int i; | |
55 | for (i = 0; i < group_info->nblocks; i++) | |
56 | free_page((unsigned long)group_info->blocks[i]); | |
57 | } | |
58 | kfree(group_info); | |
59 | } | |
60 | ||
61 | EXPORT_SYMBOL(groups_free); | |
62 | ||
63 | /* export the group_info to a user-space array */ | |
64 | static int groups_to_user(gid_t __user *grouplist, | |
65 | const struct group_info *group_info) | |
66 | { | |
ae2975bc | 67 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
68 | int i; |
69 | unsigned int count = group_info->ngroups; | |
70 | ||
ae2975bc EB |
71 | for (i = 0; i < count; i++) { |
72 | gid_t gid; | |
73 | gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i)); | |
74 | if (put_user(gid, grouplist+i)) | |
30639b6a | 75 | return -EFAULT; |
30639b6a AD |
76 | } |
77 | return 0; | |
78 | } | |
79 | ||
80 | /* fill a group_info from a user-space array - it must be allocated already */ | |
81 | static int groups_from_user(struct group_info *group_info, | |
82 | gid_t __user *grouplist) | |
83 | { | |
ae2975bc | 84 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
85 | int i; |
86 | unsigned int count = group_info->ngroups; | |
87 | ||
ae2975bc EB |
88 | for (i = 0; i < count; i++) { |
89 | gid_t gid; | |
90 | kgid_t kgid; | |
91 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
92 | return -EFAULT; |
93 | ||
ae2975bc EB |
94 | kgid = make_kgid(user_ns, gid); |
95 | if (!gid_valid(kgid)) | |
96 | return -EINVAL; | |
97 | ||
98 | GROUP_AT(group_info, i) = kgid; | |
30639b6a AD |
99 | } |
100 | return 0; | |
101 | } | |
102 | ||
103 | /* a simple Shell sort */ | |
104 | static void groups_sort(struct group_info *group_info) | |
105 | { | |
106 | int base, max, stride; | |
107 | int gidsetsize = group_info->ngroups; | |
108 | ||
109 | for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) | |
110 | ; /* nothing */ | |
111 | stride /= 3; | |
112 | ||
113 | while (stride) { | |
114 | max = gidsetsize - stride; | |
115 | for (base = 0; base < max; base++) { | |
116 | int left = base; | |
117 | int right = left + stride; | |
ae2975bc | 118 | kgid_t tmp = GROUP_AT(group_info, right); |
30639b6a | 119 | |
ae2975bc | 120 | while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) { |
30639b6a AD |
121 | GROUP_AT(group_info, right) = |
122 | GROUP_AT(group_info, left); | |
123 | right = left; | |
124 | left -= stride; | |
125 | } | |
126 | GROUP_AT(group_info, right) = tmp; | |
127 | } | |
128 | stride /= 3; | |
129 | } | |
130 | } | |
131 | ||
132 | /* a simple bsearch */ | |
ae2975bc | 133 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
134 | { |
135 | unsigned int left, right; | |
136 | ||
137 | if (!group_info) | |
138 | return 0; | |
139 | ||
140 | left = 0; | |
141 | right = group_info->ngroups; | |
142 | while (left < right) { | |
143 | unsigned int mid = (left+right)/2; | |
ae2975bc | 144 | if (gid_gt(grp, GROUP_AT(group_info, mid))) |
30639b6a | 145 | left = mid + 1; |
ae2975bc | 146 | else if (gid_lt(grp, GROUP_AT(group_info, mid))) |
30639b6a AD |
147 | right = mid; |
148 | else | |
149 | return 1; | |
150 | } | |
151 | return 0; | |
152 | } | |
153 | ||
154 | /** | |
155 | * set_groups - Change a group subscription in a set of credentials | |
156 | * @new: The newly prepared set of credentials to alter | |
157 | * @group_info: The group list to install | |
30639b6a | 158 | */ |
8f6c5ffc | 159 | void set_groups(struct cred *new, struct group_info *group_info) |
30639b6a | 160 | { |
30639b6a AD |
161 | put_group_info(new->group_info); |
162 | groups_sort(group_info); | |
163 | get_group_info(group_info); | |
164 | new->group_info = group_info; | |
30639b6a AD |
165 | } |
166 | ||
167 | EXPORT_SYMBOL(set_groups); | |
168 | ||
169 | /** | |
170 | * set_current_groups - Change current's group subscription | |
171 | * @group_info: The group list to impose | |
172 | * | |
173 | * Validate a group subscription and, if valid, impose it upon current's task | |
174 | * security record. | |
175 | */ | |
176 | int set_current_groups(struct group_info *group_info) | |
177 | { | |
178 | struct cred *new; | |
30639b6a AD |
179 | |
180 | new = prepare_creds(); | |
181 | if (!new) | |
182 | return -ENOMEM; | |
183 | ||
8f6c5ffc | 184 | set_groups(new, group_info); |
30639b6a AD |
185 | return commit_creds(new); |
186 | } | |
187 | ||
188 | EXPORT_SYMBOL(set_current_groups); | |
189 | ||
190 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
191 | { | |
192 | const struct cred *cred = current_cred(); | |
193 | int i; | |
194 | ||
195 | if (gidsetsize < 0) | |
196 | return -EINVAL; | |
197 | ||
198 | /* no need to grab task_lock here; it cannot change */ | |
199 | i = cred->group_info->ngroups; | |
200 | if (gidsetsize) { | |
201 | if (i > gidsetsize) { | |
202 | i = -EINVAL; | |
203 | goto out; | |
204 | } | |
205 | if (groups_to_user(grouplist, cred->group_info)) { | |
206 | i = -EFAULT; | |
207 | goto out; | |
208 | } | |
209 | } | |
210 | out: | |
211 | return i; | |
212 | } | |
213 | ||
7ff4d90b EB |
214 | bool may_setgroups(void) |
215 | { | |
216 | struct user_namespace *user_ns = current_user_ns(); | |
217 | ||
273d2c67 EB |
218 | return ns_capable(user_ns, CAP_SETGID) && |
219 | userns_may_setgroups(user_ns); | |
7ff4d90b EB |
220 | } |
221 | ||
30639b6a AD |
222 | /* |
223 | * SMP: Our groups are copy-on-write. We can set them safely | |
224 | * without another task interfering. | |
225 | */ | |
226 | ||
227 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
228 | { | |
229 | struct group_info *group_info; | |
230 | int retval; | |
231 | ||
7ff4d90b | 232 | if (!may_setgroups()) |
30639b6a AD |
233 | return -EPERM; |
234 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
235 | return -EINVAL; | |
236 | ||
237 | group_info = groups_alloc(gidsetsize); | |
238 | if (!group_info) | |
239 | return -ENOMEM; | |
240 | retval = groups_from_user(group_info, grouplist); | |
241 | if (retval) { | |
242 | put_group_info(group_info); | |
243 | return retval; | |
244 | } | |
245 | ||
246 | retval = set_current_groups(group_info); | |
247 | put_group_info(group_info); | |
248 | ||
249 | return retval; | |
250 | } | |
251 | ||
252 | /* | |
253 | * Check whether we're fsgid/egid or in the supplemental group.. | |
254 | */ | |
72cda3d1 | 255 | int in_group_p(kgid_t grp) |
30639b6a AD |
256 | { |
257 | const struct cred *cred = current_cred(); | |
258 | int retval = 1; | |
259 | ||
72cda3d1 EB |
260 | if (!gid_eq(grp, cred->fsgid)) |
261 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
262 | return retval; |
263 | } | |
264 | ||
265 | EXPORT_SYMBOL(in_group_p); | |
266 | ||
72cda3d1 | 267 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
268 | { |
269 | const struct cred *cred = current_cred(); | |
270 | int retval = 1; | |
271 | ||
72cda3d1 EB |
272 | if (!gid_eq(grp, cred->egid)) |
273 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
274 | return retval; |
275 | } | |
276 | ||
277 | EXPORT_SYMBOL(in_egroup_p); |