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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> |
81243eac | 10 | #include <linux/vmalloc.h> |
30639b6a AD |
11 | #include <asm/uaccess.h> |
12 | ||
30639b6a AD |
13 | struct group_info *groups_alloc(int gidsetsize) |
14 | { | |
81243eac AD |
15 | struct group_info *gi; |
16 | unsigned int len; | |
17 | ||
18 | len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize; | |
19 | gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY); | |
20 | if (!gi) | |
21 | gi = __vmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_HIGHMEM, PAGE_KERNEL); | |
22 | if (!gi) | |
30639b6a | 23 | return NULL; |
30639b6a | 24 | |
81243eac AD |
25 | atomic_set(&gi->usage, 1); |
26 | gi->ngroups = gidsetsize; | |
27 | return gi; | |
30639b6a AD |
28 | } |
29 | ||
30 | EXPORT_SYMBOL(groups_alloc); | |
31 | ||
32 | void groups_free(struct group_info *group_info) | |
33 | { | |
81243eac | 34 | kvfree(group_info); |
30639b6a AD |
35 | } |
36 | ||
37 | EXPORT_SYMBOL(groups_free); | |
38 | ||
39 | /* export the group_info to a user-space array */ | |
40 | static int groups_to_user(gid_t __user *grouplist, | |
41 | const struct group_info *group_info) | |
42 | { | |
ae2975bc | 43 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
44 | int i; |
45 | unsigned int count = group_info->ngroups; | |
46 | ||
ae2975bc EB |
47 | for (i = 0; i < count; i++) { |
48 | gid_t gid; | |
81243eac | 49 | gid = from_kgid_munged(user_ns, group_info->gid[i]); |
ae2975bc | 50 | if (put_user(gid, grouplist+i)) |
30639b6a | 51 | return -EFAULT; |
30639b6a AD |
52 | } |
53 | return 0; | |
54 | } | |
55 | ||
56 | /* fill a group_info from a user-space array - it must be allocated already */ | |
57 | static int groups_from_user(struct group_info *group_info, | |
58 | gid_t __user *grouplist) | |
59 | { | |
ae2975bc | 60 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
61 | int i; |
62 | unsigned int count = group_info->ngroups; | |
63 | ||
ae2975bc EB |
64 | for (i = 0; i < count; i++) { |
65 | gid_t gid; | |
66 | kgid_t kgid; | |
67 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
68 | return -EFAULT; |
69 | ||
ae2975bc EB |
70 | kgid = make_kgid(user_ns, gid); |
71 | if (!gid_valid(kgid)) | |
72 | return -EINVAL; | |
73 | ||
81243eac | 74 | group_info->gid[i] = kgid; |
30639b6a AD |
75 | } |
76 | return 0; | |
77 | } | |
78 | ||
79 | /* a simple Shell sort */ | |
79258d98 | 80 | void groups_sort(struct group_info *group_info) |
30639b6a AD |
81 | { |
82 | int base, max, stride; | |
83 | int gidsetsize = group_info->ngroups; | |
84 | ||
85 | for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) | |
86 | ; /* nothing */ | |
87 | stride /= 3; | |
88 | ||
89 | while (stride) { | |
90 | max = gidsetsize - stride; | |
91 | for (base = 0; base < max; base++) { | |
92 | int left = base; | |
93 | int right = left + stride; | |
81243eac | 94 | kgid_t tmp = group_info->gid[right]; |
30639b6a | 95 | |
81243eac AD |
96 | while (left >= 0 && gid_gt(group_info->gid[left], tmp)) { |
97 | group_info->gid[right] = group_info->gid[left]; | |
30639b6a AD |
98 | right = left; |
99 | left -= stride; | |
100 | } | |
81243eac | 101 | group_info->gid[right] = tmp; |
30639b6a AD |
102 | } |
103 | stride /= 3; | |
104 | } | |
105 | } | |
79258d98 | 106 | EXPORT_SYMBOL(groups_sort); |
30639b6a AD |
107 | |
108 | /* a simple bsearch */ | |
ae2975bc | 109 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
110 | { |
111 | unsigned int left, right; | |
112 | ||
113 | if (!group_info) | |
114 | return 0; | |
115 | ||
116 | left = 0; | |
117 | right = group_info->ngroups; | |
118 | while (left < right) { | |
119 | unsigned int mid = (left+right)/2; | |
81243eac | 120 | if (gid_gt(grp, group_info->gid[mid])) |
30639b6a | 121 | left = mid + 1; |
81243eac | 122 | else if (gid_lt(grp, group_info->gid[mid])) |
30639b6a AD |
123 | right = mid; |
124 | else | |
125 | return 1; | |
126 | } | |
127 | return 0; | |
128 | } | |
129 | ||
130 | /** | |
131 | * set_groups - Change a group subscription in a set of credentials | |
132 | * @new: The newly prepared set of credentials to alter | |
133 | * @group_info: The group list to install | |
30639b6a | 134 | */ |
8f6c5ffc | 135 | void set_groups(struct cred *new, struct group_info *group_info) |
30639b6a | 136 | { |
30639b6a | 137 | put_group_info(new->group_info); |
30639b6a AD |
138 | get_group_info(group_info); |
139 | new->group_info = group_info; | |
30639b6a AD |
140 | } |
141 | ||
142 | EXPORT_SYMBOL(set_groups); | |
143 | ||
144 | /** | |
145 | * set_current_groups - Change current's group subscription | |
146 | * @group_info: The group list to impose | |
147 | * | |
148 | * Validate a group subscription and, if valid, impose it upon current's task | |
149 | * security record. | |
150 | */ | |
151 | int set_current_groups(struct group_info *group_info) | |
152 | { | |
153 | struct cred *new; | |
30639b6a AD |
154 | |
155 | new = prepare_creds(); | |
156 | if (!new) | |
157 | return -ENOMEM; | |
158 | ||
8f6c5ffc | 159 | set_groups(new, group_info); |
30639b6a AD |
160 | return commit_creds(new); |
161 | } | |
162 | ||
163 | EXPORT_SYMBOL(set_current_groups); | |
164 | ||
165 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
166 | { | |
167 | const struct cred *cred = current_cred(); | |
168 | int i; | |
169 | ||
170 | if (gidsetsize < 0) | |
171 | return -EINVAL; | |
172 | ||
173 | /* no need to grab task_lock here; it cannot change */ | |
174 | i = cred->group_info->ngroups; | |
175 | if (gidsetsize) { | |
176 | if (i > gidsetsize) { | |
177 | i = -EINVAL; | |
178 | goto out; | |
179 | } | |
180 | if (groups_to_user(grouplist, cred->group_info)) { | |
181 | i = -EFAULT; | |
182 | goto out; | |
183 | } | |
184 | } | |
185 | out: | |
186 | return i; | |
187 | } | |
188 | ||
7ff4d90b EB |
189 | bool may_setgroups(void) |
190 | { | |
191 | struct user_namespace *user_ns = current_user_ns(); | |
192 | ||
273d2c67 EB |
193 | return ns_capable(user_ns, CAP_SETGID) && |
194 | userns_may_setgroups(user_ns); | |
7ff4d90b EB |
195 | } |
196 | ||
30639b6a AD |
197 | /* |
198 | * SMP: Our groups are copy-on-write. We can set them safely | |
199 | * without another task interfering. | |
200 | */ | |
201 | ||
202 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
203 | { | |
204 | struct group_info *group_info; | |
205 | int retval; | |
206 | ||
7ff4d90b | 207 | if (!may_setgroups()) |
30639b6a AD |
208 | return -EPERM; |
209 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
210 | return -EINVAL; | |
211 | ||
212 | group_info = groups_alloc(gidsetsize); | |
213 | if (!group_info) | |
214 | return -ENOMEM; | |
215 | retval = groups_from_user(group_info, grouplist); | |
216 | if (retval) { | |
217 | put_group_info(group_info); | |
218 | return retval; | |
219 | } | |
220 | ||
79258d98 | 221 | groups_sort(group_info); |
30639b6a AD |
222 | retval = set_current_groups(group_info); |
223 | put_group_info(group_info); | |
224 | ||
225 | return retval; | |
226 | } | |
227 | ||
228 | /* | |
229 | * Check whether we're fsgid/egid or in the supplemental group.. | |
230 | */ | |
72cda3d1 | 231 | int in_group_p(kgid_t grp) |
30639b6a AD |
232 | { |
233 | const struct cred *cred = current_cred(); | |
234 | int retval = 1; | |
235 | ||
72cda3d1 EB |
236 | if (!gid_eq(grp, cred->fsgid)) |
237 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
238 | return retval; |
239 | } | |
240 | ||
241 | EXPORT_SYMBOL(in_group_p); | |
242 | ||
72cda3d1 | 243 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
244 | { |
245 | const struct cred *cred = current_cred(); | |
246 | int retval = 1; | |
247 | ||
72cda3d1 EB |
248 | if (!gid_eq(grp, cred->egid)) |
249 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
250 | return retval; |
251 | } | |
252 | ||
253 | EXPORT_SYMBOL(in_egroup_p); |