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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 AD |
17 | struct group_info *gi; |
18 | unsigned int len; | |
19 | ||
20 | len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize; | |
21 | gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY); | |
22 | if (!gi) | |
19809c2d | 23 | gi = __vmalloc(len, GFP_KERNEL_ACCOUNT, PAGE_KERNEL); |
81243eac | 24 | if (!gi) |
30639b6a | 25 | return NULL; |
30639b6a | 26 | |
81243eac AD |
27 | atomic_set(&gi->usage, 1); |
28 | gi->ngroups = gidsetsize; | |
29 | return gi; | |
30639b6a AD |
30 | } |
31 | ||
32 | EXPORT_SYMBOL(groups_alloc); | |
33 | ||
34 | void groups_free(struct group_info *group_info) | |
35 | { | |
81243eac | 36 | kvfree(group_info); |
30639b6a AD |
37 | } |
38 | ||
39 | EXPORT_SYMBOL(groups_free); | |
40 | ||
41 | /* export the group_info to a user-space array */ | |
42 | static int groups_to_user(gid_t __user *grouplist, | |
43 | const struct group_info *group_info) | |
44 | { | |
ae2975bc | 45 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
46 | int i; |
47 | unsigned int count = group_info->ngroups; | |
48 | ||
ae2975bc EB |
49 | for (i = 0; i < count; i++) { |
50 | gid_t gid; | |
81243eac | 51 | gid = from_kgid_munged(user_ns, group_info->gid[i]); |
ae2975bc | 52 | if (put_user(gid, grouplist+i)) |
30639b6a | 53 | return -EFAULT; |
30639b6a AD |
54 | } |
55 | return 0; | |
56 | } | |
57 | ||
58 | /* fill a group_info from a user-space array - it must be allocated already */ | |
59 | static int groups_from_user(struct group_info *group_info, | |
60 | gid_t __user *grouplist) | |
61 | { | |
ae2975bc | 62 | struct user_namespace *user_ns = current_user_ns(); |
30639b6a AD |
63 | int i; |
64 | unsigned int count = group_info->ngroups; | |
65 | ||
ae2975bc EB |
66 | for (i = 0; i < count; i++) { |
67 | gid_t gid; | |
68 | kgid_t kgid; | |
69 | if (get_user(gid, grouplist+i)) | |
30639b6a AD |
70 | return -EFAULT; |
71 | ||
ae2975bc EB |
72 | kgid = make_kgid(user_ns, gid); |
73 | if (!gid_valid(kgid)) | |
74 | return -EINVAL; | |
75 | ||
81243eac | 76 | group_info->gid[i] = kgid; |
30639b6a AD |
77 | } |
78 | return 0; | |
79 | } | |
80 | ||
b7b2562f RV |
81 | static int gid_cmp(const void *_a, const void *_b) |
82 | { | |
83 | kgid_t a = *(kgid_t *)_a; | |
84 | kgid_t b = *(kgid_t *)_b; | |
85 | ||
86 | return gid_gt(a, b) - gid_lt(a, b); | |
87 | } | |
88 | ||
30639b6a AD |
89 | static void groups_sort(struct group_info *group_info) |
90 | { | |
b7b2562f RV |
91 | sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid), |
92 | gid_cmp, NULL); | |
30639b6a AD |
93 | } |
94 | ||
95 | /* a simple bsearch */ | |
ae2975bc | 96 | int groups_search(const struct group_info *group_info, kgid_t grp) |
30639b6a AD |
97 | { |
98 | unsigned int left, right; | |
99 | ||
100 | if (!group_info) | |
101 | return 0; | |
102 | ||
103 | left = 0; | |
104 | right = group_info->ngroups; | |
105 | while (left < right) { | |
106 | unsigned int mid = (left+right)/2; | |
81243eac | 107 | if (gid_gt(grp, group_info->gid[mid])) |
30639b6a | 108 | left = mid + 1; |
81243eac | 109 | else if (gid_lt(grp, group_info->gid[mid])) |
30639b6a AD |
110 | right = mid; |
111 | else | |
112 | return 1; | |
113 | } | |
114 | return 0; | |
115 | } | |
116 | ||
117 | /** | |
118 | * set_groups - Change a group subscription in a set of credentials | |
119 | * @new: The newly prepared set of credentials to alter | |
120 | * @group_info: The group list to install | |
30639b6a | 121 | */ |
8f6c5ffc | 122 | void set_groups(struct cred *new, struct group_info *group_info) |
30639b6a | 123 | { |
30639b6a AD |
124 | put_group_info(new->group_info); |
125 | groups_sort(group_info); | |
126 | get_group_info(group_info); | |
127 | new->group_info = group_info; | |
30639b6a AD |
128 | } |
129 | ||
130 | EXPORT_SYMBOL(set_groups); | |
131 | ||
132 | /** | |
133 | * set_current_groups - Change current's group subscription | |
134 | * @group_info: The group list to impose | |
135 | * | |
136 | * Validate a group subscription and, if valid, impose it upon current's task | |
137 | * security record. | |
138 | */ | |
139 | int set_current_groups(struct group_info *group_info) | |
140 | { | |
141 | struct cred *new; | |
30639b6a AD |
142 | |
143 | new = prepare_creds(); | |
144 | if (!new) | |
145 | return -ENOMEM; | |
146 | ||
8f6c5ffc | 147 | set_groups(new, group_info); |
30639b6a AD |
148 | return commit_creds(new); |
149 | } | |
150 | ||
151 | EXPORT_SYMBOL(set_current_groups); | |
152 | ||
153 | SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) | |
154 | { | |
155 | const struct cred *cred = current_cred(); | |
156 | int i; | |
157 | ||
158 | if (gidsetsize < 0) | |
159 | return -EINVAL; | |
160 | ||
161 | /* no need to grab task_lock here; it cannot change */ | |
162 | i = cred->group_info->ngroups; | |
163 | if (gidsetsize) { | |
164 | if (i > gidsetsize) { | |
165 | i = -EINVAL; | |
166 | goto out; | |
167 | } | |
168 | if (groups_to_user(grouplist, cred->group_info)) { | |
169 | i = -EFAULT; | |
170 | goto out; | |
171 | } | |
172 | } | |
173 | out: | |
174 | return i; | |
175 | } | |
176 | ||
7ff4d90b EB |
177 | bool may_setgroups(void) |
178 | { | |
179 | struct user_namespace *user_ns = current_user_ns(); | |
180 | ||
273d2c67 EB |
181 | return ns_capable(user_ns, CAP_SETGID) && |
182 | userns_may_setgroups(user_ns); | |
7ff4d90b EB |
183 | } |
184 | ||
30639b6a AD |
185 | /* |
186 | * SMP: Our groups are copy-on-write. We can set them safely | |
187 | * without another task interfering. | |
188 | */ | |
189 | ||
190 | SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) | |
191 | { | |
192 | struct group_info *group_info; | |
193 | int retval; | |
194 | ||
7ff4d90b | 195 | if (!may_setgroups()) |
30639b6a AD |
196 | return -EPERM; |
197 | if ((unsigned)gidsetsize > NGROUPS_MAX) | |
198 | return -EINVAL; | |
199 | ||
200 | group_info = groups_alloc(gidsetsize); | |
201 | if (!group_info) | |
202 | return -ENOMEM; | |
203 | retval = groups_from_user(group_info, grouplist); | |
204 | if (retval) { | |
205 | put_group_info(group_info); | |
206 | return retval; | |
207 | } | |
208 | ||
209 | retval = set_current_groups(group_info); | |
210 | put_group_info(group_info); | |
211 | ||
212 | return retval; | |
213 | } | |
214 | ||
215 | /* | |
216 | * Check whether we're fsgid/egid or in the supplemental group.. | |
217 | */ | |
72cda3d1 | 218 | int in_group_p(kgid_t grp) |
30639b6a AD |
219 | { |
220 | const struct cred *cred = current_cred(); | |
221 | int retval = 1; | |
222 | ||
72cda3d1 EB |
223 | if (!gid_eq(grp, cred->fsgid)) |
224 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
225 | return retval; |
226 | } | |
227 | ||
228 | EXPORT_SYMBOL(in_group_p); | |
229 | ||
72cda3d1 | 230 | int in_egroup_p(kgid_t grp) |
30639b6a AD |
231 | { |
232 | const struct cred *cred = current_cred(); | |
233 | int retval = 1; | |
234 | ||
72cda3d1 EB |
235 | if (!gid_eq(grp, cred->egid)) |
236 | retval = groups_search(cred->group_info, grp); | |
30639b6a AD |
237 | return retval; |
238 | } | |
239 | ||
240 | EXPORT_SYMBOL(in_egroup_p); |