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252 lines
5.2 KiB
252 lines
5.2 KiB
/* |
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* Supplementary group IDs |
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*/ |
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#include <linux/cred.h> |
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#include <linux/export.h> |
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#include <linux/slab.h> |
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#include <linux/security.h> |
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#include <linux/syscalls.h> |
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#include <linux/user_namespace.h> |
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#include <linux/vmalloc.h> |
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#include <asm/uaccess.h> |
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struct group_info *groups_alloc(int gidsetsize) |
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{ |
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struct group_info *gi; |
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unsigned int len; |
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len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize; |
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gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY); |
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if (!gi) |
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gi = __vmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_HIGHMEM, PAGE_KERNEL); |
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if (!gi) |
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return NULL; |
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atomic_set(&gi->usage, 1); |
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gi->ngroups = gidsetsize; |
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return gi; |
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} |
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EXPORT_SYMBOL(groups_alloc); |
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void groups_free(struct group_info *group_info) |
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{ |
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kvfree(group_info); |
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} |
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EXPORT_SYMBOL(groups_free); |
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/* export the group_info to a user-space array */ |
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static int groups_to_user(gid_t __user *grouplist, |
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const struct group_info *group_info) |
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{ |
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struct user_namespace *user_ns = current_user_ns(); |
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int i; |
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unsigned int count = group_info->ngroups; |
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for (i = 0; i < count; i++) { |
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gid_t gid; |
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gid = from_kgid_munged(user_ns, group_info->gid[i]); |
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if (put_user(gid, grouplist+i)) |
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return -EFAULT; |
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} |
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return 0; |
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} |
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/* fill a group_info from a user-space array - it must be allocated already */ |
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static int groups_from_user(struct group_info *group_info, |
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gid_t __user *grouplist) |
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{ |
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struct user_namespace *user_ns = current_user_ns(); |
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int i; |
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unsigned int count = group_info->ngroups; |
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for (i = 0; i < count; i++) { |
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gid_t gid; |
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kgid_t kgid; |
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if (get_user(gid, grouplist+i)) |
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return -EFAULT; |
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kgid = make_kgid(user_ns, gid); |
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if (!gid_valid(kgid)) |
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return -EINVAL; |
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group_info->gid[i] = kgid; |
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} |
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return 0; |
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} |
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/* a simple Shell sort */ |
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static void groups_sort(struct group_info *group_info) |
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{ |
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int base, max, stride; |
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int gidsetsize = group_info->ngroups; |
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for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) |
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; /* nothing */ |
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stride /= 3; |
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while (stride) { |
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max = gidsetsize - stride; |
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for (base = 0; base < max; base++) { |
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int left = base; |
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int right = left + stride; |
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kgid_t tmp = group_info->gid[right]; |
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while (left >= 0 && gid_gt(group_info->gid[left], tmp)) { |
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group_info->gid[right] = group_info->gid[left]; |
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right = left; |
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left -= stride; |
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} |
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group_info->gid[right] = tmp; |
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} |
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stride /= 3; |
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} |
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} |
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/* a simple bsearch */ |
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int groups_search(const struct group_info *group_info, kgid_t grp) |
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{ |
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unsigned int left, right; |
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if (!group_info) |
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return 0; |
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left = 0; |
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right = group_info->ngroups; |
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while (left < right) { |
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unsigned int mid = (left+right)/2; |
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if (gid_gt(grp, group_info->gid[mid])) |
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left = mid + 1; |
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else if (gid_lt(grp, group_info->gid[mid])) |
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right = mid; |
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else |
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return 1; |
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} |
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return 0; |
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} |
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/** |
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* set_groups - Change a group subscription in a set of credentials |
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* @new: The newly prepared set of credentials to alter |
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* @group_info: The group list to install |
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*/ |
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void set_groups(struct cred *new, struct group_info *group_info) |
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{ |
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put_group_info(new->group_info); |
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groups_sort(group_info); |
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get_group_info(group_info); |
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new->group_info = group_info; |
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} |
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EXPORT_SYMBOL(set_groups); |
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/** |
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* set_current_groups - Change current's group subscription |
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* @group_info: The group list to impose |
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* |
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* Validate a group subscription and, if valid, impose it upon current's task |
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* security record. |
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*/ |
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int set_current_groups(struct group_info *group_info) |
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{ |
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struct cred *new; |
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new = prepare_creds(); |
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if (!new) |
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return -ENOMEM; |
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set_groups(new, group_info); |
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return commit_creds(new); |
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} |
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EXPORT_SYMBOL(set_current_groups); |
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SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) |
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{ |
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const struct cred *cred = current_cred(); |
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int i; |
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if (gidsetsize < 0) |
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return -EINVAL; |
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/* no need to grab task_lock here; it cannot change */ |
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i = cred->group_info->ngroups; |
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if (gidsetsize) { |
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if (i > gidsetsize) { |
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i = -EINVAL; |
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goto out; |
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} |
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if (groups_to_user(grouplist, cred->group_info)) { |
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i = -EFAULT; |
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goto out; |
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} |
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} |
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out: |
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return i; |
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} |
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bool may_setgroups(void) |
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{ |
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struct user_namespace *user_ns = current_user_ns(); |
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return ns_capable(user_ns, CAP_SETGID) && |
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userns_may_setgroups(user_ns); |
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} |
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/* |
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* SMP: Our groups are copy-on-write. We can set them safely |
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* without another task interfering. |
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*/ |
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SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) |
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{ |
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struct group_info *group_info; |
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int retval; |
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if (!may_setgroups()) |
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return -EPERM; |
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if ((unsigned)gidsetsize > NGROUPS_MAX) |
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return -EINVAL; |
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group_info = groups_alloc(gidsetsize); |
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if (!group_info) |
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return -ENOMEM; |
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retval = groups_from_user(group_info, grouplist); |
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if (retval) { |
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put_group_info(group_info); |
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return retval; |
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} |
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retval = set_current_groups(group_info); |
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put_group_info(group_info); |
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return retval; |
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} |
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/* |
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* Check whether we're fsgid/egid or in the supplemental group.. |
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*/ |
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int in_group_p(kgid_t grp) |
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{ |
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const struct cred *cred = current_cred(); |
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int retval = 1; |
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if (!gid_eq(grp, cred->fsgid)) |
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retval = groups_search(cred->group_info, grp); |
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return retval; |
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} |
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EXPORT_SYMBOL(in_group_p); |
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int in_egroup_p(kgid_t grp) |
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{ |
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const struct cred *cred = current_cred(); |
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int retval = 1; |
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if (!gid_eq(grp, cred->egid)) |
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retval = groups_search(cred->group_info, grp); |
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return retval; |
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} |
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EXPORT_SYMBOL(in_egroup_p);
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