Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 241 insertions, 0 deletions

diff --git a/kernel/groups.c b/kernel/groups.c
new file mode 100644
index 000000000..daae2f2dc
--- /dev/null
+++ b/kernel/groups.c
@@ -0,0 +1,241 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Supplementary group IDs
+ */
+#include <linux/cred.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/sort.h>
+#include <linux/syscalls.h>
+#include <linux/user_namespace.h>
+#include <linux/vmalloc.h>
+#include <linux/uaccess.h>
+
+struct group_info *groups_alloc(int gidsetsize)
+{
+	struct group_info *gi;
+	unsigned int len;
+
+	len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize;
+	gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY);
+	if (!gi)
+		gi = __vmalloc(len, GFP_KERNEL_ACCOUNT, PAGE_KERNEL);
+	if (!gi)
+		return NULL;
+
+	atomic_set(&gi->usage, 1);
+	gi->ngroups = gidsetsize;
+	return gi;
+}
+
+EXPORT_SYMBOL(groups_alloc);
+
+void groups_free(struct group_info *group_info)
+{
+	kvfree(group_info);
+}
+
+EXPORT_SYMBOL(groups_free);
+
+/* export the group_info to a user-space array */
+static int groups_to_user(gid_t __user *grouplist,
+			  const struct group_info *group_info)
+{
+	struct user_namespace *user_ns = current_user_ns();
+	int i;
+	unsigned int count = group_info->ngroups;
+
+	for (i = 0; i < count; i++) {
+		gid_t gid;
+		gid = from_kgid_munged(user_ns, group_info->gid[i]);
+		if (put_user(gid, grouplist+i))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+/* fill a group_info from a user-space array - it must be allocated already */
+static int groups_from_user(struct group_info *group_info,
+    gid_t __user *grouplist)
+{
+	struct user_namespace *user_ns = current_user_ns();
+	int i;
+	unsigned int count = group_info->ngroups;
+
+	for (i = 0; i < count; i++) {
+		gid_t gid;
+		kgid_t kgid;
+		if (get_user(gid, grouplist+i))
+			return -EFAULT;
+
+		kgid = make_kgid(user_ns, gid);
+		if (!gid_valid(kgid))
+			return -EINVAL;
+
+		group_info->gid[i] = kgid;
+	}
+	return 0;
+}
+
+static int gid_cmp(const void *_a, const void *_b)
+{
+	kgid_t a = *(kgid_t *)_a;
+	kgid_t b = *(kgid_t *)_b;
+
+	return gid_gt(a, b) - gid_lt(a, b);
+}
+
+void groups_sort(struct group_info *group_info)
+{
+	sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),
+	     gid_cmp, NULL);
+}
+EXPORT_SYMBOL(groups_sort);
+
+/* a simple bsearch */
+int groups_search(const struct group_info *group_info, kgid_t grp)
+{
+	unsigned int left, right;
+
+	if (!group_info)
+		return 0;
+
+	left = 0;
+	right = group_info->ngroups;
+	while (left < right) {
+		unsigned int mid = (left+right)/2;
+		if (gid_gt(grp, group_info->gid[mid]))
+			left = mid + 1;
+		else if (gid_lt(grp, group_info->gid[mid]))
+			right = mid;
+		else
+			return 1;
+	}
+	return 0;
+}
+
+/**
+ * set_groups - Change a group subscription in a set of credentials
+ * @new: The newly prepared set of credentials to alter
+ * @group_info: The group list to install
+ */
+void set_groups(struct cred *new, struct group_info *group_info)
+{
+	put_group_info(new->group_info);
+	get_group_info(group_info);
+	new->group_info = group_info;
+}
+
+EXPORT_SYMBOL(set_groups);
+
+/**
+ * set_current_groups - Change current's group subscription
+ * @group_info: The group list to impose
+ *
+ * Validate a group subscription and, if valid, impose it upon current's task
+ * security record.
+ */
+int set_current_groups(struct group_info *group_info)
+{
+	struct cred *new;
+
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+
+	set_groups(new, group_info);
+	return commit_creds(new);
+}
+
+EXPORT_SYMBOL(set_current_groups);
+
+SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
+{
+	const struct cred *cred = current_cred();
+	int i;
+
+	if (gidsetsize < 0)
+		return -EINVAL;
+
+	/* no need to grab task_lock here; it cannot change */
+	i = cred->group_info->ngroups;
+	if (gidsetsize) {
+		if (i > gidsetsize) {
+			i = -EINVAL;
+			goto out;
+		}
+		if (groups_to_user(grouplist, cred->group_info)) {
+			i = -EFAULT;
+			goto out;
+		}
+	}
+out:
+	return i;
+}
+
+bool may_setgroups(void)
+{
+	struct user_namespace *user_ns = current_user_ns();
+
+	return ns_capable(user_ns, CAP_SETGID) &&
+		userns_may_setgroups(user_ns);
+}
+
+/*
+ *	SMP: Our groups are copy-on-write. We can set them safely
+ *	without another task interfering.
+ */
+
+SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
+{
+	struct group_info *group_info;
+	int retval;
+
+	if (!may_setgroups())
+		return -EPERM;
+	if ((unsigned)gidsetsize > NGROUPS_MAX)
+		return -EINVAL;
+
+	group_info = groups_alloc(gidsetsize);
+	if (!group_info)
+		return -ENOMEM;
+	retval = groups_from_user(group_info, grouplist);
+	if (retval) {
+		put_group_info(group_info);
+		return retval;
+	}
+
+	groups_sort(group_info);
+	retval = set_current_groups(group_info);
+	put_group_info(group_info);
+
+	return retval;
+}
+
+/*
+ * Check whether we're fsgid/egid or in the supplemental group..
+ */
+int in_group_p(kgid_t grp)
+{
+	const struct cred *cred = current_cred();
+	int retval = 1;
+
+	if (!gid_eq(grp, cred->fsgid))
+		retval = groups_search(cred->group_info, grp);
+	return retval;
+}
+
+EXPORT_SYMBOL(in_group_p);
+
+int in_egroup_p(kgid_t grp)
+{
+	const struct cred *cred = current_cred();
+	int retval = 1;
+
+	if (!gid_eq(grp, cred->egid))
+		retval = groups_search(cred->group_info, grp);
+	return retval;
+}
+
+EXPORT_SYMBOL(in_egroup_p);