userns: Convert group_info values from gid_t to kgid_t.

As a first step to converting struct cred to be all kuid_t and kgid_t
values convert the group values stored in group_info to always be
kgid_t values.   Unless user namespaces are used this change should
have no effect.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 37 insertions, 25 deletions

diff --git a/kernel/groups.c b/kernel/groups.c
index 99b53d1..84156f2 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -31,7 +31,7 @@ struct group_info *groups_alloc(int gidsetsize)
 		group_info->blocks[0] = group_info->small_block;
 	else {
 		for (i = 0; i < nblocks; i++) {
-			gid_t *b;
+			kgid_t *b;
 			b = (void *)__get_free_page(GFP_USER);
 			if (!b)
 				goto out_undo_partial_alloc;
@@ -66,18 +66,15 @@ EXPORT_SYMBOL(groups_free);
 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 < group_info->nblocks; i++) {
-		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
-		unsigned int len = cp_count * sizeof(*grouplist);
-
-		if (copy_to_user(grouplist, group_info->blocks[i], len))
+	for (i = 0; i < count; i++) {
+		gid_t gid;
+		gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i));
+		if (put_user(gid, grouplist+i))
 			return -EFAULT;
-
-		grouplist += NGROUPS_PER_BLOCK;
-		count -= cp_count;
 	}
 	return 0;
 }
@@ -86,18 +83,21 @@ static int groups_to_user(gid_t __user *grouplist,
 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 < group_info->nblocks; i++) {
-		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
-		unsigned int len = cp_count * sizeof(*grouplist);
-
-		if (copy_from_user(group_info->blocks[i], grouplist, len))
+	for (i = 0; i < count; i++) {
+		gid_t gid;
+		kgid_t kgid;
+		if (get_user(gid, grouplist+i))
 			return -EFAULT;
 
-		grouplist += NGROUPS_PER_BLOCK;
-		count -= cp_count;
+		kgid = make_kgid(user_ns, gid);
+		if (!gid_valid(kgid))
+			return -EINVAL;
+
+		GROUP_AT(group_info, i) = kgid;
 	}
 	return 0;
 }
@@ -117,9 +117,9 @@ static void groups_sort(struct group_info *group_info)
 		for (base = 0; base < max; base++) {
 			int left = base;
 			int right = left + stride;
-			gid_t tmp = GROUP_AT(group_info, right);
+			kgid_t tmp = GROUP_AT(group_info, right);
 
-			while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
+			while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) {
 				GROUP_AT(group_info, right) =
 				    GROUP_AT(group_info, left);
 				right = left;
@@ -132,7 +132,7 @@ static void groups_sort(struct group_info *group_info)
 }
 
 /* a simple bsearch */
-int groups_search(const struct group_info *group_info, gid_t grp)
+int groups_search(const struct group_info *group_info, kgid_t grp)
 {
 	unsigned int left, right;
 
@@ -143,9 +143,9 @@ int groups_search(const struct group_info *group_info, gid_t grp)
 	right = group_info->ngroups;
 	while (left < right) {
 		unsigned int mid = (left+right)/2;
-		if (grp > GROUP_AT(group_info, mid))
+		if (gid_gt(grp, GROUP_AT(group_info, mid)))
 			left = mid + 1;
-		else if (grp < GROUP_AT(group_info, mid))
+		else if (gid_lt(grp, GROUP_AT(group_info, mid)))
 			right = mid;
 		else
 			return 1;
@@ -262,7 +262,8 @@ int in_group_p(gid_t grp)
 	int retval = 1;
 
 	if (grp != cred->fsgid)
-		retval = groups_search(cred->group_info, grp);
+		retval = groups_search(cred->group_info,
+				       make_kgid(cred->user_ns, grp));
 	return retval;
 }
 
@@ -274,7 +275,8 @@ int in_egroup_p(gid_t grp)
 	int retval = 1;
 
 	if (grp != cred->egid)
-		retval = groups_search(cred->group_info, grp);
+		retval = groups_search(cred->group_info,
+				       make_kgid(cred->user_ns, grp));
 	return retval;
 }
 
diff --git a/kernel/uid16.c b/kernel/uid16.c
index 51c6e89..e530bc3 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -134,11 +134,14 @@ SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid)
 static int groups16_to_user(old_gid_t __user *grouplist,
     struct group_info *group_info)
 {
+	struct user_namespace *user_ns = current_user_ns();
 	int i;
 	old_gid_t group;
+	kgid_t kgid;
 
 	for (i = 0; i < group_info->ngroups; i++) {
-		group = high2lowgid(GROUP_AT(group_info, i));
+		kgid = GROUP_AT(group_info, i);
+		group = high2lowgid(from_kgid_munged(user_ns, kgid));
 		if (put_user(group, grouplist+i))
 			return -EFAULT;
 	}
@@ -149,13 +152,20 @@ static int groups16_to_user(old_gid_t __user *grouplist,
 static int groups16_from_user(struct group_info *group_info,
     old_gid_t __user *grouplist)
 {
+	struct user_namespace *user_ns = current_user_ns();
 	int i;
 	old_gid_t group;
+	kgid_t kgid;
 
 	for (i = 0; i < group_info->ngroups; i++) {
 		if (get_user(group, grouplist+i))
 			return  -EFAULT;
-		GROUP_AT(group_info, i) = low2highgid(group);
+
+		kgid = make_kgid(user_ns, low2highgid(group));
+		if (!gid_valid(kgid))
+			return -EINVAL;
+
+		GROUP_AT(group_info, i) = kgid;
 	}
 
 	return 0;