1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/mount.h> 3 #include <linux/pseudo_fs.h> 4 #include <linux/file.h> 5 #include <linux/fs.h> 6 #include <linux/proc_fs.h> 7 #include <linux/proc_ns.h> 8 #include <linux/magic.h> 9 #include <linux/ktime.h> 10 #include <linux/seq_file.h> 11 #include <linux/user_namespace.h> 12 #include <linux/nsfs.h> 13 #include <linux/uaccess.h> 14 15 #include "internal.h" 16 17 static struct vfsmount *nsfs_mnt; 18 19 static long ns_ioctl(struct file *filp, unsigned int ioctl, 20 unsigned long arg); 21 static const struct file_operations ns_file_operations = { 22 .llseek = no_llseek, 23 .unlocked_ioctl = ns_ioctl, 24 .compat_ioctl = compat_ptr_ioctl, 25 }; 26 27 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) 28 { 29 struct inode *inode = d_inode(dentry); 30 struct ns_common *ns = inode->i_private; 31 const struct proc_ns_operations *ns_ops = ns->ops; 32 33 return dynamic_dname(buffer, buflen, "%s:[%lu]", 34 ns_ops->name, inode->i_ino); 35 } 36 37 const struct dentry_operations ns_dentry_operations = { 38 .d_delete = always_delete_dentry, 39 .d_dname = ns_dname, 40 .d_prune = stashed_dentry_prune, 41 }; 42 43 static void nsfs_evict(struct inode *inode) 44 { 45 struct ns_common *ns = inode->i_private; 46 clear_inode(inode); 47 ns->ops->put(ns); 48 } 49 50 int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb, 51 void *private_data) 52 { 53 struct ns_common *ns; 54 55 ns = ns_get_cb(private_data); 56 if (!ns) 57 return -ENOENT; 58 59 return path_from_stashed(&ns->stashed, ns->inum, nsfs_mnt, ns, path); 60 } 61 62 struct ns_get_path_task_args { 63 const struct proc_ns_operations *ns_ops; 64 struct task_struct *task; 65 }; 66 67 static struct ns_common *ns_get_path_task(void *private_data) 68 { 69 struct ns_get_path_task_args *args = private_data; 70 71 return args->ns_ops->get(args->task); 72 } 73 74 int ns_get_path(struct path *path, struct task_struct *task, 75 const struct proc_ns_operations *ns_ops) 76 { 77 struct ns_get_path_task_args args = { 78 .ns_ops = ns_ops, 79 .task = task, 80 }; 81 82 return ns_get_path_cb(path, ns_get_path_task, &args); 83 } 84 85 int open_related_ns(struct ns_common *ns, 86 struct ns_common *(*get_ns)(struct ns_common *ns)) 87 { 88 struct path path = {}; 89 struct ns_common *relative; 90 struct file *f; 91 int err; 92 int fd; 93 94 fd = get_unused_fd_flags(O_CLOEXEC); 95 if (fd < 0) 96 return fd; 97 98 relative = get_ns(ns); 99 if (IS_ERR(relative)) { 100 put_unused_fd(fd); 101 return PTR_ERR(relative); 102 } 103 104 err = path_from_stashed(&relative->stashed, relative->inum, nsfs_mnt, 105 relative, &path); 106 if (err < 0) { 107 put_unused_fd(fd); 108 return err; 109 } 110 111 f = dentry_open(&path, O_RDONLY, current_cred()); 112 path_put(&path); 113 if (IS_ERR(f)) { 114 put_unused_fd(fd); 115 fd = PTR_ERR(f); 116 } else 117 fd_install(fd, f); 118 119 return fd; 120 } 121 EXPORT_SYMBOL_GPL(open_related_ns); 122 123 static long ns_ioctl(struct file *filp, unsigned int ioctl, 124 unsigned long arg) 125 { 126 struct user_namespace *user_ns; 127 struct ns_common *ns = get_proc_ns(file_inode(filp)); 128 uid_t __user *argp; 129 uid_t uid; 130 131 switch (ioctl) { 132 case NS_GET_USERNS: 133 return open_related_ns(ns, ns_get_owner); 134 case NS_GET_PARENT: 135 if (!ns->ops->get_parent) 136 return -EINVAL; 137 return open_related_ns(ns, ns->ops->get_parent); 138 case NS_GET_NSTYPE: 139 return ns->ops->type; 140 case NS_GET_OWNER_UID: 141 if (ns->ops->type != CLONE_NEWUSER) 142 return -EINVAL; 143 user_ns = container_of(ns, struct user_namespace, ns); 144 argp = (uid_t __user *) arg; 145 uid = from_kuid_munged(current_user_ns(), user_ns->owner); 146 return put_user(uid, argp); 147 default: 148 return -ENOTTY; 149 } 150 } 151 152 int ns_get_name(char *buf, size_t size, struct task_struct *task, 153 const struct proc_ns_operations *ns_ops) 154 { 155 struct ns_common *ns; 156 int res = -ENOENT; 157 const char *name; 158 ns = ns_ops->get(task); 159 if (ns) { 160 name = ns_ops->real_ns_name ? : ns_ops->name; 161 res = snprintf(buf, size, "%s:[%u]", name, ns->inum); 162 ns_ops->put(ns); 163 } 164 return res; 165 } 166 167 bool proc_ns_file(const struct file *file) 168 { 169 return file->f_op == &ns_file_operations; 170 } 171 172 /** 173 * ns_match() - Returns true if current namespace matches dev/ino provided. 174 * @ns: current namespace 175 * @dev: dev_t from nsfs that will be matched against current nsfs 176 * @ino: ino_t from nsfs that will be matched against current nsfs 177 * 178 * Return: true if dev and ino matches the current nsfs. 179 */ 180 bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino) 181 { 182 return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev); 183 } 184 185 186 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry) 187 { 188 struct inode *inode = d_inode(dentry); 189 const struct ns_common *ns = inode->i_private; 190 const struct proc_ns_operations *ns_ops = ns->ops; 191 192 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino); 193 return 0; 194 } 195 196 static const struct super_operations nsfs_ops = { 197 .statfs = simple_statfs, 198 .evict_inode = nsfs_evict, 199 .show_path = nsfs_show_path, 200 }; 201 202 static void nsfs_init_inode(struct inode *inode, void *data) 203 { 204 inode->i_private = data; 205 inode->i_mode |= S_IRUGO; 206 inode->i_fop = &ns_file_operations; 207 } 208 209 static void nsfs_put_data(void *data) 210 { 211 struct ns_common *ns = data; 212 ns->ops->put(ns); 213 } 214 215 static const struct stashed_operations nsfs_stashed_ops = { 216 .init_inode = nsfs_init_inode, 217 .put_data = nsfs_put_data, 218 }; 219 220 static int nsfs_init_fs_context(struct fs_context *fc) 221 { 222 struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); 223 if (!ctx) 224 return -ENOMEM; 225 ctx->ops = &nsfs_ops; 226 ctx->dops = &ns_dentry_operations; 227 fc->s_fs_info = (void *)&nsfs_stashed_ops; 228 return 0; 229 } 230 231 static struct file_system_type nsfs = { 232 .name = "nsfs", 233 .init_fs_context = nsfs_init_fs_context, 234 .kill_sb = kill_anon_super, 235 }; 236 237 void __init nsfs_init(void) 238 { 239 nsfs_mnt = kern_mount(&nsfs); 240 if (IS_ERR(nsfs_mnt)) 241 panic("can't set nsfs up\n"); 242 nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER; 243 } 244