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/pid_namespace.h> 12 #include <linux/user_namespace.h> 13 #include <linux/nsfs.h> 14 #include <linux/uaccess.h> 15 16 #include "mount.h" 17 #include "internal.h" 18 19 static struct vfsmount *nsfs_mnt; 20 21 static long ns_ioctl(struct file *filp, unsigned int ioctl, 22 unsigned long arg); 23 static const struct file_operations ns_file_operations = { 24 .llseek = no_llseek, 25 .unlocked_ioctl = ns_ioctl, 26 .compat_ioctl = compat_ptr_ioctl, 27 }; 28 29 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) 30 { 31 struct inode *inode = d_inode(dentry); 32 struct ns_common *ns = inode->i_private; 33 const struct proc_ns_operations *ns_ops = ns->ops; 34 35 return dynamic_dname(buffer, buflen, "%s:[%lu]", 36 ns_ops->name, inode->i_ino); 37 } 38 39 const struct dentry_operations ns_dentry_operations = { 40 .d_delete = always_delete_dentry, 41 .d_dname = ns_dname, 42 .d_prune = stashed_dentry_prune, 43 }; 44 45 static void nsfs_evict(struct inode *inode) 46 { 47 struct ns_common *ns = inode->i_private; 48 clear_inode(inode); 49 ns->ops->put(ns); 50 } 51 52 int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb, 53 void *private_data) 54 { 55 struct ns_common *ns; 56 57 ns = ns_get_cb(private_data); 58 if (!ns) 59 return -ENOENT; 60 61 return path_from_stashed(&ns->stashed, nsfs_mnt, ns, path); 62 } 63 64 struct ns_get_path_task_args { 65 const struct proc_ns_operations *ns_ops; 66 struct task_struct *task; 67 }; 68 69 static struct ns_common *ns_get_path_task(void *private_data) 70 { 71 struct ns_get_path_task_args *args = private_data; 72 73 return args->ns_ops->get(args->task); 74 } 75 76 int ns_get_path(struct path *path, struct task_struct *task, 77 const struct proc_ns_operations *ns_ops) 78 { 79 struct ns_get_path_task_args args = { 80 .ns_ops = ns_ops, 81 .task = task, 82 }; 83 84 return ns_get_path_cb(path, ns_get_path_task, &args); 85 } 86 87 /** 88 * open_namespace - open a namespace 89 * @ns: the namespace to open 90 * 91 * This will consume a reference to @ns indendent of success or failure. 92 * 93 * Return: A file descriptor on success or a negative error code on failure. 94 */ 95 int open_namespace(struct ns_common *ns) 96 { 97 struct path path __free(path_put) = {}; 98 struct file *f; 99 int err; 100 101 /* call first to consume reference */ 102 err = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path); 103 if (err < 0) 104 return err; 105 106 CLASS(get_unused_fd, fd)(O_CLOEXEC); 107 if (fd < 0) 108 return fd; 109 110 f = dentry_open(&path, O_RDONLY, current_cred()); 111 if (IS_ERR(f)) 112 return PTR_ERR(f); 113 114 fd_install(fd, f); 115 return take_fd(fd); 116 } 117 118 int open_related_ns(struct ns_common *ns, 119 struct ns_common *(*get_ns)(struct ns_common *ns)) 120 { 121 struct ns_common *relative; 122 123 relative = get_ns(ns); 124 if (IS_ERR(relative)) 125 return PTR_ERR(relative); 126 127 return open_namespace(relative); 128 } 129 EXPORT_SYMBOL_GPL(open_related_ns); 130 131 static long ns_ioctl(struct file *filp, unsigned int ioctl, 132 unsigned long arg) 133 { 134 struct user_namespace *user_ns; 135 struct pid_namespace *pid_ns; 136 struct task_struct *tsk; 137 struct ns_common *ns = get_proc_ns(file_inode(filp)); 138 uid_t __user *argp; 139 uid_t uid; 140 int ret; 141 142 switch (ioctl) { 143 case NS_GET_USERNS: 144 return open_related_ns(ns, ns_get_owner); 145 case NS_GET_PARENT: 146 if (!ns->ops->get_parent) 147 return -EINVAL; 148 return open_related_ns(ns, ns->ops->get_parent); 149 case NS_GET_NSTYPE: 150 return ns->ops->type; 151 case NS_GET_OWNER_UID: 152 if (ns->ops->type != CLONE_NEWUSER) 153 return -EINVAL; 154 user_ns = container_of(ns, struct user_namespace, ns); 155 argp = (uid_t __user *) arg; 156 uid = from_kuid_munged(current_user_ns(), user_ns->owner); 157 return put_user(uid, argp); 158 case NS_GET_MNTNS_ID: { 159 struct mnt_namespace *mnt_ns; 160 __u64 __user *idp; 161 __u64 id; 162 163 if (ns->ops->type != CLONE_NEWNS) 164 return -EINVAL; 165 166 mnt_ns = container_of(ns, struct mnt_namespace, ns); 167 idp = (__u64 __user *)arg; 168 id = mnt_ns->seq; 169 return put_user(id, idp); 170 } 171 case NS_GET_PID_FROM_PIDNS: 172 fallthrough; 173 case NS_GET_TGID_FROM_PIDNS: 174 fallthrough; 175 case NS_GET_PID_IN_PIDNS: 176 fallthrough; 177 case NS_GET_TGID_IN_PIDNS: { 178 if (ns->ops->type != CLONE_NEWPID) 179 return -EINVAL; 180 181 ret = -ESRCH; 182 pid_ns = container_of(ns, struct pid_namespace, ns); 183 184 guard(rcu)(); 185 186 if (ioctl == NS_GET_PID_IN_PIDNS || 187 ioctl == NS_GET_TGID_IN_PIDNS) 188 tsk = find_task_by_vpid(arg); 189 else 190 tsk = find_task_by_pid_ns(arg, pid_ns); 191 if (!tsk) 192 break; 193 194 switch (ioctl) { 195 case NS_GET_PID_FROM_PIDNS: 196 ret = task_pid_vnr(tsk); 197 break; 198 case NS_GET_TGID_FROM_PIDNS: 199 ret = task_tgid_vnr(tsk); 200 break; 201 case NS_GET_PID_IN_PIDNS: 202 ret = task_pid_nr_ns(tsk, pid_ns); 203 break; 204 case NS_GET_TGID_IN_PIDNS: 205 ret = task_tgid_nr_ns(tsk, pid_ns); 206 break; 207 default: 208 ret = 0; 209 break; 210 } 211 212 if (!ret) 213 ret = -ESRCH; 214 break; 215 } 216 default: 217 ret = -ENOTTY; 218 } 219 220 return ret; 221 } 222 223 int ns_get_name(char *buf, size_t size, struct task_struct *task, 224 const struct proc_ns_operations *ns_ops) 225 { 226 struct ns_common *ns; 227 int res = -ENOENT; 228 const char *name; 229 ns = ns_ops->get(task); 230 if (ns) { 231 name = ns_ops->real_ns_name ? : ns_ops->name; 232 res = snprintf(buf, size, "%s:[%u]", name, ns->inum); 233 ns_ops->put(ns); 234 } 235 return res; 236 } 237 238 bool proc_ns_file(const struct file *file) 239 { 240 return file->f_op == &ns_file_operations; 241 } 242 243 /** 244 * ns_match() - Returns true if current namespace matches dev/ino provided. 245 * @ns: current namespace 246 * @dev: dev_t from nsfs that will be matched against current nsfs 247 * @ino: ino_t from nsfs that will be matched against current nsfs 248 * 249 * Return: true if dev and ino matches the current nsfs. 250 */ 251 bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino) 252 { 253 return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev); 254 } 255 256 257 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry) 258 { 259 struct inode *inode = d_inode(dentry); 260 const struct ns_common *ns = inode->i_private; 261 const struct proc_ns_operations *ns_ops = ns->ops; 262 263 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino); 264 return 0; 265 } 266 267 static const struct super_operations nsfs_ops = { 268 .statfs = simple_statfs, 269 .evict_inode = nsfs_evict, 270 .show_path = nsfs_show_path, 271 }; 272 273 static int nsfs_init_inode(struct inode *inode, void *data) 274 { 275 struct ns_common *ns = data; 276 277 inode->i_private = data; 278 inode->i_mode |= S_IRUGO; 279 inode->i_fop = &ns_file_operations; 280 inode->i_ino = ns->inum; 281 return 0; 282 } 283 284 static void nsfs_put_data(void *data) 285 { 286 struct ns_common *ns = data; 287 ns->ops->put(ns); 288 } 289 290 static const struct stashed_operations nsfs_stashed_ops = { 291 .init_inode = nsfs_init_inode, 292 .put_data = nsfs_put_data, 293 }; 294 295 static int nsfs_init_fs_context(struct fs_context *fc) 296 { 297 struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); 298 if (!ctx) 299 return -ENOMEM; 300 ctx->ops = &nsfs_ops; 301 ctx->dops = &ns_dentry_operations; 302 fc->s_fs_info = (void *)&nsfs_stashed_ops; 303 return 0; 304 } 305 306 static struct file_system_type nsfs = { 307 .name = "nsfs", 308 .init_fs_context = nsfs_init_fs_context, 309 .kill_sb = kill_anon_super, 310 }; 311 312 void __init nsfs_init(void) 313 { 314 nsfs_mnt = kern_mount(&nsfs); 315 if (IS_ERR(nsfs_mnt)) 316 panic("can't set nsfs up\n"); 317 nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER; 318 } 319