1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Routines that mimic syscalls, but don't use the user address space or file 4 * descriptors. Only for init/ and related early init code. 5 */ 6 #include <linux/init.h> 7 #include <linux/mount.h> 8 #include <linux/namei.h> 9 #include <linux/fs.h> 10 #include <linux/fs_struct.h> 11 #include <linux/file.h> 12 #include <linux/init_syscalls.h> 13 #include <linux/security.h> 14 #include "internal.h" 15 16 int __init init_mount(const char *dev_name, const char *dir_name, 17 const char *type_page, unsigned long flags, void *data_page) 18 { 19 struct path path; 20 int ret; 21 22 ret = kern_path(dir_name, LOOKUP_FOLLOW, &path); 23 if (ret) 24 return ret; 25 ret = path_mount(dev_name, &path, type_page, flags, data_page); 26 path_put(&path); 27 return ret; 28 } 29 30 int __init init_umount(const char *name, int flags) 31 { 32 int lookup_flags = LOOKUP_MOUNTPOINT; 33 struct path path; 34 int ret; 35 36 if (!(flags & UMOUNT_NOFOLLOW)) 37 lookup_flags |= LOOKUP_FOLLOW; 38 ret = kern_path(name, lookup_flags, &path); 39 if (ret) 40 return ret; 41 return path_umount(&path, flags); 42 } 43 44 int __init init_chdir(const char *filename) 45 { 46 struct path path; 47 int error; 48 49 error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path); 50 if (error) 51 return error; 52 error = path_permission(&path, MAY_EXEC | MAY_CHDIR); 53 if (!error) 54 set_fs_pwd(current->fs, &path); 55 path_put(&path); 56 return error; 57 } 58 59 int __init init_chroot(const char *filename) 60 { 61 struct path path; 62 int error; 63 64 error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path); 65 if (error) 66 return error; 67 error = path_permission(&path, MAY_EXEC | MAY_CHDIR); 68 if (error) 69 goto dput_and_out; 70 error = -EPERM; 71 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) 72 goto dput_and_out; 73 error = security_path_chroot(&path); 74 if (error) 75 goto dput_and_out; 76 set_fs_root(current->fs, &path); 77 dput_and_out: 78 path_put(&path); 79 return error; 80 } 81 82 int __init init_chown(const char *filename, uid_t user, gid_t group, int flags) 83 { 84 int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; 85 struct path path; 86 int error; 87 88 error = kern_path(filename, lookup_flags, &path); 89 if (error) 90 return error; 91 error = mnt_want_write(path.mnt); 92 if (!error) { 93 error = chown_common(&path, user, group); 94 mnt_drop_write(path.mnt); 95 } 96 path_put(&path); 97 return error; 98 } 99 100 int __init init_chmod(const char *filename, umode_t mode) 101 { 102 struct path path; 103 int error; 104 105 error = kern_path(filename, LOOKUP_FOLLOW, &path); 106 if (error) 107 return error; 108 error = chmod_common(&path, mode); 109 path_put(&path); 110 return error; 111 } 112 113 int __init init_eaccess(const char *filename) 114 { 115 struct path path; 116 int error; 117 118 error = kern_path(filename, LOOKUP_FOLLOW, &path); 119 if (error) 120 return error; 121 error = path_permission(&path, MAY_ACCESS); 122 path_put(&path); 123 return error; 124 } 125 126 int __init init_stat(const char *filename, struct kstat *stat, int flags) 127 { 128 int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; 129 struct path path; 130 int error; 131 132 error = kern_path(filename, lookup_flags, &path); 133 if (error) 134 return error; 135 error = vfs_getattr(&path, stat, STATX_BASIC_STATS, 136 flags | AT_NO_AUTOMOUNT); 137 path_put(&path); 138 return error; 139 } 140 141 int __init init_mknod(const char *filename, umode_t mode, unsigned int dev) 142 { 143 struct dentry *dentry; 144 struct path path; 145 int error; 146 147 if (S_ISFIFO(mode) || S_ISSOCK(mode)) 148 dev = 0; 149 else if (!(S_ISBLK(mode) || S_ISCHR(mode))) 150 return -EINVAL; 151 152 dentry = kern_path_create(AT_FDCWD, filename, &path, 0); 153 if (IS_ERR(dentry)) 154 return PTR_ERR(dentry); 155 156 if (!IS_POSIXACL(path.dentry->d_inode)) 157 mode &= ~current_umask(); 158 error = security_path_mknod(&path, dentry, mode, dev); 159 if (!error) 160 error = vfs_mknod(mnt_user_ns(path.mnt), path.dentry->d_inode, 161 dentry, mode, new_decode_dev(dev)); 162 done_path_create(&path, dentry); 163 return error; 164 } 165 166 int __init init_link(const char *oldname, const char *newname) 167 { 168 struct dentry *new_dentry; 169 struct path old_path, new_path; 170 struct user_namespace *mnt_userns; 171 int error; 172 173 error = kern_path(oldname, 0, &old_path); 174 if (error) 175 return error; 176 177 new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0); 178 error = PTR_ERR(new_dentry); 179 if (IS_ERR(new_dentry)) 180 goto out; 181 182 error = -EXDEV; 183 if (old_path.mnt != new_path.mnt) 184 goto out_dput; 185 mnt_userns = mnt_user_ns(new_path.mnt); 186 error = may_linkat(mnt_userns, &old_path); 187 if (unlikely(error)) 188 goto out_dput; 189 error = security_path_link(old_path.dentry, &new_path, new_dentry); 190 if (error) 191 goto out_dput; 192 error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode, 193 new_dentry, NULL); 194 out_dput: 195 done_path_create(&new_path, new_dentry); 196 out: 197 path_put(&old_path); 198 return error; 199 } 200 201 int __init init_symlink(const char *oldname, const char *newname) 202 { 203 struct dentry *dentry; 204 struct path path; 205 int error; 206 207 dentry = kern_path_create(AT_FDCWD, newname, &path, 0); 208 if (IS_ERR(dentry)) 209 return PTR_ERR(dentry); 210 error = security_path_symlink(&path, dentry, oldname); 211 if (!error) 212 error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode, 213 dentry, oldname); 214 done_path_create(&path, dentry); 215 return error; 216 } 217 218 int __init init_unlink(const char *pathname) 219 { 220 return do_unlinkat(AT_FDCWD, getname_kernel(pathname)); 221 } 222 223 int __init init_mkdir(const char *pathname, umode_t mode) 224 { 225 struct dentry *dentry; 226 struct path path; 227 int error; 228 229 dentry = kern_path_create(AT_FDCWD, pathname, &path, LOOKUP_DIRECTORY); 230 if (IS_ERR(dentry)) 231 return PTR_ERR(dentry); 232 if (!IS_POSIXACL(path.dentry->d_inode)) 233 mode &= ~current_umask(); 234 error = security_path_mkdir(&path, dentry, mode); 235 if (!error) 236 error = vfs_mkdir(mnt_user_ns(path.mnt), path.dentry->d_inode, 237 dentry, mode); 238 done_path_create(&path, dentry); 239 return error; 240 } 241 242 int __init init_rmdir(const char *pathname) 243 { 244 return do_rmdir(AT_FDCWD, getname_kernel(pathname)); 245 } 246 247 int __init init_utimes(char *filename, struct timespec64 *ts) 248 { 249 struct path path; 250 int error; 251 252 error = kern_path(filename, 0, &path); 253 if (error) 254 return error; 255 error = vfs_utimes(&path, ts); 256 path_put(&path); 257 return error; 258 } 259 260 int __init init_dup(struct file *file) 261 { 262 int fd; 263 264 fd = get_unused_fd_flags(0); 265 if (fd < 0) 266 return fd; 267 fd_install(fd, get_file(file)); 268 return 0; 269 } 270