Daniel Campello | 35c9e24 | 2015-07-20 16:23:50 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * fs/sdcardfs/file.c |
| 3 | * |
| 4 | * Copyright (c) 2013 Samsung Electronics Co. Ltd |
| 5 | * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun, |
| 6 | * Sunghwan Yun, Sungjong Seo |
| 7 | * |
| 8 | * This program has been developed as a stackable file system based on |
| 9 | * the WrapFS which written by |
| 10 | * |
| 11 | * Copyright (c) 1998-2011 Erez Zadok |
| 12 | * Copyright (c) 2009 Shrikar Archak |
| 13 | * Copyright (c) 2003-2011 Stony Brook University |
| 14 | * Copyright (c) 2003-2011 The Research Foundation of SUNY |
| 15 | * |
| 16 | * This file is dual licensed. It may be redistributed and/or modified |
| 17 | * under the terms of the Apache 2.0 License OR version 2 of the GNU |
| 18 | * General Public License. |
| 19 | */ |
| 20 | |
| 21 | #include "sdcardfs.h" |
| 22 | #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE |
| 23 | #include <linux/backing-dev.h> |
| 24 | #endif |
| 25 | |
| 26 | static ssize_t sdcardfs_read(struct file *file, char __user *buf, |
| 27 | size_t count, loff_t *ppos) |
| 28 | { |
| 29 | int err; |
| 30 | struct file *lower_file; |
| 31 | struct dentry *dentry = file->f_path.dentry; |
| 32 | #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE |
| 33 | struct backing_dev_info *bdi; |
| 34 | #endif |
| 35 | |
| 36 | lower_file = sdcardfs_lower_file(file); |
| 37 | |
| 38 | #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE |
| 39 | if (file->f_mode & FMODE_NOACTIVE) { |
| 40 | if (!(lower_file->f_mode & FMODE_NOACTIVE)) { |
| 41 | bdi = lower_file->f_mapping->backing_dev_info; |
| 42 | lower_file->f_ra.ra_pages = bdi->ra_pages * 2; |
| 43 | spin_lock(&lower_file->f_lock); |
| 44 | lower_file->f_mode |= FMODE_NOACTIVE; |
| 45 | spin_unlock(&lower_file->f_lock); |
| 46 | } |
| 47 | } |
| 48 | #endif |
| 49 | |
| 50 | err = vfs_read(lower_file, buf, count, ppos); |
| 51 | /* update our inode atime upon a successful lower read */ |
| 52 | if (err >= 0) |
| 53 | fsstack_copy_attr_atime(dentry->d_inode, |
| 54 | lower_file->f_path.dentry->d_inode); |
| 55 | |
| 56 | return err; |
| 57 | } |
| 58 | |
| 59 | static ssize_t sdcardfs_write(struct file *file, const char __user *buf, |
| 60 | size_t count, loff_t *ppos) |
| 61 | { |
| 62 | int err = 0; |
| 63 | struct file *lower_file; |
| 64 | struct dentry *dentry = file->f_path.dentry; |
| 65 | |
| 66 | /* check disk space */ |
| 67 | if (!check_min_free_space(dentry, count, 0)) { |
| 68 | printk(KERN_INFO "No minimum free space.\n"); |
| 69 | return -ENOSPC; |
| 70 | } |
| 71 | |
| 72 | lower_file = sdcardfs_lower_file(file); |
| 73 | err = vfs_write(lower_file, buf, count, ppos); |
| 74 | /* update our inode times+sizes upon a successful lower write */ |
| 75 | if (err >= 0) { |
| 76 | fsstack_copy_inode_size(dentry->d_inode, |
| 77 | lower_file->f_path.dentry->d_inode); |
| 78 | fsstack_copy_attr_times(dentry->d_inode, |
| 79 | lower_file->f_path.dentry->d_inode); |
| 80 | } |
| 81 | |
| 82 | return err; |
| 83 | } |
| 84 | |
| 85 | static int sdcardfs_readdir(struct file *file, void *dirent, filldir_t filldir) |
| 86 | { |
| 87 | int err = 0; |
| 88 | struct file *lower_file = NULL; |
| 89 | struct dentry *dentry = file->f_path.dentry; |
| 90 | |
| 91 | lower_file = sdcardfs_lower_file(file); |
| 92 | |
| 93 | lower_file->f_pos = file->f_pos; |
| 94 | err = vfs_readdir(lower_file, filldir, dirent); |
| 95 | file->f_pos = lower_file->f_pos; |
| 96 | if (err >= 0) /* copy the atime */ |
| 97 | fsstack_copy_attr_atime(dentry->d_inode, |
| 98 | lower_file->f_path.dentry->d_inode); |
| 99 | return err; |
| 100 | } |
| 101 | |
| 102 | static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd, |
| 103 | unsigned long arg) |
| 104 | { |
| 105 | long err = -ENOTTY; |
| 106 | struct file *lower_file; |
| 107 | |
| 108 | lower_file = sdcardfs_lower_file(file); |
| 109 | |
| 110 | /* XXX: use vfs_ioctl if/when VFS exports it */ |
| 111 | if (!lower_file || !lower_file->f_op) |
| 112 | goto out; |
| 113 | if (lower_file->f_op->unlocked_ioctl) |
| 114 | err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); |
| 115 | |
| 116 | out: |
| 117 | return err; |
| 118 | } |
| 119 | |
| 120 | #ifdef CONFIG_COMPAT |
| 121 | static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd, |
| 122 | unsigned long arg) |
| 123 | { |
| 124 | long err = -ENOTTY; |
| 125 | struct file *lower_file; |
| 126 | |
| 127 | lower_file = sdcardfs_lower_file(file); |
| 128 | |
| 129 | /* XXX: use vfs_ioctl if/when VFS exports it */ |
| 130 | if (!lower_file || !lower_file->f_op) |
| 131 | goto out; |
| 132 | if (lower_file->f_op->compat_ioctl) |
| 133 | err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); |
| 134 | |
| 135 | out: |
| 136 | return err; |
| 137 | } |
| 138 | #endif |
| 139 | |
| 140 | static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma) |
| 141 | { |
| 142 | int err = 0; |
| 143 | bool willwrite; |
| 144 | struct file *lower_file; |
| 145 | const struct vm_operations_struct *saved_vm_ops = NULL; |
| 146 | |
| 147 | /* this might be deferred to mmap's writepage */ |
| 148 | willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags); |
| 149 | |
| 150 | /* |
| 151 | * File systems which do not implement ->writepage may use |
| 152 | * generic_file_readonly_mmap as their ->mmap op. If you call |
| 153 | * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL. |
| 154 | * But we cannot call the lower ->mmap op, so we can't tell that |
| 155 | * writeable mappings won't work. Therefore, our only choice is to |
| 156 | * check if the lower file system supports the ->writepage, and if |
| 157 | * not, return EINVAL (the same error that |
| 158 | * generic_file_readonly_mmap returns in that case). |
| 159 | */ |
| 160 | lower_file = sdcardfs_lower_file(file); |
| 161 | if (willwrite && !lower_file->f_mapping->a_ops->writepage) { |
| 162 | err = -EINVAL; |
| 163 | printk(KERN_ERR "sdcardfs: lower file system does not " |
| 164 | "support writeable mmap\n"); |
| 165 | goto out; |
| 166 | } |
| 167 | |
| 168 | /* |
| 169 | * find and save lower vm_ops. |
| 170 | * |
| 171 | * XXX: the VFS should have a cleaner way of finding the lower vm_ops |
| 172 | */ |
| 173 | if (!SDCARDFS_F(file)->lower_vm_ops) { |
| 174 | err = lower_file->f_op->mmap(lower_file, vma); |
| 175 | if (err) { |
| 176 | printk(KERN_ERR "sdcardfs: lower mmap failed %d\n", err); |
| 177 | goto out; |
| 178 | } |
| 179 | saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */ |
| 180 | err = do_munmap(current->mm, vma->vm_start, |
| 181 | vma->vm_end - vma->vm_start); |
| 182 | if (err) { |
| 183 | printk(KERN_ERR "sdcardfs: do_munmap failed %d\n", err); |
| 184 | goto out; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /* |
| 189 | * Next 3 lines are all I need from generic_file_mmap. I definitely |
| 190 | * don't want its test for ->readpage which returns -ENOEXEC. |
| 191 | */ |
| 192 | file_accessed(file); |
| 193 | vma->vm_ops = &sdcardfs_vm_ops; |
| 194 | vma->vm_flags |= VM_CAN_NONLINEAR; |
| 195 | |
| 196 | file->f_mapping->a_ops = &sdcardfs_aops; /* set our aops */ |
| 197 | if (!SDCARDFS_F(file)->lower_vm_ops) /* save for our ->fault */ |
| 198 | SDCARDFS_F(file)->lower_vm_ops = saved_vm_ops; |
| 199 | |
| 200 | out: |
| 201 | return err; |
| 202 | } |
| 203 | |
| 204 | static int sdcardfs_open(struct inode *inode, struct file *file) |
| 205 | { |
| 206 | int err = 0; |
| 207 | struct file *lower_file = NULL; |
| 208 | struct path lower_path; |
| 209 | struct dentry *dentry = file->f_path.dentry; |
| 210 | struct dentry *parent = dget_parent(dentry); |
| 211 | struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb); |
| 212 | const struct cred *saved_cred = NULL; |
| 213 | int has_rw; |
| 214 | |
| 215 | /* don't open unhashed/deleted files */ |
| 216 | if (d_unhashed(dentry)) { |
| 217 | err = -ENOENT; |
| 218 | goto out_err; |
| 219 | } |
| 220 | |
| 221 | has_rw = get_caller_has_rw_locked(sbi->pkgl_id, sbi->options.derive); |
| 222 | |
| 223 | if(!check_caller_access_to_name(parent->d_inode, dentry->d_name.name, |
| 224 | sbi->options.derive, |
| 225 | open_flags_to_access_mode(file->f_flags), has_rw)) { |
| 226 | printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" |
| 227 | " dentry: %s, task:%s\n", |
| 228 | __func__, dentry->d_name.name, current->comm); |
| 229 | err = -EACCES; |
| 230 | goto out_err; |
| 231 | } |
| 232 | |
| 233 | /* save current_cred and override it */ |
| 234 | OVERRIDE_CRED(sbi, saved_cred); |
| 235 | |
| 236 | file->private_data = |
| 237 | kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL); |
| 238 | if (!SDCARDFS_F(file)) { |
| 239 | err = -ENOMEM; |
| 240 | goto out_revert_cred; |
| 241 | } |
| 242 | |
| 243 | /* open lower object and link sdcardfs's file struct to lower's */ |
| 244 | sdcardfs_get_lower_path(file->f_path.dentry, &lower_path); |
| 245 | lower_file = dentry_open(lower_path.dentry, lower_path.mnt, |
| 246 | file->f_flags, current_cred()); |
| 247 | if (IS_ERR(lower_file)) { |
| 248 | err = PTR_ERR(lower_file); |
| 249 | lower_file = sdcardfs_lower_file(file); |
| 250 | if (lower_file) { |
| 251 | sdcardfs_set_lower_file(file, NULL); |
| 252 | fput(lower_file); /* fput calls dput for lower_dentry */ |
| 253 | } |
| 254 | } else { |
| 255 | sdcardfs_set_lower_file(file, lower_file); |
| 256 | } |
| 257 | |
| 258 | if (err) |
| 259 | kfree(SDCARDFS_F(file)); |
| 260 | else { |
| 261 | fsstack_copy_attr_all(inode, sdcardfs_lower_inode(inode)); |
| 262 | fix_derived_permission(inode); |
| 263 | } |
| 264 | |
| 265 | out_revert_cred: |
| 266 | REVERT_CRED(saved_cred); |
| 267 | out_err: |
| 268 | dput(parent); |
| 269 | return err; |
| 270 | } |
| 271 | |
| 272 | static int sdcardfs_flush(struct file *file, fl_owner_t id) |
| 273 | { |
| 274 | int err = 0; |
| 275 | struct file *lower_file = NULL; |
| 276 | |
| 277 | lower_file = sdcardfs_lower_file(file); |
| 278 | if (lower_file && lower_file->f_op && lower_file->f_op->flush) |
| 279 | err = lower_file->f_op->flush(lower_file, id); |
| 280 | |
| 281 | return err; |
| 282 | } |
| 283 | |
| 284 | /* release all lower object references & free the file info structure */ |
| 285 | static int sdcardfs_file_release(struct inode *inode, struct file *file) |
| 286 | { |
| 287 | struct file *lower_file; |
| 288 | |
| 289 | lower_file = sdcardfs_lower_file(file); |
| 290 | if (lower_file) { |
| 291 | sdcardfs_set_lower_file(file, NULL); |
| 292 | fput(lower_file); |
| 293 | } |
| 294 | |
| 295 | kfree(SDCARDFS_F(file)); |
| 296 | return 0; |
| 297 | } |
| 298 | |
| 299 | static int |
| 300 | sdcardfs_fsync(struct file *file, int datasync) |
| 301 | { |
| 302 | int err; |
| 303 | struct file *lower_file; |
| 304 | struct path lower_path; |
| 305 | struct dentry *dentry = file->f_path.dentry; |
| 306 | |
| 307 | lower_file = sdcardfs_lower_file(file); |
| 308 | sdcardfs_get_lower_path(dentry, &lower_path); |
| 309 | err = vfs_fsync(lower_file, datasync); |
| 310 | sdcardfs_put_lower_path(dentry, &lower_path); |
| 311 | |
| 312 | return err; |
| 313 | } |
| 314 | |
| 315 | static int sdcardfs_fasync(int fd, struct file *file, int flag) |
| 316 | { |
| 317 | int err = 0; |
| 318 | struct file *lower_file = NULL; |
| 319 | |
| 320 | lower_file = sdcardfs_lower_file(file); |
| 321 | if (lower_file->f_op && lower_file->f_op->fasync) |
| 322 | err = lower_file->f_op->fasync(fd, lower_file, flag); |
| 323 | |
| 324 | return err; |
| 325 | } |
| 326 | |
| 327 | const struct file_operations sdcardfs_main_fops = { |
| 328 | .llseek = generic_file_llseek, |
| 329 | .read = sdcardfs_read, |
| 330 | .write = sdcardfs_write, |
| 331 | .unlocked_ioctl = sdcardfs_unlocked_ioctl, |
| 332 | #ifdef CONFIG_COMPAT |
| 333 | .compat_ioctl = sdcardfs_compat_ioctl, |
| 334 | #endif |
| 335 | .mmap = sdcardfs_mmap, |
| 336 | .open = sdcardfs_open, |
| 337 | .flush = sdcardfs_flush, |
| 338 | .release = sdcardfs_file_release, |
| 339 | .fsync = sdcardfs_fsync, |
| 340 | .fasync = sdcardfs_fasync, |
| 341 | }; |
| 342 | |
| 343 | /* trimmed directory options */ |
| 344 | const struct file_operations sdcardfs_dir_fops = { |
| 345 | .llseek = generic_file_llseek, |
| 346 | .read = generic_read_dir, |
| 347 | .readdir = sdcardfs_readdir, |
| 348 | .unlocked_ioctl = sdcardfs_unlocked_ioctl, |
| 349 | #ifdef CONFIG_COMPAT |
| 350 | .compat_ioctl = sdcardfs_compat_ioctl, |
| 351 | #endif |
| 352 | .open = sdcardfs_open, |
| 353 | .release = sdcardfs_file_release, |
| 354 | .flush = sdcardfs_flush, |
| 355 | .fsync = sdcardfs_fsync, |
| 356 | .fasync = sdcardfs_fasync, |
| 357 | }; |