| /* |
| * linux/fs/open.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| #include <linux/string.h> |
| #include <linux/mm.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/fsnotify.h> |
| #include <linux/module.h> |
| #include <linux/tty.h> |
| #include <linux/namei.h> |
| #include <linux/backing-dev.h> |
| #include <linux/capability.h> |
| #include <linux/securebits.h> |
| #include <linux/security.h> |
| #include <linux/mount.h> |
| #include <linux/fcntl.h> |
| #include <linux/slab.h> |
| #include <asm/uaccess.h> |
| #include <linux/fs.h> |
| #include <linux/personality.h> |
| #include <linux/pagemap.h> |
| #include <linux/syscalls.h> |
| #include <linux/rcupdate.h> |
| #include <linux/audit.h> |
| #include <linux/falloc.h> |
| #include <linux/fs_struct.h> |
| #include <linux/ima.h> |
| #include <linux/dnotify.h> |
| |
| #include "internal.h" |
| |
| int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, |
| struct file *filp) |
| { |
| int ret; |
| struct iattr newattrs; |
| |
| /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ |
| if (length < 0) |
| return -EINVAL; |
| |
| newattrs.ia_size = length; |
| newattrs.ia_valid = ATTR_SIZE | time_attrs; |
| if (filp) { |
| newattrs.ia_file = filp; |
| newattrs.ia_valid |= ATTR_FILE; |
| } |
| |
| /* Remove suid/sgid on truncate too */ |
| ret = should_remove_suid(dentry); |
| if (ret) |
| newattrs.ia_valid |= ret | ATTR_FORCE; |
| |
| mutex_lock(&dentry->d_inode->i_mutex); |
| ret = notify_change(dentry, &newattrs); |
| mutex_unlock(&dentry->d_inode->i_mutex); |
| return ret; |
| } |
| |
| static long do_sys_truncate(const char __user *pathname, loff_t length) |
| { |
| struct path path; |
| struct inode *inode; |
| int error; |
| |
| error = -EINVAL; |
| if (length < 0) /* sorry, but loff_t says... */ |
| goto out; |
| |
| error = user_path(pathname, &path); |
| if (error) |
| goto out; |
| inode = path.dentry->d_inode; |
| |
| /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ |
| error = -EISDIR; |
| if (S_ISDIR(inode->i_mode)) |
| goto dput_and_out; |
| |
| error = -EINVAL; |
| if (!S_ISREG(inode->i_mode)) |
| goto dput_and_out; |
| |
| error = mnt_want_write(path.mnt); |
| if (error) |
| goto dput_and_out; |
| |
| error = inode_permission(inode, MAY_WRITE); |
| if (error) |
| goto mnt_drop_write_and_out; |
| |
| error = -EPERM; |
| if (IS_APPEND(inode)) |
| goto mnt_drop_write_and_out; |
| |
| error = get_write_access(inode); |
| if (error) |
| goto mnt_drop_write_and_out; |
| |
| /* |
| * Make sure that there are no leases. get_write_access() protects |
| * against the truncate racing with a lease-granting setlease(). |
| */ |
| error = break_lease(inode, O_WRONLY); |
| if (error) |
| goto put_write_and_out; |
| |
| error = locks_verify_truncate(inode, NULL, length); |
| if (!error) |
| error = security_path_truncate(&path); |
| if (!error) |
| error = do_truncate(path.dentry, length, 0, NULL); |
| |
| put_write_and_out: |
| put_write_access(inode); |
| mnt_drop_write_and_out: |
| mnt_drop_write(path.mnt); |
| dput_and_out: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE2(truncate, const char __user *, path, long, length) |
| { |
| return do_sys_truncate(path, length); |
| } |
| |
| static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) |
| { |
| struct inode * inode; |
| struct dentry *dentry; |
| struct file * file; |
| int error; |
| |
| error = -EINVAL; |
| if (length < 0) |
| goto out; |
| error = -EBADF; |
| file = fget(fd); |
| if (!file) |
| goto out; |
| |
| /* explicitly opened as large or we are on 64-bit box */ |
| if (file->f_flags & O_LARGEFILE) |
| small = 0; |
| |
| dentry = file->f_path.dentry; |
| inode = dentry->d_inode; |
| error = -EINVAL; |
| if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) |
| goto out_putf; |
| |
| error = -EINVAL; |
| /* Cannot ftruncate over 2^31 bytes without large file support */ |
| if (small && length > MAX_NON_LFS) |
| goto out_putf; |
| |
| error = -EPERM; |
| if (IS_APPEND(inode)) |
| goto out_putf; |
| |
| error = locks_verify_truncate(inode, file, length); |
| if (!error) |
| error = security_path_truncate(&file->f_path); |
| if (!error) |
| error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file); |
| out_putf: |
| fput(file); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length) |
| { |
| long ret = do_sys_ftruncate(fd, length, 1); |
| /* avoid REGPARM breakage on x86: */ |
| asmlinkage_protect(2, ret, fd, length); |
| return ret; |
| } |
| |
| /* LFS versions of truncate are only needed on 32 bit machines */ |
| #if BITS_PER_LONG == 32 |
| SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length) |
| { |
| return do_sys_truncate(path, length); |
| } |
| #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
| asmlinkage long SyS_truncate64(long path, loff_t length) |
| { |
| return SYSC_truncate64((const char __user *) path, length); |
| } |
| SYSCALL_ALIAS(sys_truncate64, SyS_truncate64); |
| #endif |
| |
| SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length) |
| { |
| long ret = do_sys_ftruncate(fd, length, 0); |
| /* avoid REGPARM breakage on x86: */ |
| asmlinkage_protect(2, ret, fd, length); |
| return ret; |
| } |
| #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
| asmlinkage long SyS_ftruncate64(long fd, loff_t length) |
| { |
| return SYSC_ftruncate64((unsigned int) fd, length); |
| } |
| SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64); |
| #endif |
| #endif /* BITS_PER_LONG == 32 */ |
| |
| |
| int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) |
| { |
| struct inode *inode = file->f_path.dentry->d_inode; |
| long ret; |
| |
| if (offset < 0 || len <= 0) |
| return -EINVAL; |
| |
| /* Return error if mode is not supported */ |
| if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) |
| return -EOPNOTSUPP; |
| |
| /* Punch hole must have keep size set */ |
| if ((mode & FALLOC_FL_PUNCH_HOLE) && |
| !(mode & FALLOC_FL_KEEP_SIZE)) |
| return -EOPNOTSUPP; |
| |
| if (!(file->f_mode & FMODE_WRITE)) |
| return -EBADF; |
| |
| /* It's not possible punch hole on append only file */ |
| if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode)) |
| return -EPERM; |
| |
| if (IS_IMMUTABLE(inode)) |
| return -EPERM; |
| |
| /* |
| * Revalidate the write permissions, in case security policy has |
| * changed since the files were opened. |
| */ |
| ret = security_file_permission(file, MAY_WRITE); |
| if (ret) |
| return ret; |
| |
| if (S_ISFIFO(inode->i_mode)) |
| return -ESPIPE; |
| |
| /* |
| * Let individual file system decide if it supports preallocation |
| * for directories or not. |
| */ |
| if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
| return -ENODEV; |
| |
| /* Check for wrap through zero too */ |
| if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) |
| return -EFBIG; |
| |
| if (!file->f_op->fallocate) |
| return -EOPNOTSUPP; |
| |
| return file->f_op->fallocate(file, mode, offset, len); |
| } |
| |
| SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len) |
| { |
| struct file *file; |
| int error = -EBADF; |
| |
| file = fget(fd); |
| if (file) { |
| error = do_fallocate(file, mode, offset, len); |
| fput(file); |
| } |
| |
| return error; |
| } |
| |
| #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
| asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len) |
| { |
| return SYSC_fallocate((int)fd, (int)mode, offset, len); |
| } |
| SYSCALL_ALIAS(sys_fallocate, SyS_fallocate); |
| #endif |
| |
| /* |
| * access() needs to use the real uid/gid, not the effective uid/gid. |
| * We do this by temporarily clearing all FS-related capabilities and |
| * switching the fsuid/fsgid around to the real ones. |
| */ |
| SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) |
| { |
| const struct cred *old_cred; |
| struct cred *override_cred; |
| struct path path; |
| struct inode *inode; |
| int res; |
| |
| if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ |
| return -EINVAL; |
| |
| override_cred = prepare_creds(); |
| if (!override_cred) |
| return -ENOMEM; |
| |
| override_cred->fsuid = override_cred->uid; |
| override_cred->fsgid = override_cred->gid; |
| |
| if (!issecure(SECURE_NO_SETUID_FIXUP)) { |
| /* Clear the capabilities if we switch to a non-root user */ |
| kuid_t root_uid = make_kuid(override_cred->user_ns, 0); |
| if (!uid_eq(override_cred->uid, root_uid)) |
| cap_clear(override_cred->cap_effective); |
| else |
| override_cred->cap_effective = |
| override_cred->cap_permitted; |
| } |
| |
| old_cred = override_creds(override_cred); |
| |
| res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); |
| if (res) |
| goto out; |
| |
| inode = path.dentry->d_inode; |
| |
| if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { |
| /* |
| * MAY_EXEC on regular files is denied if the fs is mounted |
| * with the "noexec" flag. |
| */ |
| res = -EACCES; |
| if (path.mnt->mnt_flags & MNT_NOEXEC) |
| goto out_path_release; |
| } |
| |
| res = inode_permission(inode, mode | MAY_ACCESS); |
| /* SuS v2 requires we report a read only fs too */ |
| if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) |
| goto out_path_release; |
| /* |
| * This is a rare case where using __mnt_is_readonly() |
| * is OK without a mnt_want/drop_write() pair. Since |
| * no actual write to the fs is performed here, we do |
| * not need to telegraph to that to anyone. |
| * |
| * By doing this, we accept that this access is |
| * inherently racy and know that the fs may change |
| * state before we even see this result. |
| */ |
| if (__mnt_is_readonly(path.mnt)) |
| res = -EROFS; |
| |
| out_path_release: |
| path_put(&path); |
| out: |
| revert_creds(old_cred); |
| put_cred(override_cred); |
| return res; |
| } |
| |
| SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) |
| { |
| return sys_faccessat(AT_FDCWD, filename, mode); |
| } |
| |
| SYSCALL_DEFINE1(chdir, const char __user *, filename) |
| { |
| struct path path; |
| int error; |
| |
| error = user_path_dir(filename, &path); |
| if (error) |
| goto out; |
| |
| error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); |
| if (error) |
| goto dput_and_out; |
| |
| set_fs_pwd(current->fs, &path); |
| |
| dput_and_out: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE1(fchdir, unsigned int, fd) |
| { |
| struct file *file; |
| struct inode *inode; |
| int error, fput_needed; |
| |
| error = -EBADF; |
| file = fget_raw_light(fd, &fput_needed); |
| if (!file) |
| goto out; |
| |
| inode = file->f_path.dentry->d_inode; |
| |
| error = -ENOTDIR; |
| if (!S_ISDIR(inode->i_mode)) |
| goto out_putf; |
| |
| error = inode_permission(inode, MAY_EXEC | MAY_CHDIR); |
| if (!error) |
| set_fs_pwd(current->fs, &file->f_path); |
| out_putf: |
| fput_light(file, fput_needed); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE1(chroot, const char __user *, filename) |
| { |
| struct path path; |
| int error; |
| |
| error = user_path_dir(filename, &path); |
| if (error) |
| goto out; |
| |
| error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); |
| if (error) |
| goto dput_and_out; |
| |
| error = -EPERM; |
| if (!capable(CAP_SYS_CHROOT)) |
| goto dput_and_out; |
| error = security_path_chroot(&path); |
| if (error) |
| goto dput_and_out; |
| |
| set_fs_root(current->fs, &path); |
| error = 0; |
| dput_and_out: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| static int chmod_common(struct path *path, umode_t mode) |
| { |
| struct inode *inode = path->dentry->d_inode; |
| struct iattr newattrs; |
| int error; |
| |
| error = mnt_want_write(path->mnt); |
| if (error) |
| return error; |
| mutex_lock(&inode->i_mutex); |
| error = security_path_chmod(path, mode); |
| if (error) |
| goto out_unlock; |
| newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); |
| newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; |
| error = notify_change(path->dentry, &newattrs); |
| out_unlock: |
| mutex_unlock(&inode->i_mutex); |
| mnt_drop_write(path->mnt); |
| return error; |
| } |
| |
| SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) |
| { |
| struct file * file; |
| int err = -EBADF; |
| |
| file = fget(fd); |
| if (file) { |
| audit_inode(NULL, file->f_path.dentry); |
| err = chmod_common(&file->f_path, mode); |
| fput(file); |
| } |
| return err; |
| } |
| |
| SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode) |
| { |
| struct path path; |
| int error; |
| |
| error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); |
| if (!error) { |
| error = chmod_common(&path, mode); |
| path_put(&path); |
| } |
| return error; |
| } |
| |
| SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) |
| { |
| return sys_fchmodat(AT_FDCWD, filename, mode); |
| } |
| |
| static int chown_common(struct path *path, uid_t user, gid_t group) |
| { |
| struct inode *inode = path->dentry->d_inode; |
| int error; |
| struct iattr newattrs; |
| kuid_t uid; |
| kgid_t gid; |
| |
| uid = make_kuid(current_user_ns(), user); |
| gid = make_kgid(current_user_ns(), group); |
| |
| newattrs.ia_valid = ATTR_CTIME; |
| if (user != (uid_t) -1) { |
| if (!uid_valid(uid)) |
| return -EINVAL; |
| newattrs.ia_valid |= ATTR_UID; |
| newattrs.ia_uid = uid; |
| } |
| if (group != (gid_t) -1) { |
| if (!gid_valid(gid)) |
| return -EINVAL; |
| newattrs.ia_valid |= ATTR_GID; |
| newattrs.ia_gid = gid; |
| } |
| if (!S_ISDIR(inode->i_mode)) |
| newattrs.ia_valid |= |
| ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; |
| mutex_lock(&inode->i_mutex); |
| error = security_path_chown(path, user, group); |
| if (!error) |
| error = notify_change(path->dentry, &newattrs); |
| mutex_unlock(&inode->i_mutex); |
| |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) |
| { |
| struct path path; |
| int error; |
| |
| error = user_path(filename, &path); |
| if (error) |
| goto out; |
| error = mnt_want_write(path.mnt); |
| if (error) |
| goto out_release; |
| error = chown_common(&path, user, group); |
| mnt_drop_write(path.mnt); |
| out_release: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, |
| gid_t, group, int, flag) |
| { |
| struct path path; |
| int error = -EINVAL; |
| int lookup_flags; |
| |
| if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) |
| goto out; |
| |
| lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; |
| if (flag & AT_EMPTY_PATH) |
| lookup_flags |= LOOKUP_EMPTY; |
| error = user_path_at(dfd, filename, lookup_flags, &path); |
| if (error) |
| goto out; |
| error = mnt_want_write(path.mnt); |
| if (error) |
| goto out_release; |
| error = chown_common(&path, user, group); |
| mnt_drop_write(path.mnt); |
| out_release: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) |
| { |
| struct path path; |
| int error; |
| |
| error = user_lpath(filename, &path); |
| if (error) |
| goto out; |
| error = mnt_want_write(path.mnt); |
| if (error) |
| goto out_release; |
| error = chown_common(&path, user, group); |
| mnt_drop_write(path.mnt); |
| out_release: |
| path_put(&path); |
| out: |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) |
| { |
| struct file * file; |
| int error = -EBADF; |
| struct dentry * dentry; |
| |
| file = fget(fd); |
| if (!file) |
| goto out; |
| |
| error = mnt_want_write_file(file); |
| if (error) |
| goto out_fput; |
| dentry = file->f_path.dentry; |
| audit_inode(NULL, dentry); |
| error = chown_common(&file->f_path, user, group); |
| mnt_drop_write_file(file); |
| out_fput: |
| fput(file); |
| out: |
| return error; |
| } |
| |
| /* |
| * You have to be very careful that these write |
| * counts get cleaned up in error cases and |
| * upon __fput(). This should probably never |
| * be called outside of __dentry_open(). |
| */ |
| static inline int __get_file_write_access(struct inode *inode, |
| struct vfsmount *mnt) |
| { |
| int error; |
| error = get_write_access(inode); |
| if (error) |
| return error; |
| /* |
| * Do not take mount writer counts on |
| * special files since no writes to |
| * the mount itself will occur. |
| */ |
| if (!special_file(inode->i_mode)) { |
| /* |
| * Balanced in __fput() |
| */ |
| error = mnt_want_write(mnt); |
| if (error) |
| put_write_access(inode); |
| } |
| return error; |
| } |
| |
| int open_check_o_direct(struct file *f) |
| { |
| /* NB: we're sure to have correct a_ops only after f_op->open */ |
| if (f->f_flags & O_DIRECT) { |
| if (!f->f_mapping->a_ops || |
| ((!f->f_mapping->a_ops->direct_IO) && |
| (!f->f_mapping->a_ops->get_xip_mem))) { |
| return -EINVAL; |
| } |
| } |
| return 0; |
| } |
| |
| static struct file *do_dentry_open(struct dentry *dentry, struct vfsmount *mnt, |
| struct file *f, |
| int (*open)(struct inode *, struct file *), |
| const struct cred *cred) |
| { |
| static const struct file_operations empty_fops = {}; |
| struct inode *inode; |
| int error; |
| |
| f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | |
| FMODE_PREAD | FMODE_PWRITE; |
| |
| if (unlikely(f->f_flags & O_PATH)) |
| f->f_mode = FMODE_PATH; |
| |
| inode = dentry->d_inode; |
| if (f->f_mode & FMODE_WRITE) { |
| error = __get_file_write_access(inode, mnt); |
| if (error) |
| goto cleanup_file; |
| if (!special_file(inode->i_mode)) |
| file_take_write(f); |
| } |
| |
| f->f_mapping = inode->i_mapping; |
| f->f_path.dentry = dentry; |
| f->f_path.mnt = mnt; |
| f->f_pos = 0; |
| file_sb_list_add(f, inode->i_sb); |
| |
| if (unlikely(f->f_mode & FMODE_PATH)) { |
| f->f_op = &empty_fops; |
| return f; |
| } |
| |
| f->f_op = fops_get(inode->i_fop); |
| |
| error = security_file_open(f, cred); |
| if (error) |
| goto cleanup_all; |
| |
| error = break_lease(inode, f->f_flags); |
| if (error) |
| goto cleanup_all; |
| |
| if (!open && f->f_op) |
| open = f->f_op->open; |
| if (open) { |
| error = open(inode, f); |
| if (error) |
| goto cleanup_all; |
| } |
| if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
| i_readcount_inc(inode); |
| |
| f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); |
| |
| file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); |
| |
| return f; |
| |
| cleanup_all: |
| fops_put(f->f_op); |
| if (f->f_mode & FMODE_WRITE) { |
| put_write_access(inode); |
| if (!special_file(inode->i_mode)) { |
| /* |
| * We don't consider this a real |
| * mnt_want/drop_write() pair |
| * because it all happenend right |
| * here, so just reset the state. |
| */ |
| file_reset_write(f); |
| mnt_drop_write(mnt); |
| } |
| } |
| file_sb_list_del(f); |
| f->f_path.dentry = NULL; |
| f->f_path.mnt = NULL; |
| cleanup_file: |
| dput(dentry); |
| mntput(mnt); |
| return ERR_PTR(error); |
| } |
| |
| static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, |
| struct file *f, |
| int (*open)(struct inode *, struct file *), |
| const struct cred *cred) |
| { |
| struct file *res = do_dentry_open(dentry, mnt, f, open, cred); |
| if (!IS_ERR(res)) { |
| int error = open_check_o_direct(f); |
| if (error) { |
| fput(res); |
| res = ERR_PTR(error); |
| } |
| } else { |
| put_filp(f); |
| } |
| return res; |
| } |
| |
| /** |
| * lookup_instantiate_filp - instantiates the open intent filp |
| * @nd: pointer to nameidata |
| * @dentry: pointer to dentry |
| * @open: open callback |
| * |
| * Helper for filesystems that want to use lookup open intents and pass back |
| * a fully instantiated struct file to the caller. |
| * This function is meant to be called from within a filesystem's |
| * lookup method. |
| * Beware of calling it for non-regular files! Those ->open methods might block |
| * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, |
| * leading to a deadlock, as nobody can open that fifo anymore, because |
| * another process to open fifo will block on locked parent when doing lookup). |
| * Note that in case of error, nd->intent.open.file is destroyed, but the |
| * path information remains valid. |
| * If the open callback is set to NULL, then the standard f_op->open() |
| * filesystem callback is substituted. |
| */ |
| struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, |
| int (*open)(struct inode *, struct file *)) |
| { |
| const struct cred *cred = current_cred(); |
| |
| if (IS_ERR(nd->intent.open.file)) |
| goto out; |
| if (IS_ERR(dentry)) |
| goto out_err; |
| nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), |
| nd->intent.open.file, |
| open, cred); |
| out: |
| return nd->intent.open.file; |
| out_err: |
| release_open_intent(nd); |
| nd->intent.open.file = ERR_CAST(dentry); |
| goto out; |
| } |
| EXPORT_SYMBOL_GPL(lookup_instantiate_filp); |
| |
| /** |
| * finish_open - finish opening a file |
| * @od: opaque open data |
| * @dentry: pointer to dentry |
| * @open: open callback |
| * |
| * This can be used to finish opening a file passed to i_op->atomic_open(). |
| * |
| * If the open callback is set to NULL, then the standard f_op->open() |
| * filesystem callback is substituted. |
| */ |
| struct file *finish_open(struct opendata *od, struct dentry *dentry, |
| int (*open)(struct inode *, struct file *)) |
| { |
| struct file *res; |
| |
| mntget(od->mnt); |
| dget(dentry); |
| |
| res = do_dentry_open(dentry, od->mnt, *od->filp, open, current_cred()); |
| if (!IS_ERR(res)) |
| *od->filp = NULL; |
| |
| return res; |
| } |
| EXPORT_SYMBOL(finish_open); |
| |
| /** |
| * finish_no_open - finish ->atomic_open() without opening the file |
| * |
| * @od: opaque open data |
| * @dentry: dentry or NULL (as returned from ->lookup()) |
| * |
| * This can be used to set the result of a successful lookup in ->atomic_open(). |
| * The filesystem's atomic_open() method shall return NULL after calling this. |
| */ |
| void finish_no_open(struct opendata *od, struct dentry *dentry) |
| { |
| od->dentry = dentry; |
| } |
| EXPORT_SYMBOL(finish_no_open); |
| |
| /** |
| * nameidata_to_filp - convert a nameidata to an open filp. |
| * @nd: pointer to nameidata |
| * @flags: open flags |
| * |
| * Note that this function destroys the original nameidata |
| */ |
| struct file *nameidata_to_filp(struct nameidata *nd) |
| { |
| const struct cred *cred = current_cred(); |
| struct file *filp; |
| |
| /* Pick up the filp from the open intent */ |
| filp = nd->intent.open.file; |
| |
| /* Has the filesystem initialised the file for us? */ |
| if (filp->f_path.dentry != NULL) { |
| nd->intent.open.file = NULL; |
| } else { |
| struct file *res; |
| |
| path_get(&nd->path); |
| res = do_dentry_open(nd->path.dentry, nd->path.mnt, |
| filp, NULL, cred); |
| if (!IS_ERR(res)) { |
| int error; |
| |
| nd->intent.open.file = NULL; |
| BUG_ON(res != filp); |
| |
| error = open_check_o_direct(filp); |
| if (error) { |
| fput(filp); |
| filp = ERR_PTR(error); |
| } |
| } else { |
| /* Allow nd->intent.open.file to be recycled */ |
| filp = res; |
| } |
| } |
| return filp; |
| } |
| |
| /* |
| * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an |
| * error. |
| */ |
| struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags, |
| const struct cred *cred) |
| { |
| int error; |
| struct file *f; |
| |
| validate_creds(cred); |
| |
| /* We must always pass in a valid mount pointer. */ |
| BUG_ON(!mnt); |
| |
| error = -ENFILE; |
| f = get_empty_filp(); |
| if (f == NULL) { |
| dput(dentry); |
| mntput(mnt); |
| return ERR_PTR(error); |
| } |
| |
| f->f_flags = flags; |
| return __dentry_open(dentry, mnt, f, NULL, cred); |
| } |
| EXPORT_SYMBOL(dentry_open); |
| |
| static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
| { |
| struct fdtable *fdt = files_fdtable(files); |
| __clear_open_fd(fd, fdt); |
| if (fd < files->next_fd) |
| files->next_fd = fd; |
| } |
| |
| void put_unused_fd(unsigned int fd) |
| { |
| struct files_struct *files = current->files; |
| spin_lock(&files->file_lock); |
| __put_unused_fd(files, fd); |
| spin_unlock(&files->file_lock); |
| } |
| |
| EXPORT_SYMBOL(put_unused_fd); |
| |
| /* |
| * Install a file pointer in the fd array. |
| * |
| * The VFS is full of places where we drop the files lock between |
| * setting the open_fds bitmap and installing the file in the file |
| * array. At any such point, we are vulnerable to a dup2() race |
| * installing a file in the array before us. We need to detect this and |
| * fput() the struct file we are about to overwrite in this case. |
| * |
| * It should never happen - if we allow dup2() do it, _really_ bad things |
| * will follow. |
| */ |
| |
| void fd_install(unsigned int fd, struct file *file) |
| { |
| struct files_struct *files = current->files; |
| struct fdtable *fdt; |
| spin_lock(&files->file_lock); |
| fdt = files_fdtable(files); |
| BUG_ON(fdt->fd[fd] != NULL); |
| rcu_assign_pointer(fdt->fd[fd], file); |
| spin_unlock(&files->file_lock); |
| } |
| |
| EXPORT_SYMBOL(fd_install); |
| |
| static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) |
| { |
| int lookup_flags = 0; |
| int acc_mode; |
| |
| if (!(flags & O_CREAT)) |
| mode = 0; |
| op->mode = mode; |
| |
| /* Must never be set by userspace */ |
| flags &= ~FMODE_NONOTIFY; |
| |
| /* |
| * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only |
| * check for O_DSYNC if the need any syncing at all we enforce it's |
| * always set instead of having to deal with possibly weird behaviour |
| * for malicious applications setting only __O_SYNC. |
| */ |
| if (flags & __O_SYNC) |
| flags |= O_DSYNC; |
| |
| /* |
| * If we have O_PATH in the open flag. Then we |
| * cannot have anything other than the below set of flags |
| */ |
| if (flags & O_PATH) { |
| flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH; |
| acc_mode = 0; |
| } else { |
| acc_mode = MAY_OPEN | ACC_MODE(flags); |
| } |
| |
| op->open_flag = flags; |
| |
| /* O_TRUNC implies we need access checks for write permissions */ |
| if (flags & O_TRUNC) |
| acc_mode |= MAY_WRITE; |
| |
| /* Allow the LSM permission hook to distinguish append |
| access from general write access. */ |
| if (flags & O_APPEND) |
| acc_mode |= MAY_APPEND; |
| |
| op->acc_mode = acc_mode; |
| |
| op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN; |
| |
| if (flags & O_CREAT) { |
| op->intent |= LOOKUP_CREATE; |
| if (flags & O_EXCL) |
| op->intent |= LOOKUP_EXCL; |
| } |
| |
| if (flags & O_DIRECTORY) |
| lookup_flags |= LOOKUP_DIRECTORY; |
| if (!(flags & O_NOFOLLOW)) |
| lookup_flags |= LOOKUP_FOLLOW; |
| return lookup_flags; |
| } |
| |
| /** |
| * filp_open - open file and return file pointer |
| * |
| * @filename: path to open |
| * @flags: open flags as per the open(2) second argument |
| * @mode: mode for the new file if O_CREAT is set, else ignored |
| * |
| * This is the helper to open a file from kernelspace if you really |
| * have to. But in generally you should not do this, so please move |
| * along, nothing to see here.. |
| */ |
| struct file *filp_open(const char *filename, int flags, umode_t mode) |
| { |
| struct open_flags op; |
| int lookup = build_open_flags(flags, mode, &op); |
| return do_filp_open(AT_FDCWD, filename, &op, lookup); |
| } |
| EXPORT_SYMBOL(filp_open); |
| |
| struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
| const char *filename, int flags) |
| { |
| struct open_flags op; |
| int lookup = build_open_flags(flags, 0, &op); |
| if (flags & O_CREAT) |
| return ERR_PTR(-EINVAL); |
| if (!filename && (flags & O_DIRECTORY)) |
| if (!dentry->d_inode->i_op->lookup) |
| return ERR_PTR(-ENOTDIR); |
| return do_file_open_root(dentry, mnt, filename, &op, lookup); |
| } |
| EXPORT_SYMBOL(file_open_root); |
| |
| long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) |
| { |
| struct open_flags op; |
| int lookup = build_open_flags(flags, mode, &op); |
| char *tmp = getname(filename); |
| int fd = PTR_ERR(tmp); |
| |
| if (!IS_ERR(tmp)) { |
| fd = get_unused_fd_flags(flags); |
| if (fd >= 0) { |
| struct file *f = do_filp_open(dfd, tmp, &op, lookup); |
| if (IS_ERR(f)) { |
| put_unused_fd(fd); |
| fd = PTR_ERR(f); |
| } else { |
| fsnotify_open(f); |
| fd_install(fd, f); |
| } |
| } |
| putname(tmp); |
| } |
| return fd; |
| } |
| |
| SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) |
| { |
| long ret; |
| |
| if (force_o_largefile()) |
| flags |= O_LARGEFILE; |
| |
| ret = do_sys_open(AT_FDCWD, filename, flags, mode); |
| /* avoid REGPARM breakage on x86: */ |
| asmlinkage_protect(3, ret, filename, flags, mode); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, |
| umode_t, mode) |
| { |
| long ret; |
| |
| if (force_o_largefile()) |
| flags |= O_LARGEFILE; |
| |
| ret = do_sys_open(dfd, filename, flags, mode); |
| /* avoid REGPARM breakage on x86: */ |
| asmlinkage_protect(4, ret, dfd, filename, flags, mode); |
| return ret; |
| } |
| |
| #ifndef __alpha__ |
| |
| /* |
| * For backward compatibility? Maybe this should be moved |
| * into arch/i386 instead? |
| */ |
| SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode) |
| { |
| return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); |
| } |
| |
| #endif |
| |
| /* |
| * "id" is the POSIX thread ID. We use the |
| * files pointer for this.. |
| */ |
| int filp_close(struct file *filp, fl_owner_t id) |
| { |
| int retval = 0; |
| |
| if (!file_count(filp)) { |
| printk(KERN_ERR "VFS: Close: file count is 0\n"); |
| return 0; |
| } |
| |
| if (filp->f_op && filp->f_op->flush) |
| retval = filp->f_op->flush(filp, id); |
| |
| if (likely(!(filp->f_mode & FMODE_PATH))) { |
| dnotify_flush(filp, id); |
| locks_remove_posix(filp, id); |
| } |
| fput(filp); |
| return retval; |
| } |
| |
| EXPORT_SYMBOL(filp_close); |
| |
| /* |
| * Careful here! We test whether the file pointer is NULL before |
| * releasing the fd. This ensures that one clone task can't release |
| * an fd while another clone is opening it. |
| */ |
| SYSCALL_DEFINE1(close, unsigned int, fd) |
| { |
| struct file * filp; |
| struct files_struct *files = current->files; |
| struct fdtable *fdt; |
| int retval; |
| |
| spin_lock(&files->file_lock); |
| fdt = files_fdtable(files); |
| if (fd >= fdt->max_fds) |
| goto out_unlock; |
| filp = fdt->fd[fd]; |
| if (!filp) |
| goto out_unlock; |
| rcu_assign_pointer(fdt->fd[fd], NULL); |
| __clear_close_on_exec(fd, fdt); |
| __put_unused_fd(files, fd); |
| spin_unlock(&files->file_lock); |
| retval = filp_close(filp, files); |
| |
| /* can't restart close syscall because file table entry was cleared */ |
| if (unlikely(retval == -ERESTARTSYS || |
| retval == -ERESTARTNOINTR || |
| retval == -ERESTARTNOHAND || |
| retval == -ERESTART_RESTARTBLOCK)) |
| retval = -EINTR; |
| |
| return retval; |
| |
| out_unlock: |
| spin_unlock(&files->file_lock); |
| return -EBADF; |
| } |
| EXPORT_SYMBOL(sys_close); |
| |
| /* |
| * This routine simulates a hangup on the tty, to arrange that users |
| * are given clean terminals at login time. |
| */ |
| SYSCALL_DEFINE0(vhangup) |
| { |
| if (capable(CAP_SYS_TTY_CONFIG)) { |
| tty_vhangup_self(); |
| return 0; |
| } |
| return -EPERM; |
| } |
| |
| /* |
| * Called when an inode is about to be open. |
| * We use this to disallow opening large files on 32bit systems if |
| * the caller didn't specify O_LARGEFILE. On 64bit systems we force |
| * on this flag in sys_open. |
| */ |
| int generic_file_open(struct inode * inode, struct file * filp) |
| { |
| if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) |
| return -EOVERFLOW; |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(generic_file_open); |
| |
| /* |
| * This is used by subsystems that don't want seekable |
| * file descriptors. The function is not supposed to ever fail, the only |
| * reason it returns an 'int' and not 'void' is so that it can be plugged |
| * directly into file_operations structure. |
| */ |
| int nonseekable_open(struct inode *inode, struct file *filp) |
| { |
| filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(nonseekable_open); |