/* * 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/quotaops.h> #include <linux/fsnotify.h> #include <linux/module.h> #include <linux/slab.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/vfs.h> #include <linux/fcntl.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 "internal.h" int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) { int retval = -ENODEV; if (dentry) { retval = -ENOSYS; if (dentry->d_sb->s_op->statfs) { memset(buf, 0, sizeof(*buf)); retval = security_sb_statfs(dentry); if (retval) return retval; retval = dentry->d_sb->s_op->statfs(dentry, buf); if (retval == 0 && buf->f_frsize == 0) buf->f_frsize = buf->f_bsize; } } return retval; } EXPORT_SYMBOL(vfs_statfs); static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf) { struct kstatfs st; int retval; retval = vfs_statfs(dentry, &st); if (retval) return retval; if (sizeof(*buf) == sizeof(st)) memcpy(buf, &st, sizeof(st)); else { if (sizeof buf->f_blocks == 4) { if ((st.f_blocks | st.f_bfree | st.f_bavail | st.f_bsize | st.f_frsize) & 0xffffffff00000000ULL) return -EOVERFLOW; /* * f_files and f_ffree may be -1; it's okay to stuff * that into 32 bits */ if (st.f_files != -1 && (st.f_files & 0xffffffff00000000ULL)) return -EOVERFLOW; if (st.f_ffree != -1 && (st.f_ffree & 0xffffffff00000000ULL)) return -EOVERFLOW; } buf->f_type = st.f_type; buf->f_bsize = st.f_bsize; buf->f_blocks = st.f_blocks; buf->f_bfree = st.f_bfree; buf->f_bavail = st.f_bavail; buf->f_files = st.f_files; buf->f_ffree = st.f_ffree; buf->f_fsid = st.f_fsid; buf->f_namelen = st.f_namelen; buf->f_frsize = st.f_frsize; memset(buf->f_spare, 0, sizeof(buf->f_spare)); } return 0; } static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf) { struct kstatfs st; int retval; retval = vfs_statfs(dentry, &st); if (retval) return retval; if (sizeof(*buf) == sizeof(st)) memcpy(buf, &st, sizeof(st)); else { buf->f_type = st.f_type; buf->f_bsize = st.f_bsize; buf->f_blocks = st.f_blocks; buf->f_bfree = st.f_bfree; buf->f_bavail = st.f_bavail; buf->f_files = st.f_files; buf->f_ffree = st.f_ffree; buf->f_fsid = st.f_fsid; buf->f_namelen = st.f_namelen; buf->f_frsize = st.f_frsize; memset(buf->f_spare, 0, sizeof(buf->f_spare)); } return 0; } SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf) { struct path path; int error; error = user_path(pathname, &path); if (!error) { struct statfs tmp; error = vfs_statfs_native(path.dentry, &tmp); if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) error = -EFAULT; path_put(&path); } return error; } SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf) { struct path path; long error; if (sz != sizeof(*buf)) return -EINVAL; error = user_path(pathname, &path); if (!error) { struct statfs64 tmp; error = vfs_statfs64(path.dentry, &tmp); if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) error = -EFAULT; path_put(&path); } return error; } SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf) { struct file * file; struct statfs tmp; int error; error = -EBADF; file = fget(fd); if (!file) goto out; error = vfs_statfs_native(file->f_path.dentry, &tmp); if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) error = -EFAULT; fput(file); out: return error; } SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf) { struct file * file; struct statfs64 tmp; int error; if (sz != sizeof(*buf)) return -EINVAL; error = -EBADF; file = fget(fd); if (!file) goto out; error = vfs_statfs64(file->f_path.dentry, &tmp); if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) error = -EFAULT; fput(file); out: return error; } 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, FMODE_WRITE); if (error) goto put_write_and_out; error = locks_verify_truncate(inode, NULL, length); if (!error) error = security_path_truncate(&path, length, 0); if (!error) { vfs_dq_init(inode); 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, length, ATTR_MTIME|ATTR_CTIME); 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 && !(mode & FALLOC_FL_KEEP_SIZE)) return -EOPNOTSUPP; if (!(file->f_mode & FMODE_WRITE)) return -EBADF; /* * 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 (!inode->i_op->fallocate) return -EOPNOTSUPP; return inode->i_op->fallocate(inode, 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 */ if (override_cred->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_ACCESS); 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; error = -EBADF; file = fget(fd); 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_ACCESS); if (!error) set_fs_pwd(current->fs, &file->f_path); out_putf: fput(file); 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_ACCESS); 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; } SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode) { struct inode * inode; struct dentry * dentry; struct file * file; int err = -EBADF; struct iattr newattrs; file = fget(fd); if (!file) goto out; dentry = file->f_path.dentry; inode = dentry->d_inode; audit_inode(NULL, dentry); err = mnt_want_write_file(file); if (err) goto out_putf; mutex_lock(&inode->i_mutex); err = security_path_chmod(dentry, file->f_vfsmnt, mode); if (err) goto out_unlock; if (mode == (mode_t) -1) mode = inode->i_mode; newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; err = notify_change(dentry, &newattrs); out_unlock: mutex_unlock(&inode->i_mutex); mnt_drop_write(file->f_path.mnt); out_putf: fput(file); out: return err; } SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode) { struct path path; struct inode *inode; int error; struct iattr newattrs; error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); if (error) goto out; inode = path.dentry->d_inode; error = mnt_want_write(path.mnt); if (error) goto dput_and_out; mutex_lock(&inode->i_mutex); error = security_path_chmod(path.dentry, path.mnt, mode); if (error) goto out_unlock; if (mode == (mode_t) -1) mode = inode->i_mode; 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); dput_and_out: path_put(&path); out: return error; } SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_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; newattrs.ia_valid = ATTR_CTIME; if (user != (uid_t) -1) { newattrs.ia_valid |= ATTR_UID; newattrs.ia_uid = user; } if (group != (gid_t) -1) { newattrs.ia_valid |= ATTR_GID; newattrs.ia_gid = group; } 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 follow; if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) goto out; follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; error = user_path_at(dfd, filename, follow, &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->f_path.mnt); 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; } 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 inode *inode; int error; f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; 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; f->f_op = fops_get(inode->i_fop); file_move(f, &inode->i_sb->s_files); error = security_dentry_open(f, cred); 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; } ima_counts_get(f); f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); /* 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))) { fput(f); f = ERR_PTR(-EINVAL); } } 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_kill(f); f->f_path.dentry = NULL; f->f_path.mnt = NULL; cleanup_file: put_filp(f); dput(dentry); mntput(mnt); return ERR_PTR(error); } /** * 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 = (struct file *)dentry; goto out; } EXPORT_SYMBOL_GPL(lookup_instantiate_filp); /** * 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) filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, NULL, cred); else path_put(&nd->path); 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. Historically * callers got away with not passing it, but we must enforce this at * the earliest possible point now to avoid strange problems deep in the * filesystem stack. */ if (!mnt) { printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); dump_stack(); return ERR_PTR(-EINVAL); } 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); __FD_CLR(fd, fdt->open_fds); 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); long do_sys_open(int dfd, const char __user *filename, int flags, int mode) { 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, flags, mode, 0); if (IS_ERR(f)) { put_unused_fd(fd); fd = PTR_ERR(f); } else { fsnotify_open(f->f_path.dentry); fd_install(fd, f); } } putname(tmp); } return fd; } SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, 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, int, 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, int, 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); 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); FD_CLR(fd, fdt->close_on_exec); __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 */ int nonseekable_open(struct inode *inode, struct file *filp) { filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); return 0; } EXPORT_SYMBOL(nonseekable_open);