/fs/open.c
C | 1084 lines | 778 code | 154 blank | 152 comment | 144 complexity | 52e987725663343208ce66784ec5ee75 MD5 | raw file
Possible License(s): AGPL-1.0, GPL-2.0, LGPL-2.0
- /*
- * 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;
- }
- long vfs_truncate(struct path *path, loff_t length)
- {
- struct inode *inode;
- long error;
- inode = path->dentry->d_inode;
- /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
- if (S_ISDIR(inode->i_mode))
- return -EISDIR;
- if (!S_ISREG(inode->i_mode))
- return -EINVAL;
- error = mnt_want_write(path->mnt);
- if (error)
- goto 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);
- out:
- return error;
- }
- EXPORT_SYMBOL_GPL(vfs_truncate);
- static long do_sys_truncate(const char __user *pathname, loff_t length)
- {
- unsigned int lookup_flags = LOOKUP_FOLLOW;
- struct path path;
- int error;
- if (length < 0) /* sorry, but loff_t says... */
- return -EINVAL;
- retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
- if (!error) {
- error = vfs_truncate(&path, length);
- path_put(&path);
- }
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- 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 fd f;
- int error;
- error = -EINVAL;
- if (length < 0)
- goto out;
- error = -EBADF;
- f = fdget(fd);
- if (!f.file)
- goto out;
- /* explicitly opened as large or we are on 64-bit box */
- if (f.file->f_flags & O_LARGEFILE)
- small = 0;
- dentry = f.file->f_path.dentry;
- inode = dentry->d_inode;
- error = -EINVAL;
- if (!S_ISREG(inode->i_mode) || !(f.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;
- sb_start_write(inode->i_sb);
- error = locks_verify_truncate(inode, f.file, length);
- if (!error)
- error = security_path_truncate(&f.file->f_path);
- if (!error)
- error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
- sb_end_write(inode->i_sb);
- out_putf:
- fdput(f);
- 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;
- sb_start_write(inode->i_sb);
- ret = file->f_op->fallocate(file, mode, offset, len);
- sb_end_write(inode->i_sb);
- return ret;
- }
- SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
- {
- struct fd f = fdget(fd);
- int error = -EBADF;
- if (f.file) {
- error = do_fallocate(f.file, mode, offset, len);
- fdput(f);
- }
- 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;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
- 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);
- retry:
- res = user_path_at(dfd, filename, lookup_flags, &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);
- if (retry_estale(res, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- 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;
- unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
- retry:
- error = user_path_at(AT_FDCWD, filename, lookup_flags, &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);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- out:
- return error;
- }
- SYSCALL_DEFINE1(fchdir, unsigned int, fd)
- {
- struct fd f = fdget_raw(fd);
- struct inode *inode;
- int error = -EBADF;
- error = -EBADF;
- if (!f.file)
- goto out;
- inode = f.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, &f.file->f_path);
- out_putf:
- fdput(f);
- out:
- return error;
- }
- SYSCALL_DEFINE1(chroot, const char __user *, filename)
- {
- struct path path;
- int error;
- unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
- retry:
- error = user_path_at(AT_FDCWD, filename, lookup_flags, &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 (!nsown_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);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- 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, 0);
- 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;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
- retry:
- error = user_path_at(dfd, filename, lookup_flags, &path);
- if (!error) {
- error = chmod_common(&path, mode);
- path_put(&path);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- }
- 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, uid, gid);
- if (!error)
- error = notify_change(path->dentry, &newattrs);
- mutex_unlock(&inode->i_mutex);
- 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;
- retry:
- 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);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- out:
- return error;
- }
- SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
- {
- return sys_fchownat(AT_FDCWD, filename, user, group, 0);
- }
- SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
- {
- return sys_fchownat(AT_FDCWD, filename, user, group,
- AT_SYMLINK_NOFOLLOW);
- }
- SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
- {
- struct fd f = fdget(fd);
- int error = -EBADF;
- if (!f.file)
- goto out;
- error = mnt_want_write_file(f.file);
- if (error)
- goto out_fput;
- audit_inode(NULL, f.file->f_path.dentry, 0);
- error = chown_common(&f.file->f_path, user, group);
- mnt_drop_write_file(f.file);
- out_fput:
- fdput(f);
- 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 = get_write_access(inode);
- if (error)
- return error;
- 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 int do_dentry_open(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;
- path_get(&f->f_path);
- inode = f->f_path.dentry->d_inode;
- if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
- error = __get_file_write_access(inode, f->f_path.mnt);
- if (error)
- goto cleanup_file;
- file_take_write(f);
- }
- f->f_mapping = inode->i_mapping;
- 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 0;
- }
- 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 0;
- cleanup_all:
- fops_put(f->f_op);
- file_sb_list_del(f);
- if (f->f_mode & FMODE_WRITE) {
- 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.
- */
- put_write_access(inode);
- file_reset_write(f);
- __mnt_drop_write(f->f_path.mnt);
- }
- }
- cleanup_file:
- path_put(&f->f_path);
- f->f_path.mnt = NULL;
- f->f_path.dentry = NULL;
- return error;
- }
- /**
- * 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.
- */
- int finish_open(struct file *file, struct dentry *dentry,
- int (*open)(struct inode *, struct file *),
- int *opened)
- {
- int error;
- BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
- file->f_path.dentry = dentry;
- error = do_dentry_open(file, open, current_cred());
- if (!error)
- *opened |= FILE_OPENED;
- return error;
- }
- 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.
- */
- int finish_no_open(struct file *file, struct dentry *dentry)
- {
- file->f_path.dentry = dentry;
- return 1;
- }
- EXPORT_SYMBOL(finish_no_open);
- struct file *dentry_open(const struct path *path, 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(!path->mnt);
- error = -ENFILE;
- f = get_empty_filp();
- if (f == NULL)
- return ERR_PTR(error);
- f->f_flags = flags;
- f->f_path = *path;
- error = do_dentry_open(f, NULL, cred);
- if (!error) {
- error = open_check_o_direct(f);
- if (error) {
- fput(f);
- f = ERR_PTR(error);
- }
- } else {
- put_filp(f);
- f = ERR_PTR(error);
- }
- return f;
- }
- EXPORT_SYMBOL(dentry_open);
- 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)
- op->mode = (mode & S_IALLUGO) | S_IFREG;
- else
- op->mode = 0;
- /* Must never be set by userspace */
- flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
- /*
- * 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;
- }
- /**
- * file_open_name - open file and return file pointer
- *
- * @name: struct filename containing 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 *file_open_name(struct filename *name, int flags, umode_t mode)
- {
- struct open_flags op;
- int lookup = build_open_flags(flags, mode, &op);
- return do_filp_open(AT_FDCWD, name, &op, lookup);
- }
- /**
- * 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 filename name = {.name = filename};
- return file_open_name(&name, flags, mode);
- }
- 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);
- struct filename *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)
- {
- int retval = __close_fd(current->files, fd);
- /* 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;
- }
- 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);