diff options
Diffstat (limited to 'fs/open.c')
| -rw-r--r-- | fs/open.c | 1536 |
1 files changed, 1536 insertions, 0 deletions
diff --git a/fs/open.c b/fs/open.c new file mode 100644 index 000000000..51dc46620 --- /dev/null +++ b/fs/open.c @@ -0,0 +1,1536 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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 <linux/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 <linux/compat.h> +#include <linux/mnt_idmapping.h> + +#include "internal.h" + +int do_truncate(struct user_namespace *mnt_userns, 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, and file capabilities on truncate too */ + ret = dentry_needs_remove_privs(mnt_userns, dentry); + if (ret < 0) + return ret; + if (ret) + newattrs.ia_valid |= ret | ATTR_FORCE; + + inode_lock(dentry->d_inode); + /* Note any delegations or leases have already been broken: */ + ret = notify_change(mnt_userns, dentry, &newattrs, NULL); + inode_unlock(dentry->d_inode); + return ret; +} + +long vfs_truncate(const struct path *path, loff_t length) +{ + struct user_namespace *mnt_userns; + 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; + + mnt_userns = mnt_user_ns(path->mnt); + error = inode_permission(mnt_userns, 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 = security_path_truncate(path); + if (!error) + error = do_truncate(mnt_userns, 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); + +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); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length) +{ + return do_sys_truncate(path, length); +} +#endif + +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; + /* Check IS_APPEND on real upper inode */ + if (IS_APPEND(file_inode(f.file))) + goto out_putf; + sb_start_write(inode->i_sb); + error = security_path_truncate(&f.file->f_path); + if (!error) + error = do_truncate(file_mnt_user_ns(f.file), 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) +{ + return do_sys_ftruncate(fd, length, 1); +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length) +{ + return do_sys_ftruncate(fd, length, 1); +} +#endif + +/* LFS versions of truncate are only needed on 32 bit machines */ +#if BITS_PER_LONG == 32 +SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length) +{ + return do_sys_truncate(path, length); +} + +SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length) +{ + return do_sys_ftruncate(fd, length, 0); +} +#endif /* BITS_PER_LONG == 32 */ + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64) +COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname, + compat_arg_u64_dual(length)) +{ + return ksys_truncate(pathname, compat_arg_u64_glue(length)); +} +#endif + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64) +COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd, + compat_arg_u64_dual(length)) +{ + return ksys_ftruncate(fd, compat_arg_u64_glue(length)); +} +#endif + +int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) +{ + struct inode *inode = file_inode(file); + long ret; + + if (offset < 0 || len <= 0) + return -EINVAL; + + /* Return error if mode is not supported */ + if (mode & ~FALLOC_FL_SUPPORTED_MASK) + return -EOPNOTSUPP; + + /* Punch hole and zero range are mutually exclusive */ + if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) == + (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) + return -EOPNOTSUPP; + + /* Punch hole must have keep size set */ + if ((mode & FALLOC_FL_PUNCH_HOLE) && + !(mode & FALLOC_FL_KEEP_SIZE)) + return -EOPNOTSUPP; + + /* Collapse range should only be used exclusively. */ + if ((mode & FALLOC_FL_COLLAPSE_RANGE) && + (mode & ~FALLOC_FL_COLLAPSE_RANGE)) + return -EINVAL; + + /* Insert range should only be used exclusively. */ + if ((mode & FALLOC_FL_INSERT_RANGE) && + (mode & ~FALLOC_FL_INSERT_RANGE)) + return -EINVAL; + + /* Unshare range should only be used with allocate mode. */ + if ((mode & FALLOC_FL_UNSHARE_RANGE) && + (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE))) + return -EINVAL; + + if (!(file->f_mode & FMODE_WRITE)) + return -EBADF; + + /* + * We can only allow pure fallocate on append only files + */ + if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode)) + return -EPERM; + + if (IS_IMMUTABLE(inode)) + return -EPERM; + + /* + * We cannot allow any fallocate operation on an active swapfile + */ + if (IS_SWAPFILE(inode)) + return -ETXTBSY; + + /* + * 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; + + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + + if (!S_ISREG(inode->i_mode) && !S_ISBLK(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; + + file_start_write(file); + ret = file->f_op->fallocate(file, mode, offset, len); + + /* + * Create inotify and fanotify events. + * + * To keep the logic simple always create events if fallocate succeeds. + * This implies that events are even created if the file size remains + * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE. + */ + if (ret == 0) + fsnotify_modify(file); + + file_end_write(file); + return ret; +} +EXPORT_SYMBOL_GPL(vfs_fallocate); + +int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (f.file) { + error = vfs_fallocate(f.file, mode, offset, len); + fdput(f); + } + return error; +} + +SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len) +{ + return ksys_fallocate(fd, mode, offset, len); +} + +#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE) +COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset), + compat_arg_u64_dual(len)) +{ + return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset), + compat_arg_u64_glue(len)); +} +#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. + */ +static const struct cred *access_override_creds(void) +{ + const struct cred *old_cred; + struct cred *override_cred; + + override_cred = prepare_creds(); + if (!override_cred) + return NULL; + + 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; + } + + /* + * The new set of credentials can *only* be used in + * task-synchronous circumstances, and does not need + * RCU freeing, unless somebody then takes a separate + * reference to it. + * + * NOTE! This is _only_ true because this credential + * is used purely for override_creds() that installs + * it as the subjective cred. Other threads will be + * accessing ->real_cred, not the subjective cred. + * + * If somebody _does_ make a copy of this (using the + * 'get_current_cred()' function), that will clear the + * non_rcu field, because now that other user may be + * expecting RCU freeing. But normal thread-synchronous + * cred accesses will keep things non-RCY. + */ + override_cred->non_rcu = 1; + + old_cred = override_creds(override_cred); + + /* override_cred() gets its own ref */ + put_cred(override_cred); + + return old_cred; +} + +static long do_faccessat(int dfd, const char __user *filename, int mode, int flags) +{ + struct path path; + struct inode *inode; + int res; + unsigned int lookup_flags = LOOKUP_FOLLOW; + const struct cred *old_cred = NULL; + + if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ + return -EINVAL; + + if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) + return -EINVAL; + + if (flags & AT_SYMLINK_NOFOLLOW) + lookup_flags &= ~LOOKUP_FOLLOW; + if (flags & AT_EMPTY_PATH) + lookup_flags |= LOOKUP_EMPTY; + + if (!(flags & AT_EACCESS)) { + old_cred = access_override_creds(); + if (!old_cred) + return -ENOMEM; + } + +retry: + res = user_path_at(dfd, filename, lookup_flags, &path); + if (res) + goto out; + + inode = d_backing_inode(path.dentry); + + 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_noexec(&path)) + goto out_path_release; + } + + res = inode_permission(mnt_user_ns(path.mnt), 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: + if (old_cred) + revert_creds(old_cred); + + return res; +} + +SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) +{ + return do_faccessat(dfd, filename, mode, 0); +} + +SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode, + int, flags) +{ + return do_faccessat(dfd, filename, mode, flags); +} + +SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) +{ + return do_faccessat(AT_FDCWD, filename, mode, 0); +} + +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 = path_permission(&path, 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); + int error; + + error = -EBADF; + if (!f.file) + goto out; + + error = -ENOTDIR; + if (!d_can_lookup(f.file->f_path.dentry)) + goto out_putf; + + error = file_permission(f.file, 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 = path_permission(&path, MAY_EXEC | MAY_CHDIR); + if (error) + goto dput_and_out; + + error = -EPERM; + if (!ns_capable(current_user_ns(), 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; +} + +int chmod_common(const struct path *path, umode_t mode) +{ + struct inode *inode = path->dentry->d_inode; + struct inode *delegated_inode = NULL; + struct iattr newattrs; + int error; + + error = mnt_want_write(path->mnt); + if (error) + return error; +retry_deleg: + inode_lock(inode); + 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(mnt_user_ns(path->mnt), path->dentry, + &newattrs, &delegated_inode); +out_unlock: + inode_unlock(inode); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + mnt_drop_write(path->mnt); + return error; +} + +int vfs_fchmod(struct file *file, umode_t mode) +{ + audit_file(file); + return chmod_common(&file->f_path, mode); +} + +SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) +{ + struct fd f = fdget(fd); + int err = -EBADF; + + if (f.file) { + err = vfs_fchmod(f.file, mode); + fdput(f); + } + return err; +} + +static int do_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_DEFINE3(fchmodat, int, dfd, const char __user *, filename, + umode_t, mode) +{ + return do_fchmodat(dfd, filename, mode); +} + +SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) +{ + return do_fchmodat(AT_FDCWD, filename, mode); +} + +/** + * setattr_vfsuid - check and set ia_fsuid attribute + * @kuid: new inode owner + * + * Check whether @kuid is valid and if so generate and set vfsuid_t in + * ia_vfsuid. + * + * Return: true if @kuid is valid, false if not. + */ +static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid) +{ + if (!uid_valid(kuid)) + return false; + attr->ia_valid |= ATTR_UID; + attr->ia_vfsuid = VFSUIDT_INIT(kuid); + return true; +} + +/** + * setattr_vfsgid - check and set ia_fsgid attribute + * @kgid: new inode owner + * + * Check whether @kgid is valid and if so generate and set vfsgid_t in + * ia_vfsgid. + * + * Return: true if @kgid is valid, false if not. + */ +static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid) +{ + if (!gid_valid(kgid)) + return false; + attr->ia_valid |= ATTR_GID; + attr->ia_vfsgid = VFSGIDT_INIT(kgid); + return true; +} + +int chown_common(const struct path *path, uid_t user, gid_t group) +{ + struct user_namespace *mnt_userns, *fs_userns; + struct inode *inode = path->dentry->d_inode; + struct inode *delegated_inode = NULL; + 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); + + mnt_userns = mnt_user_ns(path->mnt); + fs_userns = i_user_ns(inode); + +retry_deleg: + newattrs.ia_vfsuid = INVALID_VFSUID; + newattrs.ia_vfsgid = INVALID_VFSGID; + newattrs.ia_valid = ATTR_CTIME; + if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid)) + return -EINVAL; + if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid)) + return -EINVAL; + inode_lock(inode); + if (!S_ISDIR(inode->i_mode)) + newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV | + setattr_should_drop_sgid(mnt_userns, inode); + /* Continue to send actual fs values, not the mount values. */ + error = security_path_chown( + path, + from_vfsuid(mnt_userns, fs_userns, newattrs.ia_vfsuid), + from_vfsgid(mnt_userns, fs_userns, newattrs.ia_vfsgid)); + if (!error) + error = notify_change(mnt_userns, path->dentry, &newattrs, + &delegated_inode); + inode_unlock(inode); + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + return error; +} + +int do_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_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, + gid_t, group, int, flag) +{ + return do_fchownat(dfd, filename, user, group, flag); +} + +SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, 0); +} + +SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, + AT_SYMLINK_NOFOLLOW); +} + +int vfs_fchown(struct file *file, uid_t user, gid_t group) +{ + int error; + + error = mnt_want_write_file(file); + if (error) + return error; + audit_file(file); + error = chown_common(&file->f_path, user, group); + mnt_drop_write_file(file); + return error; +} + +int ksys_fchown(unsigned int fd, uid_t user, gid_t group) +{ + struct fd f = fdget(fd); + int error = -EBADF; + + if (f.file) { + error = vfs_fchown(f.file, user, group); + fdput(f); + } + return error; +} + +SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) +{ + return ksys_fchown(fd, user, group); +} + +static int do_dentry_open(struct file *f, + struct inode *inode, + int (*open)(struct inode *, struct file *)) +{ + static const struct file_operations empty_fops = {}; + int error; + + path_get(&f->f_path); + f->f_inode = inode; + f->f_mapping = inode->i_mapping; + f->f_wb_err = filemap_sample_wb_err(f->f_mapping); + f->f_sb_err = file_sample_sb_err(f); + + if (unlikely(f->f_flags & O_PATH)) { + f->f_mode = FMODE_PATH | FMODE_OPENED; + f->f_op = &empty_fops; + return 0; + } + + if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) { + i_readcount_inc(inode); + } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) { + error = get_write_access(inode); + if (unlikely(error)) + goto cleanup_file; + error = __mnt_want_write(f->f_path.mnt); + if (unlikely(error)) { + put_write_access(inode); + goto cleanup_file; + } + f->f_mode |= FMODE_WRITER; + } + + /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */ + if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) + f->f_mode |= FMODE_ATOMIC_POS; + + f->f_op = fops_get(inode->i_fop); + if (WARN_ON(!f->f_op)) { + error = -ENODEV; + goto cleanup_all; + } + + error = security_file_open(f); + if (error) + goto cleanup_all; + + error = break_lease(locks_inode(f), f->f_flags); + if (error) + goto cleanup_all; + + /* normally all 3 are set; ->open() can clear them if needed */ + f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; + if (!open) + open = f->f_op->open; + if (open) { + error = open(inode, f); + if (error) + goto cleanup_all; + } + f->f_mode |= FMODE_OPENED; + if ((f->f_mode & FMODE_READ) && + likely(f->f_op->read || f->f_op->read_iter)) + f->f_mode |= FMODE_CAN_READ; + if ((f->f_mode & FMODE_WRITE) && + likely(f->f_op->write || f->f_op->write_iter)) + f->f_mode |= FMODE_CAN_WRITE; + if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek) + f->f_mode &= ~FMODE_LSEEK; + if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO) + f->f_mode |= FMODE_CAN_ODIRECT; + + f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); + f->f_iocb_flags = iocb_flags(f); + + file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); + + if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; + + /* + * XXX: Huge page cache doesn't support writing yet. Drop all page + * cache for this file before processing writes. + */ + if (f->f_mode & FMODE_WRITE) { + /* + * Paired with smp_mb() in collapse_file() to ensure nr_thps + * is up to date and the update to i_writecount by + * get_write_access() is visible. Ensures subsequent insertion + * of THPs into the page cache will fail. + */ + smp_mb(); + if (filemap_nr_thps(inode->i_mapping)) { + struct address_space *mapping = inode->i_mapping; + + filemap_invalidate_lock(inode->i_mapping); + /* + * unmap_mapping_range just need to be called once + * here, because the private pages is not need to be + * unmapped mapping (e.g. data segment of dynamic + * shared libraries here). + */ + unmap_mapping_range(mapping, 0, 0, 0); + truncate_inode_pages(mapping, 0); + filemap_invalidate_unlock(inode->i_mapping); + } + } + + return 0; + +cleanup_all: + if (WARN_ON_ONCE(error > 0)) + error = -EINVAL; + fops_put(f->f_op); + put_file_access(f); +cleanup_file: + path_put(&f->f_path); + f->f_path.mnt = NULL; + f->f_path.dentry = NULL; + f->f_inode = NULL; + return error; +} + +/** + * finish_open - finish opening a file + * @file: file pointer + * @dentry: pointer to dentry + * @open: open callback + * @opened: state of open + * + * 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. + * + * NB: the dentry reference is _not_ consumed. If, for example, the dentry is + * the return value of d_splice_alias(), then the caller needs to perform dput() + * on it after finish_open(). + * + * Returns zero on success or -errno if the open failed. + */ +int finish_open(struct file *file, struct dentry *dentry, + int (*open)(struct inode *, struct file *)) +{ + BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ + + file->f_path.dentry = dentry; + return do_dentry_open(file, d_backing_inode(dentry), open); +} +EXPORT_SYMBOL(finish_open); + +/** + * finish_no_open - finish ->atomic_open() without opening the file + * + * @file: file pointer + * @dentry: dentry or NULL (as returned from ->lookup()) + * + * This can be used to set the result of a successful lookup in ->atomic_open(). + * + * NB: unlike finish_open() this function does consume the dentry reference and + * the caller need not dput() it. + * + * Returns "0" which must be the return value of ->atomic_open() after having + * called this function. + */ +int finish_no_open(struct file *file, struct dentry *dentry) +{ + file->f_path.dentry = dentry; + return 0; +} +EXPORT_SYMBOL(finish_no_open); + +char *file_path(struct file *filp, char *buf, int buflen) +{ + return d_path(&filp->f_path, buf, buflen); +} +EXPORT_SYMBOL(file_path); + +/** + * vfs_open - open the file at the given path + * @path: path to open + * @file: newly allocated file with f_flag initialized + * @cred: credentials to use + */ +int vfs_open(const struct path *path, struct file *file) +{ + file->f_path = *path; + return do_dentry_open(file, d_backing_inode(path->dentry), NULL); +} + +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); + + f = alloc_empty_file(flags, cred); + if (!IS_ERR(f)) { + error = vfs_open(path, f); + if (error) { + fput(f); + f = ERR_PTR(error); + } + } + return f; +} +EXPORT_SYMBOL(dentry_open); + +/** + * dentry_create - Create and open a file + * @path: path to create + * @flags: O_ flags + * @mode: mode bits for new file + * @cred: credentials to use + * + * Caller must hold the parent directory's lock, and have prepared + * a negative dentry, placed in @path->dentry, for the new file. + * + * Caller sets @path->mnt to the vfsmount of the filesystem where + * the new file is to be created. The parent directory and the + * negative dentry must reside on the same filesystem instance. + * + * On success, returns a "struct file *". Otherwise a ERR_PTR + * is returned. + */ +struct file *dentry_create(const struct path *path, int flags, umode_t mode, + const struct cred *cred) +{ + struct file *f; + int error; + + validate_creds(cred); + f = alloc_empty_file(flags, cred); + if (IS_ERR(f)) + return f; + + error = vfs_create(mnt_user_ns(path->mnt), + d_inode(path->dentry->d_parent), + path->dentry, mode, true); + if (!error) + error = vfs_open(path, f); + + if (unlikely(error)) { + fput(f); + return ERR_PTR(error); + } + return f; +} +EXPORT_SYMBOL(dentry_create); + +struct file *open_with_fake_path(const struct path *path, int flags, + struct inode *inode, const struct cred *cred) +{ + struct file *f = alloc_empty_file_noaccount(flags, cred); + if (!IS_ERR(f)) { + int error; + + f->f_path = *path; + error = do_dentry_open(f, inode, NULL); + if (error) { + fput(f); + f = ERR_PTR(error); + } + } + return f; +} +EXPORT_SYMBOL(open_with_fake_path); + +#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) +#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) + +inline struct open_how build_open_how(int flags, umode_t mode) +{ + struct open_how how = { + .flags = flags & VALID_OPEN_FLAGS, + .mode = mode & S_IALLUGO, + }; + + /* O_PATH beats everything else. */ + if (how.flags & O_PATH) + how.flags &= O_PATH_FLAGS; + /* Modes should only be set for create-like flags. */ + if (!WILL_CREATE(how.flags)) + how.mode = 0; + return how; +} + +inline int build_open_flags(const struct open_how *how, struct open_flags *op) +{ + u64 flags = how->flags; + u64 strip = FMODE_NONOTIFY | O_CLOEXEC; + int lookup_flags = 0; + int acc_mode = ACC_MODE(flags); + + BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS), + "struct open_flags doesn't yet handle flags > 32 bits"); + + /* + * Strip flags that either shouldn't be set by userspace like + * FMODE_NONOTIFY or that aren't relevant in determining struct + * open_flags like O_CLOEXEC. + */ + flags &= ~strip; + + /* + * Older syscalls implicitly clear all of the invalid flags or argument + * values before calling build_open_flags(), but openat2(2) checks all + * of its arguments. + */ + if (flags & ~VALID_OPEN_FLAGS) + return -EINVAL; + if (how->resolve & ~VALID_RESOLVE_FLAGS) + return -EINVAL; + + /* Scoping flags are mutually exclusive. */ + if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT)) + return -EINVAL; + + /* Deal with the mode. */ + if (WILL_CREATE(flags)) { + if (how->mode & ~S_IALLUGO) + return -EINVAL; + op->mode = how->mode | S_IFREG; + } else { + if (how->mode != 0) + return -EINVAL; + op->mode = 0; + } + + /* + * Block bugs where O_DIRECTORY | O_CREAT created regular files. + * Note, that blocking O_DIRECTORY | O_CREAT here also protects + * O_TMPFILE below which requires O_DIRECTORY being raised. + */ + if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT)) + return -EINVAL; + + /* Now handle the creative implementation of O_TMPFILE. */ + if (flags & __O_TMPFILE) { + /* + * In order to ensure programs get explicit errors when trying + * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY + * is raised alongside __O_TMPFILE. + */ + if (!(flags & O_DIRECTORY)) + return -EINVAL; + if (!(acc_mode & MAY_WRITE)) + return -EINVAL; + } + if (flags & O_PATH) { + /* O_PATH only permits certain other flags to be set. */ + if (flags & ~O_PATH_FLAGS) + return -EINVAL; + acc_mode = 0; + } + + /* + * 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; + + 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; + flags |= O_NOFOLLOW; + } + } + + if (flags & O_DIRECTORY) + lookup_flags |= LOOKUP_DIRECTORY; + if (!(flags & O_NOFOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + + if (how->resolve & RESOLVE_NO_XDEV) + lookup_flags |= LOOKUP_NO_XDEV; + if (how->resolve & RESOLVE_NO_MAGICLINKS) + lookup_flags |= LOOKUP_NO_MAGICLINKS; + if (how->resolve & RESOLVE_NO_SYMLINKS) + lookup_flags |= LOOKUP_NO_SYMLINKS; + if (how->resolve & RESOLVE_BENEATH) + lookup_flags |= LOOKUP_BENEATH; + if (how->resolve & RESOLVE_IN_ROOT) + lookup_flags |= LOOKUP_IN_ROOT; + if (how->resolve & RESOLVE_CACHED) { + /* Don't bother even trying for create/truncate/tmpfile open */ + if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE)) + return -EAGAIN; + lookup_flags |= LOOKUP_CACHED; + } + + op->lookup_flags = lookup_flags; + return 0; +} + +/** + * 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; + struct open_how how = build_open_how(flags, mode); + int err = build_open_flags(&how, &op); + if (err) + return ERR_PTR(err); + return do_filp_open(AT_FDCWD, name, &op); +} + +/** + * 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 = getname_kernel(filename); + struct file *file = ERR_CAST(name); + + if (!IS_ERR(name)) { + file = file_open_name(name, flags, mode); + putname(name); + } + return file; +} +EXPORT_SYMBOL(filp_open); + +struct file *file_open_root(const struct path *root, + const char *filename, int flags, umode_t mode) +{ + struct open_flags op; + struct open_how how = build_open_how(flags, mode); + int err = build_open_flags(&how, &op); + if (err) + return ERR_PTR(err); + return do_file_open_root(root, filename, &op); +} +EXPORT_SYMBOL(file_open_root); + +static long do_sys_openat2(int dfd, const char __user *filename, + struct open_how *how) +{ + struct open_flags op; + int fd = build_open_flags(how, &op); + struct filename *tmp; + + if (fd) + return fd; + + tmp = getname(filename); + if (IS_ERR(tmp)) + return PTR_ERR(tmp); + + fd = get_unused_fd_flags(how->flags); + if (fd >= 0) { + struct file *f = do_filp_open(dfd, tmp, &op); + if (IS_ERR(f)) { + put_unused_fd(fd); + fd = PTR_ERR(f); + } else { + fsnotify_open(f); + fd_install(fd, f); + } + } + putname(tmp); + return fd; +} + +long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) +{ + struct open_how how = build_open_how(flags, mode); + return do_sys_openat2(dfd, filename, &how); +} + + +SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(AT_FDCWD, filename, flags, mode); +} + +SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, + umode_t, mode) +{ + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(dfd, filename, flags, mode); +} + +SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename, + struct open_how __user *, how, size_t, usize) +{ + int err; + struct open_how tmp; + + BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0); + BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST); + + if (unlikely(usize < OPEN_HOW_SIZE_VER0)) + return -EINVAL; + + err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize); + if (err) + return err; + + audit_openat2_how(&tmp); + + /* O_LARGEFILE is only allowed for non-O_PATH. */ + if (!(tmp.flags & O_PATH) && force_o_largefile()) + tmp.flags |= O_LARGEFILE; + + return do_sys_openat2(dfd, filename, &tmp); +} + +#ifdef CONFIG_COMPAT +/* + * Exactly like sys_open(), except that it doesn't set the + * O_LARGEFILE flag. + */ +COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) +{ + return do_sys_open(AT_FDCWD, filename, flags, mode); +} + +/* + * Exactly like sys_openat(), except that it doesn't set the + * O_LARGEFILE flag. + */ +COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode) +{ + return do_sys_open(dfd, filename, flags, mode); +} +#endif + +#ifndef __alpha__ + +/* + * For backward compatibility? Maybe this should be moved + * into arch/i386 instead? + */ +SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode) +{ + int flags = O_CREAT | O_WRONLY | O_TRUNC; + + if (force_o_largefile()) + flags |= O_LARGEFILE; + return do_sys_open(AT_FDCWD, pathname, flags, 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 (CHECK_DATA_CORRUPTION(file_count(filp) == 0, + "VFS: Close: file count is 0 (f_op=%ps)", + filp->f_op)) { + return 0; + } + + if (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(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; +} + +/** + * close_range() - Close all file descriptors in a given range. + * + * @fd: starting file descriptor to close + * @max_fd: last file descriptor to close + * @flags: reserved for future extensions + * + * This closes a range of file descriptors. All file descriptors + * from @fd up to and including @max_fd are closed. + * Currently, errors to close a given file descriptor are ignored. + */ +SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd, + unsigned int, flags) +{ + return __close_range(fd, max_fd, flags); +} + +/* + * 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); + +/* + * stream_open is used by subsystems that want stream-like file descriptors. + * Such file descriptors are not seekable and don't have notion of position + * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL). + * Contrary to file descriptors of other regular files, .read() and .write() + * can run simultaneously. + * + * stream_open never fails and is marked to return int so that it could be + * directly used as file_operations.open . + */ +int stream_open(struct inode *inode, struct file *filp) +{ + filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS); + filp->f_mode |= FMODE_STREAM; + return 0; +} + +EXPORT_SYMBOL(stream_open); |