SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode) { struct path path; struct inode *inode; int error; struct iattr newattrs; unsigned int lookup_flags = LOOKUP_FOLLOW; retry: error = user_path_at(dfd, filename, lookup_flags, &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); 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); mutex_unlock(&inode->i_mutex); mnt_drop_write(path.mnt); dput_and_out: 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) { 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_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; }
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_ACCESS); 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; }
int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat, int flag) { struct path path; int error = -EINVAL; unsigned int lookup_flags = 0; if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | AT_EMPTY_PATH)) != 0) goto out; if (!(flag & AT_SYMLINK_NOFOLLOW)) lookup_flags |= 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 = vfs_getattr(&path, stat); path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } out: return error; }
SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname, char __user *, buf, int, bufsiz) { struct path path; int error; int empty = 0; unsigned int lookup_flags = LOOKUP_EMPTY; if (bufsiz <= 0) return -EINVAL; retry: error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty); if (!error) { struct inode *inode = d_backing_inode(path.dentry); error = empty ? -ENOENT : -EINVAL; if (inode->i_op->readlink) { error = security_inode_readlink(path.dentry); if (!error) { touch_atime(&path); error = inode->i_op->readlink(path.dentry, buf, bufsiz); } } path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } } return error; }
/* * do_utimes - change times on filename or file descriptor * @dfd: open file descriptor, -1 or AT_FDCWD * @filename: path name or NULL * @times: new times or NULL * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment) * * If filename is NULL and dfd refers to an open file, then operate on * the file. Otherwise look up filename, possibly using dfd as a * starting point. * * If times==NULL, set access and modification to current time, * must be owner or have write permission. * Else, update from *times, must be owner or super user. */ long do_utimes(int dfd, const char __user *filename, struct timespec *times, int flags) { int error = -EINVAL; if (times && (!nsec_valid(times[0].tv_nsec) || !nsec_valid(times[1].tv_nsec))) { goto out; } if (flags & ~AT_SYMLINK_NOFOLLOW) goto out; if (filename == NULL && dfd != AT_FDCWD) { struct fd f; if (flags & AT_SYMLINK_NOFOLLOW) goto out; f = fdget(dfd); error = -EBADF; if (!f.file) goto out; error = utimes_common(&f.file->f_path, times); fdput(f); } else { struct path path; int lookup_flags = 0; if (!(flags & AT_SYMLINK_NOFOLLOW)) lookup_flags |= LOOKUP_FOLLOW; retry: error = user_path_at(dfd, filename, lookup_flags, &path); if (error) goto out; error = utimes_common(&path, times); path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } } out: return error; }
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; }
int user_statfs(const char __user *pathname, struct kstatfs *st) { struct path path; int error; unsigned int lookup_flags = LOOKUP_FOLLOW; retry: error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path); if (!error) { error = vfs_statfs(&path, st); path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } } return error; }
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; }
/* * 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_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) 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)) { 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)) { res = -EACCES; if (path.mnt->mnt_flags & MNT_NOEXEC) goto out_path_release; } res = inode_permission(inode, mode | MAY_ACCESS); if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) goto out_path_release; 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; }