diff options
Diffstat (limited to 'drivers/block/ublk_drv.c')
| -rw-r--r-- | drivers/block/ublk_drv.c | 152 |
1 files changed, 146 insertions, 6 deletions
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 883f7974d105..a725a236a38f 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -42,6 +42,7 @@ #include <linux/mm.h> #include <asm/page.h> #include <linux/task_work.h> +#include <linux/namei.h> #include <uapi/linux/ublk_cmd.h> #define UBLK_MINORS (1U << MINORBITS) @@ -51,7 +52,8 @@ | UBLK_F_URING_CMD_COMP_IN_TASK \ | UBLK_F_NEED_GET_DATA \ | UBLK_F_USER_RECOVERY \ - | UBLK_F_USER_RECOVERY_REISSUE) + | UBLK_F_USER_RECOVERY_REISSUE \ + | UBLK_F_UNPRIVILEGED_DEV) /* All UBLK_PARAM_TYPE_* should be included here */ #define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \ @@ -1618,6 +1620,17 @@ out_free_cpumask: return ret; } +static void ublk_store_owner_uid_gid(struct ublksrv_ctrl_dev_info *info) +{ + kuid_t uid; + kgid_t gid; + + current_uid_gid(&uid, &gid); + + info->owner_uid = from_kuid(&init_user_ns, uid); + info->owner_gid = from_kgid(&init_user_ns, gid); +} + static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info) { pr_devel("%s: dev id %d flags %llx\n", __func__, @@ -1641,15 +1654,26 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) __func__, header->queue_id); return -EINVAL; } + if (copy_from_user(&info, argp, sizeof(info))) return -EFAULT; - ublk_dump_dev_info(&info); + + if (capable(CAP_SYS_ADMIN)) + info.flags &= ~UBLK_F_UNPRIVILEGED_DEV; + else if (!(info.flags & UBLK_F_UNPRIVILEGED_DEV)) + return -EPERM; + + /* the created device is always owned by current user */ + ublk_store_owner_uid_gid(&info); + if (header->dev_id != info.dev_id) { pr_warn("%s: dev id not match %u %u\n", __func__, header->dev_id, info.dev_id); return -EINVAL; } + ublk_dump_dev_info(&info); + ret = mutex_lock_killable(&ublk_ctl_mutex); if (ret) return ret; @@ -1982,6 +2006,115 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, return ret; } +/* + * All control commands are sent via /dev/ublk-control, so we have to check + * the destination device's permission + */ +static int ublk_char_dev_permission(struct ublk_device *ub, + const char *dev_path, int mask) +{ + int err; + struct path path; + struct kstat stat; + + err = kern_path(dev_path, LOOKUP_FOLLOW, &path); + if (err) + return err; + + err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT); + if (err) + goto exit; + + err = -EPERM; + if (stat.rdev != ub->cdev_dev.devt || !S_ISCHR(stat.mode)) + goto exit; + + err = inode_permission(&init_user_ns, + d_backing_inode(path.dentry), mask); +exit: + path_put(&path); + return err; +} + +static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub, + struct io_uring_cmd *cmd) +{ + struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd; + bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV; + void __user *argp = (void __user *)(unsigned long)header->addr; + char *dev_path = NULL; + int ret = 0; + int mask; + + if (!unprivileged) { + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + /* + * The new added command of UBLK_CMD_GET_DEV_INFO2 includes + * char_dev_path in payload too, since userspace may not + * know if the specified device is created as unprivileged + * mode. + */ + if (cmd->cmd_op != UBLK_CMD_GET_DEV_INFO2) + return 0; + } + + /* + * User has to provide the char device path for unprivileged ublk + * + * header->addr always points to the dev path buffer, and + * header->dev_path_len records length of dev path buffer. + */ + if (!header->dev_path_len || header->dev_path_len > PATH_MAX) + return -EINVAL; + + if (header->len < header->dev_path_len) + return -EINVAL; + + dev_path = kmalloc(header->dev_path_len + 1, GFP_KERNEL); + if (!dev_path) + return -ENOMEM; + + ret = -EFAULT; + if (copy_from_user(dev_path, argp, header->dev_path_len)) + goto exit; + dev_path[header->dev_path_len] = 0; + + ret = -EINVAL; + switch (cmd->cmd_op) { + case UBLK_CMD_GET_DEV_INFO: + case UBLK_CMD_GET_DEV_INFO2: + case UBLK_CMD_GET_QUEUE_AFFINITY: + case UBLK_CMD_GET_PARAMS: + mask = MAY_READ; + break; + case UBLK_CMD_START_DEV: + case UBLK_CMD_STOP_DEV: + case UBLK_CMD_ADD_DEV: + case UBLK_CMD_DEL_DEV: + case UBLK_CMD_SET_PARAMS: + case UBLK_CMD_START_USER_RECOVERY: + case UBLK_CMD_END_USER_RECOVERY: + mask = MAY_READ | MAY_WRITE; + break; + default: + goto exit; + } + + ret = ublk_char_dev_permission(ub, dev_path, mask); + if (!ret) { + header->len -= header->dev_path_len; + header->addr += header->dev_path_len; + } + pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n", + __func__, ub->ub_number, cmd->cmd_op, + ub->dev_info.owner_uid, ub->dev_info.owner_gid, + dev_path, ret); +exit: + kfree(dev_path); + return ret; +} + static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { @@ -1997,17 +2130,21 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, if (!(issue_flags & IO_URING_F_SQE128)) goto out; - ret = -EPERM; - if (!capable(CAP_SYS_ADMIN)) - goto out; - if (cmd->cmd_op != UBLK_CMD_ADD_DEV) { ret = -ENODEV; ub = ublk_get_device_from_id(header->dev_id); if (!ub) goto out; + + ret = ublk_ctrl_uring_cmd_permission(ub, cmd); + } else { + /* ADD_DEV permission check is done in command handler */ + ret = 0; } + if (ret) + goto put_dev; + switch (cmd->cmd_op) { case UBLK_CMD_START_DEV: ret = ublk_ctrl_start_dev(ub, cmd); @@ -2016,6 +2153,7 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, ret = ublk_ctrl_stop_dev(ub); break; case UBLK_CMD_GET_DEV_INFO: + case UBLK_CMD_GET_DEV_INFO2: ret = ublk_ctrl_get_dev_info(ub, cmd); break; case UBLK_CMD_ADD_DEV: @@ -2043,6 +2181,8 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, ret = -ENOTSUPP; break; } + + put_dev: if (ub) ublk_put_device(ub); out: |