ublk_drv: add mechanism for supporting unprivileged ublk device

[linux-block.git] / include / uapi / linux / ublk_cmd.h

diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 8f88e3a29998fb6e79672e3122caa88d11331945..f6238ccc7800c91677ed4e84f3c049e9feac8b1b 100644 (file)
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -19,6 +19,8 @@
 #define        UBLK_CMD_GET_PARAMS     0x09
 #define        UBLK_CMD_START_USER_RECOVERY    0x10
 #define        UBLK_CMD_END_USER_RECOVERY      0x11
+#define        UBLK_CMD_GET_DEV_INFO2          0x12
+
 /*
  * IO commands, issued by ublk server, and handled by ublk driver.
  *
@@ -79,6 +81,27 @@
 
 #define UBLK_F_USER_RECOVERY_REISSUE   (1UL << 4)
 
+/*
+ * Unprivileged user can create /dev/ublkcN and /dev/ublkbN.
+ *
+ * /dev/ublk-control needs to be available for unprivileged user, and it
+ * can be done via udev rule to make all control commands available to
+ * unprivileged user. Except for the command of UBLK_CMD_ADD_DEV, all
+ * other commands are only allowed for the owner of the specified device.
+ *
+ * When userspace sends UBLK_CMD_ADD_DEV, the device pair's owner_uid and
+ * owner_gid are stored to ublksrv_ctrl_dev_info by kernel, so far only
+ * the current user's uid/gid is stored, that said owner of the created
+ * device is always the current user.
+ *
+ * We still need udev rule to apply OWNER/GROUP with the stored owner_uid
+ * and owner_gid.
+ *
+ * Then ublk server can be run as unprivileged user, and /dev/ublkbN can
+ * be accessed and managed by its owner represented by owner_uid/owner_gid.
+ */
+#define UBLK_F_UNPRIVILEGED_DEV        (1UL << 5)
+
 /* device state */
 #define UBLK_S_DEV_DEAD        0
 #define UBLK_S_DEV_LIVE        1
@@ -98,7 +121,15 @@ struct ublksrv_ctrl_cmd {
        __u64   addr;
 
        /* inline data */
-       __u64   data[2];
+       __u64   data[1];
+
+       /*
+        * Used for UBLK_F_UNPRIVILEGED_DEV and UBLK_CMD_GET_DEV_INFO2
+        * only, include null char
+        */
+       __u16   dev_path_len;
+       __u16   pad;
+       __u32   reserved;
 };
 
 struct ublksrv_ctrl_dev_info {
@@ -118,7 +149,8 @@ struct ublksrv_ctrl_dev_info {
        /* For ublksrv internal use, invisible to ublk driver */
        __u64   ublksrv_flags;
 
-       __u64   reserved0;
+       __u32   owner_uid;      /* store by kernel */
+       __u32   owner_gid;      /* store by kernel */
        __u64   reserved1;
        __u64   reserved2;
 };
@@ -214,6 +246,17 @@ struct ublk_param_discard {
        __u16   reserved0;
 };
 
+/*
+ * read-only, can't set via UBLK_CMD_SET_PARAMS, disk_devt is available
+ * after device is started
+ */
+struct ublk_param_devt {
+       __u32   char_major;
+       __u32   char_minor;
+       __u32   disk_major;
+       __u32   disk_minor;
+};
+
 struct ublk_params {
        /*
         * Total length of parameters, userspace has to set 'len' for both
@@ -224,10 +267,12 @@ struct ublk_params {
        __u32   len;
 #define UBLK_PARAM_TYPE_BASIC           (1 << 0)
 #define UBLK_PARAM_TYPE_DISCARD         (1 << 1)
+#define UBLK_PARAM_TYPE_DEVT            (1 << 2)
        __u32   types;                  /* types of parameter included */
 
        struct ublk_param_basic         basic;
        struct ublk_param_discard       discard;
+       struct ublk_param_devt          devt;
 };
 
 #endif