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Re: [UNIKRAFT PATCH v2 05/15] plat/tap: Get/Set hw_addr



Hi Sharan,

Looks good to me so far. I only have a comment/question concerning
tap_mac_generate (inline).

regards,
Hugo

On Tue, 2020-06-30 at 11:58 +0200, Sharan Santhanam wrote:
> The patch implements support for generating a default hw_addr. The
> patch also implements get and set netdev api.
> 
> Signed-off-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>
> ---
>  plat/drivers/include/tap/tap.h              |  2 +
>  plat/drivers/tap/tap.c                      | 97
> ++++++++++++++++++++++++++++-
>  plat/linuxu/include/linuxu/syscall-arm_32.h |  1 +
>  plat/linuxu/include/linuxu/syscall-x86_64.h |  1 +
>  plat/linuxu/include/linuxu/syscall.h        | 25 ++++++++
>  plat/linuxu/include/linuxu/tap.h            |  7 +++
>  plat/linuxu/tap_io.c                        | 31 +++++++++
>  7 files changed, 161 insertions(+), 3 deletions(-)
> 
> diff --git a/plat/drivers/include/tap/tap.h
> b/plat/drivers/include/tap/tap.h
> index 3aa90b6..686b666 100644
> --- a/plat/drivers/include/tap/tap.h
> +++ b/plat/drivers/include/tap/tap.h
> @@ -45,5 +45,7 @@
>  int tap_open(__u32 flags);
>  int tap_close(int fd);
>  int tap_dev_configure(int fd, __u32 feature_flags, void *arg);
> +int tap_netif_configure(int fd, __u32 request, void *arg);
> +int tap_netif_create(void);
>  
>  #endif /* __PLAT_DRV_TAP_H */
> diff --git a/plat/drivers/tap/tap.c b/plat/drivers/tap/tap.c
> index acf958a..d60ca46 100644
> --- a/plat/drivers/tap/tap.c
> +++ b/plat/drivers/tap/tap.c
> @@ -92,12 +92,16 @@ struct tap_net_dev {
>       UK_TAILQ_HEAD(tap_txqs, struct uk_netdev_tx_queue) txqs;
>       /* The list of the tap device */
>       UK_TAILQ_ENTRY(struct tap_net_dev) next;
> +     /* Mac address of the device */
> +     struct uk_hwaddr hw_addr;
>       /* Tap Device identifier */
>       __u16 tid;
>       /* UK Netdevice identifier */
>       __u16 id;
>       /* File Descriptor for the tap device */
>       int tap_fd;
> +     /* Control socket descriptor */
> +     int ctrl_sock;
>       /* Name of the character device */
>       char name[IFNAMSIZ];
>       /* MTU of the device */
> @@ -170,6 +174,7 @@ static int tap_netdev_rxq_info_get(struct
> uk_netdev *dev, __u16 queue_id,
>  static int tap_netdev_txq_info_get(struct uk_netdev *dev, __u16
> queue_id,
>                                  struct uk_netdev_queue_info
> *qinfo);
>  static int tap_device_create(struct tap_net_dev *tdev, __u32
> feature_flags);
> +static int tap_mac_generate(__u8 *addr, int len, __u8 dev_id);
>  
>  /**
>   * Local function definitions
> @@ -284,16 +289,78 @@ static int tap_netdev_mtu_set(struct uk_netdev
> *n,  __u16 mtu __unused)
>  
>  static const struct uk_hwaddr *tap_netdev_mac_get(struct uk_netdev
> *n)
>  {
> +     struct tap_net_dev *tdev;
> +
>       UK_ASSERT(n);
> -     return NULL;
> +     tdev = to_tapnetdev(n);
> +     return &tdev->hw_addr;
>  }
>  
>  static int tap_netdev_mac_set(struct uk_netdev *n,
>                             const struct uk_hwaddr *hwaddr)
>  {
> -     int rc = -EINVAL;
> +     int rc = 0;
> +     struct tap_net_dev *tdev;
> +     struct uk_ifreq ifrq = {0};
>  
>       UK_ASSERT(n && hwaddr);
> +     tdev = to_tapnetdev(n);
> +
> +     snprintf(ifrq.ifr_name, sizeof(ifrq.ifr_name), "%s", tdev-
> >name);
> +     uk_pr_info("Setting mac address on tap device %s\n", tdev-
> >name);
> +
> +#ifdef CONFIG_TAP_DEV_DEBUG
> +     int  i;
> +
> +     for (i = 0; i < UK_NETDEV_HWADDR_LEN; i++) {
> +             uk_pr_debug("hw_address: %d - %d\n", i,
> +                         hwaddr->addr_bytes[i] & 0xFF);
> +     }
> +#endif /* CONFIG_TAP_DEV_DEBUG */
> +
> +     ifrq.ifr_hwaddr.sa_family = AF_LOCAL;
> +     memcpy(&ifrq.ifr_hwaddr.sa_data[0], &hwaddr->addr_bytes[0],
> +             UK_NETDEV_HWADDR_LEN);
> +     rc = tap_netif_configure(tdev->ctrl_sock, UK_SIOCSIFHWADDR,
> &ifrq);
> +     if (rc < 0) {
> +             uk_pr_err(DRIVER_NAME": Failed(%d) to set the
> hardware address\n",
> +                       rc);
> +             goto exit;
> +     }
> +     memcpy(&tdev->hw_addr, hwaddr, sizeof(*hwaddr));
> +
> +exit:
> +     return rc;
> +}
> +
> +static int tap_mac_generate(__u8 *addr, int len, __u8 dev_id)
> +{
> +     const char fmt[] = {0x2, 0x0, 0x0, 0x0, 0x0, 0x0};
> +
> +     UK_ASSERT(addr && len > 0);
> +
> +     if (len < UK_NETDEV_HWADDR_LEN) {
> +             uk_pr_err("Failed to generate the mac address\n");
> +             return -ENOSPC;
> +     }

What is the point of this `len` argument?

What happens if `len` is larger than UK_NETDEV_HWADDR_LEN?

To me this might result in OOB read if the caller assumes that `addr`
contains `len` > UK_NETDEV_HWADDR_LEN bytes of address data upon
returning of this function.

> +     memcpy(addr, fmt, UK_NETDEV_HWADDR_LEN - 1);
> +     *(addr + UK_NETDEV_HWADDR_LEN - 1) = (__u8) (dev_id + 1);
> +     return 0;
> +}
> +
> +static inline int tapdev_ctrlsock_create(struct tap_net_dev *tdev)
> +{
> +     int rc = 0;
> +
> +     rc = tap_netif_create();
> +     if (rc < 0) {
> +             uk_pr_err(DRIVER_NAME":Failed(%d) to create a
> control socket\n",
> +                       rc);
> +             goto exit;
> +     }
> +     tdev->ctrl_sock = rc;
> +     rc = 0;
> +exit:
>       return rc;
>  }
>  
> @@ -328,13 +395,37 @@ static int tap_netdev_configure(struct
> uk_netdev *n,
>               goto exit;
>       }
>  
> -     /* Initialize tx/rx queues list */
> +     /* Create a control socket for the network interface */
> +     rc = tapdev_ctrlsock_create(tdev);
> +     if (rc != 0) {
> +             uk_pr_err(DRIVER_NAME": Failed to create a control
> socket\n");
> +             goto close_tap_dev;
> +     }
> +
> +     /* Generate MAC address */
> +     tap_mac_generate(&tdev->hw_addr.addr_bytes[0],
> UK_NETDEV_HWADDR_LEN,
> +                      tdev->id);
> +
> +     /* MAC Address configuration */
> +     rc = tap_netdev_mac_set(n, &tdev->hw_addr);
> +     if (rc < 0) {
> +             uk_pr_err(DRIVER_NAME": Failed to set the mac
> address\n");
> +             goto close_ctrl_sock;
> +     }
> +
> +     /* Initialize the tx/rx queues */
>       UK_TAILQ_INIT(&tdev->rxqs);
>       tdev->rxq_cnt = 0;
>       UK_TAILQ_INIT(&tdev->txqs);
>       tdev->txq_cnt = 0;
>  exit:
>       return rc;
> +
> +close_ctrl_sock:
> +     tap_close(tdev->ctrl_sock);
> +close_tap_dev:
> +     tap_close(tdev->tap_fd);
> +     goto exit;
>  }
>  
>  static int tap_device_create(struct tap_net_dev *tdev, __u32
> feature_flags)
> diff --git a/plat/linuxu/include/linuxu/syscall-arm_32.h
> b/plat/linuxu/include/linuxu/syscall-arm_32.h
> index 093fd62..4b7218b 100644
> --- a/plat/linuxu/include/linuxu/syscall-arm_32.h
> +++ b/plat/linuxu/include/linuxu/syscall-arm_32.h
> @@ -56,6 +56,7 @@
>  #define __SC_TIMER_GETOVERRUN 260
>  #define __SC_TIMER_DELETE     261
>  #define __SC_CLOCK_GETTIME    263
> +#define __SC_SOCKET           281
>  #define __SC_PSELECT6 335
>  
>  #ifndef O_TMPFILE
> diff --git a/plat/linuxu/include/linuxu/syscall-x86_64.h
> b/plat/linuxu/include/linuxu/syscall-x86_64.h
> index c4b88fc..8714c92 100644
> --- a/plat/linuxu/include/linuxu/syscall-x86_64.h
> +++ b/plat/linuxu/include/linuxu/syscall-x86_64.h
> @@ -47,6 +47,7 @@
>  #define __SC_RT_SIGACTION   13
>  #define __SC_RT_SIGPROCMASK 14
>  #define __SC_IOCTL  16
> +#define __SC_SOCKET 41
>  #define __SC_EXIT   60
>  #define __SC_FCNTL  72
>  #define __SC_ARCH_PRCTL       158
> diff --git a/plat/linuxu/include/linuxu/syscall.h
> b/plat/linuxu/include/linuxu/syscall.h
> index 2c613fc..ad6f038 100644
> --- a/plat/linuxu/include/linuxu/syscall.h
> +++ b/plat/linuxu/include/linuxu/syscall.h
> @@ -125,6 +125,31 @@ static inline int sys_close(int fd)
>                                 (long) fd);
>  }
>  
> +#ifndef SOCK_STREAM
> +#define SOCK_STREAM    1
> +#endif /* SOCK_STREAM */
> +#ifndef SOCK_DGRAM
> +#define SOCK_DGRAM     2
> +#endif /* SOCK_DGRAM */
> +
> +#ifndef SOCK_RAW
> +#define SOCK_RAW       3
> +#endif /* SOCK_RAW */
> +
> +#ifndef AF_LOCAL
> +#define AF_LOCAL       1
> +#endif /* AF_LOCAL */
> +#ifndef AF_INET
> +#define AF_INET        2
> +#endif /* AF_INET */
> +static inline int sys_socket(int domain, int type, int protocol)
> +{
> +     return (ssize_t) syscall3(__SC_SOCKET,
> +                               (long) domain,
> +                               (long) type,
> +                               (long) protocol);
> +}
> +
>  static inline int sys_exit(int status)
>  {
>       return (int) syscall1(__SC_EXIT,
> diff --git a/plat/linuxu/include/linuxu/tap.h
> b/plat/linuxu/include/linuxu/tap.h
> index 65e6eb5..0f3a644 100644
> --- a/plat/linuxu/include/linuxu/tap.h
> +++ b/plat/linuxu/include/linuxu/tap.h
> @@ -58,6 +58,13 @@ struct uk_in_addr {
>       uk_in_addr_t s_addr;
>  };
>  
> +struct uk_sockaddr_in {
> +     uk_sa_family_t sin_family;
> +     uk_in_port_t sin_port;
> +     struct uk_in_addr sin_addr;
> +     __u8 sin_zero[8];
> +};
> +
>  struct uk_sockaddr {
>       uk_sa_family_t sa_family;
>       char sa_data[14];
> diff --git a/plat/linuxu/tap_io.c b/plat/linuxu/tap_io.c
> index 118bee8..888ef83 100644
> --- a/plat/linuxu/tap_io.c
> +++ b/plat/linuxu/tap_io.c
> @@ -61,6 +61,37 @@ int tap_dev_configure(int fd, __u32 feature_flags,
> void *arg)
>       return rc;
>  }
>  
> +int tap_netif_configure(int fd, __u32 request, void *arg)
> +{
> +     int rc;
> +     struct uk_ifreq *usr_ifr = (struct uk_ifreq *) arg;
> +
> +     switch (request) {
> +     case UK_SIOCGIFHWADDR:
> +     case UK_SIOCSIFHWADDR:
> +             break;
> +     default:
> +             rc = -EINVAL;
> +             uk_pr_err("Invalid ioctl request\n");
> +             goto exit_error;
> +     }
> +
> +     if ((rc = sys_ioctl(fd, request, usr_ifr)) < 0) {
> +             uk_pr_err("Failed to set device control %d\n", rc);
> +             goto exit_error;
> +     }
> +
> +     return 0;
> +
> +exit_error:
> +     return rc;
> +}
> +
> +int tap_netif_create(void)
> +{
> +     return sys_socket(AF_INET, SOCK_DGRAM, 0);
> +}
> +
>  int tap_close(int fd)
>  {
>       return sys_close(fd);



 


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