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um: Add a generic "fd" vector transport

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Learn to take a pre-opened file-descriptor for vector IO.

Instead of teaching the driver to open a FD in multiple ways, it can
rely on management layer to do it on its behalf. For example, this
allows inheriting a preconfigured device fd or a simple socketpair()
setup, without further arguments, privileges or system access by UML.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Marc-André Lureau 2020-04-07 22:28:53 +02:00 committed by Richard Weinberger
parent 38bccfbeb0
commit bc8f8e4e6e
1 changed files with 59 additions and 0 deletions
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59
arch/um/drivers/vector_user.c
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@ -29,6 +29,7 @@
#include <netdb.h>
#include <stdlib.h>
#include <os.h>
#include <limits.h>
#include <um_malloc.h>
#include "vector_user.h"
@ -42,6 +43,9 @@
#define TRANS_RAW "raw"
#define TRANS_RAW_LEN strlen(TRANS_RAW)
#define TRANS_FD "fd"
#define TRANS_FD_LEN strlen(TRANS_FD)
#define VNET_HDR_FAIL "could not enable vnet headers on fd %d"
#define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s"
#define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i"
@ -347,6 +351,59 @@ static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
return NULL;
}
static int strtofd(const char *nptr)
{
long fd;
char *endptr;
if (nptr == NULL)
return -1;
errno = 0;
fd = strtol(nptr, &endptr, 10);
if (nptr == endptr ||
errno != 0 ||
*endptr != '\0' ||
fd < 0 ||
fd > INT_MAX) {
return -1;
}
return fd;
}
static struct vector_fds *user_init_fd_fds(struct arglist *ifspec)
{
int fd = -1;
char *fdarg = NULL;
struct vector_fds *result = NULL;
fdarg = uml_vector_fetch_arg(ifspec, "fd");
fd = strtofd(fdarg);
if (fd == -1) {
printk(UM_KERN_ERR "fd open: bad or missing fd argument");
goto fd_cleanup;
}
result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
if (result == NULL) {
printk(UM_KERN_ERR "fd open: allocation failed");
goto fd_cleanup;
}
result->rx_fd = fd;
result->tx_fd = fd;
result->remote_addr_size = 0;
result->remote_addr = NULL;
return result;
fd_cleanup:
if (fd >= 0)
os_close_file(fd);
if (result != NULL)
kfree(result);
return NULL;
}
static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
{
int rxfd = -1, txfd = -1;
@ -578,6 +635,8 @@ struct vector_fds *uml_vector_user_open(
return user_init_socket_fds(parsed, ID_L2TPV3);
if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
return user_init_unix_fds(parsed, ID_BESS);
if (strncmp(transport, TRANS_FD, TRANS_FD_LEN) == 0)
return user_init_fd_fds(parsed);
return NULL;
}