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normal/main: Search for specific config files for netboot

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This patch implements a search for a specific configuration when the config
file is on a remoteserver. It uses the following order:
   1) DHCP client UUID option.
   2) MAC address (in lower case hexadecimal with dash separators);
   3) IP (in upper case hexadecimal) or IPv6;
   4) The original grub.cfg file.

This procedure is similar to what is used by pxelinux and yaboot:
http://www.syslinux.org/wiki/index.php/PXELINUX#config

It is enabled by default but can be disabled by setting the environment
variable "feature_net_search_cfg" to "n" in an embedded configuration.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=873406

Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@br.ibm.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Paulo Flabiano Smorigo 2020-01-22 12:01:55 +01:00 committed by Daniel Kiper
parent febc761e67
commit cb2f15c544
3 changed files with 155 additions and 4 deletions
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131
grub-core/net/net.c
View file

@ -1735,6 +1735,137 @@ grub_net_restore_hw (void)
return GRUB_ERR_NONE;
}
grub_err_t
grub_net_search_config_file (char *config)
{
grub_size_t config_len;
char *suffix;
auto int search_through (grub_size_t num_tries, grub_size_t slice_size);
int search_through (grub_size_t num_tries, grub_size_t slice_size)
{
while (num_tries-- > 0)
{
grub_file_t file;
grub_dprintf ("net", "attempt to fetch config %s\n", config);
file = grub_file_open (config, GRUB_FILE_TYPE_CONFIG);
if (file)
{
grub_file_close (file);
return 0;
}
else
{
if (grub_errno == GRUB_ERR_IO)
grub_errno = GRUB_ERR_NONE;
}
if (grub_strlen (suffix) < slice_size)
break;
config[grub_strlen (config) - slice_size] = '\0';
}
return 1;
}
config_len = grub_strlen (config);
config[config_len] = '-';
suffix = config + config_len + 1;
struct grub_net_network_level_interface *inf;
FOR_NET_NETWORK_LEVEL_INTERFACES (inf)
{
/* By the Client UUID. */
char *ptr;
int client_uuid_len;
char *client_uuid_var;
const char *client_uuid;
client_uuid_len = sizeof ("net_") + grub_strlen (inf->name) +
sizeof ("_clientuuid") + 1;
client_uuid_var = grub_zalloc (client_uuid_len);
if (!client_uuid_var)
return grub_errno;
grub_snprintf (client_uuid_var, client_uuid_len,
"net_%s_clientuuid", inf->name);
client_uuid = grub_env_get (client_uuid_var);
grub_free (client_uuid_var);
if (client_uuid)
{
grub_strcpy (suffix, client_uuid);
if (search_through (1, 0) == 0)
return GRUB_ERR_NONE;
}
/* By the MAC address. */
/* Add ethernet type */
grub_strcpy (suffix, "01-");
grub_net_hwaddr_to_str (&inf->hwaddress, suffix + 3);
for (ptr = suffix; *ptr; ptr++)
if (*ptr == ':')
*ptr = '-';
if (search_through (1, 0) == 0)
return GRUB_ERR_NONE;
/* By IP address */
switch ((&inf->address)->type)
{
case GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV4:
{
grub_uint32_t n = grub_be_to_cpu32 ((&inf->address)->ipv4);
grub_snprintf (suffix, GRUB_NET_MAX_STR_ADDR_LEN, "%02X%02X%02X%02X", \
((n >> 24) & 0xff), ((n >> 16) & 0xff), \
((n >> 8) & 0xff), ((n >> 0) & 0xff));
if (search_through (8, 1) == 0)
return GRUB_ERR_NONE;
break;
}
case GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV6:
{
char buf[GRUB_NET_MAX_STR_ADDR_LEN];
struct grub_net_network_level_address base;
base.type = GRUB_NET_NETWORK_LEVEL_PROTOCOL_IPV6;
grub_memcpy (&base.ipv6, ((&inf->address)->ipv6), 16);
grub_net_addr_to_str (&base, buf);
for (ptr = buf; *ptr; ptr++)
if (*ptr == ':')
*ptr = '-';
grub_snprintf (suffix, GRUB_NET_MAX_STR_ADDR_LEN, "%s", buf);
if (search_through (1, 0) == 0)
return GRUB_ERR_NONE;
break;
}
case GRUB_NET_NETWORK_LEVEL_PROTOCOL_DHCP_RECV:
return grub_error (GRUB_ERR_BUG, "shouldn't reach here");
default:
return grub_error (GRUB_ERR_BUG,
"unsupported address type %d", (&inf->address)->type);
}
}
/* Remove the remaining minus sign at the end. */
config[config_len] = '\0';
return GRUB_ERR_NONE;
}
static struct grub_preboot *fini_hnd;
static grub_command_t cmd_addaddr, cmd_deladdr, cmd_addroute, cmd_delroute;

20
grub-core/normal/main.c
View file

@ -18,6 +18,7 @@
*/
#include <grub/kernel.h>
#include <grub/net.h>
#include <grub/normal.h>
#include <grub/dl.h>
#include <grub/misc.h>
@ -324,10 +325,27 @@ grub_cmd_normal (struct grub_command *cmd __attribute__ ((unused)),
prefix = grub_env_get ("prefix");
if (prefix)
{
config = grub_xasprintf ("%s/grub.cfg", prefix);
grub_size_t config_len;
int disable_net_search = 0;
const char *net_search_cfg;
config_len = grub_strlen (prefix) +
sizeof ("/grub.cfg-XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX");
config = grub_malloc (config_len);
if (!config)
goto quit;
grub_snprintf (config, config_len, "%s/grub.cfg", prefix);
net_search_cfg = grub_env_get ("feature_net_search_cfg");
if (net_search_cfg && net_search_cfg[0] == 'n')
disable_net_search = 1;
if (grub_strncmp (prefix + 1, "tftp", sizeof ("tftp") - 1) == 0 &&
!disable_net_search)
grub_net_search_config_file (config);
grub_enter_normal_mode (config);
grub_free (config);
}

2
include/grub/net.h
View file

@ -569,6 +569,8 @@ grub_net_add_dns_server (const struct grub_net_network_level_address *s);
void
grub_net_remove_dns_server (const struct grub_net_network_level_address *s);
grub_err_t
grub_net_search_config_file (char *config);
extern char *grub_net_default_server;