mirror of
https://github.com/openwrt/openwrt.git
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e22fba1694
the UML build fails during the kernel build:
| arch/um/drivers/net_kern.c: In function 'compute_hash':
| arch/um/drivers/net_kern.c:322:1: error: the frame size of 1072 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
| 322 | }
| | ^
|cc1: all warnings being treated as errors
The compute_hash() function is added by our patch:
102-pseudo-random-mac.patch
Instead of allocating a 1024 byte buffer on the stack for the SHA1
digest input, let's allocate the data on the heap. We should be
able to do that since crypto_alloc_ahash and ahash_request_alloc
also need to allocate structures on the heap.
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
(cherry picked from commit aed2569d37)
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
152 lines
4.1 KiB
Diff
152 lines
4.1 KiB
Diff
===============================================================================
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This patch makes MAC addresses of network interfaces predictable. In
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particular, it adds a small routine that computes MAC addresses of based on
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a SHA1 hash of the virtual machine name and interface ID.
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TECHNICAL INFORMATION:
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Applies to vanilla kernel 3.9.4.
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===============================================================================
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--- a/arch/um/drivers/Kconfig
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+++ b/arch/um/drivers/Kconfig
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@@ -146,6 +146,20 @@ config UML_NET
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enable at least one of the following transport options to actually
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make use of UML networking.
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+config UML_NET_DETERMINISTIC_MAC
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+ bool "Use deterministic MAC addresses for network interfaces"
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+ default y
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+ depends on UML_NET
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+ select CRYPTO_SHA1
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+ help
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+ Virtual network devices inside a User-Mode Linux instance must be
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+ assigned a MAC (Ethernet) address. If none is specified on the UML
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+ command line, one must be automatically computed. If this option is
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+ enabled, a randomly generated address is used. Otherwise, if this
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+ option is disabled, the address is generated from a SHA1 hash of
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+ the umid of the UML instance and the interface name. The latter choice
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+ is useful to make MAC addresses predictable.
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+
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config UML_NET_ETHERTAP
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bool "Ethertap transport (obsolete)"
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depends on UML_NET
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--- a/arch/um/drivers/net_kern.c
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+++ b/arch/um/drivers/net_kern.c
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@@ -25,6 +25,14 @@
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#include <net_kern.h>
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#include <net_user.h>
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+#include <crypto/sha1.h>
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+#include <crypto/hash.h>
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+#include <linux/string.h>
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+#include <linux/crypto.h>
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+#include <linux/err.h>
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+#include <linux/scatterlist.h>
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+#include "os.h"
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+
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#define DRIVER_NAME "uml-netdev"
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static DEFINE_SPINLOCK(opened_lock);
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@@ -274,9 +282,55 @@ static const struct ethtool_ops uml_net_
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.get_ts_info = ethtool_op_get_ts_info,
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};
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+#ifdef CONFIG_UML_NET_DETERMINISTIC_MAC
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+
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+/* Compute a SHA1 hash of the UML instance's id and
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+ * * an interface name. */
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+static int compute_hash(const char *umid, const char *ifname, char *hash)
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+{
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+ struct ahash_request *desc = NULL;
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+ struct crypto_ahash *tfm = NULL;
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+ struct scatterlist sg;
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+ char *vmif = NULL;
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+ int ret = -ENOMEM;
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+
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+ vmif = kmalloc(1024, GFP_KERNEL);
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+ if (!vmif)
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+ goto out;
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+
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+ strcpy (vmif, umid);
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+ strcat (vmif, ifname);
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+
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+ tfm = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
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+ if (IS_ERR(tfm))
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+ goto out;
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+
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+ desc = ahash_request_alloc(tfm, GFP_KERNEL);
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+ if (!desc)
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+ goto out;
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+
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+ crypto_ahash_clear_flags(tfm, ~0);
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+
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+ sg_init_table(&sg, 1);
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+ sg_set_buf(&sg, vmif, strlen(vmif));
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+
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+ ahash_request_set_crypt(desc, &sg, hash, strlen(vmif));
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+
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+ ret = crypto_ahash_digest(desc);
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+out:
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+ crypto_free_ahash(tfm);
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+ ahash_request_free(desc);
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+ kfree(vmif);
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+
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+ return ret;
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+}
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+
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+#endif
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+
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void uml_net_setup_etheraddr(struct net_device *dev, char *str)
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{
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unsigned char *addr = dev->dev_addr;
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+ u8 hash[SHA1_DIGEST_SIZE];
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char *end;
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int i;
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@@ -319,9 +373,26 @@ void uml_net_setup_etheraddr(struct net_
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return;
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random:
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+#ifndef CONFIG_UML_NET_DETERMINISTIC_MAC
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printk(KERN_INFO
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"Choosing a random ethernet address for device %s\n", dev->name);
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eth_hw_addr_random(dev);
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+#else
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+ printk(KERN_INFO
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+ "Computing a digest to use as ethernet address for device %s\n", dev->name);
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+ if (compute_hash(get_umid(), dev->name, hash) < 0) {
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+ printk(KERN_WARNING
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+ "Could not compute digest to use as ethernet address for device %s. "
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+ "Using random address instead.\n", dev->name);
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+ random_ether_addr(addr);
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+ }
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+ else {
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+ for (i=0; i < 6; i++)
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+ addr[i] = (hash[i] + hash[i+6]) % 0x100;
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+ }
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+ addr [0] &= 0xfe; /* clear multicast bit */
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+ addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
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+#endif
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}
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static DEFINE_SPINLOCK(devices_lock);
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--- a/kernel/umh.c
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+++ b/kernel/umh.c
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@@ -356,12 +356,12 @@ static void helper_unlock(void)
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}
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int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info,
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- struct file **filp)
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+ struct file **filp)
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{
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struct file *f[2];
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if (create_pipe_files(f, 0) < 0)
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- return PTR_ERR(f);
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+ return PTR_ERR(f);
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sub_info->stdout = f[1];
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*filp = f[0];
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