This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / kernel / module-verify.c

diff --git a/kernel/module-verify.c b/kernel/module-verify.c
new file mode 100644 (file)
index 0000000..9dacc53
--- /dev/null
+++ b/kernel/module-verify.c
@@ -0,0 +1,127 @@
+/* module-verify.c: description
+ *
+ * Written by David Howells (dhowells@redhat.com)
+ * - Derived from GregKH's RSA module signer
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/elf.h>
+#include <linux/crypto.h>
+#include <linux/crypto/ksign.h>
+#include <asm/scatterlist.h>
+#include "module-verify.h"
+
+#if 0
+#define _debug(FMT, ...) printk(KERN_DEBUG FMT, ##__VA_ARGS__)
+#else
+#define _debug(FMT, ...) do { ; } while (0)
+#endif
+
+static int signedonly;
+
+/*****************************************************************************/
+/*
+ * verify the signature attached to a module
+ */
+int module_verify_sig(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, const char *secstrings, struct module *mod)
+{
+       struct crypto_tfm *sha1_tfm;
+       unsigned sig_index, sig_size;
+       char *sig;
+       int i;
+
+       /* pull the signature out of the file */
+       sig_index = 0;
+       for (i = 1; i < hdr->e_shnum; i++) {
+               if (strcmp(secstrings + sechdrs[i].sh_name,
+                          "module_sig") == 0) {
+                       sig_index = i;
+                       break;
+               }
+       }
+
+       if (sig_index <= 0)
+               goto no_signature;
+
+       _debug("sig in section %d (size %d)\n",
+              sig_index, sechdrs[sig_index].sh_size);
+
+       sig = (char *) sechdrs[sig_index].sh_addr;
+       sig_size = sechdrs[sig_index].sh_size;
+
+       _debug("");
+
+
+
+
+       /* grab an SHA1 transformation context
+        * - !!! if this tries to load the sha1.ko module, we will deadlock!!!
+        */
+       sha1_tfm = crypto_alloc_tfm2("sha1", 0, 1);
+       if (!sha1_tfm) {
+               printk("Couldn't load module - SHA1 transform unavailable\n");
+               return -EPERM;
+       }
+
+       crypto_digest_init(sha1_tfm);
+
+       for (i = 1; i < hdr->e_shnum; i++) {
+               uint8_t *data;
+               int size;
+               const char *name = secstrings + sechdrs[i].sh_name;
+
+               /* We only care about sections with "text" or "data" in their names */
+               if ((strstr(name, "text") == NULL) &&
+                   (strstr(name, "data") == NULL))
+                       continue;
+
+               /* avoid the ".rel.*" sections too. */
+               if (strstr(name, ".rel.") != NULL)
+                       continue;
+
+               /* avoid the ".rel.*" sections too. */
+               if (strstr(name, ".rela.") != NULL)
+                       continue;
+
+               data = (uint8_t *) sechdrs[i].sh_addr;
+               size = sechdrs[i].sh_size;
+
+               _debug("SHA1ing the %s section, size %d\n", name, size);
+               _debug("idata [ %02x%02x%02x%02x ]\n",
+                      data[0], data[1], data[2], data[3]);
+
+               crypto_digest_update_kernel(sha1_tfm, data, size);
+       }
+
+       /* do the actual signature verification */
+       i = ksign_verify_signature(sig, sig_size, sha1_tfm);
+       if (!i)
+                mod->gpgsig_ok = 1;
+       
+       return i;
+
+       /* deal with the case of an unsigned module */
+ no_signature:
+       if (!signedonly)
+               return 0;
+       printk("An attempt to load unsigned module was rejected\n");
+       return -EPERM;
+} /* end module_verify_sig() */
+
+static int __init sign_setup(char *str)
+{
+       signedonly = 1;
+       return 0;
+}
+__setup("enforcemodulesig", sign_setup);
+