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sbattach: Check that attached signatures are valid PKCS7 data

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Check detached signatures to ensure that we're attaching a valid PKCS7
object. If no, show a warning message and skip the attach action.

Signed-off-by: Ivan Hu <ivan.hu@canonical.com>
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
This commit is contained in:
Ivan Hu 2012-06-19 17:07:15 +08:00 committed by Jeremy Kerr
parent 71f6b9b5cb
commit e80a975ff9
1 changed files with 25 additions and 0 deletions
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25
sbattach.c
View file

@ -31,6 +31,9 @@
#include <getopt.h> #include <getopt.h>
#include <openssl/pkcs7.h>
#include <openssl/err.h>
#include <ccan/talloc/talloc.h> #include <ccan/talloc/talloc.h>
#include <ccan/read_write_all/read_write_all.h> #include <ccan/read_write_all/read_write_all.h>
@ -83,6 +86,8 @@ static int attach_sig(struct image *image, const char *image_filename,
uint8_t *sigbuf; uint8_t *sigbuf;
size_t size; size_t size;
int fd, rc; int fd, rc;
PKCS7 *p7;
const uint8_t *tmp_buf;
sigbuf = NULL; sigbuf = NULL;
@ -117,6 +122,23 @@ static int attach_sig(struct image *image, const char *image_filename,
image->sigbuf = sigbuf; image->sigbuf = sigbuf;
image->sigsize = size; image->sigsize = size;
tmp_buf = sigbuf;
p7 = d2i_PKCS7(NULL, &tmp_buf, image->sigsize);
if (!p7) {
fprintf(stderr, "Unable to parse signature data in file: %s\n",
sig_filename);
ERR_print_errors_fp(stderr);
goto out;
}
rc = PKCS7_verify(p7, NULL, NULL, NULL, NULL,
PKCS7_BINARY | PKCS7_NOVERIFY | PKCS7_NOSIGS);
if (!rc) {
fprintf(stderr, "PKCS7 verification failed for file %s\n",
sig_filename);
ERR_print_errors_fp(stderr);
goto out;
}
rc = image_write(image, image_filename); rc = image_write(image, image_filename);
if (rc) if (rc)
fprintf(stderr, "Error writing %s: %s\n", image_filename, fprintf(stderr, "Error writing %s: %s\n", image_filename,
@ -208,6 +230,9 @@ int main(int argc, char **argv)
return EXIT_FAILURE; return EXIT_FAILURE;
} }
ERR_load_crypto_strings();
OpenSSL_add_all_digests();
image = image_load(image_filename); image = image_load(image_filename);
if (!image) { if (!image) {
fprintf(stderr, "Can't load image file %s\n", image_filename); fprintf(stderr, "Can't load image file %s\n", image_filename);