Prevent reading of inode generation for special files in HMAC signing

Kernel API does not support at the momement reading of inode generation
number of special files, so do not do it also when do HMAC signing.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>

diff --git a/src/evmctl.c b/src/evmctl.c
index 1a94d58..9be5e8b 100644 (file)
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1429,8 +1429,8 @@ out:
 static int calc_evm_hmac(const char *file, const char *keyfile, unsigned char *hash)
 {
        struct stat st;
-       int fd, err = -1;
-       uint32_t generation;
+       int err = -1;
+       uint32_t generation = 0;
        HMAC_CTX ctx;
        unsigned int mdlen;
        char **xattrname;
@@ -1456,24 +1456,26 @@ static int calc_evm_hmac(const char *file, const char *keyfile, unsigned char *h
        memcpy(evmkey, key, keylen);
        memset(evmkey + keylen, 0, sizeof(evmkey) - keylen);
 
-       fd = open(file, 0);
-       if (fd < 0) {
-               log_err("Unable to open %s\n", file);
-               goto out;
-       }
-
-       if (fstat(fd, &st)) {
-               log_err("fstat() failed\n");
+       if (lstat(file, &st)) {
+               log_err("lstat() failed\n");
                goto out;
        }
 
-       if (ioctl(fd, EXT34_IOC_GETVERSION, &generation)) {
-               log_err("ioctl() failed\n");
-               goto out;
+       if (S_ISREG(st.st_mode) || S_ISDIR(st.st_mode)) {
+               /* we cannot at the momement to get generation of special files..
+                * kernel API does not support it */
+               int fd = open(file, 0);
+               if (fd < 0) {
+                       log_err("Unable to open %s\n", file);
+                       goto out;
+               }
+               if (ioctl(fd, EXT34_IOC_GETVERSION, &generation)) {
+                       log_err("ioctl() failed\n");
+                       goto out;
+               }
+               close(fd);
        }
 
-       close(fd);
-
        log_info("generation: %u\n", generation);
 
        list_size = llistxattr(file, list, sizeof(list));