Re: [PATCH v3 2/2] ima-evm-utils: log unknown keyid's as errors

[Mimi Zohar <zohar@linux.ibm.com>]

On Wed, 2019-07-24 at 01:18 +0300, Vitaly Chikunov wrote:
> Mimi,
> 
> On Thu, Jul 18, 2019 at 10:29:54AM -0400, Mimi Zohar wrote:
> > Each tima a new unknown key is encountered, emit a message of the format
> > "key #: <keyid> unknown".  The individual files using unknown keys are
> > then only logged in verbose mode.
> > 
> > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> > ---
> >  src/libimaevm.c | 21 +++++++++++++++++----
> >  1 file changed, 17 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/libimaevm.c b/src/libimaevm.c
> > index 43eb4ef2412c..d2194a6ca0f8 100644
> > --- a/src/libimaevm.c
> > +++ b/src/libimaevm.c
> > @@ -402,13 +402,26 @@ static struct public_key_entry *public_keys = NULL;
> >  
> >  static EVP_PKEY *find_keyid(uint32_t keyid)
> >  {
> > -	struct public_key_entry *entry;
> > +	struct public_key_entry *entry, *tail = public_keys;
> 
> If user specified in `-k` filename that does not exist no key is added
> into public_keys and it remains NULL.

Right, just the keyid is added and an error message is emitted.

> 
> > +	int i = 1;
> >  
> >  	for (entry = public_keys; entry != NULL; entry = entry->next) {
> >  		if (entry->keyid == keyid)
> >  			return entry->key;
> > +		i++;
> > +		tail = entry;
> >  	}
> > -	return NULL;
> > +
> > +	/* add unknown keys to list */
> > +	entry = calloc(1, sizeof(struct public_key_entry));
> > +	if (!entry) {
> > +		perror("calloc");
> > +		return 0;
> > +	}
> > +	entry->keyid = keyid;
> > +	tail->next = entry;
> 
> In that case here is SIGSEGV when user try to ima_verify.

find_keyid() returns NULL, which is checked before being used.
 There's only one caller of this function.

Do you have a test case to reproduce this bug?

Mimi

> 
> > +	log_err("key %d: %x unknown\n", i,  __be32_to_cpup(&keyid));
> > +	return 0;
> >  }
> >  
> >  void init_public_keys(const char *keyfiles)
> > @@ -470,8 +483,8 @@ static int verify_hash_v2(const char *file, const unsigned char *hash, int size,
> >  
> >  	pkey = find_keyid(keyid);
> >  	if (!pkey) {
> > -		log_err("%s: unknown keyid: %x\n",
> > -			file, __be32_to_cpup(&keyid));
> > +		log_info("%s: unknown keyid: %x\n",
> > +			 file, __be32_to_cpup(&keyid));
> >  		return -1;
> >  	}
> >  
>