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Subject: Re: [PATCH] security: mark expected switch fall-throughs
To:     Casey Schaufler <casey@schaufler-ca.com>,
        John Johansen <john.johansen@canonical.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc:     linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org
References: <20190125025639.GA13946@embeddedor>
 <d30c9427-29bb-4b98-ec71-0663d0f9fa7f@schaufler-ca.com>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
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Message-ID: <7b0a0b5b-38ce-a737-6420-2c96cce12527@embeddedor.com>
Date:   Thu, 24 Jan 2019 21:29:31 -0600
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On 1/24/19 9:13 PM, Casey Schaufler wrote:
> On 1/24/2019 6:56 PM, Gustavo A. R. Silva wrote:
>> In preparation to enabling -Wimplicit-fallthrough, mark switch
>> cases where we are expecting to fall through.
>>
>> This patch fixes the following warnings:
>>
>> security/integrity/ima/ima_appraise.c:116:26: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/integrity/ima/ima_template_lib.c:85:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/integrity/ima/ima_policy.c:940:18: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/integrity/ima/ima_policy.c:943:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/integrity/ima/ima_policy.c:972:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/integrity/ima/ima_policy.c:974:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/smack/smack_lsm.c:3391:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> security/apparmor/domain.c:569:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>>
>> Warning level 3 was used: -Wimplicit-fallthrough=3
>>
>> This patch is part of the ongoing efforts to enabling -Wimplicit-fallthrough.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
> 
> Ug. It can't be part of a greater comment? Grumble.
> 

Not like the one in this case.

It can be part of a one line comment like this:

/* fall through - ... */

and it has to be placed at the bottom of the case.

I know... I'd be great if this can be improved.

>> ---
>>  security/apparmor/domain.c                | 2 +-
>>  security/integrity/ima/ima_appraise.c     | 1 +
>>  security/integrity/ima/ima_policy.c       | 4 ++++
>>  security/integrity/ima/ima_template_lib.c | 1 +
>>  security/smack/smack_lsm.c                | 3 +--
>>  5 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
>> index 726910bba84b..c7c619578095 100644
>> --- a/security/apparmor/domain.c
>> +++ b/security/apparmor/domain.c
>> @@ -572,7 +572,7 @@ static struct aa_label *x_to_label(struct aa_profile *profile,
>>  			stack = NULL;
>>  			break;
>>  		}
>> -		/* fall through to X_NAME */
>> +		/* fall through - to X_NAME */
>>  	case AA_X_NAME:
>>  		if (xindex & AA_X_CHILD)
>>  			/* released by caller */
>> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
>> index a2baa85ea2f5..57daf30fb7d4 100644
>> --- a/security/integrity/ima/ima_appraise.c
>> +++ b/security/integrity/ima/ima_appraise.c
>> @@ -114,6 +114,7 @@ static void ima_set_cache_status(struct integrity_iint_cache *iint,
>>  		break;
>>  	case CREDS_CHECK:
>>  		iint->ima_creds_status = status;
>> +		/* fall through */
>>  	case FILE_CHECK:
>>  	case POST_SETATTR:
>>  		iint->ima_file_status = status;
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index 8bc8a1c8cb3f..122797023bdb 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -938,10 +938,12 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>>  		case Opt_uid_gt:
>>  		case Opt_euid_gt:
>>  			entry->uid_op = &uid_gt;
>> +			/* fall through */
>>  		case Opt_uid_lt:
>>  		case Opt_euid_lt:
>>  			if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
>>  				entry->uid_op = &uid_lt;
>> +			/* fall through */
>>  		case Opt_uid_eq:
>>  		case Opt_euid_eq:
>>  			uid_token = (token == Opt_uid_eq) ||
>> @@ -970,9 +972,11 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>>  			break;
>>  		case Opt_fowner_gt:
>>  			entry->fowner_op = &uid_gt;
>> +			/* fall through */
>>  		case Opt_fowner_lt:
>>  			if (token == Opt_fowner_lt)
>>  				entry->fowner_op = &uid_lt;
>> +			/* fall through */
>>  		case Opt_fowner_eq:
>>  			ima_log_string_op(ab, "fowner", args[0].from,
>>  					  entry->fowner_op);
>> diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
>> index 43752002c222..513b457ae900 100644
>> --- a/security/integrity/ima/ima_template_lib.c
>> +++ b/security/integrity/ima/ima_template_lib.c
>> @@ -83,6 +83,7 @@ static void ima_show_template_data_ascii(struct seq_file *m,
>>  		/* skip ':' and '\0' */
>>  		buf_ptr += 2;
>>  		buflen -= buf_ptr - field_data->data;
>> +		/* fall through */
>>  	case DATA_FMT_DIGEST:
>>  	case DATA_FMT_HEX:
>>  		if (!buflen)
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index fa98394a40d0..127aa6c58e34 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3391,13 +3391,12 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
>>  		 */
>>  		final = &smack_known_star;
>>  		/*
>> -		 * Fall through.
>> -		 *
>>  		 * If a smack value has been set we want to use it,
>>  		 * but since tmpfs isn't giving us the opportunity
>>  		 * to set mount options simulate setting the
>>  		 * superblock default.
>>  		 */
>> +		/* Fall through */
>>  	default:
>>  		/*
>>  		 * This isn't an understood special case.