[PATCH v2] security/integrity: fix pointer to ESL data and its size on pseries

[R Nageswara Sastry]

On 08/06/23 5:34 pm, Nayna Jain wrote:
> On PowerVM guest, variable data is prefixed with 8 bytes of timestamp.
> Extract ESL by stripping off the timestamp before passing to ESL parser.
> 
> Fixes: 4b3e71e9a34c ("integrity/powerpc: Support loading keys from PLPKS")
> Cc: stable at vger.kenrnel.org # v6.3
> Signed-off-by: Nayna Jain <nayna at linux.ibm.com>
> ---

Tested-by: Nageswara R Sastry <rnsastry at linux.ibm.com>

Seeing the keyring difference with and with out patch:
With out patch:
[root at ltcrain80-lp2 ~]# grep keyring /proc/keys | grep -v _ses
0131ebb4 I--Q---     1 perm 0c030000     0 65534 keyring   .user_reg: 2
039dfd93 I------     1 perm 1f0f0000     0     0 keyring   .ima: 1
03a160b5 I------     1 perm 1f0b0000     0     0 keyring 
.builtin_trusted_keys: 2
05377b73 I------     1 perm 1f0b0000     0     0 keyring   .platform: empty
0d7ea730 I------     1 perm 0f0b0000     0     0 keyring   .blacklist: empty
16235f2d I--Q---     6 perm 1f3f0000     0 65534 keyring   _uid.0: empty
1721f130 I------     1 perm 1f0f0000     0     0 keyring   .evm: empty

With patch:
[root at ltcrain80-lp2 ~]# grep keyring /proc/keys | grep -v _ses
04820159 I------     1 perm 0f0b0000     0     0 keyring   .blacklist: 1
16d05827 I--Q---     1 perm 0c030000     0 65534 keyring   .user_reg: 2
17648d6a I------     1 perm 1f0b0000     0     0 keyring 
.builtin_trusted_keys: 2
2158b34f I--Q---     6 perm 1f3f0000     0 65534 keyring   _uid.0: empty
2237eff6 I------     1 perm 1f0f0000     0     0 keyring   .evm: empty
26d0330c I------     1 perm 1f0b0000     0     0 keyring   .platform: 1
2daa48ab I------     1 perm 1f0f0000     0     0 keyring   .ima: 1

Thank you.
> Changelog:
> v2: Fixed feedback from Jarkko
>        * added CC to stable
>        * moved *data declaration to same line as *db,*dbx
>      Renamed extract_data() macro to extract_esl() for clarity
>   .../integrity/platform_certs/load_powerpc.c   | 40 ++++++++++++-------
>   1 file changed, 26 insertions(+), 14 deletions(-)
> 
> diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
> index b9de70b90826..170789dc63d2 100644
> --- a/security/integrity/platform_certs/load_powerpc.c
> +++ b/security/integrity/platform_certs/load_powerpc.c
> @@ -15,6 +15,9 @@
>   #include "keyring_handler.h"
>   #include "../integrity.h"
>   
> +#define extract_esl(db, data, size, offset)	\
> +	do { db = data + offset; size = size - offset; } while (0)
> +
>   /*
>    * Get a certificate list blob from the named secure variable.
>    *
> @@ -55,8 +58,9 @@ static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
>    */
>   static int __init load_powerpc_certs(void)
>   {
> -	void *db = NULL, *dbx = NULL;
> -	u64 dbsize = 0, dbxsize = 0;
> +	void *db = NULL, *dbx = NULL, *data = NULL;
> +	u64 dsize = 0;
> +	u64 offset = 0;
>   	int rc = 0;
>   	ssize_t len;
>   	char buf[32];
> @@ -74,38 +78,46 @@ static int __init load_powerpc_certs(void)
>   		return -ENODEV;
>   	}
>   
> +	if (strcmp("ibm,plpks-sb-v1", buf) == 0)
> +		/* PLPKS authenticated variables ESL data is prefixed with 8 bytes of timestamp */
> +		offset = 8;
> +
>   	/*
>   	 * Get db, and dbx. They might not exist, so it isn't an error if we
>   	 * can't get them.
>   	 */
> -	db = get_cert_list("db", 3, &dbsize);
> -	if (!db) {
> +	data = get_cert_list("db", 3, &dsize);
> +	if (!data) {
>   		pr_info("Couldn't get db list from firmware\n");
> -	} else if (IS_ERR(db)) {
> -		rc = PTR_ERR(db);
> +	} else if (IS_ERR(data)) {
> +		rc = PTR_ERR(data);
>   		pr_err("Error reading db from firmware: %d\n", rc);
>   		return rc;
>   	} else {
> -		rc = parse_efi_signature_list("powerpc:db", db, dbsize,
> +		extract_esl(db, data, dsize, offset);
> +
> +		rc = parse_efi_signature_list("powerpc:db", db, dsize,
>   					      get_handler_for_db);
>   		if (rc)
>   			pr_err("Couldn't parse db signatures: %d\n", rc);
> -		kfree(db);
> +		kfree(data);
>   	}
>   
> -	dbx = get_cert_list("dbx", 4,  &dbxsize);
> -	if (!dbx) {
> +	data = get_cert_list("dbx", 4,  &dsize);
> +	if (!data) {
>   		pr_info("Couldn't get dbx list from firmware\n");
> -	} else if (IS_ERR(dbx)) {
> -		rc = PTR_ERR(dbx);
> +	} else if (IS_ERR(data)) {
> +		rc = PTR_ERR(data);
>   		pr_err("Error reading dbx from firmware: %d\n", rc);
>   		return rc;
>   	} else {
> -		rc = parse_efi_signature_list("powerpc:dbx", dbx, dbxsize,
> +		extract_esl(dbx, data, dsize, offset);
> +
> +		rc = parse_efi_signature_list("powerpc:dbx", dbx, dsize,
>   					      get_handler_for_dbx);
>   		if (rc)
>   			pr_err("Couldn't parse dbx signatures: %d\n", rc);
> -		kfree(dbx);
> +		kfree(data);
>   	}
>   
>   	return rc;

-- 
Thanks and Regards
R.Nageswara Sastry