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Date: Tue, 19 Nov 2013 17:38:51 -0500
From: Paul Moore <paul@...l-moore.com>
To: Tim Gardner <tim.gardner@...onical.com>
Cc: linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, Stephen Smalley <sds@...ho.nsa.gov>,
James Morris <james.l.morris@...cle.com>,
Eric Paris <eparis@...isplace.org>
Subject: Re: [PATCH linux-next] SELinux: security_load_policy: Silence frame-larger-than warning
On Thursday, November 14, 2013 03:04:51 PM Tim Gardner wrote:
> Dynamically allocate a couple of the larger stack variables in order to
> reduce the stack footprint below 1024. gcc-4.8
>
> security/selinux/ss/services.c: In function 'security_load_policy':
> security/selinux/ss/services.c:1964:1: warning: the frame size of 1104 bytes
> is larger than 1024 bytes [-Wframe-larger-than=] }
>
> Also silence a couple of checkpatch warnings at the same time.
>
> WARNING: sizeof policydb should be sizeof(policydb)
> + memcpy(oldpolicydb, &policydb, sizeof policydb);
>
> WARNING: sizeof policydb should be sizeof(policydb)
> + memcpy(&policydb, newpolicydb, sizeof policydb);
>
> Cc: Stephen Smalley <sds@...ho.nsa.gov>
> Cc: James Morris <james.l.morris@...cle.com>
> Cc: Eric Paris <eparis@...isplace.org>
> Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
> ---
> security/selinux/ss/services.c | 54 ++++++++++++++++++++++--------------
> 1 file changed, 32 insertions(+), 22 deletions(-)
Applied, thanks. It will be pushed to my next tree once -rc1 is released.
In the future, please send SELinux patches to the SELinux mailing list.
> diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
> index b4feecc..c8317c8 100644
> --- a/security/selinux/ss/services.c
> +++ b/security/selinux/ss/services.c
> @@ -1828,7 +1828,7 @@ static int security_preserve_bools(struct policydb
> *p); */
> int security_load_policy(void *data, size_t len)
> {
> - struct policydb oldpolicydb, newpolicydb;
> + struct policydb *oldpolicydb, *newpolicydb;
> struct sidtab oldsidtab, newsidtab;
> struct selinux_mapping *oldmap, *map = NULL;
> struct convert_context_args args;
> @@ -1837,12 +1837,19 @@ int security_load_policy(void *data, size_t len)
> int rc = 0;
> struct policy_file file = { data, len }, *fp = &file;
>
> + oldpolicydb = kzalloc(2 * sizeof(*oldpolicydb), GFP_KERNEL);
> + if (!oldpolicydb) {
> + rc = -ENOMEM;
> + goto out;
> + }
> + newpolicydb = oldpolicydb + 1;
> +
> if (!ss_initialized) {
> avtab_cache_init();
> rc = policydb_read(&policydb, fp);
> if (rc) {
> avtab_cache_destroy();
> - return rc;
> + goto out;
> }
>
> policydb.len = len;
> @@ -1852,14 +1859,14 @@ int security_load_policy(void *data, size_t len)
> if (rc) {
> policydb_destroy(&policydb);
> avtab_cache_destroy();
> - return rc;
> + goto out;
> }
>
> rc = policydb_load_isids(&policydb, &sidtab);
> if (rc) {
> policydb_destroy(&policydb);
> avtab_cache_destroy();
> - return rc;
> + goto out;
> }
>
> security_load_policycaps();
> @@ -1871,36 +1878,36 @@ int security_load_policy(void *data, size_t len)
> selinux_status_update_policyload(seqno);
> selinux_netlbl_cache_invalidate();
> selinux_xfrm_notify_policyload();
> - return 0;
> + goto out;
> }
>
> #if 0
> sidtab_hash_eval(&sidtab, "sids");
> #endif
>
> - rc = policydb_read(&newpolicydb, fp);
> + rc = policydb_read(newpolicydb, fp);
> if (rc)
> - return rc;
> + goto out;
>
> - newpolicydb.len = len;
> + newpolicydb->len = len;
> /* If switching between different policy types, log MLS status */
> - if (policydb.mls_enabled && !newpolicydb.mls_enabled)
> + if (policydb.mls_enabled && !newpolicydb->mls_enabled)
> printk(KERN_INFO "SELinux: Disabling MLS support...\n");
> - else if (!policydb.mls_enabled && newpolicydb.mls_enabled)
> + else if (!policydb.mls_enabled && newpolicydb->mls_enabled)
> printk(KERN_INFO "SELinux: Enabling MLS support...\n");
>
> - rc = policydb_load_isids(&newpolicydb, &newsidtab);
> + rc = policydb_load_isids(newpolicydb, &newsidtab);
> if (rc) {
> printk(KERN_ERR "SELinux: unable to load the initial SIDs\n");
> - policydb_destroy(&newpolicydb);
> - return rc;
> + policydb_destroy(newpolicydb);
> + goto out;
> }
>
> - rc = selinux_set_mapping(&newpolicydb, secclass_map, &map, &map_size);
> + rc = selinux_set_mapping(newpolicydb, secclass_map, &map, &map_size);
> if (rc)
> goto err;
>
> - rc = security_preserve_bools(&newpolicydb);
> + rc = security_preserve_bools(newpolicydb);
> if (rc) {
> printk(KERN_ERR "SELinux: unable to preserve booleans\n");
> goto err;
> @@ -1918,7 +1925,7 @@ int security_load_policy(void *data, size_t len)
> * in the new SID table.
> */
> args.oldp = &policydb;
> - args.newp = &newpolicydb;
> + args.newp = newpolicydb;
> rc = sidtab_map(&newsidtab, convert_context, &args);
> if (rc) {
> printk(KERN_ERR "SELinux: unable to convert the internal"
> @@ -1928,12 +1935,12 @@ int security_load_policy(void *data, size_t len)
> }
>
> /* Save the old policydb and SID table to free later. */
> - memcpy(&oldpolicydb, &policydb, sizeof policydb);
> + memcpy(oldpolicydb, &policydb, sizeof(policydb));
> sidtab_set(&oldsidtab, &sidtab);
>
> /* Install the new policydb and SID table. */
> write_lock_irq(&policy_rwlock);
> - memcpy(&policydb, &newpolicydb, sizeof policydb);
> + memcpy(&policydb, newpolicydb, sizeof(policydb));
> sidtab_set(&sidtab, &newsidtab);
> security_load_policycaps();
> oldmap = current_mapping;
> @@ -1943,7 +1950,7 @@ int security_load_policy(void *data, size_t len)
> write_unlock_irq(&policy_rwlock);
>
> /* Free the old policydb and SID table. */
> - policydb_destroy(&oldpolicydb);
> + policydb_destroy(oldpolicydb);
> sidtab_destroy(&oldsidtab);
> kfree(oldmap);
>
> @@ -1953,14 +1960,17 @@ int security_load_policy(void *data, size_t len)
> selinux_netlbl_cache_invalidate();
> selinux_xfrm_notify_policyload();
>
> - return 0;
> + rc = 0;
> + goto out;
>
> err:
> kfree(map);
> sidtab_destroy(&newsidtab);
> - policydb_destroy(&newpolicydb);
> - return rc;
> + policydb_destroy(newpolicydb);
>
> +out:
> + kfree(oldpolicydb);
> + return rc;
> }
>
> size_t security_policydb_len(void)
--
paul moore
www.paul-moore.com
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