From: Andrew Morton <akpm@linux-foundation.org>
To: "Ahmed S. Darwish" <darwish.07@gmail.com>
Cc: jmorris@namei.org, sds@tycho.nsa.gov, casey@schaufler-ca.com,
bunk@kernel.org, chrisw@sous-sol.org, eparis@parisplace.org,
adobriyan@sw.ru, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH -v5 -mm] LSM: Add security= boot parameter
Date: Wed, 5 Mar 2008 14:29:48 -0800 [thread overview]
Message-ID: <20080305142948.3d391d84.akpm@linux-foundation.org> (raw)
In-Reply-To: <20080304030407.GA25686@ubuntu>
On Tue, 4 Mar 2008 05:04:07 +0200
"Ahmed S. Darwish" <darwish.07@gmail.com> wrote:
> Hi!,
>
> [
> Fix stuff mentioned by James in parent mail:
> - use spinlocks instead of atomic counter (yes, this is clearer).
> - remove redundant BUG_ON
> - don't let LSMs loudly complain when they aren't chosen.
> ]
>
> -->
>
> Add the security= boot parameter. This is done to avoid LSM
> registration clashes in case of more than one bult-in module.
>
> User can choose a security module to enable at boot. If no
> security= boot parameter is specified, only the first LSM
> asking for registration will be loaded. An invalid security
> module name will be treated as if no module has been chosen.
>
> LSM modules must check now if they are allowed to register
> by calling security_module_enable(ops) first. Modify SELinux
> and SMACK to do so.
>
> ...
>
> +/* Maximum number of letters for an LSM name string */
> +#define SECURITY_NAME_MAX 10
Is this long enough?
> struct ctl_table;
> struct audit_krule;
>
> ...
>
> -struct security_operations dummy_security_ops;
> +struct security_operations dummy_security_ops = { "dummy" };
Please don't rely upon the layout of data structures in this manner. Use
".name = ".
>
> #define set_to_dummy_if_null(ops, function) \
> do { \
> diff --git a/security/security.c b/security/security.c
> index 1bf2ee4..def9fc0 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -17,6 +17,9 @@
> #include <linux/kernel.h>
> #include <linux/security.h>
>
> +/* Boot-time LSM user choice */
> +static spinlock_t chosen_lsm_lock;
> +static char chosen_lsm[SECURITY_NAME_MAX + 1];
>
> /* things that live in dummy.c */
> extern struct security_operations dummy_security_ops;
> @@ -62,18 +65,59 @@ int __init security_init(void)
> }
>
> security_ops = &dummy_security_ops;
> + spin_lock_init(&chosen_lsm_lock);
Please remove this and use compile-time initialisation with DEFINE_SPINLOCK.
Do we actually need the lock? This code is only called at boot-time if I
understand it correctly?
Can chosen_lsm[] be __initdata?
> do_security_initcalls();
>
> return 0;
> }
>
> +/* Save user chosen LSM */
> +static int __init choose_lsm(char *str)
> +{
> + strncpy(chosen_lsm, str, SECURITY_NAME_MAX);
> + return 1;
> +}
> +__setup("security=", choose_lsm);
> +
> +/**
> + * security_module_enable - Load given security module on boot ?
> + * @ops: a pointer to the struct security_operations that is to be checked.
> + *
> + * Each LSM must pass this method before registering its own operations
> + * to avoid security registration races.
> + *
> + * Return true if:
> + * -The passed LSM is the one chosen by user at boot time,
> + * -or user didsn't specify a specific LSM and we're the first to ask
> + * for registeration permissoin.
> + * Otherwise, return false.
> + */
> +int security_module_enable(struct security_operations *ops)
> +{
> + int rc = 1;
> +
> + spin_lock(&chosen_lsm_lock);
> + if (!*chosen_lsm)
> + strncpy(chosen_lsm, ops->name, SECURITY_NAME_MAX);
> + else if (strncmp(ops->name, chosen_lsm, SECURITY_NAME_MAX))
> + rc = 0;
> + spin_unlock(&chosen_lsm_lock);
> +
> + if (rc)
> + printk(KERN_INFO "Security: Loading '%s' security module.\n",
> + ops->name);
> +
> + return rc;
> +}
I believe this can be __init.
> + if (!security_module_enable(&selinux_ops)) {
> + selinux_enabled = 0;
> + return 0;
> + }
> +
>
> ...
>
> static __init int smack_init(void)
> {
> + if (!security_module_enable(&smack_ops))
> + return 0;
> +
> printk(KERN_INFO "Smack: Initializing.\n");
>
> /*
hm. selinux has a global selinux_enabled knob, but smack seems to be able
to get by without one. +1 for smack ;)
next prev parent reply other threads:[~2008-03-05 22:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-01 19:07 [RFC PATCH -mm] LSM: Add lsm= boot parameter Ahmed S. Darwish
2008-03-01 20:28 ` Casey Schaufler
2008-03-01 21:11 ` Adrian Bunk
2008-03-01 21:29 ` Casey Schaufler
2008-03-01 23:27 ` [PATCH -v2 -mm] LSM: Add security= " Ahmed S. Darwish
2008-03-02 3:41 ` Casey Schaufler
2008-03-02 7:55 ` Ahmed S. Darwish
2008-03-02 7:49 ` Ahmed S. Darwish
2008-03-02 10:59 ` [PATCH -v3 " Ahmed S. Darwish
2008-03-02 18:37 ` Casey Schaufler
2008-03-03 8:29 ` James Morris
2008-03-03 15:35 ` Ahmed S. Darwish
2008-03-03 15:54 ` Stephen Smalley
2008-03-03 21:24 ` [PATCH -v4 " Ahmed S. Darwish
2008-03-03 22:16 ` James Morris
2008-03-04 3:04 ` [PATCH -v5 " Ahmed S. Darwish
2008-03-04 4:07 ` James Morris
2008-03-05 22:29 ` Andrew Morton [this message]
2008-03-05 22:56 ` Ahmed S. Darwish
2008-03-05 23:06 ` Ahmed S. Darwish
2008-03-05 22:56 ` James Morris
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