On Fri, Jun 24, 2016 at 7:27 PM, Casey Schaufler <ca...@schaufler-ca.com> wrote: > Subject: [PATCH v5 1/3] LSM: Add /sys/kernel/security/lsm > > I got tired of having to find indirect ways to > determine what security modules are active on a system. > I have added /sys/kernel/security/lsm, which contains a > comma separated list of the active security modules. No > more groping around in /proc/filesystems, which won't > help if the module doesn't support its own filesystem. > > Signed-off-by: Casey Schaufler <ca...@schaufler-ca.com> > > --- > Documentation/security/LSM.txt | 7 +++++++ > include/linux/lsm_hooks.h | 12 ++++-------- > security/apparmor/lsm.c | 3 ++- > security/commoncap.c | 3 ++- > security/inode.c | 26 ++++++++++++++++++++++++-- > security/loadpin/loadpin.c | 2 +- > security/security.c | 38 ++++++++++++++++++++++++++++++++++++++ > security/selinux/hooks.c | 2 +- > security/smack/smack_lsm.c | 2 +- > security/tomoyo/tomoyo.c | 2 +- > security/yama/yama_lsm.c | 2 +- > 11 files changed, 82 insertions(+), 17 deletions(-)
Thanks for moving the docs. Acked-by: Paul Moore <p...@paul-moore.com> > diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt > index 3db7e67..c2683f2 100644 > --- a/Documentation/security/LSM.txt > +++ b/Documentation/security/LSM.txt > @@ -22,6 +22,13 @@ system, building their checks on top of the defined > capability hooks. > For more details on capabilities, see capabilities(7) in the Linux > man-pages project. > > +A list of the active security modules can be found by reading > +/sys/kernel/security/lsm. This is a comma separated list, and > +will always include the capability module. The list reflects the > +order in which checks are made. The capability module will always > +be first, followed by any "minor" modules (e.g. Yama) and then > +the one "major" module (e.g. SELinux) if there is one configured. > + > Based on https://lkml.org/lkml/2007/10/26/215, > a new LSM is accepted into the kernel when its intent (a description of > what it tries to protect against and in what cases one would expect to > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index 7ae3976..0bfd441 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1841,6 +1841,7 @@ struct security_hook_list { > struct list_head list; > struct list_head *head; > union security_list_options hook; > + char *lsm; > }; > > /* > @@ -1853,15 +1854,10 @@ struct security_hook_list { > { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } } > > extern struct security_hook_heads security_hook_heads; > +extern char *lsm_names; > > -static inline void security_add_hooks(struct security_hook_list *hooks, > - int count) > -{ > - int i; > - > - for (i = 0; i < count; i++) > - list_add_tail_rcu(&hooks[i].list, hooks[i].head); > -} > +extern void security_add_hooks(struct security_hook_list *hooks, int count, > + char *lsm); > > #ifdef CONFIG_SECURITY_SELINUX_DISABLE > /* > diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c > index 2660fbc..fb0fb03 100644 > --- a/security/apparmor/lsm.c > +++ b/security/apparmor/lsm.c > @@ -880,7 +880,8 @@ static int __init apparmor_init(void) > aa_free_root_ns(); > goto alloc_out; > } > - security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks)); > + security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks), > + "apparmor"); > > /* Report that AppArmor successfully initialized */ > apparmor_initialized = 1; > diff --git a/security/commoncap.c b/security/commoncap.c > index e7fadde..d101734 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -1090,7 +1090,8 @@ struct security_hook_list capability_hooks[] = { > > void __init capability_add_hooks(void) > { > - security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks)); > + security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), > + "capability"); > } > > #endif /* CONFIG_SECURITY */ > diff --git a/security/inode.c b/security/inode.c > index 28414b0..235ad82 100644 > --- a/security/inode.c > +++ b/security/inode.c > @@ -20,6 +20,7 @@ > #include <linux/init.h> > #include <linux/namei.h> > #include <linux/security.h> > +#include <linux/lsm_hooks.h> > #include <linux/magic.h> > > static struct vfsmount *mount; > @@ -208,6 +209,21 @@ void securityfs_remove(struct dentry *dentry) > } > EXPORT_SYMBOL_GPL(securityfs_remove); > > +#ifdef CONFIG_SECURITY > +static struct dentry *lsm_dentry; > +static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, > + loff_t *ppos) > +{ > + return simple_read_from_buffer(buf, count, ppos, lsm_names, > + strlen(lsm_names)); > +} > + > +static const struct file_operations lsm_ops = { > + .read = lsm_read, > + .llseek = generic_file_llseek, > +}; > +#endif > + > static int __init securityfs_init(void) > { > int retval; > @@ -217,9 +233,15 @@ static int __init securityfs_init(void) > return retval; > > retval = register_filesystem(&fs_type); > - if (retval) > + if (retval) { > sysfs_remove_mount_point(kernel_kobj, "security"); > - return retval; > + return retval; > + } > +#ifdef CONFIG_SECURITY > + lsm_dentry = securityfs_create_file("lsm", S_IRUGO, NULL, NULL, > + &lsm_ops); > +#endif > + return 0; > } > > core_initcall(securityfs_init); > diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c > index 89a46f1..1d82eae 100644 > --- a/security/loadpin/loadpin.c > +++ b/security/loadpin/loadpin.c > @@ -182,7 +182,7 @@ static struct security_hook_list loadpin_hooks[] = { > void __init loadpin_add_hooks(void) > { > pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis"); > - security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks)); > + security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), > "loadpin"); > } > > /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */ > diff --git a/security/security.c b/security/security.c > index c4bb47d..1093f73 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -32,6 +32,7 @@ > /* Maximum number of letters for an LSM name string */ > #define SECURITY_NAME_MAX 10 > > +char *lsm_names; > /* Boot-time LSM user choice */ > static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] = > CONFIG_DEFAULT_SECURITY; > @@ -78,6 +79,22 @@ static int __init choose_lsm(char *str) > } > __setup("security=", choose_lsm); > > +static int lsm_append(char *new, char **result) > +{ > + char *cp; > + > + if (*result == NULL) { > + *result = kstrdup(new, GFP_KERNEL); > + } else { > + cp = kasprintf(GFP_KERNEL, "%s,%s", *result, new); > + if (cp == NULL) > + return -ENOMEM; > + kfree(*result); > + *result = cp; > + } > + return 0; > +} > + > /** > * security_module_enable - Load given security module on boot ? > * @module: the name of the module > @@ -97,6 +114,27 @@ int __init security_module_enable(const char *module) > return !strcmp(module, chosen_lsm); > } > > +/** > + * security_add_hooks - Add a modules hooks to the hook lists. > + * @hooks: the hooks to add > + * @count: the number of hooks to add > + * @lsm: the name of the security module > + * > + * Each LSM has to register its hooks with the infrastructure. > + */ > +void __init security_add_hooks(struct security_hook_list *hooks, int count, > + char *lsm) > +{ > + int i; > + > + for (i = 0; i < count; i++) { > + hooks[i].lsm = lsm; > + list_add_tail_rcu(&hooks[i].list, hooks[i].head); > + } > + if (lsm_append(lsm, &lsm_names) < 0) > + panic("%s - Cannot get early memory.\n", __func__); > +} > + > /* > * Hook list operation macros. > * > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index a86d537..ed3a757 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -6233,7 +6233,7 @@ static __init int selinux_init(void) > 0, SLAB_PANIC, NULL); > avc_init(); > > - security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks)); > + security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), > "selinux"); > > if (avc_add_callback(selinux_netcache_avc_callback, > AVC_CALLBACK_RESET)) > panic("SELinux: Unable to register AVC netcache callback\n"); > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c > index 6777295..3577009 100644 > --- a/security/smack/smack_lsm.c > +++ b/security/smack/smack_lsm.c > @@ -4801,7 +4801,7 @@ static __init int smack_init(void) > /* > * Register with LSM > */ > - security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks)); > + security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), "smack"); > > return 0; > } > diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c > index 75c9987..edc52d6 100644 > --- a/security/tomoyo/tomoyo.c > +++ b/security/tomoyo/tomoyo.c > @@ -542,7 +542,7 @@ static int __init tomoyo_init(void) > if (!security_module_enable("tomoyo")) > return 0; > /* register ourselves with the security framework */ > - security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks)); > + security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo"); > printk(KERN_INFO "TOMOYO Linux initialized\n"); > cred->security = &tomoyo_kernel_domain; > tomoyo_mm_init(); > diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c > index 0309f21..f8ee60e 100644 > --- a/security/yama/yama_lsm.c > +++ b/security/yama/yama_lsm.c > @@ -471,6 +471,6 @@ static inline void yama_init_sysctl(void) { } > void __init yama_add_hooks(void) > { > pr_info("Yama: becoming mindful.\n"); > - security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks)); > + security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama"); > yama_init_sysctl(); > } > > -- > To unsubscribe from this list: send the line "unsubscribe > linux-security-module" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- paul moore www.paul-moore.com
