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Message-ID: <cbd2506a-a550-45dc-9198-ac4ad4b428b8@schaufler-ca.com>
Date: Tue, 7 Nov 2023 10:46:01 -0800
From: Casey Schaufler <casey@...aufler-ca.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>,
viro@...iv.linux.org.uk, brauner@...nel.org,
chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de,
kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com,
paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com,
zohar@...ux.ibm.com, dmitry.kasatkin@...il.com,
dhowells@...hat.com, jarkko@...nel.org,
stephen.smalley.work@...il.com, eparis@...isplace.org,
mic@...ikod.net
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-nfs@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
selinux@...r.kernel.org, Roberto Sassu <roberto.sassu@...wei.com>,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH v5 22/23] integrity: Move integrity functions to the LSM
infrastructure
On 11/7/2023 5:40 AM, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
>
> Remove hardcoded calls to integrity functions from the LSM infrastructure
> and, instead, register them in integrity_lsm_init() with the IMA or EVM
> LSM ID (the first non-NULL returned by ima_get_lsm_id() and
> evm_get_lsm_id()).
>
> Also move the global declaration of integrity_inode_get() to
> security/integrity/integrity.h, so that the function can be still called by
> IMA.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
Reviewed-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> include/linux/integrity.h | 26 --------------------------
> security/integrity/iint.c | 30 +++++++++++++++++++++++++++++-
> security/integrity/integrity.h | 7 +++++++
> security/security.c | 9 +--------
> 4 files changed, 37 insertions(+), 35 deletions(-)
>
> diff --git a/include/linux/integrity.h b/include/linux/integrity.h
> index 2ea0f2f65ab6..afaae7ad26f4 100644
> --- a/include/linux/integrity.h
> +++ b/include/linux/integrity.h
> @@ -21,38 +21,12 @@ enum integrity_status {
>
> /* List of EVM protected security xattrs */
> #ifdef CONFIG_INTEGRITY
> -extern struct integrity_iint_cache *integrity_inode_get(struct inode *inode);
> -extern void integrity_inode_free(struct inode *inode);
> extern void __init integrity_load_keys(void);
>
> #else
> -static inline struct integrity_iint_cache *
> - integrity_inode_get(struct inode *inode)
> -{
> - return NULL;
> -}
> -
> -static inline void integrity_inode_free(struct inode *inode)
> -{
> - return;
> -}
> -
> static inline void integrity_load_keys(void)
> {
> }
> #endif /* CONFIG_INTEGRITY */
>
> -#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
> -
> -extern int integrity_kernel_module_request(char *kmod_name);
> -
> -#else
> -
> -static inline int integrity_kernel_module_request(char *kmod_name)
> -{
> - return 0;
> -}
> -
> -#endif /* CONFIG_INTEGRITY_ASYMMETRIC_KEYS */
> -
> #endif /* _LINUX_INTEGRITY_H */
> diff --git a/security/integrity/iint.c b/security/integrity/iint.c
> index 0b0ac71142e8..882fde2a2607 100644
> --- a/security/integrity/iint.c
> +++ b/security/integrity/iint.c
> @@ -171,7 +171,7 @@ struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
> *
> * Free the integrity information(iint) associated with an inode.
> */
> -void integrity_inode_free(struct inode *inode)
> +static void integrity_inode_free(struct inode *inode)
> {
> struct integrity_iint_cache *iint;
>
> @@ -193,11 +193,39 @@ static void iint_init_once(void *foo)
> memset(iint, 0, sizeof(*iint));
> }
>
> +static struct security_hook_list integrity_hooks[] __ro_after_init = {
> + LSM_HOOK_INIT(inode_free_security, integrity_inode_free),
> +#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
> + LSM_HOOK_INIT(kernel_module_request, integrity_kernel_module_request),
> +#endif
> +};
> +
> +/*
> + * Perform the initialization of the 'integrity', 'ima' and 'evm' LSMs to
> + * ensure that the management of integrity metadata is working at the time
> + * IMA and EVM hooks are registered to the LSM infrastructure, and to keep
> + * the original ordering of IMA and EVM functions as when they were hardcoded.
> + */
> static int __init integrity_lsm_init(void)
> {
> + const struct lsm_id *lsmid;
> +
> iint_cache =
> kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
> 0, SLAB_PANIC, iint_init_once);
> + /*
> + * Obtain either the IMA or EVM LSM ID to register integrity-specific
> + * hooks under that LSM, since there is no LSM ID assigned to the
> + * 'integrity' LSM.
> + */
> + lsmid = ima_get_lsm_id();
> + if (!lsmid)
> + lsmid = evm_get_lsm_id();
> + /* No point in continuing, since both IMA and EVM are disabled. */
> + if (!lsmid)
> + return 0;
> +
> + security_add_hooks(integrity_hooks, ARRAY_SIZE(integrity_hooks), lsmid);
> init_ima_lsm();
> init_evm_lsm();
> return 0;
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index 7534ec06324e..e4df82d6f6e7 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -180,6 +180,7 @@ struct integrity_iint_cache {
> * integrity data associated with an inode.
> */
> struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
> +struct integrity_iint_cache *integrity_inode_get(struct inode *inode);
>
> int integrity_kernel_read(struct file *file, loff_t offset,
> void *addr, unsigned long count);
> @@ -266,12 +267,18 @@ static inline int __init integrity_load_cert(const unsigned int id,
> #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
> int asymmetric_verify(struct key *keyring, const char *sig,
> int siglen, const char *data, int datalen);
> +int integrity_kernel_module_request(char *kmod_name);
> #else
> static inline int asymmetric_verify(struct key *keyring, const char *sig,
> int siglen, const char *data, int datalen)
> {
> return -EOPNOTSUPP;
> }
> +
> +static inline int integrity_kernel_module_request(char *kmod_name)
> +{
> + return 0;
> +}
> #endif
>
> #ifdef CONFIG_IMA_APPRAISE_MODSIG
> diff --git a/security/security.c b/security/security.c
> index 9703549b6ddc..0d9eaa4cd260 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -19,7 +19,6 @@
> #include <linux/kernel.h>
> #include <linux/kernel_read_file.h>
> #include <linux/lsm_hooks.h>
> -#include <linux/integrity.h>
> #include <linux/fsnotify.h>
> #include <linux/mman.h>
> #include <linux/mount.h>
> @@ -1597,7 +1596,6 @@ static void inode_free_by_rcu(struct rcu_head *head)
> */
> void security_inode_free(struct inode *inode)
> {
> - integrity_inode_free(inode);
> call_void_hook(inode_free_security, inode);
> /*
> * The inode may still be referenced in a path walk and
> @@ -3182,12 +3180,7 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode)
> */
> int security_kernel_module_request(char *kmod_name)
> {
> - int ret;
> -
> - ret = call_int_hook(kernel_module_request, 0, kmod_name);
> - if (ret)
> - return ret;
> - return integrity_kernel_module_request(kmod_name);
> + return call_int_hook(kernel_module_request, 0, kmod_name);
> }
>
> /**
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