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Message-ID: <5259a6a3-5f9a-4c41-851b-ffd6bd245be3@schaufler-ca.com>
Date: Tue, 16 Jan 2024 11:03:34 -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, eric.snowberg@...cle.com,
dhowells@...hat.com, jarkko@...nel.org, stephen.smalley.work@...il.com,
eparis@...isplace.org, shuah@...nel.org, mic@...ikod.net
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...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, linux-kselftest@...r.kernel.org,
Roberto Sassu <roberto.sassu@...wei.com>,
Stefan Berger <stefanb@...ux.ibm.com>,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH v9 21/25] ima: Move IMA-Appraisal to LSM infrastructure
On 1/15/2024 10:18 AM, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
>
> A few additional IMA hooks are needed to reset the cached appraisal
> status, causing the file's integrity to be re-evaluated on next access.
> Register these IMA-appraisal only functions separately from the rest of IMA
> functions, as appraisal is a separate feature not necessarily enabled in
> the kernel configuration.
>
> Reuse the same approach as for other IMA functions, move hardcoded calls
> from various places in the kernel to the LSM infrastructure. Declare the
> functions as static and register them as hook implementations in
> init_ima_appraise_lsm(), called by init_ima_lsm().
>
> Also move the inline function ima_inode_remove_acl() from the public ima.h
> header to ima_appraise.c.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
Reviewed-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> fs/attr.c | 2 -
> include/linux/ima.h | 55 ---------------------------
> security/integrity/ima/ima.h | 5 +++
> security/integrity/ima/ima_appraise.c | 38 +++++++++++++-----
> security/integrity/ima/ima_main.c | 1 +
> security/security.c | 13 -------
> 6 files changed, 35 insertions(+), 79 deletions(-)
>
> diff --git a/fs/attr.c b/fs/attr.c
> index 221d2bb0a906..38841f3ebbcb 100644
> --- a/fs/attr.c
> +++ b/fs/attr.c
> @@ -17,7 +17,6 @@
> #include <linux/filelock.h>
> #include <linux/security.h>
> #include <linux/evm.h>
> -#include <linux/ima.h>
>
> #include "internal.h"
>
> @@ -503,7 +502,6 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
> if (!error) {
> fsnotify_change(dentry, ia_valid);
> security_inode_post_setattr(idmap, dentry, ia_valid);
> - ima_inode_post_setattr(idmap, dentry, ia_valid);
> evm_inode_post_setattr(idmap, dentry, ia_valid);
> }
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index 23ae24b60ecf..0bae61a15b60 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -92,66 +92,11 @@ static inline void ima_add_kexec_buffer(struct kimage *image)
>
> #ifdef CONFIG_IMA_APPRAISE
> extern bool is_ima_appraise_enabled(void);
> -extern void ima_inode_post_setattr(struct mnt_idmap *idmap,
> - struct dentry *dentry, int ia_valid);
> -extern int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
> - const char *xattr_name, const void *xattr_value,
> - size_t xattr_value_len, int flags);
> -extern int ima_inode_set_acl(struct mnt_idmap *idmap,
> - struct dentry *dentry, const char *acl_name,
> - struct posix_acl *kacl);
> -static inline int ima_inode_remove_acl(struct mnt_idmap *idmap,
> - struct dentry *dentry,
> - const char *acl_name)
> -{
> - return ima_inode_set_acl(idmap, dentry, acl_name, NULL);
> -}
> -
> -extern int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
> - const char *xattr_name);
> #else
> static inline bool is_ima_appraise_enabled(void)
> {
> return 0;
> }
> -
> -static inline void ima_inode_post_setattr(struct mnt_idmap *idmap,
> - struct dentry *dentry, int ia_valid)
> -{
> - return;
> -}
> -
> -static inline int ima_inode_setxattr(struct mnt_idmap *idmap,
> - struct dentry *dentry,
> - const char *xattr_name,
> - const void *xattr_value,
> - size_t xattr_value_len,
> - int flags)
> -{
> - return 0;
> -}
> -
> -static inline int ima_inode_set_acl(struct mnt_idmap *idmap,
> - struct dentry *dentry, const char *acl_name,
> - struct posix_acl *kacl)
> -{
> -
> - return 0;
> -}
> -
> -static inline int ima_inode_removexattr(struct mnt_idmap *idmap,
> - struct dentry *dentry,
> - const char *xattr_name)
> -{
> - return 0;
> -}
> -
> -static inline int ima_inode_remove_acl(struct mnt_idmap *idmap,
> - struct dentry *dentry,
> - const char *acl_name)
> -{
> - return 0;
> -}
> #endif /* CONFIG_IMA_APPRAISE */
>
> #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index c0412100023e..a27fc10f84f7 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -334,6 +334,7 @@ enum hash_algo ima_get_hash_algo(const struct evm_ima_xattr_data *xattr_value,
> int xattr_len);
> int ima_read_xattr(struct dentry *dentry,
> struct evm_ima_xattr_data **xattr_value, int xattr_len);
> +void __init init_ima_appraise_lsm(const struct lsm_id *lsmid);
>
> #else
> static inline int ima_check_blacklist(struct integrity_iint_cache *iint,
> @@ -385,6 +386,10 @@ static inline int ima_read_xattr(struct dentry *dentry,
> return 0;
> }
>
> +static inline void __init init_ima_appraise_lsm(const struct lsm_id *lsmid)
> +{
> +}
> +
> #endif /* CONFIG_IMA_APPRAISE */
>
> #ifdef CONFIG_IMA_APPRAISE_MODSIG
> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> index 36abc84ba299..076451109637 100644
> --- a/security/integrity/ima/ima_appraise.c
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -636,8 +636,8 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
> * This function is called from notify_change(), which expects the caller
> * to lock the inode's i_mutex.
> */
> -void ima_inode_post_setattr(struct mnt_idmap *idmap,
> - struct dentry *dentry, int ia_valid)
> +static void ima_inode_post_setattr(struct mnt_idmap *idmap,
> + struct dentry *dentry, int ia_valid)
> {
> struct inode *inode = d_backing_inode(dentry);
> struct integrity_iint_cache *iint;
> @@ -750,9 +750,9 @@ static int validate_hash_algo(struct dentry *dentry,
> return -EACCES;
> }
>
> -int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
> - const char *xattr_name, const void *xattr_value,
> - size_t xattr_value_len, int flags)
> +static int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
> + const char *xattr_name, const void *xattr_value,
> + size_t xattr_value_len, int flags)
> {
> const struct evm_ima_xattr_data *xvalue = xattr_value;
> int digsig = 0;
> @@ -781,8 +781,8 @@ int ima_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
> return result;
> }
>
> -int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
> - const char *acl_name, struct posix_acl *kacl)
> +static int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
> + const char *acl_name, struct posix_acl *kacl)
> {
> if (evm_revalidate_status(acl_name))
> ima_reset_appraise_flags(d_backing_inode(dentry), 0);
> @@ -790,8 +790,8 @@ int ima_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
> return 0;
> }
>
> -int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
> - const char *xattr_name)
> +static int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
> + const char *xattr_name)
> {
> int result;
>
> @@ -803,3 +803,23 @@ int ima_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
> }
> return result;
> }
> +
> +static int ima_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
> + const char *acl_name)
> +{
> + return ima_inode_set_acl(idmap, dentry, acl_name, NULL);
> +}
> +
> +static struct security_hook_list ima_appraise_hooks[] __ro_after_init = {
> + LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr),
> + LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr),
> + LSM_HOOK_INIT(inode_set_acl, ima_inode_set_acl),
> + LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr),
> + LSM_HOOK_INIT(inode_remove_acl, ima_inode_remove_acl),
> +};
> +
> +void __init init_ima_appraise_lsm(const struct lsm_id *lsmid)
> +{
> + security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks),
> + lsmid);
> +}
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 483ccd24e214..77d0d4e4b582 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -1178,6 +1178,7 @@ static const struct lsm_id ima_lsmid = {
> static int __init init_ima_lsm(void)
> {
> security_add_hooks(ima_hooks, ARRAY_SIZE(ima_hooks), &ima_lsmid);
> + init_ima_appraise_lsm(&ima_lsmid);
> return 0;
> }
>
> diff --git a/security/security.c b/security/security.c
> index aa17b47d44c1..c07ad3c5f767 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -20,7 +20,6 @@
> #include <linux/kernel_read_file.h>
> #include <linux/lsm_hooks.h>
> #include <linux/integrity.h>
> -#include <linux/ima.h>
> #include <linux/evm.h>
> #include <linux/fsnotify.h>
> #include <linux/mman.h>
> @@ -2308,9 +2307,6 @@ int security_inode_setxattr(struct mnt_idmap *idmap,
>
> if (ret == 1)
> ret = cap_inode_setxattr(dentry, name, value, size, flags);
> - if (ret)
> - return ret;
> - ret = ima_inode_setxattr(idmap, dentry, name, value, size, flags);
> if (ret)
> return ret;
> return evm_inode_setxattr(idmap, dentry, name, value, size, flags);
> @@ -2338,9 +2334,6 @@ int security_inode_set_acl(struct mnt_idmap *idmap,
> return 0;
> ret = call_int_hook(inode_set_acl, 0, idmap, dentry, acl_name,
> kacl);
> - if (ret)
> - return ret;
> - ret = ima_inode_set_acl(idmap, dentry, acl_name, kacl);
> if (ret)
> return ret;
> return evm_inode_set_acl(idmap, dentry, acl_name, kacl);
> @@ -2401,9 +2394,6 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
> if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> return 0;
> ret = call_int_hook(inode_remove_acl, 0, idmap, dentry, acl_name);
> - if (ret)
> - return ret;
> - ret = ima_inode_remove_acl(idmap, dentry, acl_name);
> if (ret)
> return ret;
> return evm_inode_remove_acl(idmap, dentry, acl_name);
> @@ -2503,9 +2493,6 @@ int security_inode_removexattr(struct mnt_idmap *idmap,
> ret = call_int_hook(inode_removexattr, 1, idmap, dentry, name);
> if (ret == 1)
> ret = cap_inode_removexattr(idmap, dentry, name);
> - if (ret)
> - return ret;
> - ret = ima_inode_removexattr(idmap, dentry, name);
> if (ret)
> return ret;
> return evm_inode_removexattr(idmap, dentry, name);
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