Re: [PATCH v3 22/25] ima: Move IMA-Appraisal to LSM infrastructure

Stefan Berger
2023-09-05T20:55:36Z

On 9/4/23 09:40, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Do the registration of IMA-Appraisal 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, remove hardcoded calls
> from the LSM infrastructure or the other places, declare the functions as
> static and register them as hook implementations in
> init_ima_appraise_lsm(), called by init_ima_lsm() to chain the
> initialization.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.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 3c309eb456c6..63fb60195409 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"
>
> @@ -487,7 +486,6 @@ 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 58591b5cbdb4..586e2e18e494 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -98,66 +98,11 @@ 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);
> -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);
> -}
> -
> -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..d19aa9c068da 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(void);
>
> #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(void)
> +{
> +}
> +
> #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 c35e3537eb87..8fe6ea70f02b 100644
> --- a/security/integrity/ima/ima_appraise.c
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -634,8 +634,8 @@ 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;
> @@ -748,9 +748,9 @@ 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;
> @@ -779,8 +779,8 @@ 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);
> @@ -788,8 +788,8 @@ 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;
>
> @@ -801,3 +801,23 @@ 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(void)
> +{
> + security_add_hooks(ima_appraise_hooks, ARRAY_SIZE(ima_appraise_hooks),
> + "integrity");
> +}
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 0e4f882fcdce..c31e11a5bc31 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -1141,6 +1141,7 @@ static struct security_hook_list ima_hooks[] __ro_after_init = {
> void __init init_ima_lsm(void)
> {
> security_add_hooks(ima_hooks, ARRAY_SIZE(ima_hooks), "integrity");
> + init_ima_appraise_lsm();
> }
>
> late_initcall(init_ima); /* Start IMA after the TPM is available */
> diff --git a/security/security.c b/security/security.c
> index 0b196d3f01b8..eb686f9471ea 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>
> @@ -2217,9 +2216,6 @@ 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);
> @@ -2247,9 +2243,6 @@ 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);
> @@ -2310,9 +2303,6 @@ 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);
> @@ -2412,9 +2402,6 @@ 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);

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>