| Message ID | 20231107134012.682009-22-roberto.sassu@huaweicloud.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | security: Move IMA and EVM to the LSM infrastructure | expand |
On 11/7/2023 5:40 AM, Roberto Sassu wrote: > From: Roberto Sassu <roberto.sassu@huawei.com> > > As for IMA, move hardcoded EVM function calls from various places in the > kernel to the LSM infrastructure, by introducing a new LSM named 'evm' > (at the end of the LSM list and always enabled, like 'ima' and > 'integrity'). > > Make EVM functions as static (except for evm_inode_init_security(), which > is exported), and register them as hook implementations in init_evm_lsm(), > called by integrity_lsm_init() to keep the original ordering of IMA and EVM > functions. > > Introduce evm_get_lsm_id() to pass the EVM LSM ID back to the 'integrity' > LSM for registration of the integrity-specific hooks. > > Finally, switch to the LSM reservation mechanism for the EVM xattr, and > consequently decrement by one the number of xattrs to allocate in > security_inode_init_security(). > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> > --- > fs/attr.c | 2 - > fs/posix_acl.c | 3 - > fs/xattr.c | 2 - > include/linux/evm.h | 107 ----------------------- > include/uapi/linux/lsm.h | 1 + > security/integrity/evm/evm_main.c | 137 ++++++++++++++++++++++++++---- > security/integrity/iint.c | 1 + > security/integrity/integrity.h | 15 ++++ > security/security.c | 45 +++------- > 9 files changed, 150 insertions(+), 163 deletions(-) > > diff --git a/fs/attr.c b/fs/attr.c > index 38841f3ebbcb..b51bd7c9b4a7 100644 > --- a/fs/attr.c > +++ b/fs/attr.c > @@ -16,7 +16,6 @@ > #include <linux/fcntl.h> > #include <linux/filelock.h> > #include <linux/security.h> > -#include <linux/evm.h> > > #include "internal.h" > > @@ -502,7 +501,6 @@ 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); > - evm_inode_post_setattr(idmap, dentry, ia_valid); > } > > return error; > diff --git a/fs/posix_acl.c b/fs/posix_acl.c > index e3fbe1a9f3f5..ae67479cd2b6 100644 > --- a/fs/posix_acl.c > +++ b/fs/posix_acl.c > @@ -26,7 +26,6 @@ > #include <linux/mnt_idmapping.h> > #include <linux/iversion.h> > #include <linux/security.h> > -#include <linux/evm.h> > #include <linux/fsnotify.h> > #include <linux/filelock.h> > > @@ -1138,7 +1137,6 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, > if (!error) { > fsnotify_xattr(dentry); > security_inode_post_set_acl(dentry, acl_name, kacl); > - evm_inode_post_set_acl(dentry, acl_name, kacl); > } > > out_inode_unlock: > @@ -1247,7 +1245,6 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, > if (!error) { > fsnotify_xattr(dentry); > security_inode_post_remove_acl(idmap, dentry, acl_name); > - evm_inode_post_remove_acl(idmap, dentry, acl_name); > } > > out_inode_unlock: > diff --git a/fs/xattr.c b/fs/xattr.c > index 84a4aa566c02..2660bc7effdc 100644 > --- a/fs/xattr.c > +++ b/fs/xattr.c > @@ -16,7 +16,6 @@ > #include <linux/mount.h> > #include <linux/namei.h> > #include <linux/security.h> > -#include <linux/evm.h> > #include <linux/syscalls.h> > #include <linux/export.h> > #include <linux/fsnotify.h> > @@ -557,7 +556,6 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap, > > fsnotify_xattr(dentry); > security_inode_post_removexattr(dentry, name); > - evm_inode_post_removexattr(dentry, name); > > out: > return error; > diff --git a/include/linux/evm.h b/include/linux/evm.h > index 437d4076a3b3..cb481eccc967 100644 > --- a/include/linux/evm.h > +++ b/include/linux/evm.h > @@ -21,44 +21,6 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry, > void *xattr_value, > size_t xattr_value_len, > struct integrity_iint_cache *iint); > -extern int evm_inode_setattr(struct mnt_idmap *idmap, > - struct dentry *dentry, struct iattr *attr); > -extern void evm_inode_post_setattr(struct mnt_idmap *idmap, > - struct dentry *dentry, int ia_valid); > -extern int evm_inode_setxattr(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *name, > - const void *value, size_t size, int flags); > -extern void evm_inode_post_setxattr(struct dentry *dentry, > - const char *xattr_name, > - const void *xattr_value, > - size_t xattr_value_len, > - int flags); > -extern int evm_inode_removexattr(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *xattr_name); > -extern void evm_inode_post_removexattr(struct dentry *dentry, > - const char *xattr_name); > -static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, > - const char *acl_name) > -{ > - evm_inode_post_removexattr(dentry, acl_name); > -} > -extern int evm_inode_set_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *acl_name, > - struct posix_acl *kacl); > -static inline int evm_inode_remove_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, > - const char *acl_name) > -{ > - return evm_inode_set_acl(idmap, dentry, acl_name, NULL); > -} > -static inline void evm_inode_post_set_acl(struct dentry *dentry, > - const char *acl_name, > - struct posix_acl *kacl) > -{ > - return evm_inode_post_setxattr(dentry, acl_name, NULL, 0, 0); > -} > - > int evm_inode_init_security(struct inode *inode, struct inode *dir, > const struct qstr *qstr, struct xattr *xattrs, > int *xattr_count); > @@ -93,75 +55,6 @@ static inline enum integrity_status evm_verifyxattr(struct dentry *dentry, > } > #endif > > -static inline int evm_inode_setattr(struct mnt_idmap *idmap, > - struct dentry *dentry, struct iattr *attr) > -{ > - return 0; > -} > - > -static inline void evm_inode_post_setattr(struct mnt_idmap *idmap, > - struct dentry *dentry, int ia_valid) > -{ > - return; > -} > - > -static inline int evm_inode_setxattr(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *name, > - const void *value, size_t size, int flags) > -{ > - return 0; > -} > - > -static inline void evm_inode_post_setxattr(struct dentry *dentry, > - const char *xattr_name, > - const void *xattr_value, > - size_t xattr_value_len, > - int flags) > -{ > - return; > -} > - > -static inline int evm_inode_removexattr(struct mnt_idmap *idmap, > - struct dentry *dentry, > - const char *xattr_name) > -{ > - return 0; > -} > - > -static inline void evm_inode_post_removexattr(struct dentry *dentry, > - const char *xattr_name) > -{ > - return; > -} > - > -static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, > - const char *acl_name) > -{ > - return; > -} > - > -static inline int evm_inode_set_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *acl_name, > - struct posix_acl *kacl) > -{ > - return 0; > -} > - > -static inline int evm_inode_remove_acl(struct mnt_idmap *idmap, > - struct dentry *dentry, > - const char *acl_name) > -{ > - return 0; > -} > - > -static inline void evm_inode_post_set_acl(struct dentry *dentry, > - const char *acl_name, > - struct posix_acl *kacl) > -{ > - return; > -} > - > static inline int evm_inode_init_security(struct inode *inode, struct inode *dir, > const struct qstr *qstr, > struct xattr *xattrs, > diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h > index ee7d034255a9..825339bcd580 100644 > --- a/include/uapi/linux/lsm.h > +++ b/include/uapi/linux/lsm.h > @@ -62,6 +62,7 @@ struct lsm_ctx { > #define LSM_ID_BPF 109 > #define LSM_ID_LANDLOCK 110 > #define LSM_ID_IMA 111 > +#define LSM_ID_EVM 112 > > /* > * LSM_ATTR_XXX definitions identify different LSM attributes > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > index ea84a6f835ff..21560874e5fc 100644 > --- a/security/integrity/evm/evm_main.c > +++ b/security/integrity/evm/evm_main.c > @@ -566,9 +566,9 @@ static int evm_protect_xattr(struct mnt_idmap *idmap, > * userspace from writing HMAC value. Writing 'security.evm' requires > * requires CAP_SYS_ADMIN privileges. > */ > -int evm_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 evm_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 *xattr_data = xattr_value; > > @@ -598,8 +598,8 @@ int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, > * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that > * the current value is valid. > */ > -int evm_inode_removexattr(struct mnt_idmap *idmap, > - struct dentry *dentry, const char *xattr_name) > +static int evm_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, > + const char *xattr_name) > { > /* Policy permits modification of the protected xattrs even though > * there's no HMAC key loaded > @@ -649,9 +649,11 @@ static inline int evm_inode_set_acl_change(struct mnt_idmap *idmap, > * Prevent modifying posix acls causing the EVM HMAC to be re-calculated > * and 'security.evm' xattr updated, unless the existing 'security.evm' is > * valid. > + * > + * Return: zero on success, -EPERM on failure. > */ > -int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, > - const char *acl_name, struct posix_acl *kacl) > +static int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, > + const char *acl_name, struct posix_acl *kacl) > { > enum integrity_status evm_status; > > @@ -690,6 +692,24 @@ int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, > return -EPERM; > } > > +/** > + * evm_inode_remove_acl - Protect the EVM extended attribute from posix acls > + * @idmap: idmap of the mount > + * @dentry: pointer to the affected dentry > + * @acl_name: name of the posix acl > + * > + * Prevent removing posix acls causing the EVM HMAC to be re-calculated > + * and 'security.evm' xattr updated, unless the existing 'security.evm' is > + * valid. > + * > + * Return: zero on success, -EPERM on failure. > + */ > +static int evm_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, > + const char *acl_name) > +{ > + return evm_inode_set_acl(idmap, dentry, acl_name, NULL); > +} > + > static void evm_reset_status(struct inode *inode) > { > struct integrity_iint_cache *iint; > @@ -738,9 +758,11 @@ bool evm_revalidate_status(const char *xattr_name) > * __vfs_setxattr_noperm(). The caller of which has taken the inode's > * i_mutex lock. > */ > -void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, > - const void *xattr_value, size_t xattr_value_len, > - int flags) > +static void evm_inode_post_setxattr(struct dentry *dentry, > + const char *xattr_name, > + const void *xattr_value, > + size_t xattr_value_len, > + int flags) > { > if (!evm_revalidate_status(xattr_name)) > return; > @@ -756,6 +778,21 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, > evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len); > } > > +/** > + * evm_inode_post_set_acl - Update the EVM extended attribute from posix acls > + * @dentry: pointer to the affected dentry > + * @acl_name: name of the posix acl > + * @kacl: pointer to the posix acls > + * > + * Update the 'security.evm' xattr with the EVM HMAC re-calculated after setting > + * posix acls. > + */ > +static void evm_inode_post_set_acl(struct dentry *dentry, const char *acl_name, > + struct posix_acl *kacl) > +{ > + return evm_inode_post_setxattr(dentry, acl_name, NULL, 0, 0); > +} > + > /** > * evm_inode_post_removexattr - update 'security.evm' after removing the xattr > * @dentry: pointer to the affected dentry > @@ -766,7 +803,8 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, > * No need to take the i_mutex lock here, as this function is called from > * vfs_removexattr() which takes the i_mutex. > */ > -void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) > +static void evm_inode_post_removexattr(struct dentry *dentry, > + const char *xattr_name) > { > if (!evm_revalidate_status(xattr_name)) > return; > @@ -782,6 +820,22 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) > evm_update_evmxattr(dentry, xattr_name, NULL, 0); > } > > +/** > + * evm_inode_post_remove_acl - Update the EVM extended attribute from posix acls > + * @idmap: idmap of the mount > + * @dentry: pointer to the affected dentry > + * @acl_name: name of the posix acl > + * > + * Update the 'security.evm' xattr with the EVM HMAC re-calculated after > + * removing posix acls. > + */ > +static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, > + struct dentry *dentry, > + const char *acl_name) > +{ > + evm_inode_post_removexattr(dentry, acl_name); > +} > + > static int evm_attr_change(struct mnt_idmap *idmap, > struct dentry *dentry, struct iattr *attr) > { > @@ -805,8 +859,8 @@ static int evm_attr_change(struct mnt_idmap *idmap, > * Permit update of file attributes when files have a valid EVM signature, > * except in the case of them having an immutable portable signature. > */ > -int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, > - struct iattr *attr) > +static int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, > + struct iattr *attr) > { > unsigned int ia_valid = attr->ia_valid; > enum integrity_status evm_status; > @@ -853,8 +907,8 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, > * This function is called from notify_change(), which expects the caller > * to lock the inode's i_mutex. > */ > -void evm_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, > - int ia_valid) > +static void evm_inode_post_setattr(struct mnt_idmap *idmap, > + struct dentry *dentry, int ia_valid) > { > if (!evm_revalidate_status(NULL)) > return; > @@ -964,4 +1018,57 @@ static int __init init_evm(void) > return error; > } > > +static struct security_hook_list evm_hooks[] __ro_after_init = { > + LSM_HOOK_INIT(inode_setattr, evm_inode_setattr), > + LSM_HOOK_INIT(inode_post_setattr, evm_inode_post_setattr), > + LSM_HOOK_INIT(inode_setxattr, evm_inode_setxattr), > + LSM_HOOK_INIT(inode_set_acl, evm_inode_set_acl), > + LSM_HOOK_INIT(inode_post_set_acl, evm_inode_post_set_acl), > + LSM_HOOK_INIT(inode_remove_acl, evm_inode_remove_acl), > + LSM_HOOK_INIT(inode_post_remove_acl, evm_inode_post_remove_acl), > + LSM_HOOK_INIT(inode_post_setxattr, evm_inode_post_setxattr), > + LSM_HOOK_INIT(inode_removexattr, evm_inode_removexattr), > + LSM_HOOK_INIT(inode_post_removexattr, evm_inode_post_removexattr), > + LSM_HOOK_INIT(inode_init_security, evm_inode_init_security), > +}; > + > +static const struct lsm_id evm_lsmid = { > + .name = "evm", > + .id = LSM_ID_EVM, > +}; > + > +/* Return the EVM LSM ID, if EVM is enabled or NULL if not. */ > +const struct lsm_id *evm_get_lsm_id(void) > +{ > + return &evm_lsmid; > +} > + > +/* > + * Since with the LSM_ORDER_LAST there is no guarantee about the ordering > + * within the .lsm_info.init section, ensure that IMA hooks are before EVM > + * ones, by letting the 'integrity' LSM call init_evm_lsm() to initialize the > + * 'ima' and 'evm' LSMs in this sequence. > + */ > +void __init init_evm_lsm(void) > +{ > + security_add_hooks(evm_hooks, ARRAY_SIZE(evm_hooks), &evm_lsmid); > +} > + > +static struct lsm_blob_sizes evm_blob_sizes __ro_after_init = { > + .lbs_xattr_count = 1, > +}; > + > +/* Introduce a dummy function as 'evm' init method (it cannot be NULL). */ > +static int __init dummy_init_evm_lsm(void) > +{ > + return 0; > +} > + > +DEFINE_LSM(evm) = { > + .name = "evm", > + .init = dummy_init_evm_lsm, > + .order = LSM_ORDER_LAST, > + .blobs = &evm_blob_sizes, > +}; > + > late_initcall(init_evm); > diff --git a/security/integrity/iint.c b/security/integrity/iint.c > index 87f2c0d69f78..0b0ac71142e8 100644 > --- a/security/integrity/iint.c > +++ b/security/integrity/iint.c > @@ -199,6 +199,7 @@ static int __init integrity_lsm_init(void) > kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), > 0, SLAB_PANIC, iint_init_once); > init_ima_lsm(); > + init_evm_lsm(); > return 0; > } > > diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h > index 3098cae1c27c..7534ec06324e 100644 > --- a/security/integrity/integrity.h > +++ b/security/integrity/integrity.h > @@ -209,6 +209,21 @@ static inline void __init init_ima_lsm(void) > > #endif > > +#ifdef CONFIG_EVM > +const struct lsm_id *evm_get_lsm_id(void); > +void __init init_evm_lsm(void); > +#else > +static inline const struct lsm_id *evm_get_lsm_id(void) > +{ > + return NULL; > +} > + > +static inline void __init init_evm_lsm(void) > +{ > +} > + > +#endif > + > #ifdef CONFIG_INTEGRITY_SIGNATURE > > int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, > diff --git a/security/security.c b/security/security.c > index 456f3fe74116..9703549b6ddc 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -20,13 +20,13 @@ > #include <linux/kernel_read_file.h> > #include <linux/lsm_hooks.h> > #include <linux/integrity.h> > -#include <linux/evm.h> > #include <linux/fsnotify.h> > #include <linux/mman.h> > #include <linux/mount.h> > #include <linux/personality.h> > #include <linux/backing-dev.h> > #include <linux/string.h> > +#include <linux/xattr.h> > #include <linux/msg.h> > #include <net/flow.h> > > @@ -50,7 +50,8 @@ > (IS_ENABLED(CONFIG_SECURITY_LOCKDOWN_LSM) ? 1 : 0) + \ > (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \ > (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \ > - (IS_ENABLED(CONFIG_IMA) ? 1 : 0)) > + (IS_ENABLED(CONFIG_IMA) ? 1 : 0) + \ > + (IS_ENABLED(CONFIG_EVM) ? 1 : 0)) > > /* > * These are descriptions of the reasons that can be passed to the > @@ -1715,8 +1716,8 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > return 0; > > if (initxattrs) { > - /* Allocate +1 for EVM and +1 as terminator. */ > - new_xattrs = kcalloc(blob_sizes.lbs_xattr_count + 2, > + /* Allocate +1 as terminator. */ > + new_xattrs = kcalloc(blob_sizes.lbs_xattr_count + 1, > sizeof(*new_xattrs), GFP_NOFS); > if (!new_xattrs) > return -ENOMEM; > @@ -1740,10 +1741,6 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > if (!xattr_count) > goto out; > > - ret = evm_inode_init_security(inode, dir, qstr, new_xattrs, > - &xattr_count); > - if (ret) > - goto out; > ret = initxattrs(inode, new_xattrs, fs_data); > out: > for (; xattr_count > 0; xattr_count--) > @@ -2235,14 +2232,9 @@ int security_inode_permission(struct inode *inode, int mask) > int security_inode_setattr(struct mnt_idmap *idmap, > struct dentry *dentry, struct iattr *attr) > { > - int ret; > - > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > return 0; > - ret = call_int_hook(inode_setattr, 0, idmap, dentry, attr); > - if (ret) > - return ret; > - return evm_inode_setattr(idmap, dentry, attr); > + return call_int_hook(inode_setattr, 0, idmap, dentry, attr); > } > EXPORT_SYMBOL_GPL(security_inode_setattr); > > @@ -2307,9 +2299,7 @@ int security_inode_setxattr(struct mnt_idmap *idmap, > > if (ret == 1) > ret = cap_inode_setxattr(dentry, name, value, size, flags); > - if (ret) > - return ret; > - return evm_inode_setxattr(idmap, dentry, name, value, size, flags); > + return ret; > } > > /** > @@ -2328,15 +2318,10 @@ int security_inode_set_acl(struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name, > struct posix_acl *kacl) > { > - int ret; > - > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > return 0; > - ret = call_int_hook(inode_set_acl, 0, idmap, dentry, acl_name, > - kacl); > - if (ret) > - return ret; > - return evm_inode_set_acl(idmap, dentry, acl_name, kacl); > + return call_int_hook(inode_set_acl, 0, idmap, dentry, acl_name, > + kacl); > } > > /** > @@ -2389,14 +2374,9 @@ int security_inode_get_acl(struct mnt_idmap *idmap, > int security_inode_remove_acl(struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name) > { > - int ret; > - > 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; > - return evm_inode_remove_acl(idmap, dentry, acl_name); > + return call_int_hook(inode_remove_acl, 0, idmap, dentry, acl_name); > } > > /** > @@ -2432,7 +2412,6 @@ void security_inode_post_setxattr(struct dentry *dentry, const char *name, > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > return; > call_void_hook(inode_post_setxattr, dentry, name, value, size, flags); > - evm_inode_post_setxattr(dentry, name, value, size, flags); > } > > /** > @@ -2493,9 +2472,7 @@ 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; > - return evm_inode_removexattr(idmap, dentry, name); > + return ret; > } > > /**
diff --git a/fs/attr.c b/fs/attr.c index 38841f3ebbcb..b51bd7c9b4a7 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -16,7 +16,6 @@ #include <linux/fcntl.h> #include <linux/filelock.h> #include <linux/security.h> -#include <linux/evm.h> #include "internal.h" @@ -502,7 +501,6 @@ 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); - evm_inode_post_setattr(idmap, dentry, ia_valid); } return error; diff --git a/fs/posix_acl.c b/fs/posix_acl.c index e3fbe1a9f3f5..ae67479cd2b6 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -26,7 +26,6 @@ #include <linux/mnt_idmapping.h> #include <linux/iversion.h> #include <linux/security.h> -#include <linux/evm.h> #include <linux/fsnotify.h> #include <linux/filelock.h> @@ -1138,7 +1137,6 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, if (!error) { fsnotify_xattr(dentry); security_inode_post_set_acl(dentry, acl_name, kacl); - evm_inode_post_set_acl(dentry, acl_name, kacl); } out_inode_unlock: @@ -1247,7 +1245,6 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, if (!error) { fsnotify_xattr(dentry); security_inode_post_remove_acl(idmap, dentry, acl_name); - evm_inode_post_remove_acl(idmap, dentry, acl_name); } out_inode_unlock: diff --git a/fs/xattr.c b/fs/xattr.c index 84a4aa566c02..2660bc7effdc 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -16,7 +16,6 @@ #include <linux/mount.h> #include <linux/namei.h> #include <linux/security.h> -#include <linux/evm.h> #include <linux/syscalls.h> #include <linux/export.h> #include <linux/fsnotify.h> @@ -557,7 +556,6 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap, fsnotify_xattr(dentry); security_inode_post_removexattr(dentry, name); - evm_inode_post_removexattr(dentry, name); out: return error; diff --git a/include/linux/evm.h b/include/linux/evm.h index 437d4076a3b3..cb481eccc967 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -21,44 +21,6 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry, void *xattr_value, size_t xattr_value_len, struct integrity_iint_cache *iint); -extern int evm_inode_setattr(struct mnt_idmap *idmap, - struct dentry *dentry, struct iattr *attr); -extern void evm_inode_post_setattr(struct mnt_idmap *idmap, - struct dentry *dentry, int ia_valid); -extern int evm_inode_setxattr(struct mnt_idmap *idmap, - struct dentry *dentry, const char *name, - const void *value, size_t size, int flags); -extern void evm_inode_post_setxattr(struct dentry *dentry, - const char *xattr_name, - const void *xattr_value, - size_t xattr_value_len, - int flags); -extern int evm_inode_removexattr(struct mnt_idmap *idmap, - struct dentry *dentry, const char *xattr_name); -extern void evm_inode_post_removexattr(struct dentry *dentry, - const char *xattr_name); -static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, - struct dentry *dentry, - const char *acl_name) -{ - evm_inode_post_removexattr(dentry, acl_name); -} -extern int evm_inode_set_acl(struct mnt_idmap *idmap, - struct dentry *dentry, const char *acl_name, - struct posix_acl *kacl); -static inline int evm_inode_remove_acl(struct mnt_idmap *idmap, - struct dentry *dentry, - const char *acl_name) -{ - return evm_inode_set_acl(idmap, dentry, acl_name, NULL); -} -static inline void evm_inode_post_set_acl(struct dentry *dentry, - const char *acl_name, - struct posix_acl *kacl) -{ - return evm_inode_post_setxattr(dentry, acl_name, NULL, 0, 0); -} - int evm_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, struct xattr *xattrs, int *xattr_count); @@ -93,75 +55,6 @@ static inline enum integrity_status evm_verifyxattr(struct dentry *dentry, } #endif -static inline int evm_inode_setattr(struct mnt_idmap *idmap, - struct dentry *dentry, struct iattr *attr) -{ - return 0; -} - -static inline void evm_inode_post_setattr(struct mnt_idmap *idmap, - struct dentry *dentry, int ia_valid) -{ - return; -} - -static inline int evm_inode_setxattr(struct mnt_idmap *idmap, - struct dentry *dentry, const char *name, - const void *value, size_t size, int flags) -{ - return 0; -} - -static inline void evm_inode_post_setxattr(struct dentry *dentry, - const char *xattr_name, - const void *xattr_value, - size_t xattr_value_len, - int flags) -{ - return; -} - -static inline int evm_inode_removexattr(struct mnt_idmap *idmap, - struct dentry *dentry, - const char *xattr_name) -{ - return 0; -} - -static inline void evm_inode_post_removexattr(struct dentry *dentry, - const char *xattr_name) -{ - return; -} - -static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, - struct dentry *dentry, - const char *acl_name) -{ - return; -} - -static inline int evm_inode_set_acl(struct mnt_idmap *idmap, - struct dentry *dentry, const char *acl_name, - struct posix_acl *kacl) -{ - return 0; -} - -static inline int evm_inode_remove_acl(struct mnt_idmap *idmap, - struct dentry *dentry, - const char *acl_name) -{ - return 0; -} - -static inline void evm_inode_post_set_acl(struct dentry *dentry, - const char *acl_name, - struct posix_acl *kacl) -{ - return; -} - static inline int evm_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, struct xattr *xattrs, diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h index ee7d034255a9..825339bcd580 100644 --- a/include/uapi/linux/lsm.h +++ b/include/uapi/linux/lsm.h @@ -62,6 +62,7 @@ struct lsm_ctx { #define LSM_ID_BPF 109 #define LSM_ID_LANDLOCK 110 #define LSM_ID_IMA 111 +#define LSM_ID_EVM 112 /* * LSM_ATTR_XXX definitions identify different LSM attributes diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index ea84a6f835ff..21560874e5fc 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -566,9 +566,9 @@ static int evm_protect_xattr(struct mnt_idmap *idmap, * userspace from writing HMAC value. Writing 'security.evm' requires * requires CAP_SYS_ADMIN privileges. */ -int evm_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 evm_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 *xattr_data = xattr_value; @@ -598,8 +598,8 @@ int evm_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that * the current value is valid. */ -int evm_inode_removexattr(struct mnt_idmap *idmap, - struct dentry *dentry, const char *xattr_name) +static int evm_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, + const char *xattr_name) { /* Policy permits modification of the protected xattrs even though * there's no HMAC key loaded @@ -649,9 +649,11 @@ static inline int evm_inode_set_acl_change(struct mnt_idmap *idmap, * Prevent modifying posix acls causing the EVM HMAC to be re-calculated * and 'security.evm' xattr updated, unless the existing 'security.evm' is * valid. + * + * Return: zero on success, -EPERM on failure. */ -int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, - const char *acl_name, struct posix_acl *kacl) +static int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, + const char *acl_name, struct posix_acl *kacl) { enum integrity_status evm_status; @@ -690,6 +692,24 @@ int evm_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, return -EPERM; } +/** + * evm_inode_remove_acl - Protect the EVM extended attribute from posix acls + * @idmap: idmap of the mount + * @dentry: pointer to the affected dentry + * @acl_name: name of the posix acl + * + * Prevent removing posix acls causing the EVM HMAC to be re-calculated + * and 'security.evm' xattr updated, unless the existing 'security.evm' is + * valid. + * + * Return: zero on success, -EPERM on failure. + */ +static int evm_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, + const char *acl_name) +{ + return evm_inode_set_acl(idmap, dentry, acl_name, NULL); +} + static void evm_reset_status(struct inode *inode) { struct integrity_iint_cache *iint; @@ -738,9 +758,11 @@ bool evm_revalidate_status(const char *xattr_name) * __vfs_setxattr_noperm(). The caller of which has taken the inode's * i_mutex lock. */ -void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, - const void *xattr_value, size_t xattr_value_len, - int flags) +static void evm_inode_post_setxattr(struct dentry *dentry, + const char *xattr_name, + const void *xattr_value, + size_t xattr_value_len, + int flags) { if (!evm_revalidate_status(xattr_name)) return; @@ -756,6 +778,21 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len); } +/** + * evm_inode_post_set_acl - Update the EVM extended attribute from posix acls + * @dentry: pointer to the affected dentry + * @acl_name: name of the posix acl + * @kacl: pointer to the posix acls + * + * Update the 'security.evm' xattr with the EVM HMAC re-calculated after setting + * posix acls. + */ +static void evm_inode_post_set_acl(struct dentry *dentry, const char *acl_name, + struct posix_acl *kacl) +{ + return evm_inode_post_setxattr(dentry, acl_name, NULL, 0, 0); +} + /** * evm_inode_post_removexattr - update 'security.evm' after removing the xattr * @dentry: pointer to the affected dentry @@ -766,7 +803,8 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, * No need to take the i_mutex lock here, as this function is called from * vfs_removexattr() which takes the i_mutex. */ -void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) +static void evm_inode_post_removexattr(struct dentry *dentry, + const char *xattr_name) { if (!evm_revalidate_status(xattr_name)) return; @@ -782,6 +820,22 @@ void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name) evm_update_evmxattr(dentry, xattr_name, NULL, 0); } +/** + * evm_inode_post_remove_acl - Update the EVM extended attribute from posix acls + * @idmap: idmap of the mount + * @dentry: pointer to the affected dentry + * @acl_name: name of the posix acl + * + * Update the 'security.evm' xattr with the EVM HMAC re-calculated after + * removing posix acls. + */ +static inline void evm_inode_post_remove_acl(struct mnt_idmap *idmap, + struct dentry *dentry, + const char *acl_name) +{ + evm_inode_post_removexattr(dentry, acl_name); +} + static int evm_attr_change(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { @@ -805,8 +859,8 @@ static int evm_attr_change(struct mnt_idmap *idmap, * Permit update of file attributes when files have a valid EVM signature, * except in the case of them having an immutable portable signature. */ -int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, - struct iattr *attr) +static int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + struct iattr *attr) { unsigned int ia_valid = attr->ia_valid; enum integrity_status evm_status; @@ -853,8 +907,8 @@ int evm_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, * This function is called from notify_change(), which expects the caller * to lock the inode's i_mutex. */ -void evm_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, - int ia_valid) +static void evm_inode_post_setattr(struct mnt_idmap *idmap, + struct dentry *dentry, int ia_valid) { if (!evm_revalidate_status(NULL)) return; @@ -964,4 +1018,57 @@ static int __init init_evm(void) return error; } +static struct security_hook_list evm_hooks[] __ro_after_init = { + LSM_HOOK_INIT(inode_setattr, evm_inode_setattr), + LSM_HOOK_INIT(inode_post_setattr, evm_inode_post_setattr), + LSM_HOOK_INIT(inode_setxattr, evm_inode_setxattr), + LSM_HOOK_INIT(inode_set_acl, evm_inode_set_acl), + LSM_HOOK_INIT(inode_post_set_acl, evm_inode_post_set_acl), + LSM_HOOK_INIT(inode_remove_acl, evm_inode_remove_acl), + LSM_HOOK_INIT(inode_post_remove_acl, evm_inode_post_remove_acl), + LSM_HOOK_INIT(inode_post_setxattr, evm_inode_post_setxattr), + LSM_HOOK_INIT(inode_removexattr, evm_inode_removexattr), + LSM_HOOK_INIT(inode_post_removexattr, evm_inode_post_removexattr), + LSM_HOOK_INIT(inode_init_security, evm_inode_init_security), +}; + +static const struct lsm_id evm_lsmid = { + .name = "evm", + .id = LSM_ID_EVM, +}; + +/* Return the EVM LSM ID, if EVM is enabled or NULL if not. */ +const struct lsm_id *evm_get_lsm_id(void) +{ + return &evm_lsmid; +} + +/* + * Since with the LSM_ORDER_LAST there is no guarantee about the ordering + * within the .lsm_info.init section, ensure that IMA hooks are before EVM + * ones, by letting the 'integrity' LSM call init_evm_lsm() to initialize the + * 'ima' and 'evm' LSMs in this sequence. + */ +void __init init_evm_lsm(void) +{ + security_add_hooks(evm_hooks, ARRAY_SIZE(evm_hooks), &evm_lsmid); +} + +static struct lsm_blob_sizes evm_blob_sizes __ro_after_init = { + .lbs_xattr_count = 1, +}; + +/* Introduce a dummy function as 'evm' init method (it cannot be NULL). */ +static int __init dummy_init_evm_lsm(void) +{ + return 0; +} + +DEFINE_LSM(evm) = { + .name = "evm", + .init = dummy_init_evm_lsm, + .order = LSM_ORDER_LAST, + .blobs = &evm_blob_sizes, +}; + late_initcall(init_evm); diff --git a/security/integrity/iint.c b/security/integrity/iint.c index 87f2c0d69f78..0b0ac71142e8 100644 --- a/security/integrity/iint.c +++ b/security/integrity/iint.c @@ -199,6 +199,7 @@ static int __init integrity_lsm_init(void) kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 0, SLAB_PANIC, iint_init_once); init_ima_lsm(); + init_evm_lsm(); return 0; } diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 3098cae1c27c..7534ec06324e 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -209,6 +209,21 @@ static inline void __init init_ima_lsm(void) #endif +#ifdef CONFIG_EVM +const struct lsm_id *evm_get_lsm_id(void); +void __init init_evm_lsm(void); +#else +static inline const struct lsm_id *evm_get_lsm_id(void) +{ + return NULL; +} + +static inline void __init init_evm_lsm(void) +{ +} + +#endif + #ifdef CONFIG_INTEGRITY_SIGNATURE int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, diff --git a/security/security.c b/security/security.c index 456f3fe74116..9703549b6ddc 100644 --- a/security/security.c +++ b/security/security.c @@ -20,13 +20,13 @@ #include <linux/kernel_read_file.h> #include <linux/lsm_hooks.h> #include <linux/integrity.h> -#include <linux/evm.h> #include <linux/fsnotify.h> #include <linux/mman.h> #include <linux/mount.h> #include <linux/personality.h> #include <linux/backing-dev.h> #include <linux/string.h> +#include <linux/xattr.h> #include <linux/msg.h> #include <net/flow.h> @@ -50,7 +50,8 @@ (IS_ENABLED(CONFIG_SECURITY_LOCKDOWN_LSM) ? 1 : 0) + \ (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \ (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \ - (IS_ENABLED(CONFIG_IMA) ? 1 : 0)) + (IS_ENABLED(CONFIG_IMA) ? 1 : 0) + \ + (IS_ENABLED(CONFIG_EVM) ? 1 : 0)) /* * These are descriptions of the reasons that can be passed to the @@ -1715,8 +1716,8 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, return 0; if (initxattrs) { - /* Allocate +1 for EVM and +1 as terminator. */ - new_xattrs = kcalloc(blob_sizes.lbs_xattr_count + 2, + /* Allocate +1 as terminator. */ + new_xattrs = kcalloc(blob_sizes.lbs_xattr_count + 1, sizeof(*new_xattrs), GFP_NOFS); if (!new_xattrs) return -ENOMEM; @@ -1740,10 +1741,6 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, if (!xattr_count) goto out; - ret = evm_inode_init_security(inode, dir, qstr, new_xattrs, - &xattr_count); - if (ret) - goto out; ret = initxattrs(inode, new_xattrs, fs_data); out: for (; xattr_count > 0; xattr_count--) @@ -2235,14 +2232,9 @@ int security_inode_permission(struct inode *inode, int mask) int security_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { - int ret; - if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) return 0; - ret = call_int_hook(inode_setattr, 0, idmap, dentry, attr); - if (ret) - return ret; - return evm_inode_setattr(idmap, dentry, attr); + return call_int_hook(inode_setattr, 0, idmap, dentry, attr); } EXPORT_SYMBOL_GPL(security_inode_setattr); @@ -2307,9 +2299,7 @@ int security_inode_setxattr(struct mnt_idmap *idmap, if (ret == 1) ret = cap_inode_setxattr(dentry, name, value, size, flags); - if (ret) - return ret; - return evm_inode_setxattr(idmap, dentry, name, value, size, flags); + return ret; } /** @@ -2328,15 +2318,10 @@ int security_inode_set_acl(struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) { - int ret; - if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) return 0; - ret = call_int_hook(inode_set_acl, 0, idmap, dentry, acl_name, - kacl); - if (ret) - return ret; - return evm_inode_set_acl(idmap, dentry, acl_name, kacl); + return call_int_hook(inode_set_acl, 0, idmap, dentry, acl_name, + kacl); } /** @@ -2389,14 +2374,9 @@ int security_inode_get_acl(struct mnt_idmap *idmap, int security_inode_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name) { - int ret; - 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; - return evm_inode_remove_acl(idmap, dentry, acl_name); + return call_int_hook(inode_remove_acl, 0, idmap, dentry, acl_name); } /** @@ -2432,7 +2412,6 @@ void security_inode_post_setxattr(struct dentry *dentry, const char *name, if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) return; call_void_hook(inode_post_setxattr, dentry, name, value, size, flags); - evm_inode_post_setxattr(dentry, name, value, size, flags); } /** @@ -2493,9 +2472,7 @@ 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; - return evm_inode_removexattr(idmap, dentry, name); + return ret; } /**