| Message ID | 20240115181809.885385-11-roberto.sassu@huaweicloud.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | security: Move IMA and EVM to the LSM infrastructure | expand |
On Jan 15, 2024 Roberto Sassu <roberto.sassu@huaweicloud.com> wrote: > > In preparation for moving IMA and EVM to the LSM infrastructure, introduce > the inode_post_setattr hook. > > At inode_setattr hook, EVM verifies the file's existing HMAC value. At > inode_post_setattr, EVM re-calculates the file's HMAC based on the modified > file attributes and other file metadata. > > Other LSMs could similarly take some action after successful file attribute > change. > > The new hook cannot return an error and cannot cause the operation to be > reverted. > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > --- > fs/attr.c | 1 + > include/linux/lsm_hook_defs.h | 2 ++ > include/linux/security.h | 7 +++++++ > security/security.c | 16 ++++++++++++++++ > 4 files changed, 26 insertions(+) Acked-by: Paul Moore <paul@paul-moore.com> -- paul-moore.com
On Mon, Jan 15, 2024 at 07:17:54PM +0100, Roberto Sassu wrote: > From: Roberto Sassu <roberto.sassu@huawei.com> > > In preparation for moving IMA and EVM to the LSM infrastructure, introduce > the inode_post_setattr hook. > > At inode_setattr hook, EVM verifies the file's existing HMAC value. At > inode_post_setattr, EVM re-calculates the file's HMAC based on the modified > file attributes and other file metadata. > > Other LSMs could similarly take some action after successful file attribute > change. > > The new hook cannot return an error and cannot cause the operation to be > reverted. > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > --- > fs/attr.c | 1 + Acked-by: Christian Brauner <brauner@kernel.org>
diff --git a/fs/attr.c b/fs/attr.c index 498e673bdf06..221d2bb0a906 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -502,6 +502,7 @@ 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/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index a843bb5f6f4b..e1731d0b63f8 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -137,6 +137,8 @@ LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode, LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask) LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) +LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, struct mnt_idmap *idmap, + struct dentry *dentry, int ia_valid) LSM_HOOK(int, 0, inode_getattr, const struct path *path) LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name, const void *value, diff --git a/include/linux/security.h b/include/linux/security.h index d0eb20f90b26..56c841aa3994 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -361,6 +361,8 @@ int security_inode_follow_link(struct dentry *dentry, struct inode *inode, int security_inode_permission(struct inode *inode, int mask); int security_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr); +void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid); int security_inode_getattr(const struct path *path); int security_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name, @@ -879,6 +881,11 @@ static inline int security_inode_setattr(struct mnt_idmap *idmap, return 0; } +static inline void +security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid) +{ } + static inline int security_inode_getattr(const struct path *path) { return 0; diff --git a/security/security.c b/security/security.c index 1d332e294704..06ffe0bcf711 100644 --- a/security/security.c +++ b/security/security.c @@ -2222,6 +2222,22 @@ int security_inode_setattr(struct mnt_idmap *idmap, } EXPORT_SYMBOL_GPL(security_inode_setattr); +/** + * security_inode_post_setattr() - Update the inode after a setattr operation + * @idmap: idmap of the mount + * @dentry: file + * @ia_valid: file attributes set + * + * Update inode security field after successful setting file attributes. + */ +void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(inode_post_setattr, idmap, dentry, ia_valid); +} + /** * security_inode_getattr() - Check if getting file attributes is allowed * @path: file