| Message ID | 20231214170834.3324559-12-roberto.sassu@huaweicloud.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Paul Moore |
| Headers | show |
| Series | security: Move IMA and EVM to the LSM infrastructure | expand |
On 12/14/2023 9:08 AM, 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_removexattr hook. > > At inode_removexattr hook, EVM verifies the file's existing HMAC value. At > inode_post_removexattr, EVM re-calculates the file's HMAC with the passed > xattr removed and other file metadata. > > Other LSMs could similarly take some action after successful xattr removal. > > 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> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com> > --- > fs/xattr.c | 9 +++++---- > include/linux/lsm_hook_defs.h | 2 ++ > include/linux/security.h | 5 +++++ > security/security.c | 14 ++++++++++++++ > 4 files changed, 26 insertions(+), 4 deletions(-) > > diff --git a/fs/xattr.c b/fs/xattr.c > index 09d927603433..f891c260a971 100644 > --- a/fs/xattr.c > +++ b/fs/xattr.c > @@ -552,11 +552,12 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap, > goto out; > > error = __vfs_removexattr(idmap, dentry, name); > + if (error) > + return error; > > - if (!error) { > - fsnotify_xattr(dentry); > - evm_inode_post_removexattr(dentry, name); > - } > + fsnotify_xattr(dentry); > + security_inode_post_removexattr(dentry, name); > + evm_inode_post_removexattr(dentry, name); > > out: > return error; > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 091cddb4e6de..c3199bb69103 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -149,6 +149,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) > LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) > LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, > struct dentry *dentry, const char *name) > +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, > + const char *name) > LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap, > struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) > LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap, > diff --git a/include/linux/security.h b/include/linux/security.h > index 664df46b22a9..922ea7709bae 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -380,6 +380,7 @@ int security_inode_getxattr(struct dentry *dentry, const char *name); > int security_inode_listxattr(struct dentry *dentry); > int security_inode_removexattr(struct mnt_idmap *idmap, > struct dentry *dentry, const char *name); > +void security_inode_post_removexattr(struct dentry *dentry, const char *name); > int security_inode_need_killpriv(struct dentry *dentry); > int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); > int security_inode_getsecurity(struct mnt_idmap *idmap, > @@ -940,6 +941,10 @@ static inline int security_inode_removexattr(struct mnt_idmap *idmap, > return cap_inode_removexattr(idmap, dentry, name); > } > > +static inline void security_inode_post_removexattr(struct dentry *dentry, > + const char *name) > +{ } > + > static inline int security_inode_need_killpriv(struct dentry *dentry) > { > return cap_inode_need_killpriv(dentry); > diff --git a/security/security.c b/security/security.c > index ce3bc7642e18..8aa6e9f316dd 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -2452,6 +2452,20 @@ int security_inode_removexattr(struct mnt_idmap *idmap, > return evm_inode_removexattr(idmap, dentry, name); > } > > +/** > + * security_inode_post_removexattr() - Update the inode after a removexattr op > + * @dentry: file > + * @name: xattr name > + * > + * Update the inode after a successful removexattr operation. > + */ > +void security_inode_post_removexattr(struct dentry *dentry, const char *name) > +{ > + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > + return; > + call_void_hook(inode_post_removexattr, dentry, name); > +} > + > /** > * security_inode_need_killpriv() - Check if security_inode_killpriv() required > * @dentry: associated dentry
diff --git a/fs/xattr.c b/fs/xattr.c index 09d927603433..f891c260a971 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -552,11 +552,12 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap, goto out; error = __vfs_removexattr(idmap, dentry, name); + if (error) + return error; - if (!error) { - fsnotify_xattr(dentry); - evm_inode_post_removexattr(dentry, name); - } + fsnotify_xattr(dentry); + security_inode_post_removexattr(dentry, name); + evm_inode_post_removexattr(dentry, name); out: return error; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 091cddb4e6de..c3199bb69103 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -149,6 +149,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name) +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, + const char *name) LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap, diff --git a/include/linux/security.h b/include/linux/security.h index 664df46b22a9..922ea7709bae 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -380,6 +380,7 @@ int security_inode_getxattr(struct dentry *dentry, const char *name); int security_inode_listxattr(struct dentry *dentry); int security_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name); +void security_inode_post_removexattr(struct dentry *dentry, const char *name); int security_inode_need_killpriv(struct dentry *dentry); int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); int security_inode_getsecurity(struct mnt_idmap *idmap, @@ -940,6 +941,10 @@ static inline int security_inode_removexattr(struct mnt_idmap *idmap, return cap_inode_removexattr(idmap, dentry, name); } +static inline void security_inode_post_removexattr(struct dentry *dentry, + const char *name) +{ } + static inline int security_inode_need_killpriv(struct dentry *dentry) { return cap_inode_need_killpriv(dentry); diff --git a/security/security.c b/security/security.c index ce3bc7642e18..8aa6e9f316dd 100644 --- a/security/security.c +++ b/security/security.c @@ -2452,6 +2452,20 @@ int security_inode_removexattr(struct mnt_idmap *idmap, return evm_inode_removexattr(idmap, dentry, name); } +/** + * security_inode_post_removexattr() - Update the inode after a removexattr op + * @dentry: file + * @name: xattr name + * + * Update the inode after a successful removexattr operation. + */ +void security_inode_post_removexattr(struct dentry *dentry, const char *name) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(inode_post_removexattr, dentry, name); +} + /** * security_inode_need_killpriv() - Check if security_inode_killpriv() required * @dentry: associated dentry