On 10/4/2015 12:19 PM, Andreas Gruenbacher wrote: > Add a hook to invalidate an inode's security label when the cached > information becomes invalid.
Where is this used? If I need to do the same for Smack or any other module, how would I know that it works right? > > Implement the new hook in selinux: set a flag when a security label becomes > invalid. When hitting a security label which has been marked as invalid in > inode_has_perm, try reloading the label. > > If an inode does not have any dentries attached, we cannot reload its > security label because we cannot use the getxattr inode operation. In that > case, continue using the old, invalid label until a dentry becomes > available. > > Signed-off-by: Andreas Gruenbacher <agrue...@redhat.com> > Cc: Paul Moore <p...@paul-moore.com> > Cc: Stephen Smalley <s...@tycho.nsa.gov> > Cc: Eric Paris <epa...@parisplace.org> > Cc: seli...@tycho.nsa.gov > --- > include/linux/lsm_hooks.h | 6 ++++++ > include/linux/security.h | 5 +++++ > security/security.c | 8 ++++++++ > security/selinux/hooks.c | 23 +++++++++++++++++++++-- > security/selinux/include/objsec.h | 3 ++- > 5 files changed, 42 insertions(+), 3 deletions(-) > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index ec3a6ba..945ae1d 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1261,6 +1261,10 @@ > * audit_rule_init. > * @rule contains the allocated rule > * > + * @inode_invalidate_secctx: > + * Notify the security module that it must revalidate the security context > + * of an inode. > + * > * @inode_notifysecctx: > * Notify the security module of what the security context of an inode > * should be. Initializes the incore security context managed by the > @@ -1516,6 +1520,7 @@ union security_list_options { > int (*secctx_to_secid)(const char *secdata, u32 seclen, u32 *secid); > void (*release_secctx)(char *secdata, u32 seclen); > > + void (*inode_invalidate_secctx)(struct inode *inode); > int (*inode_notifysecctx)(struct inode *inode, void *ctx, u32 ctxlen); > int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen); > int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen); > @@ -1757,6 +1762,7 @@ struct security_hook_heads { > struct list_head secid_to_secctx; > struct list_head secctx_to_secid; > struct list_head release_secctx; > + struct list_head inode_invalidate_secctx; > struct list_head inode_notifysecctx; > struct list_head inode_setsecctx; > struct list_head inode_getsecctx; > diff --git a/include/linux/security.h b/include/linux/security.h > index 2f4c1f7..9692571 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -353,6 +353,7 @@ int security_secid_to_secctx(u32 secid, char **secdata, > u32 *seclen); > int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid); > void security_release_secctx(char *secdata, u32 seclen); > > +void security_inode_invalidate_secctx(struct inode *inode); > int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen); > int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen); > int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen); > @@ -1093,6 +1094,10 @@ static inline void security_release_secctx(char > *secdata, u32 seclen) > { > } > > +static inline void security_inode_invalidate_secctx(struct inode *inode) > +{ > +} > + > static inline int security_inode_notifysecctx(struct inode *inode, void > *ctx, u32 ctxlen) > { > return -EOPNOTSUPP; > diff --git a/security/security.c b/security/security.c > index 46f405c..e4371cd 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1161,6 +1161,12 @@ void security_release_secctx(char *secdata, u32 seclen) > } > EXPORT_SYMBOL(security_release_secctx); > > +void security_inode_invalidate_secctx(struct inode *inode) > +{ > + call_void_hook(inode_invalidate_secctx, inode); > +} > +EXPORT_SYMBOL(security_inode_invalidate_secctx); > + > int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen) > { > return call_int_hook(inode_notifysecctx, 0, inode, ctx, ctxlen); > @@ -1763,6 +1769,8 @@ struct security_hook_heads security_hook_heads = { > LIST_HEAD_INIT(security_hook_heads.secctx_to_secid), > .release_secctx = > LIST_HEAD_INIT(security_hook_heads.release_secctx), > + .inode_invalidate_secctx = > + LIST_HEAD_INIT(security_hook_heads.inode_invalidate_secctx), > .inode_notifysecctx = > LIST_HEAD_INIT(security_hook_heads.inode_notifysecctx), > .inode_setsecctx = > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index e4369d8..c5e4ca8 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -1293,11 +1293,11 @@ static int inode_doinit_with_dentry(struct inode > *inode, struct dentry *opt_dent > unsigned len = 0; > int rc = 0; > > - if (isec->initialized) > + if (isec->initialized == 1) > goto out; > > mutex_lock(&isec->lock); > - if (isec->initialized) > + if (isec->initialized == 1) > goto out_unlock; > > sbsec = inode->i_sb->s_security; > @@ -1625,6 +1625,14 @@ static int inode_has_perm(const struct cred *cred, > sid = cred_sid(cred); > isec = inode->i_security; > > + /* > + * Try reloading the inode security label when it has been invalidated. > + * This will fail if no dentry for this inode can be found; in that > case, > + * we will continue using the old label. > + */ > + if (isec->initialized == 2) > + inode_doinit(inode); > + > return avc_has_perm(sid, isec->sid, isec->sclass, perms, adp); > } > > @@ -3509,6 +3517,7 @@ static int selinux_file_open(struct file *file, const > struct cred *cred) > > fsec = file->f_security; > isec = file_inode(file)->i_security; > + > /* > * Save inode label and policy sequence number > * at open-time so that selinux_file_permission > @@ -5762,6 +5771,15 @@ static void selinux_release_secctx(char *secdata, u32 > seclen) > kfree(secdata); > } > > +static void selinux_inode_invalidate_secctx(struct inode *inode) > +{ > + struct inode_security_struct *isec = inode->i_security; > + > + mutex_lock(&isec->lock); > + isec->initialized = 2; > + mutex_unlock(&isec->lock); > +} > + > /* > * called with inode->i_mutex locked > */ > @@ -5993,6 +6011,7 @@ static struct security_hook_list selinux_hooks[] = { > LSM_HOOK_INIT(secid_to_secctx, selinux_secid_to_secctx), > LSM_HOOK_INIT(secctx_to_secid, selinux_secctx_to_secid), > LSM_HOOK_INIT(release_secctx, selinux_release_secctx), > + LSM_HOOK_INIT(inode_invalidate_secctx, selinux_inode_invalidate_secctx), > LSM_HOOK_INIT(inode_notifysecctx, selinux_inode_notifysecctx), > LSM_HOOK_INIT(inode_setsecctx, selinux_inode_setsecctx), > LSM_HOOK_INIT(inode_getsecctx, selinux_inode_getsecctx), > diff --git a/security/selinux/include/objsec.h > b/security/selinux/include/objsec.h > index 81fa718..6d1fe19 100644 > --- a/security/selinux/include/objsec.h > +++ b/security/selinux/include/objsec.h > @@ -46,7 +46,8 @@ struct inode_security_struct { > u32 task_sid; /* SID of creating task */ > u32 sid; /* SID of this object */ > u16 sclass; /* security class of this object */ > - unsigned char initialized; /* initialization flag */ > + unsigned char initialized; /* 0: not initialized, 1: initialized, > + 2: invalidated */ > struct mutex lock; > }; > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html