| Message ID | 20200827063522.2563293-3-lokeshgidra@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SELinux support for anonymous inodes and UFFD | expand |
On Thu, Aug 27, 2020 at 2:35 AM Lokesh Gidra <lokeshgidra@google.com> wrote: > > From: Daniel Colascione <dancol@google.com> > > This change uses the anon_inodes and LSM infrastructure introduced in > the previous patch to give SELinux the ability to control > anonymous-inode files that are created using the new anon_inode_getfd_secure() > function. > > A SELinux policy author detects and controls these anonymous inodes by > adding a name-based type_transition rule that assigns a new security > type to anonymous-inode files created in some domain. The name used > for the name-based transition is the name associated with the > anonymous inode for file listings --- e.g., "[userfaultfd]" or > "[perf_event]". > > Example: > > type uffd_t; > type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]"; > allow sysadm_t uffd_t:anon_inode { create }; > > (The next patch in this series is necessary for making userfaultfd > support this new interface. The example above is just > for exposition.) > > Signed-off-by: Daniel Colascione <dancol@google.com> > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> > Cc: Al Viro <viro@zeniv.linux.org.uk> > Cc: Andrew Morton <akpm@linux-foundation.org> > --- > security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++ > security/selinux/include/classmap.h | 2 ++ > 2 files changed, 55 insertions(+) > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index a340986aa92e..b83f56e5ef40 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -2926,6 +2926,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, > return 0; > } > > +static int selinux_inode_init_security_anon(struct inode *inode, > + const struct qstr *name, > + const struct inode *context_inode) > +{ > + const struct task_security_struct *tsec = selinux_cred(current_cred()); > + struct common_audit_data ad; > + struct inode_security_struct *isec; > + int rc; > + > + if (unlikely(!selinux_state.initialized)) This should use selinux_initialized(&selinux_state) instead.
On Mon, Aug 31, 2020 at 11:05 AM Stephen Smalley <stephen.smalley.work@gmail.com> wrote: > > On Thu, Aug 27, 2020 at 2:35 AM Lokesh Gidra <lokeshgidra@google.com> wrote: > > > > From: Daniel Colascione <dancol@google.com> > > > > This change uses the anon_inodes and LSM infrastructure introduced in > > the previous patch to give SELinux the ability to control > > anonymous-inode files that are created using the new anon_inode_getfd_secure() > > function. > > > > A SELinux policy author detects and controls these anonymous inodes by > > adding a name-based type_transition rule that assigns a new security > > type to anonymous-inode files created in some domain. The name used > > for the name-based transition is the name associated with the > > anonymous inode for file listings --- e.g., "[userfaultfd]" or > > "[perf_event]". > > > > Example: > > > > type uffd_t; > > type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]"; > > allow sysadm_t uffd_t:anon_inode { create }; > > > > (The next patch in this series is necessary for making userfaultfd > > support this new interface. The example above is just > > for exposition.) > > > > Signed-off-by: Daniel Colascione <dancol@google.com> > > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > > Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com> > > Cc: Al Viro <viro@zeniv.linux.org.uk> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > --- > > security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++ > > security/selinux/include/classmap.h | 2 ++ > > 2 files changed, 55 insertions(+) > > > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > > index a340986aa92e..b83f56e5ef40 100644 > > --- a/security/selinux/hooks.c > > +++ b/security/selinux/hooks.c > > @@ -2926,6 +2926,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, > > return 0; > > } > > > > +static int selinux_inode_init_security_anon(struct inode *inode, > > + const struct qstr *name, > > + const struct inode *context_inode) > > +{ > > + const struct task_security_struct *tsec = selinux_cred(current_cred()); > > + struct common_audit_data ad; > > + struct inode_security_struct *isec; > > + int rc; > > + > > + if (unlikely(!selinux_state.initialized)) > > This should use selinux_initialized(&selinux_state) instead. Thanks for the review. I'll make the change in the next version. Kindly have a look at other patches in the series as well.
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index a340986aa92e..b83f56e5ef40 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2926,6 +2926,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, return 0; } +static int selinux_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode) +{ + const struct task_security_struct *tsec = selinux_cred(current_cred()); + struct common_audit_data ad; + struct inode_security_struct *isec; + int rc; + + if (unlikely(!selinux_state.initialized)) + return 0; + + isec = selinux_inode(inode); + + /* + * We only get here once per ephemeral inode. The inode has + * been initialized via inode_alloc_security but is otherwise + * untouched. + */ + + if (context_inode) { + struct inode_security_struct *context_isec = + selinux_inode(context_inode); + isec->sclass = context_isec->sclass; + isec->sid = context_isec->sid; + } else { + isec->sclass = SECCLASS_ANON_INODE; + rc = security_transition_sid( + &selinux_state, tsec->sid, tsec->sid, + isec->sclass, name, &isec->sid); + if (rc) + return rc; + } + + isec->initialized = LABEL_INITIALIZED; + + /* + * Now that we've initialized security, check whether we're + * allowed to actually create this type of anonymous inode. + */ + + ad.type = LSM_AUDIT_DATA_INODE; + ad.u.inode = inode; + + return avc_has_perm(&selinux_state, + tsec->sid, + isec->sid, + isec->sclass, + FILE__CREATE, + &ad); +} + static int selinux_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode) { return may_create(dir, dentry, SECCLASS_FILE); @@ -6987,6 +7039,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_free_security, selinux_inode_free_security), LSM_HOOK_INIT(inode_init_security, selinux_inode_init_security), + LSM_HOOK_INIT(inode_init_security_anon, selinux_inode_init_security_anon), LSM_HOOK_INIT(inode_create, selinux_inode_create), LSM_HOOK_INIT(inode_link, selinux_inode_link), LSM_HOOK_INIT(inode_unlink, selinux_inode_unlink), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 40cebde62856..ba2e01a6955c 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -249,6 +249,8 @@ struct security_class_mapping secclass_map[] = { {"open", "cpu", "kernel", "tracepoint", "read", "write"} }, { "lockdown", { "integrity", "confidentiality", NULL } }, + { "anon_inode", + { COMMON_FILE_PERMS, NULL } }, { NULL } };