[PATCH v5 19/23] LSM: Use lsmcontext in security_inode_getsecctx
Casey Schaufler
casey at schaufler-ca.com
Wed Jul 3 21:25:34 UTC 2019
Change the security_inode_getsecctx() interface to fill
a lsmcontext structure instead of data and length pointers.
This provides the information about which LSM created the
context so that security_release_secctx() can use the
correct hook. A lsmcontext is used within kernfs to store
the security information as well.
security_inode_getsecctx() does not use the "display"
value. There's only one possible user at any time at
this point, and the use is only internal.
Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
---
fs/kernfs/dir.c | 9 ++-------
fs/kernfs/inode.c | 34 ++++++++++++----------------------
fs/kernfs/kernfs-internal.h | 3 +--
fs/nfsd/nfs4xdr.c | 23 +++++++++--------------
include/linux/security.h | 5 +++--
security/security.c | 13 +++++++++++--
6 files changed, 38 insertions(+), 49 deletions(-)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index c8362b6d556e..1d000289d8b7 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -532,13 +532,8 @@ void kernfs_put(struct kernfs_node *kn)
kfree_const(kn->name);
if (kn->iattr) {
- struct lsmcontext scaff; /* scaffolding */
-
- if (kn->iattr->ia_secdata) {
- lsmcontext_init(&scaff, kn->iattr->ia_secdata,
- kn->iattr->ia_secdata_len, 0);
- security_release_secctx(&scaff);
- }
+ if (kn->iattr->ia_context.context)
+ security_release_secctx(&kn->iattr->ia_context);
simple_xattrs_free(&kn->iattr->xattrs);
kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
}
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 02cde9dac5ee..ffbf7863306d 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -135,21 +135,14 @@ int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
return error;
}
-static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
- u32 *secdata_len)
+static void kernfs_node_setsecdata(struct kernfs_iattrs *attrs,
+ struct lsmcontext *cp)
{
- void *old_secdata;
- size_t old_secdata_len;
+ struct lsmcontext old_context;
- old_secdata = attrs->ia_secdata;
- old_secdata_len = attrs->ia_secdata_len;
-
- attrs->ia_secdata = *secdata;
- attrs->ia_secdata_len = *secdata_len;
-
- *secdata = old_secdata;
- *secdata_len = old_secdata_len;
- return 0;
+ old_context = attrs->ia_context;
+ attrs->ia_context = *cp;
+ *cp = old_context;
}
ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
@@ -192,8 +185,8 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
* persistent copy in kernfs_node.
*/
set_inode_attr(inode, &attrs->ia_iattr);
- security_inode_notifysecctx(inode, attrs->ia_secdata,
- attrs->ia_secdata_len);
+ security_inode_notifysecctx(inode, attrs->ia_context.context,
+ attrs->ia_context.len);
}
if (kernfs_type(kn) == KERNFS_DIR)
@@ -350,8 +343,6 @@ static int kernfs_security_xattr_set(const struct xattr_handler *handler,
struct kernfs_node *kn = inode->i_private;
struct kernfs_iattrs *attrs;
struct lsmcontext context;
- void *secdata;
- u32 secdata_len = 0;
int error;
attrs = kernfs_iattrs(kn);
@@ -361,18 +352,17 @@ static int kernfs_security_xattr_set(const struct xattr_handler *handler,
error = security_inode_setsecurity(inode, suffix, value, size, flags);
if (error)
return error;
- error = security_inode_getsecctx(inode, &secdata, &secdata_len);
+ error = security_inode_getsecctx(inode, &context);
if (error)
return error;
mutex_lock(&kernfs_mutex);
- error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
+ kernfs_node_setsecdata(attrs, &context);
mutex_unlock(&kernfs_mutex);
- if (secdata) {
- lsmcontext_init(&context, secdata, secdata_len, 0);
+ if (context.context)
security_release_secctx(&context);
- }
+
return error;
}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0b7d197a904c..844a028d282f 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -21,8 +21,7 @@
struct kernfs_iattrs {
struct iattr ia_iattr;
- void *ia_secdata;
- u32 ia_secdata_len;
+ struct lsmcontext ia_context;
struct simple_xattrs xattrs;
};
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index bb3db033e144..d2dbec9c3340 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2304,11 +2304,11 @@ nfsd4_encode_layout_types(struct xdr_stream *xdr, u32 layout_types)
#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
static inline __be32
nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
- void *context, int len)
+ struct lsmcontext *context)
{
__be32 *p;
- p = xdr_reserve_space(xdr, len + 4 + 4 + 4);
+ p = xdr_reserve_space(xdr, context->len + 4 + 4 + 4);
if (!p)
return nfserr_resource;
@@ -2318,13 +2318,13 @@ nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
*/
*p++ = cpu_to_be32(0); /* lfs */
*p++ = cpu_to_be32(0); /* pi */
- p = xdr_encode_opaque(p, context, len);
+ p = xdr_encode_opaque(p, context->context, context->len);
return 0;
}
#else
static inline __be32
nfsd4_encode_security_label(struct xdr_stream *xdr, struct svc_rqst *rqstp,
- void *context, int len)
+ struct lsmcontext *context)
{ return 0; }
#endif
@@ -2420,9 +2420,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
__be32 status;
int err;
struct nfs4_acl *acl = NULL;
- struct lsmcontext scaff; /* scaffolding */
- void *context = NULL;
- int contextlen;
+ struct lsmcontext context = { };
bool contextsupport = false;
struct nfsd4_compoundres *resp = rqstp->rq_resp;
u32 minorversion = resp->cstate.minorversion;
@@ -2479,7 +2477,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
bmval0 & FATTR4_WORD0_SUPPORTED_ATTRS) {
if (exp->ex_flags & NFSEXP_SECURITY_LABEL)
err = security_inode_getsecctx(d_inode(dentry),
- &context, &contextlen);
+ &context);
else
err = -EOPNOTSUPP;
contextsupport = (err == 0);
@@ -2908,8 +2906,7 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
}
if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
- status = nfsd4_encode_security_label(xdr, rqstp, context,
- contextlen);
+ status = nfsd4_encode_security_label(xdr, rqstp, &context);
if (status)
goto out;
}
@@ -2920,10 +2917,8 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
out:
#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
- if (context) {
- lsmcontext_init(&scaff, context, contextlen, 0); /*scaffolding*/
- security_release_secctx(&scaff);
- }
+ if (context.context)
+ security_release_secctx(&context);
#endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
kfree(acl);
if (tempfh) {
diff --git a/include/linux/security.h b/include/linux/security.h
index 2674eb70c2d7..c16aea55be97 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -489,7 +489,7 @@ void security_release_secctx(struct lsmcontext *cp);
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);
+int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp);
#else /* CONFIG_SECURITY */
static inline int call_lsm_notifier(enum lsm_event event, void *data)
@@ -1290,7 +1290,8 @@ static inline int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32
{
return -EOPNOTSUPP;
}
-static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
+static inline int security_inode_getsecctx(struct inode *inode,
+ struct lsmcontext *cp)
{
return -EOPNOTSUPP;
}
diff --git a/security/security.c b/security/security.c
index 54d7e7f02a8b..7c1c50ac2278 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2179,9 +2179,18 @@ int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
}
EXPORT_SYMBOL(security_inode_setsecctx);
-int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
+int security_inode_getsecctx(struct inode *inode, struct lsmcontext *cp)
{
- return call_int_hook(inode_getsecctx, -EOPNOTSUPP, inode, ctx, ctxlen);
+ struct security_hook_list *hp;
+
+ memset(cp, 0, sizeof(*cp));
+
+ hlist_for_each_entry(hp, &security_hook_heads.inode_getsecctx, list) {
+ cp->slot = hp->lsmid->slot;
+ return hp->hook.inode_getsecctx(inode, (void **)&cp->context,
+ &cp->len);
+ }
+ return -EOPNOTSUPP;
}
EXPORT_SYMBOL(security_inode_getsecctx);
--
2.20.1
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