[PATCH v2 16/25] LSM: Ensure the correct LSM context releaser
Kees Cook
keescook at chromium.org
Wed Jun 19 05:34:24 UTC 2019
On Tue, Jun 18, 2019 at 04:05:42PM -0700, Casey Schaufler wrote:
> Add a new lsmcontext data structure to hold all the information
> about a "security context", including the string, its size and
> which LSM allocated the string. The allocation information is
> necessary because LSMs have different policies regarding the
> lifecycle of these strings. SELinux allocates and destroys
> them on each use, whereas Smack provides a pointer to an entry
> in a list that never goes away.
>
> Change the security_release_secctx() interface to use the
> lsmcontext and call only the appropiate LSM hook. Change
> the callers of security_release_secctx() to provide the
> correct type of data, introducing scaffolding where required.
>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> ---
> drivers/android/binder.c | 10 +++++--
> fs/kernfs/dir.c | 9 ++++--
> fs/kernfs/inode.c | 7 +++--
> fs/nfs/nfs4proc.c | 8 ++++--
> fs/nfsd/nfs4xdr.c | 7 +++--
> include/linux/security.h | 37 +++++++++++++++++++++++--
> include/net/scm.h | 4 ++-
> kernel/audit.c | 14 +++++++---
> kernel/auditsc.c | 12 ++++++--
> net/ipv4/ip_sockglue.c | 4 ++-
> net/netfilter/nf_conntrack_netlink.c | 4 ++-
> net/netfilter/nf_conntrack_standalone.c | 4 ++-
> net/netfilter/nfnetlink_queue.c | 13 ++++++---
> net/netlabel/netlabel_unlabeled.c | 19 ++++++++++---
> net/netlabel/netlabel_user.c | 4 ++-
> security/security.c | 12 +++++---
> security/smack/smack_lsm.c | 14 +++++++---
> 17 files changed, 140 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 9eb790200fba..f11b5ca5bc30 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -2876,6 +2876,7 @@ static void binder_transaction(struct binder_proc *proc,
> int t_debug_id = atomic_inc_return(&binder_last_id);
> char *secctx = NULL;
> u32 secctx_sz = 0;
> + struct lsmcontext scaff; /* scaffolding */
>
> e = binder_transaction_log_add(&binder_transaction_log);
> e->debug_id = t_debug_id;
> @@ -3158,7 +3159,8 @@ static void binder_transaction(struct binder_proc *proc,
> binder_alloc_copy_to_buffer(&target_proc->alloc,
> t->buffer, buf_offset,
> secctx, secctx_sz);
> - security_release_secctx(secctx, secctx_sz);
> + lsmcontext_init(&scaff, secctx, secctx_sz, 0);
> + security_release_secctx(&scaff);
> secctx = NULL;
> }
> t->buffer->debug_id = t->debug_id;
> @@ -3479,8 +3481,10 @@ static void binder_transaction(struct binder_proc *proc,
> t->buffer->transaction = NULL;
> binder_alloc_free_buf(&target_proc->alloc, t->buffer);
> err_binder_alloc_buf_failed:
> - if (secctx)
> - security_release_secctx(secctx, secctx_sz);
> + if (secctx) {
> + lsmcontext_init(&scaff, secctx, secctx_sz, 0);
> + security_release_secctx(&scaff);
> + }
> err_get_secctx_failed:
> kfree(tcomplete);
> binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
> diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
> index b84d635567d3..92afad387237 100644
> --- a/fs/kernfs/dir.c
> +++ b/fs/kernfs/dir.c
> @@ -532,9 +532,12 @@ void kernfs_put(struct kernfs_node *kn)
> kfree_const(kn->name);
>
> if (kn->iattr) {
> - if (kn->iattr->ia_secdata)
> - security_release_secctx(kn->iattr->ia_secdata,
> - kn->iattr->ia_secdata_len);
> + 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);
> + }
> 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 0c1fd945ce42..02cde9dac5ee 100644
> --- a/fs/kernfs/inode.c
> +++ b/fs/kernfs/inode.c
> @@ -349,6 +349,7 @@ 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;
> @@ -368,8 +369,10 @@ static int kernfs_security_xattr_set(const struct xattr_handler *handler,
> error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
> mutex_unlock(&kernfs_mutex);
>
> - if (secdata)
> - security_release_secctx(secdata, secdata_len);
> + if (secdata) {
> + lsmcontext_init(&context, secdata, secdata_len, 0);
> + security_release_secctx(&context);
> + }
> return error;
> }
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 4dbb0ee23432..af1c0db29c39 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -131,8 +131,12 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry,
> static inline void
> nfs4_label_release_security(struct nfs4_label *label)
> {
> - if (label)
> - security_release_secctx(label->label, label->len);
> + struct lsmcontext scaff; /* scaffolding */
> +
> + if (label) {
> + lsmcontext_init(&scaff, label->label, label->len, 0);
> + security_release_secctx(&scaff);
> + }
> }
> static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label)
> {
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 3de42a729093..bb3db033e144 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -2420,6 +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;
> bool contextsupport = false;
> @@ -2919,8 +2920,10 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>
> out:
> #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
> - if (context)
> - security_release_secctx(context, contextlen);
> + if (context) {
> + lsmcontext_init(&scaff, context, contextlen, 0); /*scaffolding*/
> + security_release_secctx(&scaff);
> + }
> #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
> kfree(acl);
> if (tempfh) {
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 07a239292e02..8bd4f28ef532 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -76,6 +76,39 @@ enum lsm_event {
> LSM_POLICY_CHANGE,
> };
>
> +/*
> + * A "security context" is the text representation of
> + * the information used by LSMs.
> + * This structure contains the string, its length, and which LSM
> + * it is useful for.
> + */
> +struct lsmcontext {
> + char *context; /* Provided by the module */
> + u32 len;
> + int slot; /* Identifies the module */
> +};
> +
> +/**
> + * lsmcontext_init - initialize an lsmcontext structure.
> + * @cp: Pointer to the context to initialize
> + * @context: Initial context, or NULL
> + * @size: Size of context, or 0
> + * @slot: Which LSM provided the context
> + *
> + * Fill in the lsmcontext from the provided information.
> + */
> +static inline void lsmcontext_init(struct lsmcontext *cp, char *context,
> + u32 size, int slot)
> +{
> + cp->slot = slot;
> + cp->context = context;
> +
> + if (context == NULL || size == 0)
> + cp->len = 0;
> + else
> + cp->len = strlen(context);
> +}
I worry about the use of the "size" argument (or rather, lack of use).
If all contexts are going to be NUL-terminated strings, there should be
no "size" arg. If not, then "size" (or strneln(context, size)) should
be used instead of strlen().
> +
> /*
> * Data exported by the security modules
> */
> @@ -445,7 +478,7 @@ int security_ismaclabel(const char *name);
> int security_secid_to_secctx(struct lsmblob *l, char **secdata, u32 *seclen);
> int security_secctx_to_secid(const char *secdata, u32 seclen,
> struct lsmblob *l);
> -void security_release_secctx(char *secdata, u32 seclen);
> +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);
> @@ -1236,7 +1269,7 @@ static inline int security_secctx_to_secid(const char *secdata,
> return -EOPNOTSUPP;
> }
>
> -static inline void security_release_secctx(char *secdata, u32 seclen)
> +static inline void security_release_secctx(struct lsmcontext *cp)
> {
> }
>
> diff --git a/include/net/scm.h b/include/net/scm.h
> index bcb0f8560cdf..d3e0ac961a11 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -92,6 +92,7 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
> #ifdef CONFIG_SECURITY_NETWORK
> static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
> {
> + struct lsmcontext context;
> char *secdata;
> u32 seclen;
> int err;
> @@ -101,7 +102,8 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
>
> if (!err) {
> put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
> - security_release_secctx(secdata, seclen);
> + lsmcontext_init(&context, secdata, seclen, 0);/*scaffolding*/
> + security_release_secctx(&context);
> }
> }
> }
> diff --git a/kernel/audit.c b/kernel/audit.c
> index a52f8772477f..0467b2d284fa 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1193,6 +1193,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
> struct audit_sig_info *sig_data;
> char *ctx = NULL;
> u32 len;
> + struct lsmcontext scaff; /* scaffolding */
>
> err = audit_netlink_ok(skb, msg_type);
> if (err)
> @@ -1437,15 +1438,18 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
> }
> sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
> if (!sig_data) {
> - if (lsmblob_is_set(&audit_sig_lsm))
> - security_release_secctx(ctx, len);
> + if (lsmblob_is_set(&audit_sig_lsm)) {
> + lsmcontext_init(&scaff, ctx, len, 0);
> + security_release_secctx(&scaff);
> + }
> return -ENOMEM;
> }
> sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
> sig_data->pid = audit_sig_pid;
> if (lsmblob_is_set(&audit_sig_lsm)) {
> memcpy(sig_data->ctx, ctx, len);
> - security_release_secctx(ctx, len);
> + lsmcontext_init(&scaff, ctx, len, 0);
> + security_release_secctx(&scaff);
> }
> audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
> sig_data, sizeof(*sig_data) + len);
> @@ -2074,6 +2078,7 @@ int audit_log_task_context(struct audit_buffer *ab)
> unsigned len;
> int error;
> struct lsmblob le;
> + struct lsmcontext scaff; /* scaffolding */
>
> security_task_getsecid(current, &le);
> if (!lsmblob_is_set(&le))
> @@ -2087,7 +2092,8 @@ int audit_log_task_context(struct audit_buffer *ab)
> }
>
> audit_log_format(ab, " subj=%s", ctx);
> - security_release_secctx(ctx, len);
> + lsmcontext_init(&scaff, ctx, len, 0);
> + security_release_secctx(&scaff);
> return 0;
>
> error_path:
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index ebdd7eab9247..917e7550767a 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -942,6 +942,7 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
> struct lsmblob *l, char *comm)
> {
> struct audit_buffer *ab;
> + struct lsmcontext lsmcxt;
> char *ctx = NULL;
> u32 len;
> int rc = 0;
> @@ -959,7 +960,8 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
> rc = 1;
> } else {
> audit_log_format(ab, " obj=%s", ctx);
> - security_release_secctx(ctx, len);
> + lsmcontext_init(&lsmcxt, ctx, len, 0); /*scaffolding*/
> + security_release_secctx(&lsmcxt);
> }
> }
> audit_log_format(ab, " ocomm=");
> @@ -1171,6 +1173,7 @@ static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
>
> static void show_special(struct audit_context *context, int *call_panic)
> {
> + struct lsmcontext lsmcxt;
> struct audit_buffer *ab;
> int i;
>
> @@ -1203,7 +1206,8 @@ static void show_special(struct audit_context *context, int *call_panic)
> *call_panic = 1;
> } else {
> audit_log_format(ab, " obj=%s", ctx);
> - security_release_secctx(ctx, len);
> + lsmcontext_init(&lsmcxt, ctx, len, 0);
> + security_release_secctx(&lsmcxt);
> }
> }
> if (context->ipc.has_perm) {
> @@ -1350,6 +1354,7 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
> char *ctx = NULL;
> u32 len;
> struct lsmblob le;
> + struct lsmcontext lsmcxt;
>
> lsmblob_init(&le, n->osid);
> if (security_secid_to_secctx(&le, &ctx, &len)) {
> @@ -1358,7 +1363,8 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
> *call_panic = 2;
> } else {
> audit_log_format(ab, " obj=%s", ctx);
> - security_release_secctx(ctx, len);
> + lsmcontext_init(&lsmcxt, ctx, len, 0); /* scaffolding */
> + security_release_secctx(&lsmcxt);
> }
> }
>
> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index e05f4ef68bd8..7834c357b60b 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -130,6 +130,7 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
>
> static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
> {
> + struct lsmcontext context;
> struct lsmblob lb;
> char *secdata;
> u32 seclen;
> @@ -144,7 +145,8 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
> return;
>
> put_cmsg(msg, SOL_IP, SCM_SECURITY, seclen, secdata);
> - security_release_secctx(secdata, seclen);
> + lsmcontext_init(&context, secdata, seclen, 0); /* scaffolding */
> + security_release_secctx(&context);
> }
>
> static void ip_cmsg_recv_dstaddr(struct msghdr *msg, struct sk_buff *skb)
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index 6098b586da07..93f308b5845d 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -331,6 +331,7 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
> int len, ret;
> char *secctx;
> struct lsmblob le;
> + struct lsmcontext context;
>
> lsmblob_init(&le, ct->secmark);
> ret = security_secid_to_secctx(&le, &secctx, &len);
> @@ -348,7 +349,8 @@ static int ctnetlink_dump_secctx(struct sk_buff *skb, const struct nf_conn *ct)
>
> ret = 0;
> nla_put_failure:
> - security_release_secctx(secctx, len);
> + lsmcontext_init(&context, secctx, len, 0); /* scaffolding */
> + security_release_secctx(&context);
> return ret;
> }
> #else
> diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
> index 6e6fb1f9f6ba..0bde6a4426e3 100644
> --- a/net/netfilter/nf_conntrack_standalone.c
> +++ b/net/netfilter/nf_conntrack_standalone.c
> @@ -176,6 +176,7 @@ static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
> u32 len;
> char *secctx;
> struct lsmblob le;
> + struct lsmcontext context;
>
> lsmblob_init(&le, ct->secmark);
> ret = security_secid_to_secctx(&le, &secctx, &len);
> @@ -184,7 +185,8 @@ static void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
>
> seq_printf(s, "secctx=%s ", secctx);
>
> - security_release_secctx(secctx, len);
> + lsmcontext_init(&context, secctx, len, 0); /* scaffolding */
> + security_release_secctx(&context);
> }
> #else
> static inline void ct_show_secctx(struct seq_file *s, const struct nf_conn *ct)
> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index 105018d19318..ba767bdd1a9a 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -399,6 +399,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
> enum ip_conntrack_info uninitialized_var(ctinfo);
> struct nfnl_ct_hook *nfnl_ct;
> bool csum_verify;
> + struct lsmcontext scaff; /* scaffolding */
> char *secdata = NULL;
> u32 seclen = 0;
>
> @@ -629,8 +630,10 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
> }
>
> nlh->nlmsg_len = skb->len;
> - if (seclen)
> - security_release_secctx(secdata, seclen);
> + if (seclen) {
> + lsmcontext_init(&scaff, secdata, seclen, 0);
> + security_release_secctx(&scaff);
> + }
> return skb;
>
> nla_put_failure:
> @@ -638,8 +641,10 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
> kfree_skb(skb);
> net_err_ratelimited("nf_queue: error creating packet message\n");
> nlmsg_failure:
> - if (seclen)
> - security_release_secctx(secdata, seclen);
> + if (seclen) {
> + lsmcontext_init(&scaff, secdata, seclen, 0);
> + security_release_secctx(&scaff);
> + }
> return NULL;
> }
>
> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
> index 57e0f81a2ec5..2f8c7415b6ff 100644
> --- a/net/netlabel/netlabel_unlabeled.c
> +++ b/net/netlabel/netlabel_unlabeled.c
> @@ -387,6 +387,7 @@ int netlbl_unlhsh_add(struct net *net,
> struct net_device *dev;
> struct netlbl_unlhsh_iface *iface;
> struct audit_buffer *audit_buf = NULL;
> + struct lsmcontext context;
> char *secctx = NULL;
> u32 secctx_len;
> struct lsmblob le;
> @@ -457,7 +458,9 @@ int netlbl_unlhsh_add(struct net *net,
> &secctx,
> &secctx_len) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s", secctx);
> - security_release_secctx(secctx, secctx_len);
> + /* scaffolding */
> + lsmcontext_init(&context, secctx, secctx_len, 0);
> + security_release_secctx(&context);
> }
> audit_log_format(audit_buf, " res=%u", ret_val == 0 ? 1 : 0);
> audit_log_end(audit_buf);
> @@ -488,6 +491,7 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
> struct netlbl_unlhsh_addr4 *entry;
> struct audit_buffer *audit_buf;
> struct net_device *dev;
> + struct lsmcontext context;
> char *secctx;
> u32 secctx_len;
> struct lsmblob le;
> @@ -516,7 +520,9 @@ static int netlbl_unlhsh_remove_addr4(struct net *net,
> security_secid_to_secctx(&le,
> &secctx, &secctx_len) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s", secctx);
> - security_release_secctx(secctx, secctx_len);
> + /* scaffolding */
> + lsmcontext_init(&context, secctx, secctx_len, 0);
> + security_release_secctx(&context);
> }
> audit_log_format(audit_buf, " res=%u", entry != NULL ? 1 : 0);
> audit_log_end(audit_buf);
> @@ -553,6 +559,7 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
> struct netlbl_unlhsh_addr6 *entry;
> struct audit_buffer *audit_buf;
> struct net_device *dev;
> + struct lsmcontext context;
> char *secctx;
> u32 secctx_len;
> struct lsmblob le;
> @@ -580,7 +587,8 @@ static int netlbl_unlhsh_remove_addr6(struct net *net,
> security_secid_to_secctx(&le,
> &secctx, &secctx_len) == 0) {
> audit_log_format(audit_buf, " sec_obj=%s", secctx);
> - security_release_secctx(secctx, secctx_len);
> + lsmcontext_init(&context, secctx, secctx_len, 0);
> + security_release_secctx(&context);
> }
> audit_log_format(audit_buf, " res=%u", entry != NULL ? 1 : 0);
> audit_log_end(audit_buf);
> @@ -1094,6 +1102,7 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
> int ret_val = -ENOMEM;
> struct netlbl_unlhsh_walk_arg *cb_arg = arg;
> struct net_device *dev;
> + struct lsmcontext context;
> void *data;
> u32 secid;
> char *secctx;
> @@ -1161,7 +1170,9 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd,
> NLBL_UNLABEL_A_SECCTX,
> secctx_len,
> secctx);
> - security_release_secctx(secctx, secctx_len);
> + /* scaffolding */
> + lsmcontext_init(&context, secctx, secctx_len, 0);
> + security_release_secctx(&context);
> if (ret_val != 0)
> goto list_cb_failure;
>
> diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
> index 4145adf55a22..fba861c4ffbb 100644
> --- a/net/netlabel/netlabel_user.c
> +++ b/net/netlabel/netlabel_user.c
> @@ -98,6 +98,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
> struct netlbl_audit *audit_info)
> {
> struct audit_buffer *audit_buf;
> + struct lsmcontext context;
> char *secctx;
> u32 secctx_len;
> struct lsmblob le;
> @@ -117,7 +118,8 @@ struct audit_buffer *netlbl_audit_start_common(int type,
> if (audit_info->secid != 0 &&
> security_secid_to_secctx(&le, &secctx, &secctx_len) == 0) {
> audit_log_format(audit_buf, " subj=%s", secctx);
> - security_release_secctx(secctx, secctx_len);
> + lsmcontext_init(&context, secctx, secctx_len, 0);/*scaffolding*/
> + security_release_secctx(&context);
> }
>
> return audit_buf;
> diff --git a/security/security.c b/security/security.c
> index 9cfdc664239e..d25c099b46d1 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -458,6 +458,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
> &security_hook_heads.socket_getpeersec_dgram ||
> hooks[i].head == &security_hook_heads.secctx_to_secid ||
> hooks[i].head == &security_hook_heads.secid_to_secctx ||
> + hooks[i].head == &security_hook_heads.release_secctx ||
> hooks[i].head == &security_hook_heads.ipc_getsecid ||
> hooks[i].head == &security_hook_heads.task_getsecid ||
> hooks[i].head == &security_hook_heads.inode_getsecid ||
> @@ -2083,16 +2084,19 @@ int security_secctx_to_secid(const char *secdata, u32 seclen, struct lsmblob *l)
> }
> EXPORT_SYMBOL(security_secctx_to_secid);
>
> -void security_release_secctx(char *secdata, u32 seclen)
> +void security_release_secctx(struct lsmcontext *cp)
> {
> - int *display = current->security;
> struct security_hook_list *hp;
>
> hlist_for_each_entry(hp, &security_hook_heads.release_secctx, list)
> - if (*display == LSMDATA_INVALID || *display == hp->slot) {
> - hp->hook.release_secctx(secdata, seclen);
> + if (cp->slot == hp->slot) {
> + hp->hook.release_secctx(cp->context, cp->len);
> + lsmcontext_init(cp, NULL, 0, 0);
> return;
> }
> +
> + pr_warn("%s context \"%s\" from slot %d not released\n", __func__,
> + cp->context, cp->slot);
> }
> EXPORT_SYMBOL(security_release_secctx);
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index e9560b078efe..3834b751d1e9 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -4439,11 +4439,16 @@ static int smack_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
> return 0;
> }
>
> -/*
> - * There used to be a smack_release_secctx hook
> - * that did nothing back when hooks were in a vector.
> - * Now that there's a list such a hook adds cost.
> +/**
> + * smack_release_secctx - do everything necessary to free a context
> + * @secdata: Unused
> + * @seclen: Unused
> + *
> + * Do nothing but hold a slot in the hooks list.
> */
> +static void smack_release_secctx(char *secdata, u32 seclen)
> +{
> +}
>
> static int smack_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
> {
> @@ -4683,6 +4688,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
> LSM_HOOK_INIT(ismaclabel, smack_ismaclabel),
> LSM_HOOK_INIT(secid_to_secctx, smack_secid_to_secctx),
> LSM_HOOK_INIT(secctx_to_secid, smack_secctx_to_secid),
> + LSM_HOOK_INIT(release_secctx, smack_release_secctx),
> LSM_HOOK_INIT(inode_notifysecctx, smack_inode_notifysecctx),
> LSM_HOOK_INIT(inode_setsecctx, smack_inode_setsecctx),
> LSM_HOOK_INIT(inode_getsecctx, smack_inode_getsecctx),
> --
> 2.20.1
>
--
Kees Cook
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