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Subject[PATCH 14/14] net: pass user_ns to cap_netlink_recv()
Date
From: Serge E. Hallyn <serge.hallyn@canonical.com>

and make cap_netlink_recv() userns-aware

cap_netlink_recv() was granting privilege if a capability is in
current_cap(), regardless of the user namespace. Fix that by
targeting the capability check against the user namespace which
owns the skb.

Because sock_net is static inline defined in net/sock.h, which we
don't want to #include at the cap_netlink_recv function (commoncap.h).

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
drivers/scsi/scsi_netlink.c | 3 ++-
include/linux/security.h | 14 +++++++++-----
kernel/audit.c | 6 ++++--
net/core/rtnetlink.c | 3 ++-
net/decnet/netfilter/dn_rtmsg.c | 3 ++-
net/ipv4/netfilter/ip_queue.c | 3 ++-
net/ipv6/netfilter/ip6_queue.c | 3 ++-
net/netfilter/nfnetlink.c | 2 +-
net/netlink/genetlink.c | 2 +-
net/xfrm/xfrm_user.c | 2 +-
security/commoncap.c | 6 ++----
security/security.c | 4 ++--
security/selinux/hooks.c | 5 +++--
13 files changed, 33 insertions(+), 23 deletions(-)
diff --git a/drivers/scsi/scsi_netlink.c b/drivers/scsi/scsi_netlink.c
index 26a8a45..0aa2e57 100644
--- a/drivers/scsi/scsi_netlink.c
+++ b/drivers/scsi/scsi_netlink.c
@@ -111,7 +111,8 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
goto next_msg;
}

- if (security_netlink_recv(skb, CAP_SYS_ADMIN)) {
+ if (security_netlink_recv(skb, CAP_SYS_ADMIN,
+ sock_net(skb->sk)->user_ns)) {
err = -EPERM;
goto next_msg;
}
diff --git a/include/linux/security.h b/include/linux/security.h
index ebd2a53..cfa1f47 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -95,7 +95,8 @@ struct xfrm_user_sec_ctx;
struct seq_file;

extern int cap_netlink_send(struct sock *sk, struct sk_buff *skb);
-extern int cap_netlink_recv(struct sk_buff *skb, int cap);
+extern int cap_netlink_recv(struct sk_buff *skb, int cap,
+ struct user_namespace *ns);

void reset_security_ops(void);

@@ -797,6 +798,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* @skb.
* @skb contains the sk_buff structure for the netlink message.
* @cap indicates the capability required
+ * @ns is the user namespace which owns skb
* Return 0 if permission is granted.
*
* Security hooks for Unix domain networking.
@@ -1557,7 +1559,8 @@ struct security_operations {
struct sembuf *sops, unsigned nsops, int alter);

int (*netlink_send) (struct sock *sk, struct sk_buff *skb);
- int (*netlink_recv) (struct sk_buff *skb, int cap);
+ int (*netlink_recv) (struct sk_buff *skb, int cap,
+ struct user_namespace *ns);

void (*d_instantiate) (struct dentry *dentry, struct inode *inode);

@@ -1806,7 +1809,7 @@ void security_d_instantiate(struct dentry *dentry, struct inode *inode);
int security_getprocattr(struct task_struct *p, char *name, char **value);
int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size);
int security_netlink_send(struct sock *sk, struct sk_buff *skb);
-int security_netlink_recv(struct sk_buff *skb, int cap);
+int security_netlink_recv(struct sk_buff *skb, int cap, struct user_namespace *ns);
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);
@@ -2498,9 +2501,10 @@ static inline int security_netlink_send(struct sock *sk, struct sk_buff *skb)
return cap_netlink_send(sk, skb);
}

-static inline int security_netlink_recv(struct sk_buff *skb, int cap)
+static inline int security_netlink_recv(struct sk_buff *skb, int cap,
+ struct user_namespace *ns)
{
- return cap_netlink_recv(skb, cap);
+ return cap_netlink_recv(skb, cap, ns);
}

static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
diff --git a/kernel/audit.c b/kernel/audit.c
index 52501b5..bed1c50 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -601,13 +601,15 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
case AUDIT_TTY_SET:
case AUDIT_TRIM:
case AUDIT_MAKE_EQUIV:
- if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
+ if (security_netlink_recv(skb, CAP_AUDIT_CONTROL,
+ sock_net(skb->sk)->user_ns))
err = -EPERM;
break;
case AUDIT_USER:
case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
- if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
+ if (security_netlink_recv(skb, CAP_AUDIT_WRITE,
+ sock_net(skb->sk)->user_ns))
err = -EPERM;
break;
default: /* bad msg */
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 99d9e95..4a444de 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1931,7 +1931,8 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
sz_idx = type>>2;
kind = type&3;

- if (kind != 2 && security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (kind != 2 && security_netlink_recv(skb, CAP_NET_ADMIN,
+ net->user_ns))
return -EPERM;

if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {
diff --git a/net/decnet/netfilter/dn_rtmsg.c b/net/decnet/netfilter/dn_rtmsg.c
index 69975e0..2d052ab 100644
--- a/net/decnet/netfilter/dn_rtmsg.c
+++ b/net/decnet/netfilter/dn_rtmsg.c
@@ -108,7 +108,8 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
return;

- if (security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (security_netlink_recv(skb, CAP_NET_ADMIN,
+ sock_net(skb->sk)->user_ns))
RCV_SKB_FAIL(-EPERM);

/* Eventually we might send routing messages too */
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index 5c9b9d9..51d7c52 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -432,7 +432,8 @@ __ipq_rcv_skb(struct sk_buff *skb)
if (type <= IPQM_BASE)
return;

- if (security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (security_netlink_recv(skb, CAP_NET_ADMIN,
+ sock_net(skb->sk)->user_ns))
RCV_SKB_FAIL(-EPERM);

spin_lock_bh(&queue_lock);
diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c
index 2493948..8206bf3 100644
--- a/net/ipv6/netfilter/ip6_queue.c
+++ b/net/ipv6/netfilter/ip6_queue.c
@@ -433,7 +433,8 @@ __ipq_rcv_skb(struct sk_buff *skb)
if (type <= IPQM_BASE)
return;

- if (security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (security_netlink_recv(skb, CAP_NET_ADMIN,
+ sock_net(skb->sk)->user_ns))
RCV_SKB_FAIL(-EPERM);

spin_lock_bh(&queue_lock);
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 1905976..bcaff9d 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -130,7 +130,7 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
const struct nfnetlink_subsystem *ss;
int type, err;

- if (security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (security_netlink_recv(skb, CAP_NET_ADMIN, net->user_ns))
return -EPERM;

/* All the messages must at least contain nfgenmsg */
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 482fa57..00a101c 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -516,7 +516,7 @@ static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
return -EOPNOTSUPP;

if ((ops->flags & GENL_ADMIN_PERM) &&
- security_netlink_recv(skb, CAP_NET_ADMIN))
+ security_netlink_recv(skb, CAP_NET_ADMIN, net->user_ns))
return -EPERM;

if (nlh->nlmsg_flags & NLM_F_DUMP) {
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 0256b8a..1808e1e 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2290,7 +2290,7 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
link = &xfrm_dispatch[type];

/* All operations require privileges, even GET */
- if (security_netlink_recv(skb, CAP_NET_ADMIN))
+ if (security_netlink_recv(skb, CAP_NET_ADMIN, net->user_ns))
return -EPERM;

if ((type == (XFRM_MSG_GETSA - XFRM_MSG_BASE) ||
diff --git a/security/commoncap.c b/security/commoncap.c
index a93b3b7..1e48e6a 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -56,11 +56,9 @@ int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
return 0;
}

-int cap_netlink_recv(struct sk_buff *skb, int cap)
+int cap_netlink_recv(struct sk_buff *skb, int cap, struct user_namespace *ns)
{
- if (!cap_raised(current_cap(), cap))
- return -EPERM;
- return 0;
+ return security_capable(ns, current_cred(), cap);
}
EXPORT_SYMBOL(cap_netlink_recv);

diff --git a/security/security.c b/security/security.c
index 0e4fccf..0a1453e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -941,9 +941,9 @@ int security_netlink_send(struct sock *sk, struct sk_buff *skb)
return security_ops->netlink_send(sk, skb);
}

-int security_netlink_recv(struct sk_buff *skb, int cap)
+int security_netlink_recv(struct sk_buff *skb, int cap, struct user_namespace *ns)
{
- return security_ops->netlink_recv(skb, cap);
+ return security_ops->netlink_recv(skb, cap, ns);
}
EXPORT_SYMBOL(security_netlink_recv);

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 9f4c77d..c80a063 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4723,13 +4723,14 @@ static int selinux_netlink_send(struct sock *sk, struct sk_buff *skb)
return selinux_nlmsg_perm(sk, skb);
}

-static int selinux_netlink_recv(struct sk_buff *skb, int capability)
+static int selinux_netlink_recv(struct sk_buff *skb, int capability,
+ struct user_namespace *ns)
{
int err;
struct common_audit_data ad;
u32 sid;

- err = cap_netlink_recv(skb, capability);
+ err = cap_netlink_recv(skb, capability, ns);
if (err)
return err;

--
1.7.4.1


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