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Subject[PATCH v3 2/7] xfrm/compat: Add 64=>32-bit messages translator
Date
Provide the kernel-to-user translator under XFRM_USER_COMPAT, that
creates for 64-bit xfrm-user message a 32-bit translation and puts it
in skb's frag_list. net/compat.c layer provides MSG_CMSG_COMPAT to
decide if the message should be taken from skb or frag_list.
(used by wext-core which has also an ABI difference)

Kernel sends 64-bit xfrm messages to the userspace for:
- multicast (monitor events)
- netlink dumps

Wire up the translator to xfrm_nlmsg_multicast().

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
include/net/xfrm.h | 5 +
net/xfrm/xfrm_compat.c | 296 +++++++++++++++++++++++++++++++++++++++++
net/xfrm/xfrm_user.c | 15 ++-
3 files changed, 315 insertions(+), 1 deletion(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index fe2e3717da14..5b6cc62c9354 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -2000,7 +2000,12 @@ static inline int xfrm_tunnel_check(struct sk_buff *skb, struct xfrm_state *x,
return 0;
}

+extern const int xfrm_msg_min[XFRM_NR_MSGTYPES];
+
struct xfrm_translator {
+ /* Allocate frag_list and put compat translation there */
+ int (*alloc_compat)(struct sk_buff *skb, const struct nlmsghdr *src);
+
struct module *owner;
};

diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c
index f01d9af41c55..aece41b44ff2 100644
--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -8,8 +8,304 @@
#include <linux/xfrm.h>
#include <net/xfrm.h>

+struct compat_xfrm_lifetime_cfg {
+ compat_u64 soft_byte_limit, hard_byte_limit;
+ compat_u64 soft_packet_limit, hard_packet_limit;
+ compat_u64 soft_add_expires_seconds, hard_add_expires_seconds;
+ compat_u64 soft_use_expires_seconds, hard_use_expires_seconds;
+}; /* same size on 32bit, but only 4 byte alignment required */
+
+struct compat_xfrm_lifetime_cur {
+ compat_u64 bytes, packets, add_time, use_time;
+}; /* same size on 32bit, but only 4 byte alignment required */
+
+struct compat_xfrm_userpolicy_info {
+ struct xfrm_selector sel;
+ struct compat_xfrm_lifetime_cfg lft;
+ struct compat_xfrm_lifetime_cur curlft;
+ __u32 priority, index;
+ u8 dir, action, flags, share;
+ /* 4 bytes additional padding on 64bit */
+};
+
+struct compat_xfrm_usersa_info {
+ struct xfrm_selector sel;
+ struct xfrm_id id;
+ xfrm_address_t saddr;
+ struct compat_xfrm_lifetime_cfg lft;
+ struct compat_xfrm_lifetime_cur curlft;
+ struct xfrm_stats stats;
+ __u32 seq, reqid;
+ u16 family;
+ u8 mode, replay_window, flags;
+ /* 4 bytes additional padding on 64bit */
+};
+
+struct compat_xfrm_user_acquire {
+ struct xfrm_id id;
+ xfrm_address_t saddr;
+ struct xfrm_selector sel;
+ struct compat_xfrm_userpolicy_info policy;
+ /* 4 bytes additional padding on 64bit */
+ __u32 aalgos, ealgos, calgos, seq;
+};
+
+struct compat_xfrm_userspi_info {
+ struct compat_xfrm_usersa_info info;
+ /* 4 bytes additional padding on 64bit */
+ __u32 min, max;
+};
+
+struct compat_xfrm_user_expire {
+ struct compat_xfrm_usersa_info state;
+ /* 8 bytes additional padding on 64bit */
+ u8 hard;
+};
+
+struct compat_xfrm_user_polexpire {
+ struct compat_xfrm_userpolicy_info pol;
+ /* 8 bytes additional padding on 64bit */
+ u8 hard;
+};
+
+#define XMSGSIZE(type) sizeof(struct type)
+
+static const int compat_msg_min[XFRM_NR_MSGTYPES] = {
+ [XFRM_MSG_NEWSA - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_usersa_info),
+ [XFRM_MSG_DELSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
+ [XFRM_MSG_GETSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
+ [XFRM_MSG_NEWPOLICY - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userpolicy_info),
+ [XFRM_MSG_DELPOLICY - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
+ [XFRM_MSG_GETPOLICY - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
+ [XFRM_MSG_ALLOCSPI - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userspi_info),
+ [XFRM_MSG_ACQUIRE - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_acquire),
+ [XFRM_MSG_EXPIRE - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_expire),
+ [XFRM_MSG_UPDPOLICY - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_userpolicy_info),
+ [XFRM_MSG_UPDSA - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_usersa_info),
+ [XFRM_MSG_POLEXPIRE - XFRM_MSG_BASE] = XMSGSIZE(compat_xfrm_user_polexpire),
+ [XFRM_MSG_FLUSHSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_flush),
+ [XFRM_MSG_FLUSHPOLICY - XFRM_MSG_BASE] = 0,
+ [XFRM_MSG_NEWAE - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
+ [XFRM_MSG_GETAE - XFRM_MSG_BASE] = XMSGSIZE(xfrm_aevent_id),
+ [XFRM_MSG_REPORT - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_report),
+ [XFRM_MSG_MIGRATE - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_id),
+ [XFRM_MSG_NEWSADINFO - XFRM_MSG_BASE] = sizeof(u32),
+ [XFRM_MSG_GETSADINFO - XFRM_MSG_BASE] = sizeof(u32),
+ [XFRM_MSG_NEWSPDINFO - XFRM_MSG_BASE] = sizeof(u32),
+ [XFRM_MSG_GETSPDINFO - XFRM_MSG_BASE] = sizeof(u32),
+ [XFRM_MSG_MAPPING - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_mapping)
+};
+
+static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb,
+ const struct nlmsghdr *nlh_src, u16 type)
+{
+ int payload = compat_msg_min[type];
+ int src_len = xfrm_msg_min[type];
+ struct nlmsghdr *nlh_dst;
+
+ /* Compat messages are shorter or equal to native (+padding) */
+ if (WARN_ON_ONCE(src_len < payload))
+ return ERR_PTR(-EMSGSIZE);
+
+ nlh_dst = nlmsg_put(skb, nlh_src->nlmsg_pid, nlh_src->nlmsg_seq,
+ nlh_src->nlmsg_type, payload, nlh_src->nlmsg_flags);
+ if (!nlh_dst)
+ return ERR_PTR(-EMSGSIZE);
+
+ memset(nlmsg_data(nlh_dst), 0, payload);
+
+ switch (nlh_src->nlmsg_type) {
+ /* Compat message has the same layout as native */
+ case XFRM_MSG_DELSA:
+ case XFRM_MSG_DELPOLICY:
+ case XFRM_MSG_FLUSHSA:
+ case XFRM_MSG_FLUSHPOLICY:
+ case XFRM_MSG_NEWAE:
+ case XFRM_MSG_REPORT:
+ case XFRM_MSG_MIGRATE:
+ case XFRM_MSG_NEWSADINFO:
+ case XFRM_MSG_NEWSPDINFO:
+ case XFRM_MSG_MAPPING:
+ WARN_ON_ONCE(src_len != payload);
+ memcpy(nlmsg_data(nlh_dst), nlmsg_data(nlh_src), src_len);
+ break;
+ /* 4 byte alignment for trailing u64 on native, but not on compat */
+ case XFRM_MSG_NEWSA:
+ case XFRM_MSG_NEWPOLICY:
+ case XFRM_MSG_UPDSA:
+ case XFRM_MSG_UPDPOLICY:
+ WARN_ON_ONCE(src_len != payload + 4);
+ memcpy(nlmsg_data(nlh_dst), nlmsg_data(nlh_src), payload);
+ break;
+ case XFRM_MSG_EXPIRE: {
+ const struct xfrm_user_expire *src_ue = nlmsg_data(nlh_src);
+ struct compat_xfrm_user_expire *dst_ue = nlmsg_data(nlh_dst);
+
+ /* compat_xfrm_user_expire has 4-byte smaller state */
+ memcpy(dst_ue, src_ue, sizeof(dst_ue->state));
+ dst_ue->hard = src_ue->hard;
+ break;
+ }
+ case XFRM_MSG_ACQUIRE: {
+ const struct xfrm_user_acquire *src_ua = nlmsg_data(nlh_src);
+ struct compat_xfrm_user_acquire *dst_ua = nlmsg_data(nlh_dst);
+
+ memcpy(dst_ua, src_ua, offsetof(struct compat_xfrm_user_acquire, aalgos));
+ dst_ua->aalgos = src_ua->aalgos;
+ dst_ua->ealgos = src_ua->ealgos;
+ dst_ua->calgos = src_ua->calgos;
+ dst_ua->seq = src_ua->seq;
+ break;
+ }
+ case XFRM_MSG_POLEXPIRE: {
+ const struct xfrm_user_polexpire *src_upe = nlmsg_data(nlh_src);
+ struct compat_xfrm_user_polexpire *dst_upe = nlmsg_data(nlh_dst);
+
+ /* compat_xfrm_user_polexpire has 4-byte smaller state */
+ memcpy(dst_upe, src_upe, sizeof(dst_upe->pol));
+ dst_upe->hard = src_upe->hard;
+ break;
+ }
+ case XFRM_MSG_ALLOCSPI: {
+ const struct xfrm_userspi_info *src_usi = nlmsg_data(nlh_src);
+ struct compat_xfrm_userspi_info *dst_usi = nlmsg_data(nlh_dst);
+
+ /* compat_xfrm_user_polexpire has 4-byte smaller state */
+ memcpy(dst_usi, src_usi, sizeof(src_usi->info));
+ dst_usi->min = src_usi->min;
+ dst_usi->max = src_usi->max;
+ break;
+ }
+ /* Not being sent by kernel */
+ case XFRM_MSG_GETSA:
+ case XFRM_MSG_GETPOLICY:
+ case XFRM_MSG_GETAE:
+ case XFRM_MSG_GETSADINFO:
+ case XFRM_MSG_GETSPDINFO:
+ default:
+ WARN_ONCE(1, "unsupported nlmsg_type %d", nlh_src->nlmsg_type);
+ return ERR_PTR(-EOPNOTSUPP);
+ }
+
+ return nlh_dst;
+}
+
+static int xfrm_nla_cpy(struct sk_buff *dst, const struct nlattr *src, int len)
+{
+ return nla_put(dst, src->nla_type, len, nla_data(src));
+}
+
+static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
+{
+ switch (src->nla_type) {
+ case XFRMA_PAD:
+ /* Ignore */
+ return 0;
+ case XFRMA_ALG_AUTH:
+ case XFRMA_ALG_CRYPT:
+ case XFRMA_ALG_COMP:
+ case XFRMA_ENCAP:
+ case XFRMA_TMPL:
+ return xfrm_nla_cpy(dst, src, nla_len(src));
+ case XFRMA_SA:
+ return xfrm_nla_cpy(dst, src, XMSGSIZE(compat_xfrm_usersa_info));
+ case XFRMA_POLICY:
+ return xfrm_nla_cpy(dst, src, XMSGSIZE(compat_xfrm_userpolicy_info));
+ case XFRMA_SEC_CTX:
+ return xfrm_nla_cpy(dst, src, nla_len(src));
+ case XFRMA_LTIME_VAL:
+ return nla_put_64bit(dst, src->nla_type, nla_len(src),
+ nla_data(src), XFRMA_PAD);
+ case XFRMA_REPLAY_VAL:
+ case XFRMA_REPLAY_THRESH:
+ case XFRMA_ETIMER_THRESH:
+ case XFRMA_SRCADDR:
+ case XFRMA_COADDR:
+ return xfrm_nla_cpy(dst, src, nla_len(src));
+ case XFRMA_LASTUSED:
+ return nla_put_64bit(dst, src->nla_type, nla_len(src),
+ nla_data(src), XFRMA_PAD);
+ case XFRMA_POLICY_TYPE:
+ case XFRMA_MIGRATE:
+ case XFRMA_ALG_AEAD:
+ case XFRMA_KMADDRESS:
+ case XFRMA_ALG_AUTH_TRUNC:
+ case XFRMA_MARK:
+ case XFRMA_TFCPAD:
+ case XFRMA_REPLAY_ESN_VAL:
+ case XFRMA_SA_EXTRA_FLAGS:
+ case XFRMA_PROTO:
+ case XFRMA_ADDRESS_FILTER:
+ case XFRMA_OFFLOAD_DEV:
+ case XFRMA_SET_MARK:
+ case XFRMA_SET_MARK_MASK:
+ case XFRMA_IF_ID:
+ return xfrm_nla_cpy(dst, src, nla_len(src));
+ default:
+ BUILD_BUG_ON(XFRMA_MAX != XFRMA_IF_ID);
+ WARN_ONCE(1, "unsupported nla_type %d", src->nla_type);
+ return -EOPNOTSUPP;
+ }
+}
+
+/* Take kernel-built (64bit layout) and create 32bit layout for userspace */
+static int xfrm_xlate64(struct sk_buff *dst, const struct nlmsghdr *nlh_src)
+{
+ u16 type = nlh_src->nlmsg_type - XFRM_MSG_BASE;
+ const struct nlattr *nla, *attrs;
+ struct nlmsghdr *nlh_dst;
+ int len, remaining;
+
+ nlh_dst = xfrm_nlmsg_put_compat(dst, nlh_src, type);
+ if (IS_ERR(nlh_dst))
+ return PTR_ERR(nlh_dst);
+
+ attrs = nlmsg_attrdata(nlh_src, xfrm_msg_min[type]);
+ len = nlmsg_attrlen(nlh_src, xfrm_msg_min[type]);
+
+ nla_for_each_attr(nla, attrs, len, remaining) {
+ int err = xfrm_xlate64_attr(dst, nla);
+
+ if (err)
+ return err;
+ }
+
+ nlmsg_end(dst, nlh_dst);
+
+ return 0;
+}
+
+static int xfrm_alloc_compat(struct sk_buff *skb, const struct nlmsghdr *nlh_src)
+{
+ u16 type = nlh_src->nlmsg_type - XFRM_MSG_BASE;
+ struct sk_buff *new = NULL;
+ int err;
+
+ if (WARN_ON_ONCE(type >= ARRAY_SIZE(xfrm_msg_min)))
+ return -EOPNOTSUPP;
+
+ if (skb_shinfo(skb)->frag_list == NULL) {
+ new = alloc_skb(skb->len + skb_tailroom(skb), GFP_ATOMIC);
+ if (!new)
+ return -ENOMEM;
+ skb_shinfo(skb)->frag_list = new;
+ }
+
+ err = xfrm_xlate64(skb_shinfo(skb)->frag_list, nlh_src);
+ if (err) {
+ if (new) {
+ kfree_skb(new);
+ skb_shinfo(skb)->frag_list = NULL;
+ }
+ return err;
+ }
+
+ return 0;
+}
+
static struct xfrm_translator xfrm_translator = {
.owner = THIS_MODULE,
+ .alloc_compat = xfrm_alloc_compat,
};

static int __init xfrm_compat_init(void)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index fbb7d9d06478..3769227ed4e1 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1083,12 +1083,24 @@ static inline int xfrm_nlmsg_multicast(struct net *net, struct sk_buff *skb,
u32 pid, unsigned int group)
{
struct sock *nlsk = rcu_dereference(net->xfrm.nlsk);
+ struct xfrm_translator *xtr;

if (!nlsk) {
kfree_skb(skb);
return -EPIPE;
}

+ xtr = xfrm_get_translator();
+ if (xtr) {
+ int err = xtr->alloc_compat(skb, nlmsg_hdr(skb));
+
+ xfrm_put_translator(xtr);
+ if (err) {
+ kfree_skb(skb);
+ return err;
+ }
+ }
+
return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC);
}

@@ -2533,7 +2545,7 @@ static int xfrm_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,

#define XMSGSIZE(type) sizeof(struct type)

-static const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
+const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
[XFRM_MSG_NEWSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_info),
[XFRM_MSG_DELSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
[XFRM_MSG_GETSA - XFRM_MSG_BASE] = XMSGSIZE(xfrm_usersa_id),
@@ -2556,6 +2568,7 @@ static const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
[XFRM_MSG_NEWSPDINFO - XFRM_MSG_BASE] = sizeof(u32),
[XFRM_MSG_GETSPDINFO - XFRM_MSG_BASE] = sizeof(u32),
};
+EXPORT_SYMBOL_GPL(xfrm_msg_min);

#undef XMSGSIZE

--
2.28.0
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