[PATCH 3.16 303/305] netfilter: x_tables: introduce and use xt_copy_counters_from_user

Ben Hutchings
2016-08-14T18:00:25Z

From: Florian Westphal <fw@strlen.de>

commit d7591f0c41ce3e67600a982bab6989ef0f07b3ce upstream.

The three variants use same copy&pasted code, condense this into a
helper and use that.

Make sure info.name is 0-terminated.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/linux/netfilter/x_tables.h | 3 ++
net/ipv4/netfilter/arp_tables.c | 48 +++----------------------
net/ipv4/netfilter/ip_tables.c | 48 +++----------------------
net/ipv6/netfilter/ip6_tables.c | 49 +++----------------------
net/netfilter/x_tables.c | 74 ++++++++++++++++++++++++++++++++++++++
5 files changed, 92 insertions(+), 130 deletions(-)

--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -248,6 +248,9 @@ int xt_check_match(struct xt_mtchk_param
int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
bool inv_proto);

+void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
+ struct xt_counters_info *info, bool compat);
+
struct xt_table *xt_register_table(struct net *net,
const struct xt_table *table,
struct xt_table_info *bootstrap,
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1122,56 +1122,18 @@ static int do_add_counters(struct net *n
unsigned int i, curcpu;
struct xt_counters_info tmp;
struct xt_counters *paddc;
- unsigned int num_counters;
- const char *name;
- int size;
- void *ptmp;
struct xt_table *t;
const struct xt_table_info *private;
int ret = 0;
void *loc_cpu_entry;
struct arpt_entry *iter;
unsigned int addend;
-#ifdef CONFIG_COMPAT
- struct compat_xt_counters_info compat_tmp;

- if (compat) {
- ptmp = &compat_tmp;
- size = sizeof(struct compat_xt_counters_info);
- } else
-#endif
- {
- ptmp = &tmp;
- size = sizeof(struct xt_counters_info);
- }
-
- if (copy_from_user(ptmp, user, size) != 0)
- return -EFAULT;
-
-#ifdef CONFIG_COMPAT
- if (compat) {
- num_counters = compat_tmp.num_counters;
- name = compat_tmp.name;
- } else
-#endif
- {
- num_counters = tmp.num_counters;
- name = tmp.name;
- }
-
- if (len != size + num_counters * sizeof(struct xt_counters))
- return -EINVAL;
-
- paddc = vmalloc(len - size);
- if (!paddc)
- return -ENOMEM;
-
- if (copy_from_user(paddc, user + size, len - size) != 0) {
- ret = -EFAULT;
- goto free;
- }
+ paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
+ if (IS_ERR(paddc))
+ return PTR_ERR(paddc);

- t = xt_find_table_lock(net, NFPROTO_ARP, name);
+ t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
if (IS_ERR_OR_NULL(t)) {
ret = t ? PTR_ERR(t) : -ENOENT;
goto free;
@@ -1179,7 +1141,7 @@ static int do_add_counters(struct net *n

local_bh_disable();
private = t->private;
- if (private->number != num_counters) {
+ if (private->number != tmp.num_counters) {
ret = -EINVAL;
goto unlock_up_free;
}
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1309,56 +1309,18 @@ do_add_counters(struct net *net, const v
unsigned int i, curcpu;
struct xt_counters_info tmp;
struct xt_counters *paddc;
- unsigned int num_counters;
- const char *name;
- int size;
- void *ptmp;
struct xt_table *t;
const struct xt_table_info *private;
int ret = 0;
void *loc_cpu_entry;
struct ipt_entry *iter;
unsigned int addend;
-#ifdef CONFIG_COMPAT
- struct compat_xt_counters_info compat_tmp;

- if (compat) {
- ptmp = &compat_tmp;
- size = sizeof(struct compat_xt_counters_info);
- } else
-#endif
- {
- ptmp = &tmp;
- size = sizeof(struct xt_counters_info);
- }
-
- if (copy_from_user(ptmp, user, size) != 0)
- return -EFAULT;
-
-#ifdef CONFIG_COMPAT
- if (compat) {
- num_counters = compat_tmp.num_counters;
- name = compat_tmp.name;
- } else
-#endif
- {
- num_counters = tmp.num_counters;
- name = tmp.name;
- }
-
- if (len != size + num_counters * sizeof(struct xt_counters))
- return -EINVAL;
-
- paddc = vmalloc(len - size);
- if (!paddc)
- return -ENOMEM;
-
- if (copy_from_user(paddc, user + size, len - size) != 0) {
- ret = -EFAULT;
- goto free;
- }
+ paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
+ if (IS_ERR(paddc))
+ return PTR_ERR(paddc);

- t = xt_find_table_lock(net, AF_INET, name);
+ t = xt_find_table_lock(net, AF_INET, tmp.name);
if (IS_ERR_OR_NULL(t)) {
ret = t ? PTR_ERR(t) : -ENOENT;
goto free;
@@ -1366,7 +1328,7 @@ do_add_counters(struct net *net, const v

local_bh_disable();
private = t->private;
- if (private->number != num_counters) {
+ if (private->number != tmp.num_counters) {
ret = -EINVAL;
goto unlock_up_free;
}
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1319,56 +1319,17 @@ do_add_counters(struct net *net, const v
unsigned int i, curcpu;
struct xt_counters_info tmp;
struct xt_counters *paddc;
- unsigned int num_counters;
- char *name;
- int size;
- void *ptmp;
struct xt_table *t;
const struct xt_table_info *private;
int ret = 0;
const void *loc_cpu_entry;
struct ip6t_entry *iter;
unsigned int addend;
-#ifdef CONFIG_COMPAT
- struct compat_xt_counters_info compat_tmp;

- if (compat) {
- ptmp = &compat_tmp;
- size = sizeof(struct compat_xt_counters_info);
- } else
-#endif
- {
- ptmp = &tmp;
- size = sizeof(struct xt_counters_info);
- }
-
- if (copy_from_user(ptmp, user, size) != 0)
- return -EFAULT;
-
-#ifdef CONFIG_COMPAT
- if (compat) {
- num_counters = compat_tmp.num_counters;
- name = compat_tmp.name;
- } else
-#endif
- {
- num_counters = tmp.num_counters;
- name = tmp.name;
- }
-
- if (len != size + num_counters * sizeof(struct xt_counters))
- return -EINVAL;
-
- paddc = vmalloc(len - size);
- if (!paddc)
- return -ENOMEM;
-
- if (copy_from_user(paddc, user + size, len - size) != 0) {
- ret = -EFAULT;
- goto free;
- }
-
- t = xt_find_table_lock(net, AF_INET6, name);
+ paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
+ if (IS_ERR(paddc))
+ return PTR_ERR(paddc);
+ t = xt_find_table_lock(net, AF_INET6, tmp.name);
if (IS_ERR_OR_NULL(t)) {
ret = t ? PTR_ERR(t) : -ENOENT;
goto free;
@@ -1377,7 +1338,7 @@ do_add_counters(struct net *net, const v

local_bh_disable();
private = t->private;
- if (private->number != num_counters) {
+ if (private->number != tmp.num_counters) {
ret = -EINVAL;
goto unlock_up_free;
}
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -771,6 +771,80 @@ int xt_check_target(struct xt_tgchk_para
}
EXPORT_SYMBOL_GPL(xt_check_target);

+/**
+ * xt_copy_counters_from_user - copy counters and metadata from userspace
+ *
+ * @user: src pointer to userspace memory
+ * @len: alleged size of userspace memory
+ * @info: where to store the xt_counters_info metadata
+ * @compat: true if we setsockopt call is done by 32bit task on 64bit kernel
+ *
+ * Copies counter meta data from @user and stores it in @info.
+ *
+ * vmallocs memory to hold the counters, then copies the counter data
+ * from @user to the new memory and returns a pointer to it.
+ *
+ * If @compat is true, @info gets converted automatically to the 64bit
+ * representation.
+ *
+ * The metadata associated with the counters is stored in @info.
+ *
+ * Return: returns pointer that caller has to test via IS_ERR().
+ * If IS_ERR is false, caller has to vfree the pointer.
+ */
+void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
+ struct xt_counters_info *info, bool compat)
+{
+ void *mem;
+ u64 size;
+
+#ifdef CONFIG_COMPAT
+ if (compat) {
+ /* structures only differ in size due to alignment */
+ struct compat_xt_counters_info compat_tmp;
+
+ if (len <= sizeof(compat_tmp))
+ return ERR_PTR(-EINVAL);
+
+ len -= sizeof(compat_tmp);
+ if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
+ return ERR_PTR(-EFAULT);
+
+ strlcpy(info->name, compat_tmp.name, sizeof(info->name));
+ info->num_counters = compat_tmp.num_counters;
+ user += sizeof(compat_tmp);
+ } else
+#endif
+ {
+ if (len <= sizeof(*info))
+ return ERR_PTR(-EINVAL);
+
+ len -= sizeof(*info);
+ if (copy_from_user(info, user, sizeof(*info)) != 0)
+ return ERR_PTR(-EFAULT);
+
+ info->name[sizeof(info->name) - 1] = '\0';
+ user += sizeof(*info);
+ }
+
+ size = sizeof(struct xt_counters);
+ size *= info->num_counters;
+
+ if (size != (u64)len)
+ return ERR_PTR(-EINVAL);
+
+ mem = vmalloc(len);
+ if (!mem)
+ return ERR_PTR(-ENOMEM);
+
+ if (copy_from_user(mem, user, len) == 0)
+ return mem;
+
+ vfree(mem);
+ return ERR_PTR(-EFAULT);
+}
+EXPORT_SYMBOL_GPL(xt_copy_counters_from_user);
+
#ifdef CONFIG_COMPAT
int xt_compat_target_offset(const struct xt_target *target)
{