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[NETFILTER]: x_tables: simplify compat API
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Split the xt_compat_match/xt_compat_target into smaller type-safe functions
performing just one operation. Handle all alignment and size-related
conversions centrally in these function instead of requiring each module to
implement a full-blown conversion function. Replace ->compat callback by
->compat_from_user and ->compat_to_user callbacks, responsible for
converting just a single private structure.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@kaber
kaber authored and David S. Miller committed Sep 22, 2006
1 parent 79030ed commit 9fa492c
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Showing 3 changed files with 151 additions and 185 deletions.
29 changes: 18 additions & 11 deletions include/linux/netfilter/x_tables.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -138,12 +138,6 @@ struct xt_counters_info

#include <linux/netdevice.h>

#ifdef CONFIG_COMPAT
#define COMPAT_TO_USER 1
#define COMPAT_FROM_USER -1
#define COMPAT_CALC_SIZE 0
#endif

struct xt_match
{
struct list_head list;
Expand Down Expand Up @@ -176,7 +170,8 @@ struct xt_match
void (*destroy)(const struct xt_match *match, void *matchinfo);

/* Called when userspace align differs from kernel space one */
int (*compat)(void *match, void **dstptr, int *size, int convert);
void (*compat_from_user)(void *dst, void *src);
int (*compat_to_user)(void __user *dst, void *src);

/* Set this to THIS_MODULE if you are a module, otherwise NULL */
struct module *me;
Expand All @@ -186,6 +181,7 @@ struct xt_match

char *table;
unsigned int matchsize;
unsigned int compatsize;
unsigned int hooks;
unsigned short proto;

Expand Down Expand Up @@ -224,13 +220,15 @@ struct xt_target
void (*destroy)(const struct xt_target *target, void *targinfo);

/* Called when userspace align differs from kernel space one */
int (*compat)(void *target, void **dstptr, int *size, int convert);
void (*compat_from_user)(void *dst, void *src);
int (*compat_to_user)(void __user *dst, void *src);

/* Set this to THIS_MODULE if you are a module, otherwise NULL */
struct module *me;

char *table;
unsigned int targetsize;
unsigned int compatsize;
unsigned int hooks;
unsigned short proto;

Expand Down Expand Up @@ -387,9 +385,18 @@ struct compat_xt_counters_info

extern void xt_compat_lock(int af);
extern void xt_compat_unlock(int af);
extern int xt_compat_match(void *match, void **dstptr, int *size, int convert);
extern int xt_compat_target(void *target, void **dstptr, int *size,
int convert);

extern int xt_compat_match_offset(struct xt_match *match);
extern void xt_compat_match_from_user(struct xt_entry_match *m,
void **dstptr, int *size);
extern int xt_compat_match_to_user(struct xt_entry_match *m,
void * __user *dstptr, int *size);

extern int xt_compat_target_offset(struct xt_target *target);
extern void xt_compat_target_from_user(struct xt_entry_target *t,
void **dstptr, int *size);
extern int xt_compat_target_to_user(struct xt_entry_target *t,
void * __user *dstptr, int *size);

#endif /* CONFIG_COMPAT */
#endif /* __KERNEL__ */
Expand Down
115 changes: 24 additions & 91 deletions net/ipv4/netfilter/ip_tables.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -942,73 +942,28 @@ static short compat_calc_jump(u_int16_t offset)
return delta;
}

struct compat_ipt_standard_target
static void compat_standard_from_user(void *dst, void *src)
{
struct compat_xt_entry_target target;
compat_int_t verdict;
};

struct compat_ipt_standard
{
struct compat_ipt_entry entry;
struct compat_ipt_standard_target target;
};
int v = *(compat_int_t *)src;

#define IPT_ST_LEN XT_ALIGN(sizeof(struct ipt_standard_target))
#define IPT_ST_COMPAT_LEN COMPAT_XT_ALIGN(sizeof(struct compat_ipt_standard_target))
#define IPT_ST_OFFSET (IPT_ST_LEN - IPT_ST_COMPAT_LEN)
if (v > 0)
v += compat_calc_jump(v);
memcpy(dst, &v, sizeof(v));
}

static int compat_ipt_standard_fn(void *target,
void **dstptr, int *size, int convert)
static int compat_standard_to_user(void __user *dst, void *src)
{
struct compat_ipt_standard_target compat_st, *pcompat_st;
struct ipt_standard_target st, *pst;
int ret;
compat_int_t cv = *(int *)src;

ret = 0;
switch (convert) {
case COMPAT_TO_USER:
pst = target;
memcpy(&compat_st.target, &pst->target,
sizeof(compat_st.target));
compat_st.verdict = pst->verdict;
if (compat_st.verdict > 0)
compat_st.verdict -=
compat_calc_jump(compat_st.verdict);
compat_st.target.u.user.target_size = IPT_ST_COMPAT_LEN;
if (copy_to_user(*dstptr, &compat_st, IPT_ST_COMPAT_LEN))
ret = -EFAULT;
*size -= IPT_ST_OFFSET;
*dstptr += IPT_ST_COMPAT_LEN;
break;
case COMPAT_FROM_USER:
pcompat_st = target;
memcpy(&st.target, &pcompat_st->target, IPT_ST_COMPAT_LEN);
st.verdict = pcompat_st->verdict;
if (st.verdict > 0)
st.verdict += compat_calc_jump(st.verdict);
st.target.u.user.target_size = IPT_ST_LEN;
memcpy(*dstptr, &st, IPT_ST_LEN);
*size += IPT_ST_OFFSET;
*dstptr += IPT_ST_LEN;
break;
case COMPAT_CALC_SIZE:
*size += IPT_ST_OFFSET;
break;
default:
ret = -ENOPROTOOPT;
break;
}
return ret;
if (cv > 0)
cv -= compat_calc_jump(cv);
return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
}

static inline int
compat_calc_match(struct ipt_entry_match *m, int * size)
{
if (m->u.kernel.match->compat)
m->u.kernel.match->compat(m, NULL, size, COMPAT_CALC_SIZE);
else
xt_compat_match(m, NULL, size, COMPAT_CALC_SIZE);
*size += xt_compat_match_offset(m->u.kernel.match);
return 0;
}

Expand All @@ -1023,10 +978,7 @@ static int compat_calc_entry(struct ipt_entry *e, struct xt_table_info *info,
entry_offset = (void *)e - base;
IPT_MATCH_ITERATE(e, compat_calc_match, &off);
t = ipt_get_target(e);
if (t->u.kernel.target->compat)
t->u.kernel.target->compat(t, NULL, &off, COMPAT_CALC_SIZE);
else
xt_compat_target(t, NULL, &off, COMPAT_CALC_SIZE);
off += xt_compat_target_offset(t->u.kernel.target);
newinfo->size -= off;
ret = compat_add_offset(entry_offset, off);
if (ret)
Expand Down Expand Up @@ -1412,17 +1364,13 @@ struct compat_ipt_replace {
};

static inline int compat_copy_match_to_user(struct ipt_entry_match *m,
void __user **dstptr, compat_uint_t *size)
void * __user *dstptr, compat_uint_t *size)
{
if (m->u.kernel.match->compat)
return m->u.kernel.match->compat(m, dstptr, size,
COMPAT_TO_USER);
else
return xt_compat_match(m, dstptr, size, COMPAT_TO_USER);
return xt_compat_match_to_user(m, dstptr, size);
}

static int compat_copy_entry_to_user(struct ipt_entry *e,
void __user **dstptr, compat_uint_t *size)
void * __user *dstptr, compat_uint_t *size)
{
struct ipt_entry_target __user *t;
struct compat_ipt_entry __user *ce;
Expand All @@ -1442,11 +1390,7 @@ static int compat_copy_entry_to_user(struct ipt_entry *e,
if (ret)
goto out;
t = ipt_get_target(e);
if (t->u.kernel.target->compat)
ret = t->u.kernel.target->compat(t, dstptr, size,
COMPAT_TO_USER);
else
ret = xt_compat_target(t, dstptr, size, COMPAT_TO_USER);
ret = xt_compat_target_to_user(t, dstptr, size);
if (ret)
goto out;
ret = -EFAULT;
Expand Down Expand Up @@ -1478,11 +1422,7 @@ compat_check_calc_match(struct ipt_entry_match *m,
return match ? PTR_ERR(match) : -ENOENT;
}
m->u.kernel.match = match;

if (m->u.kernel.match->compat)
m->u.kernel.match->compat(m, NULL, size, COMPAT_CALC_SIZE);
else
xt_compat_match(m, NULL, size, COMPAT_CALC_SIZE);
*size += xt_compat_match_offset(match);

(*i)++;
return 0;
Expand Down Expand Up @@ -1543,10 +1483,7 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e,
}
t->u.kernel.target = target;

if (t->u.kernel.target->compat)
t->u.kernel.target->compat(t, NULL, &off, COMPAT_CALC_SIZE);
else
xt_compat_target(t, NULL, &off, COMPAT_CALC_SIZE);
off += xt_compat_target_offset(target);
*size += off;
ret = compat_add_offset(entry_offset, off);
if (ret)
Expand Down Expand Up @@ -1584,10 +1521,7 @@ static inline int compat_copy_match_from_user(struct ipt_entry_match *m,

dm = (struct ipt_entry_match *)*dstptr;
match = m->u.kernel.match;
if (match->compat)
match->compat(m, dstptr, size, COMPAT_FROM_USER);
else
xt_compat_match(m, dstptr, size, COMPAT_FROM_USER);
xt_compat_match_from_user(m, dstptr, size);

ret = xt_check_match(match, AF_INET, dm->u.match_size - sizeof(*dm),
name, hookmask, ip->proto,
Expand Down Expand Up @@ -1635,10 +1569,7 @@ static int compat_copy_entry_from_user(struct ipt_entry *e, void **dstptr,
de->target_offset = e->target_offset - (origsize - *size);
t = ipt_get_target(e);
target = t->u.kernel.target;
if (target->compat)
target->compat(t, dstptr, size, COMPAT_FROM_USER);
else
xt_compat_target(t, dstptr, size, COMPAT_FROM_USER);
xt_compat_target_from_user(t, dstptr, size);

de->next_offset = e->next_offset - (origsize - *size);
for (h = 0; h < NF_IP_NUMHOOKS; h++) {
Expand Down Expand Up @@ -2205,7 +2136,9 @@ static struct ipt_target ipt_standard_target = {
.targetsize = sizeof(int),
.family = AF_INET,
#ifdef CONFIG_COMPAT
.compat = &compat_ipt_standard_fn,
.compatsize = sizeof(compat_int_t),
.compat_from_user = compat_standard_from_user,
.compat_to_user = compat_standard_to_user,
#endif
};

Expand Down
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