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netlink: move extack setting into validate_nla()

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This unifies the code between nla_parse() which sets the bad
attribute pointer and an error message, and nla_validate()
which only sets the bad attribute pointer.

It also cleans up the code for NLA_REJECT and paves the way
for nested policy validation, as it will allow us to easily
skip setting the "generic" message without any extra args
like the **error_msg now, just passing the extack through is
now enough.

While at it, remove the unnecessary label in nla_parse().

Suggested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Johannes Berg 2018-09-26 11:15:32 +02:00 • committed by David S. Miller
parent 48fde90a78
commit c29f1845b2
1 changed files with 36 additions and 32 deletions
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68
lib/nlattr.c
View file

@ -69,10 +69,11 @@ static int validate_nla_bitfield32(const struct nlattr *nla,
static int validate_nla(const struct nlattr *nla, int maxtype, static int validate_nla(const struct nlattr *nla, int maxtype,
const struct nla_policy *policy, const struct nla_policy *policy,
const char **error_msg) struct netlink_ext_ack *extack)
{ {
const struct nla_policy *pt; const struct nla_policy *pt;
int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla); int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
int err = -ERANGE;
if (type <= 0 || type > maxtype) if (type <= 0 || type > maxtype)
return 0; return 0;
@ -90,24 +91,31 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
switch (pt->type) { switch (pt->type) {
case NLA_EXACT_LEN: case NLA_EXACT_LEN:
if (attrlen != pt->len) if (attrlen != pt->len)
return -ERANGE; goto out_err;
break; break;
case NLA_REJECT: case NLA_REJECT:
if (pt->validation_data && error_msg) if (extack && pt->validation_data) {
*error_msg = pt->validation_data; NL_SET_BAD_ATTR(extack, nla);
return -EINVAL; extack->_msg = pt->validation_data;
return -EINVAL;
}
err = -EINVAL;
goto out_err;
case NLA_FLAG: case NLA_FLAG:
if (attrlen > 0) if (attrlen > 0)
return -ERANGE; goto out_err;
break; break;
case NLA_BITFIELD32: case NLA_BITFIELD32:
if (attrlen != sizeof(struct nla_bitfield32)) if (attrlen != sizeof(struct nla_bitfield32))
return -ERANGE; goto out_err;
return validate_nla_bitfield32(nla, pt->validation_data); err = validate_nla_bitfield32(nla, pt->validation_data);
if (err)
goto out_err;
break;
case NLA_NUL_STRING: case NLA_NUL_STRING:
if (pt->len) if (pt->len)
@ -115,13 +123,15 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
else else
minlen = attrlen; minlen = attrlen;
if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) {
return -EINVAL; err = -EINVAL;
goto out_err;
}
/* fall through */ /* fall through */
case NLA_STRING: case NLA_STRING:
if (attrlen < 1) if (attrlen < 1)
return -ERANGE; goto out_err;
if (pt->len) { if (pt->len) {
char *buf = nla_data(nla); char *buf = nla_data(nla);
@ -130,13 +140,13 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
attrlen--; attrlen--;
if (attrlen > pt->len) if (attrlen > pt->len)
return -ERANGE; goto out_err;
} }
break; break;
case NLA_BINARY: case NLA_BINARY:
if (pt->len && attrlen > pt->len) if (pt->len && attrlen > pt->len)
return -ERANGE; goto out_err;
break; break;
case NLA_NESTED: case NLA_NESTED:
@ -152,10 +162,13 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
minlen = nla_attr_minlen[pt->type]; minlen = nla_attr_minlen[pt->type];
if (attrlen < minlen) if (attrlen < minlen)
return -ERANGE; goto out_err;
} }
return 0; return 0;
out_err:
NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
return err;
} }
/** /**
@ -180,12 +193,10 @@ int nla_validate(const struct nlattr *head, int len, int maxtype,
int rem; int rem;
nla_for_each_attr(nla, head, len, rem) { nla_for_each_attr(nla, head, len, rem) {
int err = validate_nla(nla, maxtype, policy, NULL); int err = validate_nla(nla, maxtype, policy, extack);
if (err < 0) { if (err < 0)
NL_SET_BAD_ATTR(extack, nla);
return err; return err;
}
} }
return 0; return 0;
@ -241,7 +252,7 @@ int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
struct netlink_ext_ack *extack) struct netlink_ext_ack *extack)
{ {
const struct nlattr *nla; const struct nlattr *nla;
int rem, err; int rem;
memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1)); memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
@ -249,17 +260,12 @@ int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
u16 type = nla_type(nla); u16 type = nla_type(nla);
if (type > 0 && type <= maxtype) { if (type > 0 && type <= maxtype) {
static const char _msg[] = "Attribute failed policy validation";
const char *msg = _msg;
if (policy) { if (policy) {
err = validate_nla(nla, maxtype, policy, &msg); int err = validate_nla(nla, maxtype, policy,
if (err < 0) { extack);
NL_SET_BAD_ATTR(extack, nla);
if (extack) if (err < 0)
extack->_msg = msg; return err;
goto errout;
}
} }
tb[type] = (struct nlattr *)nla; tb[type] = (struct nlattr *)nla;
@ -270,9 +276,7 @@ int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n", pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
rem, current->comm); rem, current->comm);
err = 0; return 0;
errout:
return err;
} }
EXPORT_SYMBOL(nla_parse); EXPORT_SYMBOL(nla_parse);