From a5531a5d852008be40811496029012f4ad3093d1 Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Sat, 26 Aug 2006 20:11:47 -0700 Subject: [PATCH] [NETLINK]: Improve string attribute validation Introduces a new attribute type NLA_NUL_STRING to support NUL terminated strings. Attributes of this kind require to carry a terminating NUL within the maximum specified in the policy. The `old' NLA_STRING which is not required to be NUL terminated is extended to provide means to specify a maximum length of the string. Aims at easing the pain with using nla_strlcpy() on temporary buffers. Signed-off-by: Thomas Graf Signed-off-by: David S. Miller --- include/net/netlink.h | 15 +++++++++---- net/netlink/attr.c | 49 ++++++++++++++++++++++++++++++++++--------- 2 files changed, 50 insertions(+), 14 deletions(-) diff --git a/include/net/netlink.h b/include/net/netlink.h index bcb27e3a31..11dc2e7f67 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -167,6 +167,7 @@ enum { NLA_FLAG, NLA_MSECS, NLA_NESTED, + NLA_NUL_STRING, __NLA_TYPE_MAX, }; @@ -175,21 +176,27 @@ enum { /** * struct nla_policy - attribute validation policy * @type: Type of attribute or NLA_UNSPEC - * @minlen: Minimal length of payload required to be available + * @len: Type specific length of payload * * Policies are defined as arrays of this struct, the array must be * accessible by attribute type up to the highest identifier to be expected. * + * Meaning of `len' field: + * NLA_STRING Maximum length of string + * NLA_NUL_STRING Maximum length of string (excluding NUL) + * NLA_FLAG Unused + * All other Exact length of attribute payload + * * Example: * static struct nla_policy my_policy[ATTR_MAX+1] __read_mostly = { * [ATTR_FOO] = { .type = NLA_U16 }, - * [ATTR_BAR] = { .type = NLA_STRING }, - * [ATTR_BAZ] = { .minlen = sizeof(struct mystruct) }, + * [ATTR_BAR] = { .type = NLA_STRING, len = BARSIZ }, + * [ATTR_BAZ] = { .len = sizeof(struct mystruct) }, * }; */ struct nla_policy { u16 type; - u16 minlen; + u16 len; }; /** diff --git a/net/netlink/attr.c b/net/netlink/attr.c index 136e529e57..004139557e 100644 --- a/net/netlink/attr.c +++ b/net/netlink/attr.c @@ -20,7 +20,6 @@ static u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = { [NLA_U16] = sizeof(u16), [NLA_U32] = sizeof(u32), [NLA_U64] = sizeof(u64), - [NLA_STRING] = 1, [NLA_NESTED] = NLA_HDRLEN, }; @@ -28,7 +27,7 @@ static int validate_nla(struct nlattr *nla, int maxtype, struct nla_policy *policy) { struct nla_policy *pt; - int minlen = 0; + int minlen = 0, attrlen = nla_len(nla); if (nla->nla_type <= 0 || nla->nla_type > maxtype) return 0; @@ -37,16 +36,46 @@ static int validate_nla(struct nlattr *nla, int maxtype, BUG_ON(pt->type > NLA_TYPE_MAX); - if (pt->minlen) - minlen = pt->minlen; - else if (pt->type != NLA_UNSPEC) - minlen = nla_attr_minlen[pt->type]; + switch (pt->type) { + case NLA_FLAG: + if (attrlen > 0) + return -ERANGE; + break; - if (pt->type == NLA_FLAG && nla_len(nla) > 0) - return -ERANGE; + case NLA_NUL_STRING: + if (pt->len) + minlen = min_t(int, attrlen, pt->len + 1); + else + minlen = attrlen; - if (nla_len(nla) < minlen) - return -ERANGE; + if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL) + return -EINVAL; + /* fall through */ + + case NLA_STRING: + if (attrlen < 1) + return -ERANGE; + + if (pt->len) { + char *buf = nla_data(nla); + + if (buf[attrlen - 1] == '\0') + attrlen--; + + if (attrlen > pt->len) + return -ERANGE; + } + break; + + default: + if (pt->len) + minlen = pt->len; + else if (pt->type != NLA_UNSPEC) + minlen = nla_attr_minlen[pt->type]; + + if (attrlen < minlen) + return -ERANGE; + } return 0; } -- 2.39.5