[PATCH net-next v11 1/4] net netlink: Add new type NLA_BITFIELD_32
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: 2017-07-24 01:36:07
Subsystem:
library code, networking [general], the rest · Maintainers:
Andrew Morton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Jamal Hadi Salim <jhs@mojatatu.com>
Generic bitflags attribute content sent to the kernel by user.
With this type the user can either set or unset a flag in the
kernel.
The nla_value is a bitmap that defines the values being set
The nla_selector is a bitmask that defines which value is legit.
A check is made to ensure the rules that a kernel subsystem always
conforms to bitflags the kernel already knows about. i.e
if the user tries to set a bit flag that is not understood then
the _it will be rejected_.
In the most basic form, the user specifies the attribute policy as:
[ATTR_GOO] = { .type = NLA_BITFIELD_32, .validation_data = &myvalidflags },
where myvalidflags is the bit mask of the flags the kernel understands.
If the user _does not_ provide myvalidflags then the attribute will
also be rejected.
Examples:
nla_value = 0x0, and nla_selector = 0x1
implies we are selecting bit 1 and we want to set its value to 0.
nla_value = 0x2, and nla_selector = 0x2
implies we are selecting bit 2 and we want to set its value to 1.
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
include/net/netlink.h | 4 ++++
include/uapi/linux/netlink.h | 17 +++++++++++++++++
lib/nlattr.c | 21 +++++++++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index ef8e6c3..e33d1fb 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h@@ -178,6 +178,7 @@ enum { NLA_S16, NLA_S32, NLA_S64, + NLA_BITFIELD_32, __NLA_TYPE_MAX, };
@@ -206,6 +207,7 @@ enum { * NLA_MSECS Leaving the length field zero will verify the * given type fits, using it verifies minimum length * just like "All other" + * NLA_BITFIELD_32 A 32-bit bitmap/bitselector attribute * All other Minimum length of attribute payload * * Example:
@@ -213,11 +215,13 @@ enum { * [ATTR_FOO] = { .type = NLA_U16 }, * [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ }, * [ATTR_BAZ] = { .len = sizeof(struct mystruct) }, + * [ATTR_GOO] = { .type = NLA_BITFIELD_32, .validation_data = &myvalidflags }, * }; */ struct nla_policy { u16 type; u16 len; + void *validation_data; }; /**
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index f86127a..0ac05a6 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h@@ -226,5 +226,22 @@ struct nlattr { #define NLA_ALIGN(len) (((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1)) #define NLA_HDRLEN ((int) NLA_ALIGN(sizeof(struct nlattr))) +/* Generic 32 bitflags attribute content sent to the kernel. + * + * The nla_value is a bitmap that defines the values being set + * The nla_selector is a bitmask that defines which value is legit + * + * Examples: + * nla_value = 0x0, and nla_selector = 0x1 + * implies we are selecting bit 1 and we want to set its value to 0. + * + * nla_value = 0x2, and nla_selector = 0x2 + * implies we are selecting bit 2 and we want to set its value to 1. + * + */ +struct nla_bitfield_32 { + __u32 nla_value; + __u32 nla_selector; +}; #endif /* _UAPI__LINUX_NETLINK_H */
diff --git a/lib/nlattr.c b/lib/nlattr.c
index fb52435..c8aad7e 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c@@ -27,6 +27,20 @@ [NLA_S64] = sizeof(s64), }; +static int validate_nla_bitfield_32(const struct nlattr *nla, void *valid_data) +{ + const struct nla_bitfield_32 *nbf = nla_data(nla); + u32 *valid_flags_mask = valid_data; + + if (!valid_data) + return -EINVAL; + + if (nbf->nla_value & ~*valid_flags_mask) + return -EINVAL; + + return 0; +} + static int validate_nla(const struct nlattr *nla, int maxtype, const struct nla_policy *policy) {
@@ -46,6 +60,13 @@ static int validate_nla(const struct nlattr *nla, int maxtype, return -ERANGE; break; + case NLA_BITFIELD_32: + if (attrlen != sizeof(struct nla_bitfield_32)) + return -ERANGE; + + return validate_nla_bitfield_32(nla, pt->validation_data); + break; + case NLA_NUL_STRING: if (pt->len) minlen = min_t(int, attrlen, pt->len + 1);
--
1.9.1