Messages in this thread Patch in this message | | | From | Rocco Yue <> | Subject | [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode | Date | Thu, 1 Jul 2021 09:59:40 +0800 |
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This patch provides an ipv6 proc file named "disable_gen_linklocal_addr", its absolute path is as follows: "/proc/sys/net/ipv6/conf/<iface>/disable_gen_linklocal_addr".
When the "disable_gen_linklocal_addr" value of a device is 1, it means that this device does not need the Linux kernel to automatically generate the ipv6 link-local address no matter which IN6_ADDR_GEN_MODE is used.
The reasons why the kernel does not need to automatically generate the ipv6 link-local address are as follows:
(1) In the 3GPP TS 29.061, here is a description as follows: "in order to avoid any conflict between the link-local address of the MS and that of the GGSN, the Interface-Identifier used by the MS to build its link-local address shall be assigned by the GGSN. The GGSN ensures the uniqueness of this Interface- Identifier. The MT shall then enforce the use of this Interface-Identifier by the TE"
In other words, in the cellular network, GGSN determines whether to reply a solicited RA message by identifying the low 64 bits of the source address of the received RS message. Therefore, cellular network device's ipv6 link-local address should be set as the format of fe80::(GGSN assigned IID).
For example: When using a new kernel and ARPHRD_RAWIP, kernel will generate an EUI64 format ipv6 link-local address, and the Linux kernel will uses this link-local address to send RS message. The result is that the GGSN will not reply to the RS message with a solicited RA message.
Although the combination of IN6_ADDR_GEN_MODE_NONE + ARPHRD_NONE can avoid the above problem (1), when the addr_gen_mode is changed to the IN6_ADDR_GEN_MODE_STABLE_PRIVACY, the above problem still exist. The detail as follows:
(2) Among global mobile operators, some operators have already request MT (Mobile Terminal) to support RFC7217, such as AT&T. This means that the device not only needs the IID assigned by the GGSN to build the ipv6 link-local address to trigger the RS message, but also needs to use the stable privacy mode to build the ipv6 global address after receiving the RA.
Obviously using APRHRD_NONE and IN6_ADDR_GEN_MODE_STABLE_PRIVACY mode cannot achieve this.
In summary, using the "disable_gen_linklocal_addr" proc file can disable kernel auto generate ipv6 link-local address no matter which addr_gen_mode is used.
Signed-off-by: Rocco Yue <rocco.yue@mediatek.com> --- include/linux/ipv6.h | 1 + include/uapi/linux/ipv6.h | 1 + net/ipv6/addrconf.c | 16 ++++++++++++++++ 3 files changed, 18 insertions(+)
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 70b2ad3b9884..60c5da76e207 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -76,6 +76,7 @@ struct ipv6_devconf { __s32 disable_policy; __s32 ndisc_tclass; __s32 rpl_seg_enabled; + __s32 disable_gen_linklocal_addr; struct ctl_table_header *sysctl_header; }; diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h index 70603775fe91..0449d908b8c2 100644 --- a/include/uapi/linux/ipv6.h +++ b/include/uapi/linux/ipv6.h @@ -190,6 +190,7 @@ enum { DEVCONF_NDISC_TCLASS, DEVCONF_RPL_SEG_ENABLED, DEVCONF_RA_DEFRTR_METRIC, + DEVCONF_DISABLE_GEN_LINKLOCAL_ADDR, DEVCONF_MAX }; diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 701eb82acd1c..0035f935b25a 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -237,6 +237,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { .addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64, .disable_policy = 0, .rpl_seg_enabled = 0, + .disable_gen_linklocal_addr = 0, }; static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { @@ -293,6 +294,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { .addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64, .disable_policy = 0, .rpl_seg_enabled = 0, + .disable_gen_linklocal_addr = 0, }; /* Check if link is ready: is it up and is a valid qdisc available */ @@ -3352,6 +3354,12 @@ static void addrconf_dev_config(struct net_device *dev) if (IS_ERR(idev)) return; + if (idev->cnf.disable_gen_linklocal_addr) { + pr_info("%s: IPv6 link-local address being disabled\n", + idev->dev->name); + return; + } + /* this device type has no EUI support */ if (dev->type == ARPHRD_NONE && idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_EUI64) @@ -5526,6 +5534,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, array[DEVCONF_DISABLE_POLICY] = cnf->disable_policy; array[DEVCONF_NDISC_TCLASS] = cnf->ndisc_tclass; array[DEVCONF_RPL_SEG_ENABLED] = cnf->rpl_seg_enabled; + array[DEVCONF_DISABLE_GEN_LINKLOCAL_ADDR] = cnf->disable_gen_linklocal_addr; } static inline size_t inet6_ifla6_size(void) @@ -6932,6 +6941,13 @@ static const struct ctl_table addrconf_sysctl[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "disable_gen_linklocal_addr", + .data = &ipv6_devconf.disable_gen_linklocal_addr, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { /* sentinel */ } -- 2.18.0
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