From a5fcea2d2f790aa90b6e996d411ae2cf8db55186 Mon Sep 17 00:00:00 2001 From: Alex Henrie Date: Tue, 13 Feb 2024 23:26:31 -0700 Subject: [PATCH] net: ipv6/addrconf: introduce a regen_min_advance sysctl In RFC 8981, REGEN_ADVANCE cannot be less than 2 seconds, and the RFC does not permit the creation of temporary addresses with lifetimes shorter than that: > When processing a Router Advertisement with a > Prefix Information option carrying a prefix for the purposes of > address autoconfiguration (i.e., the A bit is set), the host MUST > perform the following steps: > 5. A temporary address is created only if this calculated preferred > lifetime is greater than REGEN_ADVANCE time units. However, some users want to change their IPv6 address as frequently as possible regardless of the RFC's arbitrary minimum lifetime. For the benefit of those users, add a regen_min_advance sysctl parameter that can be set to below or above 2 seconds. Link: https://datatracker.ietf.org/doc/html/rfc8981 Signed-off-by: Alex Henrie Reviewed-by: David Ahern Signed-off-by: Paolo Abeni --- Documentation/networking/ip-sysctl.rst | 10 ++++++++++ include/linux/ipv6.h | 1 + include/net/addrconf.h | 5 +++-- net/ipv6/addrconf.c | 11 ++++++++++- 4 files changed, 24 insertions(+), 3 deletions(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 4583059313453..407d917d1a367 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -2535,6 +2535,16 @@ max_desync_factor - INTEGER Default: 600 +regen_min_advance - INTEGER + How far in advance (in seconds), at minimum, to create a new temporary + address before the current one is deprecated. This value is added to + the amount of time that may be required for duplicate address detection + to determine when to create a new address. Linux permits setting this + value to less than the default of 2 seconds, but a value less than 2 + does not conform to RFC 8981. + + Default: 2 + regen_max_retry - INTEGER Number of attempts before give up attempting to generate valid temporary addresses. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index 5e605e384aac8..ef3aa060a289e 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -27,6 +27,7 @@ struct ipv6_devconf { __s32 use_tempaddr; __s32 temp_valid_lft; __s32 temp_prefered_lft; + __s32 regen_min_advance; __s32 regen_max_retry; __s32 max_desync_factor; __s32 max_addresses; diff --git a/include/net/addrconf.h b/include/net/addrconf.h index 61ebe723ee4d5..30d6f1e84e465 100644 --- a/include/net/addrconf.h +++ b/include/net/addrconf.h @@ -8,8 +8,9 @@ #define MIN_VALID_LIFETIME (2*3600) /* 2 hours */ -#define TEMP_VALID_LIFETIME (7*86400) -#define TEMP_PREFERRED_LIFETIME (86400) +#define TEMP_VALID_LIFETIME (7*86400) /* 1 week */ +#define TEMP_PREFERRED_LIFETIME (86400) /* 24 hours */ +#define REGEN_MIN_ADVANCE (2) /* 2 seconds */ #define REGEN_MAX_RETRY (3) #define MAX_DESYNC_FACTOR (600) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 65e886d7d80cc..283823fba96a8 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -195,6 +195,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { .use_tempaddr = 0, .temp_valid_lft = TEMP_VALID_LIFETIME, .temp_prefered_lft = TEMP_PREFERRED_LIFETIME, + .regen_min_advance = REGEN_MIN_ADVANCE, .regen_max_retry = REGEN_MAX_RETRY, .max_desync_factor = MAX_DESYNC_FACTOR, .max_addresses = IPV6_MAX_ADDRESSES, @@ -257,6 +258,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { .use_tempaddr = 0, .temp_valid_lft = TEMP_VALID_LIFETIME, .temp_prefered_lft = TEMP_PREFERRED_LIFETIME, + .regen_min_advance = REGEN_MIN_ADVANCE, .regen_max_retry = REGEN_MAX_RETRY, .max_desync_factor = MAX_DESYNC_FACTOR, .max_addresses = IPV6_MAX_ADDRESSES, @@ -1341,7 +1343,7 @@ out: static unsigned long ipv6_get_regen_advance(struct inet6_dev *idev) { - return 2 + idev->cnf.regen_max_retry * + return idev->cnf.regen_min_advance + idev->cnf.regen_max_retry * idev->cnf.dad_transmits * max(NEIGH_VAR(idev->nd_parms, RETRANS_TIME), HZ/100) / HZ; } @@ -6819,6 +6821,13 @@ static const struct ctl_table addrconf_sysctl[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "regen_min_advance", + .data = &ipv6_devconf.regen_min_advance, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { .procname = "regen_max_retry", .data = &ipv6_devconf.regen_max_retry, -- 2.30.2