Re: [PATCH linux v2] net/ipv4: ping_group_range: allow GID from 2147483648 to 4294967294

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: ~akihirosuda <akihirosuda@git.sr.ht>
Date: Wed, 31 May 2023 19:42:49 +0900
> From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
> 
> With this commit, all the GIDs ("0 4294967294") can be written to the
> "net.ipv4.ping_group_range" sysctl.
> 
> Note that 4294967295 (0xffffffff) is an invalid GID (see gid_valid() in
> include/linux/uidgid.h), and an attempt to register this number will cause
> -EINVAL.
> 
> Prior to this commit, only up to GID 2147483647 could be covered.
> Documentation/networking/ip-sysctl.rst had "0 4294967295" as an example
> value, but this example was wrong and causing -EINVAL.
> 
> v1->v2: Simplified the patch (Thanks to Kuniyuki Iwashima for suggestion)

Changelog should be placed under '---'.

Also could you use 'net' instead of 'linux' in Subject so that
patchwork will be happy ?

https://patchwork.kernel.org/project/netdevbpf/patch/168557950756.14226.6470993129419598644-0@git.sr.ht/


> 
> Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind")
> Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
> ---
>  Documentation/networking/ip-sysctl.rst | 4 ++--
>  include/net/ping.h                     | 6 +-----
>  net/ipv4/sysctl_net_ipv4.c             | 8 ++++----
>  3 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index 6ec06a33688a..80b8f73a0244 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -1352,8 +1352,8 @@ ping_group_range - 2 INTEGERS
>  	Restrict ICMP_PROTO datagram sockets to users in the group range.
>  	The default is "1 0", meaning, that nobody (not even root) may
>  	create ping sockets.  Setting it to "100 100" would grant permissions
> -	to the single group. "0 4294967295" would enable it for the world, "100
> -	4294967295" would enable it for the users, but not daemons.
> +	to the single group. "0 4294967294" would enable it for the world, "100
> +	4294967294" would enable it for the users, but not daemons.
>  
>  tcp_early_demux - BOOLEAN
>  	Enable early demux for established TCP sockets.
> diff --git a/include/net/ping.h b/include/net/ping.h
> index 9233ad3de0ad..bc7779262e60 100644
> --- a/include/net/ping.h
> +++ b/include/net/ping.h
> @@ -16,11 +16,7 @@
>  #define PING_HTABLE_SIZE 	64
>  #define PING_HTABLE_MASK 	(PING_HTABLE_SIZE-1)
>  
> -/*
> - * gid_t is either uint or ushort.  We want to pass it to
> - * proc_dointvec_minmax(), so it must not be larger than MAX_INT
> - */
> -#define GID_T_MAX (((gid_t)~0U) >> 1)
> +#define GID_T_MAX (((gid_t)~0U) - 1)
>  
>  /* Compatibility glue so we can support IPv6 when it's compiled as a module */
>  struct pingv6_ops {
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index 40fe70fc2015..bb49d9407c45 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -34,8 +34,8 @@ static int ip_ttl_min = 1;
>  static int ip_ttl_max = 255;
>  static int tcp_syn_retries_min = 1;
>  static int tcp_syn_retries_max = MAX_TCP_SYNCNT;
> -static int ip_ping_group_range_min[] = { 0, 0 };
> -static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX };
> +static long ip_ping_group_range_min[] = { 0, 0 };
> +static long ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX };

nit: s/long/unsigned long/

Then, add

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Thanks!


>  static u32 u32_max_div_HZ = UINT_MAX / HZ;
>  static int one_day_secs = 24 * 3600;
>  static u32 fib_multipath_hash_fields_all_mask __maybe_unused =
> @@ -165,7 +165,7 @@ static int ipv4_ping_group_range(struct ctl_table *table, int write,
>  {
>  	struct user_namespace *user_ns = current_user_ns();
>  	int ret;
> -	gid_t urange[2];
> +	unsigned long urange[2];
>  	kgid_t low, high;
>  	struct ctl_table tmp = {
>  		.data = &urange,
> @@ -178,7 +178,7 @@ static int ipv4_ping_group_range(struct ctl_table *table, int write,
>  	inet_get_ping_group_range_table(table, &low, &high);
>  	urange[0] = from_kgid_munged(user_ns, low);
>  	urange[1] = from_kgid_munged(user_ns, high);
> -	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
> +	ret = proc_doulongvec_minmax(&tmp, write, buffer, lenp, ppos);
>  
>  	if (write && ret == 0) {
>  		low = make_kgid(user_ns, urange[0]);
> -- 
> 2.38.4