diff options
| author | Carsten Emde <C.Emde@osadl.org> | 2011-07-19 12:51:17 (GMT) |
|---|---|---|
| committer | Emil Medve <Emilian.Medve@Freescale.com> | 2013-04-30 08:17:22 (GMT) |
| commit | 42b7a151bb6effb667a2f5d72b167bf38a88ce37 (patch) | |
| tree | a558c4d200a5719d60cc8c6dc94eac9e6dc80677 /net/ipv4 | |
| parent | 511239788448a25b2b79a1bccbab89c51775ade5 (diff) | |
| download | linux-fsl-qoriq-42b7a151bb6effb667a2f5d72b167bf38a88ce37.tar.xz | |
net: sysrq via icmp
There are (probably rare) situations when a system crashed and the system
console becomes unresponsive but the network icmp layer still is alive.
Wouldn't it be wonderful, if we then could submit a sysreq command via ping?
This patch provides this facility. Please consult the updated documentation
Documentation/sysrq.txt for details.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/icmp.c | 30 | ||||
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 7 |
2 files changed, 37 insertions, 0 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 3ac5dff..d8bbe94 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -69,6 +69,7 @@ #include <linux/jiffies.h> #include <linux/kernel.h> #include <linux/fcntl.h> +#include <linux/sysrq.h> #include <linux/socket.h> #include <linux/in.h> #include <linux/inet.h> @@ -768,6 +769,30 @@ static void icmp_redirect(struct sk_buff *skb) } /* + * 32bit and 64bit have different timestamp length, so we check for + * the cookie at offset 20 and verify it is repeated at offset 50 + */ +#define CO_POS0 20 +#define CO_POS1 50 +#define CO_SIZE sizeof(int) +#define ICMP_SYSRQ_SIZE 57 + +/* + * We got a ICMP_SYSRQ_SIZE sized ping request. Check for the cookie + * pattern and if it matches send the next byte as a trigger to sysrq. + */ +static void icmp_check_sysrq(struct net *net, struct sk_buff *skb) +{ + int cookie = htonl(net->ipv4.sysctl_icmp_echo_sysrq); + char *p = skb->data; + + if (!memcmp(&cookie, p + CO_POS0, CO_SIZE) && + !memcmp(&cookie, p + CO_POS1, CO_SIZE) && + p[CO_POS0 + CO_SIZE] == p[CO_POS1 + CO_SIZE]) + handle_sysrq(p[CO_POS0 + CO_SIZE]); +} + +/* * Handle ICMP_ECHO ("ping") requests. * * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo @@ -794,6 +819,11 @@ static void icmp_echo(struct sk_buff *skb) icmp_param.data_len = skb->len; icmp_param.head_len = sizeof(struct icmphdr); icmp_reply(&icmp_param, skb); + + if (skb->len == ICMP_SYSRQ_SIZE && + net->ipv4.sysctl_icmp_echo_sysrq) { + icmp_check_sysrq(net, skb); + } } } diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index d84400b..44bf3b0 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -815,6 +815,13 @@ static struct ctl_table ipv4_net_table[] = { .proc_handler = proc_dointvec }, { + .procname = "icmp_echo_sysrq", + .data = &init_net.ipv4.sysctl_icmp_echo_sysrq, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { .procname = "icmp_ignore_bogus_error_responses", .data = &init_net.ipv4.sysctl_icmp_ignore_bogus_error_responses, .maxlen = sizeof(int), |