From 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 Mon Sep 17 00:00:00 2001 From: Cedric Le Goater Date: Mon, 2 Oct 2006 02:19:00 -0700 Subject: [PATCH] replace cad_pid by a struct pid There are a few places in the kernel where the init task is signaled. The ctrl+alt+del sequence is one them. It kills a task, usually init, using a cached pid (cad_pid). This patch replaces the pid_t by a struct pid to avoid pid wrap around problem. The struct pid is initialized at boot time in init() and can be modified through systctl with /proc/sys/kernel/cad_pid [ I haven't found any distro using it ? ] It also introduces a small helper routine kill_cad_pid() which is used where it seemed ok to use cad_pid instead of pid 1. [akpm@osdl.org: cleanups, build fix] Signed-off-by: Cedric Le Goater Cc: Eric W. Biederman Cc: Martin Schwidefsky Cc: Paul Mackerras Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/mips/sgi-ip22/ip22-reset.c | 3 ++- arch/mips/sgi-ip32/ip32-reset.c | 2 +- arch/powerpc/platforms/iseries/mf.c | 2 +- drivers/char/nwbutton.c | 5 ++--- drivers/char/snsc_event.c | 2 +- drivers/parisc/power.c | 3 +-- drivers/s390/s390mach.c | 2 +- include/linux/sched.h | 7 +++++++ init/main.c | 2 ++ kernel/sys.c | 6 +++--- kernel/sysctl.c | 30 +++++++++++++++++++++++++++--- 11 files changed, 48 insertions(+), 16 deletions(-) diff --git a/arch/mips/sgi-ip22/ip22-reset.c b/arch/mips/sgi-ip22/ip22-reset.c index 8134220ed600..7a941ecff3bb 100644 --- a/arch/mips/sgi-ip22/ip22-reset.c +++ b/arch/mips/sgi-ip22/ip22-reset.c @@ -123,7 +123,8 @@ static inline void power_button(void) if (machine_state & MACHINE_PANICED) return; - if ((machine_state & MACHINE_SHUTTING_DOWN) || kill_proc(1,SIGINT,1)) { + if ((machine_state & MACHINE_SHUTTING_DOWN) || + kill_cad_pid(SIGINT, 1)) { /* No init process or button pressed twice. */ sgi_machine_power_off(); } diff --git a/arch/mips/sgi-ip32/ip32-reset.c b/arch/mips/sgi-ip32/ip32-reset.c index 79ddb4605659..fd0932b2d521 100644 --- a/arch/mips/sgi-ip32/ip32-reset.c +++ b/arch/mips/sgi-ip32/ip32-reset.c @@ -120,7 +120,7 @@ static inline void ip32_power_button(void) if (has_panicked) return; - if (shuting_down || kill_proc(1, SIGINT, 1)) { + if (shuting_down || kill_cad_pid(SIGINT, 1)) { /* No init process or button pressed twice. */ ip32_machine_power_off(); } diff --git a/arch/powerpc/platforms/iseries/mf.c b/arch/powerpc/platforms/iseries/mf.c index 1a2c2a50f922..1983b640bac1 100644 --- a/arch/powerpc/platforms/iseries/mf.c +++ b/arch/powerpc/platforms/iseries/mf.c @@ -357,7 +357,7 @@ static int dma_and_signal_ce_msg(char *ce_msg, */ static int shutdown(void) { - int rc = kill_proc(1, SIGINT, 1); + int rc = kill_cad_pid(SIGINT, 1); if (rc) { printk(KERN_ALERT "mf.c: SIGINT to init failed (%d), " diff --git a/drivers/char/nwbutton.c b/drivers/char/nwbutton.c index 7c57ebfa8640..ea1aa7764f8e 100644 --- a/drivers/char/nwbutton.c +++ b/drivers/char/nwbutton.c @@ -127,9 +127,8 @@ static void button_consume_callbacks (int bpcount) static void button_sequence_finished (unsigned long parameters) { #ifdef CONFIG_NWBUTTON_REBOOT /* Reboot using button is enabled */ - if (button_press_count == reboot_count) { - kill_proc (1, SIGINT, 1); /* Ask init to reboot us */ - } + if (button_press_count == reboot_count) + kill_cad_pid(SIGINT, 1); /* Ask init to reboot us */ #endif /* CONFIG_NWBUTTON_REBOOT */ button_consume_callbacks (button_press_count); bcount = sprintf (button_output_buffer, "%d\n", button_press_count); diff --git a/drivers/char/snsc_event.c b/drivers/char/snsc_event.c index d12d4f629cec..864854c58866 100644 --- a/drivers/char/snsc_event.c +++ b/drivers/char/snsc_event.c @@ -220,7 +220,7 @@ scdrv_dispatch_event(char *event, int len) " Sending SIGPWR to init...\n"); /* give a SIGPWR signal to init proc */ - kill_proc(1, SIGPWR, 0); + kill_cad_pid(SIGPWR, 0); } else { /* print to system log */ printk("%s|$(0x%x)%s\n", severity, esp_code, desc); diff --git a/drivers/parisc/power.c b/drivers/parisc/power.c index fad5a33bf0fa..4a9f025a6b58 100644 --- a/drivers/parisc/power.c +++ b/drivers/parisc/power.c @@ -84,8 +84,7 @@ static void deferred_poweroff(void *dummy) { - extern int cad_pid; /* from kernel/sys.c */ - if (kill_proc(cad_pid, SIGINT, 1)) { + if (kill_cad_pid(SIGINT, 1)) { /* just in case killing init process failed */ machine_power_off(); } diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c index 479364d0332a..e088b5e28711 100644 --- a/drivers/s390/s390mach.c +++ b/drivers/s390/s390mach.c @@ -208,7 +208,7 @@ s390_handle_mcck(void) */ __ctl_clear_bit(14, 24); /* Disable WARNING MCH */ if (xchg(&mchchk_wng_posted, 1) == 0) - kill_proc(1, SIGPWR, 1); + kill_cad_pid(SIGPWR, 1); } #endif diff --git a/include/linux/sched.h b/include/linux/sched.h index 9ba959e34266..38530232d92f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1065,6 +1065,8 @@ static inline int is_init(struct task_struct *tsk) return tsk->pid == 1; } +extern struct pid *cad_pid; + extern void free_task(struct task_struct *tsk); #define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0) @@ -1292,6 +1294,11 @@ extern int send_group_sigqueue(int, struct sigqueue *, struct task_struct *); extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *); extern int do_sigaltstack(const stack_t __user *, stack_t __user *, unsigned long); +static inline int kill_cad_pid(int sig, int priv) +{ + return kill_pid(cad_pid, sig, priv); +} + /* These can be the second arg to send_sig_info/send_group_sig_info. */ #define SEND_SIG_NOINFO ((struct siginfo *) 0) #define SEND_SIG_PRIV ((struct siginfo *) 1) diff --git a/init/main.c b/init/main.c index a49b00235bda..ee123243fb53 100644 --- a/init/main.c +++ b/init/main.c @@ -721,6 +721,8 @@ static int init(void * unused) */ child_reaper = current; + cad_pid = task_pid(current); + smp_prepare_cpus(max_cpus); do_pre_smp_initcalls(); diff --git a/kernel/sys.c b/kernel/sys.c index 3a4776e8f16e..2314867ae34f 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -92,7 +92,8 @@ EXPORT_SYMBOL(fs_overflowgid); */ int C_A_D = 1; -int cad_pid = 1; +struct pid *cad_pid; +EXPORT_SYMBOL(cad_pid); /* * Notifier list for kernel code which wants to be called @@ -773,10 +774,9 @@ void ctrl_alt_del(void) if (C_A_D) schedule_work(&cad_work); else - kill_proc(cad_pid, SIGINT, 1); + kill_cad_pid(SIGINT, 1); } - /* * Unprivileged users may change the real gid to the effective gid * or vice versa. (BSD-style) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index a79ccf9d113b..8020fb273c4f 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -68,7 +68,6 @@ extern int sysrq_enabled; extern int core_uses_pid; extern int suid_dumpable; extern char core_pattern[]; -extern int cad_pid; extern int pid_max; extern int min_free_kbytes; extern int printk_ratelimit_jiffies; @@ -137,6 +136,9 @@ static int parse_table(int __user *, int, void __user *, size_t __user *, static int proc_do_uts_string(ctl_table *table, int write, struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos); +static int proc_do_cad_pid(ctl_table *table, int write, struct file *filp, + void __user *buffer, size_t *lenp, loff_t *ppos); + static ctl_table root_table[]; static struct ctl_table_header root_table_header = { root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) }; @@ -543,10 +545,10 @@ static ctl_table kern_table[] = { { .ctl_name = KERN_CADPID, .procname = "cad_pid", - .data = &cad_pid, + .data = NULL, .maxlen = sizeof (int), .mode = 0600, - .proc_handler = &proc_dointvec, + .proc_handler = &proc_do_cad_pid, }, { .ctl_name = KERN_MAX_THREADS, @@ -2427,6 +2429,28 @@ proc_minmax: } #endif +static int proc_do_cad_pid(ctl_table *table, int write, struct file *filp, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + struct pid *new_pid; + pid_t tmp; + int r; + + tmp = pid_nr(cad_pid); + + r = __do_proc_dointvec(&tmp, table, write, filp, buffer, + lenp, ppos, NULL, NULL); + if (r || !write) + return r; + + new_pid = find_get_pid(tmp); + if (!new_pid) + return -ESRCH; + + put_pid(xchg(&cad_pid, new_pid)); + return 0; +} + #else /* CONFIG_PROC_FS */ int proc_dostring(ctl_table *table, int write, struct file *filp, -- cgit v1.2.3