diff options
| author | Cedric Le Goater <clg@fr.ibm.com> | 2006-10-02 11:19:00 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 16:57:25 +0200 |
| commit | 9ec52099e4b8678a60e9f93e41ad87885d64f3e6 (patch) | |
| tree | a68fe051b39f8f8e8be469cbd3c2f653b9b71a9d /kernel | |
| parent | [PATCH] introduce get_task_pid() to fix unsafe get_pid() (diff) | |
| download | linux-9ec52099e4b8678a60e9f93e41ad87885d64f3e6.tar.xz linux-9ec52099e4b8678a60e9f93e41ad87885d64f3e6.zip | |
[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 <clg@fr.ibm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sys.c | 6 | ||||
| -rw-r--r-- | kernel/sysctl.c | 30 |
2 files changed, 30 insertions, 6 deletions
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, |