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[PATCH] ipc: save the ipc namespace while reading proc files 

The problem we were assuming that current->nsproxy->ipc_ns would never
change while someone has our file in /proc/sysvipc/ file open.  Given that
this can change with both unshare and by passing the file descriptor to
another process that assumption is occasionally wrong.

Therefore this patch causes /proc/sysvipc/* to cache the namespace and
increment it's count when we open the file and to decrement the count when
we close the file, ensuring consistent operation with no surprises.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric W. Biederman 2007-02-12 00:52:10 -08:00 committed by Linus Torvalds
parent 79a81aef76
commit bc1fc6d88c
1 changed files with 45 additions and 13 deletions
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58
ipc/util.c
View File

@ -738,14 +738,20 @@ int ipc_parse_version (int *cmd)
#endif /* __ARCH_WANT_IPC_PARSE_VERSION */
#ifdef CONFIG_PROC_FS
struct ipc_proc_iter {
struct ipc_namespace *ns;
struct ipc_proc_iface *iface;
};
static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
{
struct ipc_proc_iface *iface = s->private;
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct kern_ipc_perm *ipc = it;
loff_t p;
struct ipc_ids *ids;
ids = current->nsproxy->ipc_ns->ids[iface->ids];
ids = iter->ns->ids[iface->ids];
/* If we had an ipc id locked before, unlock it */
if (ipc && ipc != SEQ_START_TOKEN)
@ -772,12 +778,13 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
*/
static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
{
struct ipc_proc_iface *iface = s->private;
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct kern_ipc_perm *ipc;
loff_t p;
struct ipc_ids *ids;
ids = current->nsproxy->ipc_ns->ids[iface->ids];
ids = iter->ns->ids[iface->ids];
/*
* Take the lock - this will be released by the corresponding
@ -806,21 +813,23 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
static void sysvipc_proc_stop(struct seq_file *s, void *it)
{
struct kern_ipc_perm *ipc = it;
struct ipc_proc_iface *iface = s->private;
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct ipc_ids *ids;
/* If we had a locked segment, release it */
if (ipc && ipc != SEQ_START_TOKEN)
ipc_unlock(ipc);
ids = current->nsproxy->ipc_ns->ids[iface->ids];
ids = iter->ns->ids[iface->ids];
/* Release the lock we took in start() */
mutex_unlock(&ids->mutex);
}
static int sysvipc_proc_show(struct seq_file *s, void *it)
{
struct ipc_proc_iface *iface = s->private;
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
if (it == SEQ_START_TOKEN)
return seq_puts(s, iface->header);
@ -835,22 +844,45 @@ static struct seq_operations sysvipc_proc_seqops = {
.show = sysvipc_proc_show,
};
static int sysvipc_proc_open(struct inode *inode, struct file *file) {
static int sysvipc_proc_open(struct inode *inode, struct file *file)
{
int ret;
struct seq_file *seq;
struct ipc_proc_iter *iter;
ret = -ENOMEM;
iter = kmalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
goto out;
ret = seq_open(file, &sysvipc_proc_seqops);
if (!ret) {
seq = file->private_data;
seq->private = PDE(inode)->data;
}
if (ret)
goto out_kfree;
seq = file->private_data;
seq->private = iter;
iter->iface = PDE(inode)->data;
iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
out:
return ret;
out_kfree:
kfree(iter);
goto out;
}
static int sysvipc_proc_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
struct ipc_proc_iter *iter = seq->private;
put_ipc_ns(iter->ns);
return seq_release_private(inode, file);
}
static struct file_operations sysvipc_proc_fops = {
.open = sysvipc_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
.release = sysvipc_proc_release,
};
#endif /* CONFIG_PROC_FS */