Nathan Lynch <ntl@xxxxxxxxx> writes:
> Hi Eric,
>
> A few comments on your patch set.
>
>
> On Fri, 2011-05-06 at 19:24 -0700, Eric W. Biederman wrote:
>> diff --git a/fs/proc/inode.c b/fs/proc/inode.c
>> index d15aa1b..74b48cf 100644
>> --- a/fs/proc/inode.c
>> +++ b/fs/proc/inode.c
>> @@ -28,6 +28,7 @@ static void proc_evict_inode(struct inode *inode)
>> {
>> struct proc_dir_entry *de;
>> struct ctl_table_header *head;
>> + const struct proc_ns_operations *ns_ops;
>>
>> truncate_inode_pages(&inode->i_data, 0);
>> end_writeback(inode);
>> @@ -44,6 +45,10 @@ static void proc_evict_inode(struct inode *inode)
>> rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
>> sysctl_head_put(head);
>> }
>> + /* Release any associated namespace */
>> + ns_ops = PROC_I(inode)->ns_ops;
>> + if (ns_ops && ns_ops->put)
>> + ns_ops->put(PROC_I(inode)->ns);
>
> Is it ever valid for ns_ops->put to be null? If not, I suggest removing
> the check.
>
>
>> diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
>> new file mode 100644
>> index 0000000..6ae9f07
>> --- /dev/null
>> +++ b/fs/proc/namespaces.c
>
> ...
>
>> +static struct dentry *proc_ns_dir_lookup(struct inode *dir,
>> + struct dentry *dentry, struct nameidata *nd)
>> +{
>> + struct dentry *error;
>> + struct task_struct *task = get_proc_task(dir);
>> + const struct proc_ns_operations **entry, **last;
>> + unsigned int len = dentry->d_name.len;
>> +
>> + error = ERR_PTR(-ENOENT);
>> +
>> + if (!task)
>> + goto out_no_task;
>> +
>> + error = ERR_PTR(-EPERM);
>> + if (!ptrace_may_access(task, PTRACE_MODE_READ))
>> + goto out;
>> +
>> + last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
>> + for (entry = ns_entries; entry <= last; entry++) {
>> + if (strlen((*entry)->name) != len)
>> + continue;
>> + if (!memcmp(dentry->d_name.name, (*entry)->name, len))
>> + break;
>> + }
>> + if (entry > last)
>> + goto out;
>
> This returns EPERM when it should return ENOENT?
Good catch.
And fixed now.
>> union proc_op {
>> int (*proc_get_link)(struct inode *, struct path *);
>> int (*proc_read)(struct task_struct *task, char *page);
>> @@ -268,6 +284,8 @@ struct proc_inode {
>> struct proc_dir_entry *pde;
>> struct ctl_table_header *sysctl;
>> struct ctl_table *sysctl_entry;
>> + void *ns;
>> + const struct proc_ns_operations *ns_ops;
>> struct inode vfs_inode;
>> };
>
> Not that I have any better ideas, but it seems a bit undesirable to
> increase the size of proc_inode for this one purpose.
Of the options I could think of this was the cleanest, and proc_inode
is just a caching data structure which means that the effect should be
comparatively minimal.
That said I won't oppose a change at some point to reduce the
proc_inode, there are a lot of fields that are not used for most proc
entries.
Eric
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