Re: [RFC PATCH ghak32 V2 13/13] debug audit: read container ID of a process

Steve Grubb
2018-05-21T19:16:01Z

On Friday, March 16, 2018 5:00:40 AM EDT Richard Guy Briggs wrote:
> Add support for reading the container ID from the proc filesystem.

I think this could be useful in general. Please consider this to be part of
the full patch set and not something merely used to debug the patches.

-Steve

> This is a read from the proc entry of the form /proc/PID/containerid
> where PID is the process ID of the task whose container ID is sought.
>
> The read expects up to a u64 value (unset: 18446744073709551615).
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
> fs/proc/base.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 6ce4fbe..f66d1e2 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1300,6 +1300,21 @@ static ssize_t proc_sessionid_read(struct file *
> file, char __user * buf, .llseek = generic_file_llseek,
> };
>
> +static ssize_t proc_containerid_read(struct file *file, char __user *buf,
> + size_t count, loff_t *ppos)
> +{
> + struct inode *inode = file_inode(file);
> + struct task_struct *task = get_proc_task(inode);
> + ssize_t length;
> + char tmpbuf[TMPBUFLEN*2];
> +
> + if (!task)
> + return -ESRCH;
> + length = scnprintf(tmpbuf, TMPBUFLEN*2, "%llu",
> audit_get_containerid(task)); + put_task_struct(task);
> + return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
> +}
> +
> static ssize_t proc_containerid_write(struct file *file, const char __user
> *buf, size_t count, loff_t *ppos)
> {
> @@ -1330,6 +1345,7 @@ static ssize_t proc_containerid_write(struct file
> *file, const char __user *buf, }
>
> static const struct file_operations proc_containerid_operations = {
> + .read = proc_containerid_read,
> .write = proc_containerid_write,
> .llseek = generic_file_llseek,
> };
> @@ -2996,7 +3012,7 @@ static int proc_pid_patch_state(struct seq_file *m,
> struct pid_namespace *ns, #ifdef CONFIG_AUDITSYSCALL
> REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
> REG("sessionid", S_IRUGO, proc_sessionid_operations),
> - REG("containerid", S_IWUSR, proc_containerid_operations),
> + REG("containerid", S_IWUSR|S_IRUSR, proc_containerid_operations),
> #endif
> #ifdef CONFIG_FAULT_INJECTION
> REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
> @@ -3391,7 +3407,7 @@ static int proc_tid_comm_permission(struct inode
> *inode, int mask) #ifdef CONFIG_AUDITSYSCALL
> REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
> REG("sessionid", S_IRUGO, proc_sessionid_operations),
> - REG("containerid", S_IWUSR, proc_containerid_operations),
> + REG("containerid", S_IWUSR|S_IRUSR, proc_containerid_operations),
> #endif
> #ifdef CONFIG_FAULT_INJECTION
> REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),