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

Richard Guy Briggs
2018-03-16T09:00:40Z

Add support for reading the container ID from the proc filesystem.

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),
--
1.8.3.1