[PATCH ghak90 V6 03/10] audit: read container ID of a process

Richard Guy Briggs
2019-04-09T03:39:10Z

Add support for reading the audit container identifier from the proc
filesystem.

This is a read from the proc entry of the form
/proc/PID/audit_containerid where PID is the process ID of the task
whose audit container identifier is sought.

The read expects up to a u64 value (unset: 18446744073709551615).

This read requires CAP_AUDIT_CONTROL.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
---
fs/proc/base.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 43fd0c4b87de..acc70239d0cb 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1211,7 +1211,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
};

#ifdef CONFIG_AUDIT
-#define TMPBUFLEN 11
+#define TMPBUFLEN 21
static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
{
@@ -1295,6 +1295,24 @@ static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
.llseek = generic_file_llseek,
};

+static ssize_t proc_contid_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];
+
+ if (!task)
+ return -ESRCH;
+ /* if we don't have caps, reject */
+ if (!capable(CAP_AUDIT_CONTROL))
+ return -EPERM;
+ length = scnprintf(tmpbuf, TMPBUFLEN, "%llu", audit_get_contid(task));
+ put_task_struct(task);
+ return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
+}
+
static ssize_t proc_contid_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
@@ -1325,6 +1343,7 @@ static ssize_t proc_contid_write(struct file *file, const char __user *buf,
}

static const struct file_operations proc_contid_operations = {
+ .read = proc_contid_read,
.write = proc_contid_write,
.llseek = generic_file_llseek,
};
@@ -3067,7 +3086,7 @@ static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
#ifdef CONFIG_AUDIT
REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
REG("sessionid", S_IRUGO, proc_sessionid_operations),
- REG("audit_containerid", S_IWUSR, proc_contid_operations),
+ REG("audit_containerid", S_IWUSR|S_IRUSR, proc_contid_operations),
#endif
#ifdef CONFIG_FAULT_INJECTION
REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
@@ -3466,7 +3485,7 @@ static int proc_tid_comm_permission(struct inode *inode, int mask)
#ifdef CONFIG_AUDIT
REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
REG("sessionid", S_IRUGO, proc_sessionid_operations),
- REG("audit_containerid", S_IWUSR, proc_contid_operations),
+ REG("audit_containerid", S_IWUSR|S_IRUSR, proc_contid_operations),
#endif
#ifdef CONFIG_FAULT_INJECTION
REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
--
1.8.3.1