[PATCH v3 03/11] security: Replace memcpy() with __get_task_comm()

Yafang Shao
2024-06-21T02:31:10Z

Quoted from Linus [0]:

selinux never wanted a lock, and never wanted any kind of *consistent*
result, it just wanted a *stable* result.

Using __get_task_comm() to read the task comm ensures that the name is
always NUL-terminated, regardless of the source string. This approach also
facilitates future extensions to the task comm.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
LINK: https://lore.kernel.org/all/CAHk-=wivfrF0_zvf+oj6==Sh=-npJooP8chLPEfaFV0oNYTTBA@mail.gmail.com/ [0]
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
---
security/lsm_audit.c | 4 ++--
security/selinux/selinuxfs.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 849e832719e2..a922e4339dd5 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -207,7 +207,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);

audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
- audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
+ audit_log_untrustedstring(ab, __get_task_comm(comm, sizeof(comm), current));

switch (a->type) {
case LSM_AUDIT_DATA_NONE:
@@ -302,7 +302,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
char comm[sizeof(tsk->comm)];
audit_log_format(ab, " opid=%d ocomm=", pid);
audit_log_untrustedstring(ab,
- memcpy(comm, tsk->comm, sizeof(comm)));
+ __get_task_comm(comm, sizeof(comm), tsk));
}
}
break;
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index e172f182b65c..a8a2ec742576 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -708,7 +708,7 @@ static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf,
if (new_value) {
char comm[sizeof(current->comm)];

- memcpy(comm, current->comm, sizeof(comm));
+ __get_task_comm(comm, sizeof(comm), current);
pr_err("SELinux: %s (%d) set checkreqprot to 1. This is no longer supported.\n",
comm, current->pid);
}
--
2.39.1