On 8/8/2019 3:22 PM, Kees Cook wrote:
> On Wed, Aug 07, 2019 at 12:44:09PM -0700, Casey Schaufler wrote:
>> Add an entry /proc/.../attr/context which displays the full
>> process security "context" in compound format:'
>> lsm1\0value\0lsm2\0value\0...
>> This entry is not writable.
>>
>> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
>> ---
>> fs/proc/base.c | 1 +
>> security/security.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 46 insertions(+)
>>
>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>> index 7bf70e041315..79600df5f7a2 100644
>> --- a/fs/proc/base.c
>> +++ b/fs/proc/base.c
>> @@ -2619,6 +2619,7 @@ static const struct pid_entry attr_dir_stuff[] = {
>> ATTR(NULL, "keycreate", 0666),
>> ATTR(NULL, "sockcreate", 0666),
>> ATTR(NULL, "display", 0666),
>> + ATTR(NULL, "context", 0666),
>> #ifdef CONFIG_SECURITY_SMACK
>> DIR("smack", 0555,
>> proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
>> diff --git a/security/security.c b/security/security.c
>> index 0ea7ee27e331..e9f579483d12 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2046,6 +2046,14 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>> char **value)
>> {
>> struct security_hook_list *hp;
>> + char *final = NULL;
>> + char *cp;
>> + char *tp;
>> + int rc = 0;
>> + int finallen = 0;
>> + int llen;
>> + int clen;
>> + int tlen;
>> int display = lsm_task_display(current);
>> int slot = 0;
>>
>> @@ -2063,6 +2071,43 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>> return -ENOMEM;
>> }
>>
>> + if (!strcmp(name, "context")) {
>> + hlist_for_each_entry(hp, &security_hook_heads.getprocattr,
>> + list) {
>> + rc = hp->hook.getprocattr(p, "current", &cp);
>> + if (rc == -EINVAL || rc == -ENOPROTOOPT)
>> + continue;
>> + if (rc < 0) {
>> + kfree(final);
>> + return rc;
>> + }
>> + llen = strlen(hp->lsmid->lsm) + 1;
>> + clen = strlen(cp) + 1;
>> + tlen = llen + clen;
>> + if (final)
>> + tlen += finallen;
>> + tp = kzalloc(tlen, GFP_KERNEL);
>> + if (tp == NULL) {
>> + kfree(cp);
>> + kfree(final);
>> + return -ENOMEM;
>> + }
>> + if (final)
>> + memcpy(tp, final, finallen);
>> + memcpy(tp + finallen, hp->lsmid->lsm, llen);
>> + memcpy(tp + finallen + llen, cp, clen);
>> + kfree(cp);
>> + if (final)
>> + kfree(final);
>> + final = tp;
>> + finallen = tlen;
>> + }
>> + if (final == NULL)
>> + return -EINVAL;
>> + *value = final;
>> + return finallen;
>> + }
> Instead of a copy-paste here, please add a helper for use in both
> places...
I added an append_ctx() helper in the "full" series. I can pull it
back to here.
>
>> +
>> hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
>> if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
>> continue;
>> --
>> 2.20.1
>>
