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...
> +
> hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
> if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
> continue;
> --
> 2.20.1
>
--
Kees Cook
