On 12/24/19 6:59 PM, 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.
My takeaway from the earlier exchange with Simon on v12 was that we
should either define a new LSM hook for /proc/pid/attr/context that is
guaranteed to return a value in a consistent format with SO_PEERCONTEXT
or fix AppArmor to return consistent results from its existing
getprocattr hook (particularly with respect to the newline character).
Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
cc: linux-api@xxxxxxxxxxxxxxx
---
fs/proc/base.c | 1 +
security/security.c | 27 +++++++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 950c200cb9ad..d13c2cf50e4b 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2653,6 +2653,7 @@ 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 80539dfd0245..e94de64e114c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2099,6 +2099,10 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
char **value)
{
struct security_hook_list *hp;
+ char *final = NULL;
+ char *cp;
+ int rc = 0;
+ int finallen = 0;
int display = lsm_task_display(current);
int slot = 0;
@@ -2126,6 +2130,29 @@ 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;
+ }
+ rc = append_ctx(&final, &finallen, hp->lsmid->lsm,
+ cp, rc);
+ if (rc < 0) {
+ kfree(final);
+ return rc;
+ }
+ }
+ if (final == NULL)
+ return -EINVAL;
+ *value = final;
+ return finallen;
+ }
+
hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
continue;
