On Thu, Mar 05, 2015 at 09:26:24AM -0600, Christoph Lameter wrote:
On Sun, 1 Mar 2015, Serge E. Hallyn wrote:
quoted
quoted
+++ linux/security/commoncap.c 2015-02-26 16:10:02.347913397 -0600
@@ -347,15 +347,17 @@ static inline int bprm_caps_from_vfs_cap
*has_cap = true;
CAP_FOR_EACH_U32(i) {
+ __u32 ambient = current_cred()->cap_ambient.cap[i];
__u32 permitted = caps->permitted.cap[i];
__u32 inheritable = caps->inheritable.cap[i];
/*
- * pP' = (X & fP) | (pI & fI)
+ * pP' = (X & fP) | (pI & (fI | pA))
*/
new->cap_permitted.cap[i] =
(new->cap_bset.cap[i] & permitted) |
- (new->cap_inheritable.cap[i] & inheritable);
+ (new->cap_inheritable.cap[i] &
+ (inheritable | ambient));
So I'd say drop this change ^
Then the ambient caps get ignored for a executables that have capabilities
seton the file?
Yes. Those are assumed to already know what they're doing.
I think we need to keep this one.
Why? Do you foresee cases where a file that has fP set needs capabilities
that aren't in its fP?
It seems more likely that they'll risk misbehaving due to an unexpected set
of caps.
If you have a good use case I'm not entirely opposed, but it just seems
unneeded and a potentially bad idea.
quoted hunk ↗ jump to hunk
quoted
quoted
@@ -453,8 +455,18 @@ static int get_file_caps(struct linux_bi
if (rc == -EINVAL)
printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
__func__, rc, bprm->filename);
- else if (rc == -ENODATA)
+ else if (rc == -ENODATA) {
rc = 0;
+ if (!cap_isclear(current_cred()->cap_ambient)) {
+ /*
+ * The ambient caps are permitted for
+ * files that have no caps
+ */
+ bprm->cred->cap_permitted =
+ current_cred()->cap_ambient;
and here set vcaps inheritable to current_cred()->ambient.
We do not call bprm_caps_from_vfs_cap() for files that have no caps so
this would have no effect. But we could set cap_inheritable here?
Fixup patch:
Subject: ambient_caps: Set inheritable bits too
We were not setting the inheritable bits as they ought to be set.
Signed-off-by: Christoph Lameter <redacted>
Index: linux/security/commoncap.c
===================================================================
--- linux.orig/security/commoncap.c 2015-03-05 09:22:32.123047869 -0600
+++ linux/security/commoncap.c 2015-03-05 09:22:32.119048001 -0600
@@ -461,6 +461,8 @@ static int get_file_caps(struct linux_bi
*/
bprm->cred->cap_permitted =
current_cred()->cap_ambient;
+ bprm->cred->cap_inheritable =
+ current_cred()->cap_ambient;
*effective = true;
}
}