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| author | Eric W. Biederman <ebiederm@xmission.com> | 2020-05-25 12:56:15 -0500 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-05-26 13:11:00 -0500 |
| commit | a4ae32c71fe90794127b32d26d7ad795813b502e (patch) | |
| tree | c4fafbc9f1123b48542ac6c22246928e6a15aed3 /security | |
| parent | 6a8b55ed4056ea5559ebe4f6a4b247f627870d4c (diff) | |
| download | linux-a4ae32c71fe90794127b32d26d7ad795813b502e.tar.bz2 | |
exec: Always set cap_ambient in cap_bprm_set_creds
An invariant of cap_bprm_set_creds is that every field in the new cred
structure that cap_bprm_set_creds might set, needs to be set every
time to ensure the fields does not get a stale value.
The field cap_ambient is not set every time cap_bprm_set_creds is
called, which means that if there is a suid or sgid script with an
interpreter that has neither the suid nor the sgid bits set the
interpreter should be able to accept ambient credentials.
Unfortuantely because cap_ambient is not reset to it's original value
the interpreter can not accept ambient credentials.
Given that the ambient capability set is expected to be controlled by
the caller, I don't think this is particularly serious. But it is
definitely worth fixing so the code works correctly.
I have tested to verify my reading of the code is correct and the
interpreter of a sgid can receive ambient capabilities with this
change and cannot receive ambient capabilities without this change.
Cc: stable@vger.kernel.org
Cc: Andy Lutomirski <luto@kernel.org>
Fixes: 58319057b784 ("capabilities: ambient capabilities")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'security')
| -rw-r--r-- | security/commoncap.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index f4ee0ae106b2..0ca31c8bc0b1 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -812,6 +812,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) int ret; kuid_t root_uid; + new->cap_ambient = old->cap_ambient; if (WARN_ON(!cap_ambient_invariant_ok(old))) return -EPERM; |