Per Andrew Morgan's request, add a securebit to allow admins to disable PR_CAP_AMBIENT_RAISE. This securebit will prevent processes from adding capabilities to their ambient set. For simplicity, this disables PR_CAP_AMBIENT_RAISE entirely rather than just disabling setting previously cleared bits. Acked-By: Andrew G. Morgan <morgan@xxxxxxxxxx> Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Aaron Jones <aaronmdjones@xxxxxxxxx> CC: Ted Ts'o <tytso@xxxxxxx> Cc: linux-security-module@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: linux-api@xxxxxxxxxxxxxxx Cc: akpm@xxxxxxxxxxxxxxxxxxx Cc: Andrew G. Morgan <morgan@xxxxxxxxxx> Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> Cc: Austin S Hemmelgarn <ahferroin7@xxxxxxxxx> Cc: Markku Savela <msa@xxxxxxxxxxx> Cc: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> --- include/uapi/linux/securebits.h | 11 ++++++++++- security/commoncap.c | 3 ++- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/securebits.h b/include/uapi/linux/securebits.h index 985aac9e6bf8..35ac35cef217 100644 --- a/include/uapi/linux/securebits.h +++ b/include/uapi/linux/securebits.h @@ -43,9 +43,18 @@ #define SECBIT_KEEP_CAPS (issecure_mask(SECURE_KEEP_CAPS)) #define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED)) +/* When set, a process cannot add new capabilities to its ambient set. */ +#define SECURE_NO_CAP_AMBIENT_RAISE 6 +#define SECURE_NO_CAP_AMBIENT_RAISE_LOCKED 7 /* make bit-6 immutable */ + +#define SECBIT_NO_CAP_AMBIENT_RAISE (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE)) +#define SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED \ + (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED)) + #define SECURE_ALL_BITS (issecure_mask(SECURE_NOROOT) | \ issecure_mask(SECURE_NO_SETUID_FIXUP) | \ - issecure_mask(SECURE_KEEP_CAPS)) + issecure_mask(SECURE_KEEP_CAPS) | \ + issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE)) #define SECURE_ALL_LOCKS (SECURE_ALL_BITS << 1) #endif /* _UAPI_LINUX_SECUREBITS_H */ diff --git a/security/commoncap.c b/security/commoncap.c index 1f74dde1063e..1832cf701c3d 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -993,7 +993,8 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, if (arg2 == PR_CAP_AMBIENT_RAISE && (!cap_raised(current_cred()->cap_permitted, arg3) || !cap_raised(current_cred()->cap_inheritable, - arg3))) + arg3) || + issecure(SECURE_NO_CAP_AMBIENT_RAISE))) return -EPERM; new = prepare_creds(); -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
