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authorAndy Lutomirski <luto@kernel.org>2015-09-04 15:42:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-04 16:54:41 -0700
commit746bf6d64275be0c65b0631d8a72b16f1454cfa1 (patch)
tree5debc8e6f0207fdea53271f631f37e319d39fff4
parent32ae976ed3b5ba39c9208ace41bcdf4157d21db3 (diff)
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capabilities: add a securebit to disable PR_CAP_AMBIENT_RAISE
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. Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Andrew G. Morgan <morgan@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Cc: Kees Cook <keescook@chromium.org> Cc: Christoph Lameter <cl@linux.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Aaron Jones <aaronmdjones@gmail.com> Cc: Ted Ts'o <tytso@mit.edu> Cc: Andrew G. Morgan <morgan@kernel.org> Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Austin S Hemmelgarn <ahferroin7@gmail.com> Cc: Markku Savela <msa@moth.iki.fi> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: James Morris <james.l.morris@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/uapi/linux/securebits.h11
-rw-r--r--security/commoncap.c3
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();