From 2651225b5ebcdde60f684c4db8ec7e9e3800a74f Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Tue, 28 Feb 2017 10:35:56 -0500 Subject: selinux: wrap cgroup seclabel support with its own policy capability commit 1ea0ce40690dff38935538e8dab7b12683ded0d3 ("selinux: allow changing labels for cgroupfs") broke the Android init program, which looks up security contexts whenever creating directories and attempts to assign them via setfscreatecon(). When creating subdirectories in cgroup mounts, this would previously be ignored since cgroup did not support userspace setting of security contexts. However, after the commit, SELinux would attempt to honor the requested context on cgroup directories and fail due to permission denial. Avoid breaking existing userspace/policy by wrapping this change with a conditional on a new cgroup_seclabel policy capability. This preserves existing behavior until/unless a new policy explicitly enables this capability. Reported-by: John Stultz Signed-off-by: Stephen Smalley Signed-off-by: Paul Moore Signed-off-by: James Morris --- security/selinux/hooks.c | 7 ++++--- security/selinux/include/security.h | 2 ++ security/selinux/selinuxfs.c | 3 ++- security/selinux/ss/services.c | 4 ++++ 4 files changed, 12 insertions(+), 4 deletions(-) (limited to 'security/selinux') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 9a8f12f8d5b7..0a4b4b040e0a 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -480,12 +480,13 @@ static int selinux_is_sblabel_mnt(struct super_block *sb) sbsec->behavior == SECURITY_FS_USE_NATIVE || /* Special handling. Genfs but also in-core setxattr handler */ !strcmp(sb->s_type->name, "sysfs") || - !strcmp(sb->s_type->name, "cgroup") || - !strcmp(sb->s_type->name, "cgroup2") || !strcmp(sb->s_type->name, "pstore") || !strcmp(sb->s_type->name, "debugfs") || !strcmp(sb->s_type->name, "tracefs") || - !strcmp(sb->s_type->name, "rootfs"); + !strcmp(sb->s_type->name, "rootfs") || + (selinux_policycap_cgroupseclabel && + (!strcmp(sb->s_type->name, "cgroup") || + !strcmp(sb->s_type->name, "cgroup2"))); } static int sb_finish_set_opts(struct super_block *sb) diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index beaa14b8b6cf..f979c35e037e 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -71,6 +71,7 @@ enum { POLICYDB_CAPABILITY_OPENPERM, POLICYDB_CAPABILITY_EXTSOCKCLASS, POLICYDB_CAPABILITY_ALWAYSNETWORK, + POLICYDB_CAPABILITY_CGROUPSECLABEL, __POLICYDB_CAPABILITY_MAX }; #define POLICYDB_CAPABILITY_MAX (__POLICYDB_CAPABILITY_MAX - 1) @@ -79,6 +80,7 @@ extern int selinux_policycap_netpeer; extern int selinux_policycap_openperm; extern int selinux_policycap_extsockclass; extern int selinux_policycap_alwaysnetwork; +extern int selinux_policycap_cgroupseclabel; /* * type_datum properties diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c index c9e8a9898ce4..cb3fd98fb05a 100644 --- a/security/selinux/selinuxfs.c +++ b/security/selinux/selinuxfs.c @@ -46,7 +46,8 @@ static char *policycap_names[] = { "network_peer_controls", "open_perms", "extended_socket_class", - "always_check_network" + "always_check_network", + "cgroup_seclabel" }; unsigned int selinux_checkreqprot = CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE; diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index a70fcee9824b..b4aa491a0a23 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -74,6 +74,7 @@ int selinux_policycap_netpeer; int selinux_policycap_openperm; int selinux_policycap_extsockclass; int selinux_policycap_alwaysnetwork; +int selinux_policycap_cgroupseclabel; static DEFINE_RWLOCK(policy_rwlock); @@ -1993,6 +1994,9 @@ static void security_load_policycaps(void) POLICYDB_CAPABILITY_EXTSOCKCLASS); selinux_policycap_alwaysnetwork = ebitmap_get_bit(&policydb.policycaps, POLICYDB_CAPABILITY_ALWAYSNETWORK); + selinux_policycap_cgroupseclabel = + ebitmap_get_bit(&policydb.policycaps, + POLICYDB_CAPABILITY_CGROUPSECLABEL); } static int security_preserve_bools(struct policydb *p); -- cgit v1.2.3-59-g8ed1b