From 6f8540b7442e0fd7c5c02059f6328f55b0f7d36a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bram=20Bonn=C3=A9?= Date: Fri, 30 Apr 2021 11:50:19 +0200 Subject: [PATCH] ANDROID: selinux: modify RTM_GETNEIGH{TBL} MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Map the permission gating RTM_GETNEIGH/RTM_GETNEIGHTBL messages to a new permission so that it can be distinguished from the other netlink route permissions in selinux policy. The new permission is triggered by a flag set in system images T and up. This change is intended to be backported to all kernels that a T system image can run on top of. Bug: 171572148 Test: atest NetworkInterfaceTest Test: atest CtsSelinuxTargetSdkCurrentTestCases Test: atest bionic-unit-tests-static Test: On Cuttlefish, run combinations of: - Policy bit set or omitted (see https://r.android.com/1701847) - This patch applied or omitted - App having nlmsg_readneigh permission or not Verify that only the combination of this patch + the policy bit being set + the app not having the nlmsg_readneigh permission prevents the app from sending RTM_GETNEIGH messages. Change-Id: I4bcfce4decb34ea9388eeedfc4be67403de8a980 Signed-off-by: Bram Bonné (cherry picked from commit fac07550bdac9adea0dbe3edbdbec7a9a690a178) --- security/selinux/include/classmap.h | 3 ++- security/selinux/include/security.h | 9 +++++++++ security/selinux/nlmsgtab.c | 24 ++++++++++++++++++++---- security/selinux/ss/policydb.c | 4 ++++ security/selinux/ss/policydb.h | 2 ++ security/selinux/ss/services.c | 1 + 6 files changed, 38 insertions(+), 5 deletions(-) diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 562bd1802c99..896ccad73ee8 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -116,7 +116,8 @@ struct security_class_mapping secclass_map[] = { { COMMON_IPC_PERMS, NULL } }, { "netlink_route_socket", { COMMON_SOCK_PERMS, - "nlmsg_read", "nlmsg_write", "nlmsg_readpriv", NULL } }, + "nlmsg_read", "nlmsg_write", "nlmsg_readpriv", "nlmsg_getneigh", + NULL } }, { "netlink_tcpdiag_socket", { COMMON_SOCK_PERMS, "nlmsg_read", "nlmsg_write", NULL } }, diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h index 6d6068490466..6f5abff4109b 100644 --- a/security/selinux/include/security.h +++ b/security/selinux/include/security.h @@ -106,6 +106,8 @@ struct selinux_state { bool initialized; bool policycap[__POLICYDB_CAPABILITY_MAX]; bool android_netlink_route; + bool android_netlink_getneigh; + struct selinux_avc *avc; struct selinux_ss *ss; }; @@ -185,6 +187,13 @@ static inline bool selinux_android_nlroute_getlink(void) return state->android_netlink_route; } +static inline bool selinux_android_nlroute_getneigh(void) +{ + struct selinux_state *state = &selinux_state; + + return state->android_netlink_getneigh; +} + int security_mls_enabled(struct selinux_state *state); int security_load_policy(struct selinux_state *state, void *data, size_t len); diff --git a/security/selinux/nlmsgtab.c b/security/selinux/nlmsgtab.c index d1bec5a281db..328f5ffc30a9 100644 --- a/security/selinux/nlmsgtab.c +++ b/security/selinux/nlmsgtab.c @@ -207,12 +207,12 @@ int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm) return err; } -static void nlmsg_set_getlink_perm(u32 perm) +static void nlmsg_set_perm_for_type(u32 perm, u16 type) { int i; for (i = 0; i < ARRAY_SIZE(nlmsg_route_perms); i++) { - if (nlmsg_route_perms[i].nlmsg_type == RTM_GETLINK) { + if (nlmsg_route_perms[i].nlmsg_type == type) { nlmsg_route_perms[i].perm = perm; break; } @@ -222,11 +222,27 @@ static void nlmsg_set_getlink_perm(u32 perm) /** * Use nlmsg_readpriv as the permission for RTM_GETLINK messages if the * netlink_route_getlink policy capability is set. Otherwise use nlmsg_read. + * Similarly, use nlmsg_getneigh for RTM_GETNEIGH and RTM_GETNEIGHTBL if the + * netlink_route_getneigh policy capability is set. Otherwise use nlmsg_read. */ void selinux_nlmsg_init(void) { if (selinux_android_nlroute_getlink()) - nlmsg_set_getlink_perm(NETLINK_ROUTE_SOCKET__NLMSG_READPRIV); + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_READPRIV, + RTM_GETLINK); else - nlmsg_set_getlink_perm(NETLINK_ROUTE_SOCKET__NLMSG_READ); + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_READ, + RTM_GETLINK); + + if (selinux_android_nlroute_getneigh()) { + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_GETNEIGH, + RTM_GETNEIGH); + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_GETNEIGH, + RTM_GETNEIGHTBL); + } else { + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_READ, + RTM_GETNEIGH); + nlmsg_set_perm_for_type(NETLINK_ROUTE_SOCKET__NLMSG_READ, + RTM_GETNEIGHTBL); + } } diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index 99a207784ce9..b2393555d471 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -2353,6 +2353,10 @@ int policydb_read(struct policydb *p, void *fp) p->android_netlink_route = 1; } + if ((le32_to_cpu(buf[1]) & POLICYDB_CONFIG_ANDROID_NETLINK_GETNEIGH)) { + p->android_netlink_getneigh = 1; + } + if (p->policyvers >= POLICYDB_VERSION_POLCAP) { rc = ebitmap_read(&p->policycaps, fp); if (rc) diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h index 95fb3607f07c..eefacd40d491 100644 --- a/security/selinux/ss/policydb.h +++ b/security/selinux/ss/policydb.h @@ -235,6 +235,7 @@ struct genfs { struct policydb { int mls_enabled; int android_netlink_route; + int android_netlink_getneigh; /* symbol tables */ struct symtab symtab[SYM_NUM]; @@ -322,6 +323,7 @@ extern int policydb_write(struct policydb *p, void *fp); #define POLICYDB_CONFIG_MLS 1 #define POLICYDB_CONFIG_ANDROID_NETLINK_ROUTE (1 << 31) +#define POLICYDB_CONFIG_ANDROID_NETLINK_GETNEIGH (1 << 30) /* the config flags related to unknown classes/perms are bits 2 and 3 */ #define REJECT_UNKNOWN 0x00000002 diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 5199dd3f3db5..6559767d3444 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -2127,6 +2127,7 @@ static void security_load_policycaps(struct selinux_state *state) } state->android_netlink_route = p->android_netlink_route; + state->android_netlink_getneigh = p->android_netlink_getneigh; selinux_nlmsg_init(); }