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ANDROID: selinux: modify RTM_GETLINK permission

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Map the permission gating RTM_GETLINK messages to a new permission so
that it can be distinguished from the other netlink route permissions
in selinux policy.

This is a temporary Android-only patch that will be deprecated in
newer kernels once the long-term solution lands as discusssed on the
mailing list [1]. The maintainer's recommended solution is more
general, much more complex, and likely not suitable for backporting.
This patch provides the minimal change needed for Android including
the userspace settable trigger which ensures that the permission
change is only applied to the newest version of Android which
contains the changes needed for userpace compatibility.

[1]: https://lore.kernel.org/selinux/20200116142653.61738-1-jeffv@google.com/

Bug: 141455849
Bug: 148218425

Test: CtsSelinuxTargetSdkCurrentTestCases
Test: atest bionic-unit-tests-static
Test: atest NetworkInterfaceTest
Test: Connect to Wi-Fi network
Test: Set up hotspot
Test: Cast from device
Test: Pair Bluetooth device
Test: Call getifaddrs() directly from within an app.
Test: Call NetworkInterface#getNetworkInterfaces() from within an app.

Change-Id: I7b44ce60ad98f858c412722d41b9842f8577151f
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Git-repo: https://android.googlesource.com/kernel/common
Git-commit: ba835f8db4a3005e34542a3af7f19fce30ade6fd
Signed-off-by: Alam Md Danish <amddan@codeaurora.org>
This commit is contained in:
Jeff Vander Stoep
2020-01-22 11:19:58 +01:00
committed by amddan
parent dcc90d4ab5
commit d2cccade36
6 changed files with 44 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
security/selinux/include/classmap.h
View File

@@ -115,7 +115,7 @@ struct security_class_mapping secclass_map[] = {
{ COMMON_IPC_PERMS, NULL } },
{ "netlink_route_socket",
{ COMMON_SOCK_PERMS,
"nlmsg_read", "nlmsg_write", NULL } },
"nlmsg_read", "nlmsg_write", "nlmsg_readpriv", NULL } },
{ "netlink_tcpdiag_socket",
{ COMMON_SOCK_PERMS,
"nlmsg_read", "nlmsg_write", NULL } },

9
security/selinux/include/security.h
View File

@@ -103,6 +103,7 @@ struct selinux_state {
bool checkreqprot;
bool initialized;
bool policycap[__POLICYDB_CAPABILITY_MAX];
bool android_netlink_route;
struct selinux_avc *avc;
struct selinux_ss *ss;
};
@@ -175,6 +176,13 @@ static inline bool selinux_policycap_nnp_nosuid_transition(void)
return state->policycap[POLICYDB_CAPABILITY_NNP_NOSUID_TRANSITION];
}
static inline bool selinux_android_nlroute_getlink(void)
{
struct selinux_state *state = &selinux_state;
return state->android_netlink_route;
}
int security_mls_enabled(struct selinux_state *state);
int security_load_policy(struct selinux_state *state,
void *data, size_t len);
@@ -390,5 +398,6 @@ extern void avtab_cache_init(void);
extern void ebitmap_cache_init(void);
extern void hashtab_cache_init(void);
extern int security_sidtab_hash_stats(struct selinux_state *state, char *page);
extern void selinux_nlmsg_init(void);
#endif /* _SELINUX_SECURITY_H_ */

26
security/selinux/nlmsgtab.c
View File

@@ -28,7 +28,7 @@ struct nlmsg_perm {
u32 perm;
};
static const struct nlmsg_perm nlmsg_route_perms[] =
static struct nlmsg_perm nlmsg_route_perms[] =
{
{ RTM_NEWLINK, NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
{ RTM_DELLINK, NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
@@ -206,3 +206,27 @@ int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm)
return err;
}
static void nlmsg_set_getlink_perm(u32 perm)
{
int i;
for (i = 0; i < ARRAY_SIZE(nlmsg_route_perms); i++) {
if (nlmsg_route_perms[i].nlmsg_type == RTM_GETLINK) {
nlmsg_route_perms[i].perm = perm;
break;
}
}
}
/**
* Use nlmsg_readpriv as the permission for RTM_GETLINK messages if the
* netlink_route_getlink 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);
else
nlmsg_set_getlink_perm(NETLINK_ROUTE_SOCKET__NLMSG_READ);
}

4
security/selinux/ss/policydb.c
View File

@@ -2400,6 +2400,10 @@ int policydb_read(struct policydb *p, void *fp)
p->reject_unknown = !!(le32_to_cpu(buf[1]) & REJECT_UNKNOWN);
p->allow_unknown = !!(le32_to_cpu(buf[1]) & ALLOW_UNKNOWN);
if ((le32_to_cpu(buf[1]) & POLICYDB_CONFIG_ANDROID_NETLINK_ROUTE)) {
p->android_netlink_route = 1;
}
if (p->policyvers >= POLICYDB_VERSION_POLCAP) {
rc = ebitmap_read(&p->policycaps, fp);
if (rc)

2
security/selinux/ss/policydb.h
View File

@@ -238,6 +238,7 @@ struct genfs {
/* The policy database */
struct policydb {
int mls_enabled;
int android_netlink_route;
/* symbol tables */
struct symtab symtab[SYM_NUM];
@@ -324,6 +325,7 @@ extern int policydb_write(struct policydb *p, void *fp);
#define PERM_SYMTAB_SIZE 32
#define POLICYDB_CONFIG_MLS 1
#define POLICYDB_CONFIG_ANDROID_NETLINK_ROUTE (1 << 31)
/* the config flags related to unknown classes/perms are bits 2 and 3 */
#define REJECT_UNKNOWN 0x00000002

3
security/selinux/ss/services.c
View File

@@ -2107,6 +2107,9 @@ static void security_load_policycaps(struct selinux_state *state)
pr_info("SELinux: unknown policy capability %u\n",
i);
}
state->android_netlink_route = p->android_netlink_route;
selinux_nlmsg_init();
}
static int security_preserve_bools(struct selinux_state *state,