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dscpPolicy: lock down bpf cache map

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(since this map relies on percpu access semantics,
 and we don't even have userspace helpers to access PERCPU_ maps)

This will also be used by the upcoming satellite egress limiting logic.
See aosp/3235142

With this change we see:
  $ adbz shell ls -lZ /sys/fs/bpf/net_shared/*_dscpPolicy_*
  -rw-rw---- 1 root system u:object_r:fs_bpf_net_shared:s0  0 2024-09-04 17:01 /sys/fs/bpf/net_shared/map_dscpPolicy_ipv4_dscp_policies_map
  -rw-rw---- 1 root system u:object_r:fs_bpf_net_shared:s0  0 2024-09-04 17:01 /sys/fs/bpf/net_shared/map_dscpPolicy_ipv6_dscp_policies_map
  ---------- 1 root root   u:object_r:fs_bpf_loader:s0      0 2024-09-04 17:01 /sys/fs/bpf/net_shared/map_dscpPolicy_socket_policy_cache_map
  -r--r----- 1 root system u:object_r:fs_bpf_net_shared:s0  0 2024-09-04 17:01 /sys/fs/bpf/net_shared/prog_dscpPolicy_schedcls_set_dscp_ether

Test: TreeHugger, atest CtsNetTestCases:android.net.cts.DscpPolicyTest
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I50a12ca4cd5587342f8aaf9df8cb28917f555252
This commit is contained in:
Maciej Żenczykowski 2024-09-04 16:44:04 -07:00
commit 1ec8d7df58
3 changed files with 18 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

16
bpf/headers/include/bpf_helpers.h
View file

@ -349,11 +349,17 @@ static void (*bpf_ringbuf_submit_unsafe)(const void* data, __u64 flags) = (void*
#error "Bpf Map UID must be left at default of AID_ROOT for BpfLoader prior to v0.28"
#endif
#define DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md) \
DEFINE_BPF_MAP_EXT(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md, \
DEFAULT_BPF_MAP_SELINUX_CONTEXT, DEFAULT_BPF_MAP_PIN_SUBDIR, PRIVATE, \
BPFLOADER_MIN_VER, BPFLOADER_MAX_VER, LOAD_ON_ENG, \
LOAD_ON_USER, LOAD_ON_USERDEBUG)
// for maps not meant to be accessed from userspace
#define DEFINE_BPF_MAP_KERNEL_INTERNAL(the_map, TYPE, KeyType, ValueType, num_entries) \
DEFINE_BPF_MAP_EXT(the_map, TYPE, KeyType, ValueType, num_entries, AID_ROOT, AID_ROOT, \
0000, "fs_bpf_loader", "", PRIVATE, BPFLOADER_MIN_VER, BPFLOADER_MAX_VER, \
LOAD_ON_ENG, LOAD_ON_USER, LOAD_ON_USERDEBUG)
#define DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md) \
DEFINE_BPF_MAP_EXT(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md, \
DEFAULT_BPF_MAP_SELINUX_CONTEXT, DEFAULT_BPF_MAP_PIN_SUBDIR, \
PRIVATE, BPFLOADER_MIN_VER, BPFLOADER_MAX_VER, \
LOAD_ON_ENG, LOAD_ON_USER, LOAD_ON_USERDEBUG)
#define DEFINE_BPF_MAP(the_map, TYPE, KeyType, ValueType, num_entries) \
DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, \

5
bpf/loader/NetBpfLoad.cpp
View file

@ -97,6 +97,8 @@ enum class domain : int {
net_shared, // (T+) fs_bpf_net_shared /sys/fs/bpf/net_shared
netd_readonly, // (T+) fs_bpf_netd_readonly /sys/fs/bpf/netd_readonly
netd_shared, // (T+) fs_bpf_netd_shared /sys/fs/bpf/netd_shared
loader, // (U+) fs_bpf_loader /sys/fs/bpf/loader
// on T due to lack of sepolicy/genfscon rules it behaves simply as 'fs_bpf'
};
static constexpr domain AllDomains[] = {
@ -106,6 +108,7 @@ static constexpr domain AllDomains[] = {
domain::net_shared,
domain::netd_readonly,
domain::netd_shared,
domain::loader,
};
static constexpr bool specified(domain d) {
@ -151,6 +154,7 @@ constexpr const char* lookupSelinuxContext(const domain d) {
case domain::net_shared: return "fs_bpf_net_shared";
case domain::netd_readonly: return "fs_bpf_netd_readonly";
case domain::netd_shared: return "fs_bpf_netd_shared";
case domain::loader: return "fs_bpf_loader";
}
}
@ -174,6 +178,7 @@ constexpr const char* lookupPinSubdir(const domain d, const char* const unspecif
case domain::net_shared: return "net_shared/";
case domain::netd_readonly: return "netd_readonly/";
case domain::netd_shared: return "netd_shared/";
case domain::loader: return "loader/";
}
};

4
bpf/progs/dscpPolicy.c
View file

@ -25,8 +25,8 @@
// The cache is never read nor written by userspace and is indexed by socket cookie % CACHE_MAP_SIZE
#define CACHE_MAP_SIZE 32 // should be a power of two so we can % cheaply
DEFINE_BPF_MAP_GRO(socket_policy_cache_map, PERCPU_ARRAY, uint32_t, RuleEntry, CACHE_MAP_SIZE,
AID_SYSTEM)
DEFINE_BPF_MAP_KERNEL_INTERNAL(socket_policy_cache_map, PERCPU_ARRAY, uint32_t, RuleEntry,
CACHE_MAP_SIZE)
DEFINE_BPF_MAP_GRW(ipv4_dscp_policies_map, ARRAY, uint32_t, DscpPolicy, MAX_POLICIES, AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv6_dscp_policies_map, ARRAY, uint32_t, DscpPolicy, MAX_POLICIES, AID_SYSTEM)