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Refactor the parsing of seinfo am: 7fd89c00f7

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Original change: https://android-review.googlesource.com/c/platform/external/selinux/+/2836178

Change-Id: Ifa4dbb6ccaa95af13c388fb60736517b77b34475
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This commit is contained in:
Thiébaud Weksteen 2023-11-21 22:28:21 +00:00 committed by Automerger Merge Worker
commit 4bf49f0fb0
3 changed files with 188 additions and 97 deletions
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19
libselinux/src/android/android_internal.h
View file

@ -100,6 +100,25 @@ int set_range_from_level(context_t ctx, enum levelFrom levelFrom, uid_t userid,
/* Similar to seapp_context_reload, but does not implicitly load the default
* context files. It should only be used for unit tests. */
int seapp_context_reload_internal(const path_alts_t *context_paths);
#define SEINFO_BUFSIZ 256
/* A parsed seinfo */
struct parsed_seinfo {
char base[SEINFO_BUFSIZ];
#define IS_PRIV_APP (1 << 0)
#define IS_FROM_RUN_AS (1 << 1)
#define IS_EPHEMERAL_APP (1 << 2)
#define IS_ISOLATED_COMPUTE_APP (1 << 3)
#define IS_SDK_SANDBOX_AUDIT (1 << 4)
#define IS_SDK_SANDBOX_NEXT (1 << 5)
int32_t is;
bool isPreinstalledApp;
char partition[SEINFO_BUFSIZ];
int32_t targetSdkVersion;
};
/* Parses an seinfo string. Returns -1 if an error occurred. */
int parse_seinfo(const char* seinfo, struct parsed_seinfo* info);
#ifdef __cplusplus
}
#endif

204
libselinux/src/android/android_seapp.c
View file

@ -675,51 +675,15 @@ void selinux_android_seapp_context_init(void) {
*/
#define CAT_MAPPING_MAX_ID (0x1<<16)
#define PRIVILEGED_APP_STR ":privapp"
#define ISOLATED_COMPUTE_APP_STR ":isolatedComputeApp"
#define APPLY_SDK_SANDBOX_AUDIT_RESTRICTIONS_STR ":isSdkSandboxAudit"
#define APPLY_SDK_SANDBOX_NEXT_RESTRICTIONS_STR ":isSdkSandboxNext"
#define EPHEMERAL_APP_STR ":ephemeralapp"
#define TARGETSDKVERSION_STR ":targetSdkVersion="
#define PARTITION_STR ":partition="
#define FROM_RUNAS_STR ":fromRunAs"
static int32_t get_app_targetSdkVersion(const char *seinfo)
{
char *substr = strstr(seinfo, TARGETSDKVERSION_STR);
long targetSdkVersion;
char *endptr;
if (substr != NULL) {
substr = substr + strlen(TARGETSDKVERSION_STR);
if (substr != NULL) {
targetSdkVersion = strtol(substr, &endptr, 10);
if (('\0' != *endptr && ':' != *endptr)
|| (targetSdkVersion < 0) || (targetSdkVersion > INT32_MAX)) {
return -1; /* malformed targetSdkVersion value in seinfo */
} else {
return (int32_t) targetSdkVersion;
}
}
}
return 0; /* default to 0 when targetSdkVersion= is not present in seinfo */
}
// returns true if found, false if not found or error
static bool get_partition(const char *seinfo, char partition[], size_t size)
{
if (size == 0) return false;
const char *substr = strstr(seinfo, PARTITION_STR);
if (substr == NULL) return false;
const char *src = substr + strlen(PARTITION_STR);
const char *p = strchr(src, ':');
size_t len = p ? p - src : strlen(src);
if (len > size - 1) return -1;
strncpy(partition, src, len);
partition[len] = '\0';
return true;
}
#define PRIVILEGED_APP_STR "privapp"
#define ISOLATED_COMPUTE_APP_STR "isolatedComputeApp"
#define APPLY_SDK_SANDBOX_AUDIT_RESTRICTIONS_STR "isSdkSandboxAudit"
#define APPLY_SDK_SANDBOX_NEXT_RESTRICTIONS_STR "isSdkSandboxNext"
#define EPHEMERAL_APP_STR "ephemeralapp"
#define TARGETSDKVERSION_STR "targetSdkVersion"
#define PARTITION_STR "partition"
#define FROM_RUNAS_STR "fromRunAs"
#define COMPLETE_STR "complete"
static bool is_preinstalled_app_partition_valid(const char *app_policy, const char *app_partition) {
// We forbid system/system_ext/product installed apps from being labeled with vendor sepolicy.
@ -727,26 +691,6 @@ static bool is_preinstalled_app_partition_valid(const char *app_policy, const ch
return !(is_platform(app_partition) && !is_platform(app_policy));
}
static int seinfo_parse(char *dest, const char *src, size_t size)
{
size_t len;
char *p;
if ((p = strchr(src, ':')) != NULL)
len = p - src;
else
len = strlen(src);
if (len > size - 1)
return -1;
strncpy(dest, src, len);
dest[len] = '\0';
return 0;
}
/* Sets the categories of ctx based on the level request */
int set_range_from_level(context_t ctx, enum levelFrom levelFrom, uid_t userid, uid_t appid)
{
@ -781,6 +725,86 @@ int set_range_from_level(context_t ctx, enum levelFrom levelFrom, uid_t userid,
return 0;
}
int parse_seinfo(const char* seinfo, struct parsed_seinfo* info) {
char local_seinfo[SEINFO_BUFSIZ];
memset(info, 0, sizeof(*info));
if (strlen(seinfo) >= SEINFO_BUFSIZ) {
selinux_log(SELINUX_ERROR, "%s: seinfo is too large to be parsed: %zu\n",
__FUNCTION__, strlen(seinfo));
return -1;
}
strncpy(local_seinfo, seinfo, SEINFO_BUFSIZ);
char *token;
char *saved_colon_ptr = NULL;
char *saved_equal_ptr;
bool first = true;
for (token = strtok_r(local_seinfo, ":", &saved_colon_ptr); token; token = strtok_r(NULL, ":", &saved_colon_ptr)) {
if (first) {
strncpy(info->base, token, SEINFO_BUFSIZ);
first = false;
continue;
}
if (!strcmp(token, PRIVILEGED_APP_STR)) {
info->is |= IS_PRIV_APP;
continue;
}
if (!strcmp(token, EPHEMERAL_APP_STR)) {
info->is |= IS_EPHEMERAL_APP;
continue;
}
if (!strcmp(token, ISOLATED_COMPUTE_APP_STR)) {
info->is |= IS_ISOLATED_COMPUTE_APP;
continue;
}
if (!strcmp(token, APPLY_SDK_SANDBOX_AUDIT_RESTRICTIONS_STR)) {
info->is |= IS_SDK_SANDBOX_AUDIT;
continue;
}
if (!strcmp(token, APPLY_SDK_SANDBOX_NEXT_RESTRICTIONS_STR)) {
info->is |= IS_SDK_SANDBOX_NEXT;
continue;
}
if (!strcmp(token, FROM_RUNAS_STR)) {
info->is |= IS_FROM_RUN_AS;
continue;
}
if (!strncmp(token, TARGETSDKVERSION_STR, strlen(TARGETSDKVERSION_STR))) {
saved_equal_ptr = NULL;
char *subtoken = strtok_r(token, "=", &saved_equal_ptr);
subtoken = strtok_r(NULL, "=", &saved_equal_ptr);
if (!subtoken) {
selinux_log(SELINUX_ERROR, "%s: Invalid targetSdkVersion: %s in %s\n",
__FUNCTION__, token, seinfo);
return -1;
}
info->targetSdkVersion = strtol(subtoken, NULL, 10);
continue;
}
if (!strncmp(token, PARTITION_STR, strlen(PARTITION_STR))) {
saved_equal_ptr = NULL;
char *subtoken = strtok_r(token, "=", &saved_equal_ptr);
subtoken = strtok_r(NULL, "=", &saved_equal_ptr);
if (!subtoken) {
selinux_log(SELINUX_ERROR, "%s: Invalid partition: %s in %s\n",
__FUNCTION__, token, seinfo);
return -1;
}
info->isPreinstalledApp = true;
strncpy(info->partition, subtoken, strlen(subtoken));
continue;
}
if (!strcmp(token, COMPLETE_STR)) {
break;
}
selinux_log(SELINUX_WARNING, "%s: Ignoring unknown seinfo field: %s in %s\n",
__FUNCTION__, token, seinfo);
}
return 0;
}
/*
* This code is Android specific, bionic guarantees that
* calls to non-reentrant getpwuid() are thread safe.
@ -800,35 +824,21 @@ int seapp_context_lookup_internal(enum seapp_kind kind,
int i;
uid_t userid;
uid_t appid;
bool isPrivApp = false;
bool isEphemeralApp = false;
bool isIsolatedComputeApp = false;
bool isSdkSandboxAudit = false;
bool isSdkSandboxNext = false;
int32_t targetSdkVersion = 0;
bool fromRunAs = false;
bool isPreinstalledApp = false;
char partition[BUFSIZ];
char parsedseinfo[BUFSIZ];
struct parsed_seinfo info;
memset(&info, 0, sizeof(info));
if (seinfo) {
if (seinfo_parse(parsedseinfo, seinfo, BUFSIZ))
int ret = parse_seinfo(seinfo, &info);
if (ret) {
selinux_log(SELINUX_ERROR, "%s: Invalid seinfo: %s\n", __FUNCTION__, seinfo);
goto err;
isPrivApp = strstr(seinfo, PRIVILEGED_APP_STR) ? true : false;
isEphemeralApp = strstr(seinfo, EPHEMERAL_APP_STR) ? true : false;
isIsolatedComputeApp = strstr(seinfo, ISOLATED_COMPUTE_APP_STR) ? true : false;
isSdkSandboxAudit = strstr(seinfo, APPLY_SDK_SANDBOX_AUDIT_RESTRICTIONS_STR) ? true : false;
isSdkSandboxNext = strstr(seinfo, APPLY_SDK_SANDBOX_NEXT_RESTRICTIONS_STR) ? true : false;
fromRunAs = strstr(seinfo, FROM_RUNAS_STR) ? true : false;
targetSdkVersion = get_app_targetSdkVersion(seinfo);
isPreinstalledApp = get_partition(seinfo, partition, BUFSIZ);
if (targetSdkVersion < 0) {
}
if (info.targetSdkVersion < 0) {
selinux_log(SELINUX_ERROR,
"%s: Invalid targetSdkVersion passed for app with uid %d, seinfo %s, name %s\n",
__FUNCTION__, uid, seinfo, pkgname);
goto err;
}
seinfo = parsedseinfo;
}
userid = uid / AID_USER_OFFSET;
@ -858,7 +868,7 @@ int seapp_context_lookup_internal(enum seapp_kind kind,
if (cur->isSystemServer != isSystemServer)
continue;
if (cur->isEphemeralAppSet && cur->isEphemeralApp != isEphemeralApp)
if (cur->isEphemeralAppSet && cur->isEphemeralApp != ((info.is & IS_EPHEMERAL_APP) != 0))
continue;
if (cur->user.str) {
@ -872,7 +882,7 @@ int seapp_context_lookup_internal(enum seapp_kind kind,
}
if (cur->seinfo) {
if (!seinfo || strcasecmp(seinfo, cur->seinfo))
if (!seinfo || strcasecmp(info.base, cur->seinfo))
continue;
}
@ -889,22 +899,22 @@ int seapp_context_lookup_internal(enum seapp_kind kind,
}
}
if (cur->isPrivAppSet && cur->isPrivApp != isPrivApp)
if (cur->isPrivAppSet && cur->isPrivApp != ((info.is & IS_PRIV_APP) != 0))
continue;
if (cur->minTargetSdkVersion > targetSdkVersion)
if (cur->minTargetSdkVersion > info.targetSdkVersion)
continue;
if (cur->fromRunAs != fromRunAs)
if (cur->fromRunAs != ((info.is & IS_FROM_RUN_AS) != 0))
continue;
if (cur->isIsolatedComputeApp != isIsolatedComputeApp)
if (cur->isIsolatedComputeApp != ((info.is & IS_ISOLATED_COMPUTE_APP) != 0))
continue;
if (cur->isSdkSandboxAudit != isSdkSandboxAudit)
if (cur->isSdkSandboxAudit != ((info.is & IS_SDK_SANDBOX_AUDIT) != 0))
continue;
if (cur->isSdkSandboxNext != isSdkSandboxNext)
if (cur->isSdkSandboxNext != ((info.is & IS_SDK_SANDBOX_NEXT) != 0))
continue;
if (kind == SEAPP_TYPE && !cur->type)
@ -930,12 +940,12 @@ int seapp_context_lookup_internal(enum seapp_kind kind,
goto oom;
}
if (isPreinstalledApp
&& !is_preinstalled_app_partition_valid(cur->partition, partition)) {
if (info.isPreinstalledApp
&& !is_preinstalled_app_partition_valid(cur->partition, info.partition)) {
// TODO(b/280547417): make this an error after fixing violations
selinux_log(SELINUX_WARNING,
"%s: App %s preinstalled to %s can't be labeled with %s sepolicy",
__FUNCTION__, pkgname, partition, cur->partition);
__FUNCTION__, pkgname, info.partition, cur->partition);
}
break;

62
libselinux/src/android/android_unittest.cpp
View file

@ -110,3 +110,65 @@ TEST_F(AndroidSELinuxTest, LoadAndLookupSeAppContext)
EXPECT_STREQ(context_str(ctx), "u:r:app_data_file:s0:c512,c768");
context_free(ctx);
}
TEST(AndroidSeAppTest, ParseValidSeInfo)
{
struct parsed_seinfo info;
memset(&info, 0, sizeof(info));
string seinfo = "default:privapp:targetSdkVersion=10000:partition=system:complete";
int ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, 0);
EXPECT_STREQ(info.base, "default");
EXPECT_EQ(info.targetSdkVersion, 10000);
EXPECT_EQ(info.is, IS_PRIV_APP);
EXPECT_EQ(info.isPreinstalledApp, true);
EXPECT_STREQ(info.partition, "system");
seinfo = "platform:ephemeralapp:partition=system:complete";
ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, 0);
EXPECT_STREQ(info.base, "platform");
EXPECT_EQ(info.targetSdkVersion, 0);
EXPECT_EQ(info.is, IS_EPHEMERAL_APP);
EXPECT_EQ(info.isPreinstalledApp, true);
EXPECT_STREQ(info.partition, "system");
seinfo = "bluetooth";
ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, 0);
EXPECT_STREQ(info.base, "bluetooth");
EXPECT_EQ(info.targetSdkVersion, 0);
EXPECT_EQ(info.isPreinstalledApp, false);
EXPECT_EQ(info.is, 0);
}
TEST(AndroidSeAppTest, ParseInvalidSeInfo)
{
struct parsed_seinfo info;
string seinfo = "default:targetSdkVersion:complete";
int ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, -1);
seinfo = "default:targetSdkVersion=:complete";
ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, -1);
}
TEST(AndroidSeAppTest, ParseOverflow)
{
struct parsed_seinfo info;
string seinfo = std::string(255, 'x');
int ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, 0);
EXPECT_STREQ(info.base, seinfo.c_str());
seinfo = std::string(256, 'x');
ret = parse_seinfo(seinfo.c_str(), &info);
EXPECT_EQ(ret, -1);
}