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Define range of GIDs for cached app data.

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To support upcoming disk usage calculation optimizations, this change
creates a new GID for each app that will be used to mark its cached
data.  We're allocating these unique GIDs so that we can use
quotactl() to track cached data on a per-app basis.

Test: builds, boots, tests pass
Bug: 27948817
Change-Id: Ic00c39ccedc23d5d43988029e9921679126f8f2d
This commit is contained in:
Jeff Sharkey 2016-12-13 14:03:19 -07:00
parent 2eaba9343f
commit 934bc86df3
2 changed files with 52 additions and 27 deletions
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63
libc/bionic/grp_pwd.cpp
View file

@ -205,10 +205,11 @@ static group* android_name_to_group(group_state_t* state, const char* name) {
}
// Translate a user/group name to the corresponding user/group id.
// all_a1234 -> 0 * AID_USER + AID_SHARED_GID_START + 1234 (group name only)
// u0_a1234 -> 0 * AID_USER + AID_APP + 1234
// u2_i1000 -> 2 * AID_USER + AID_ISOLATED_START + 1000
// u1_system -> 1 * AID_USER + android_ids['system']
// all_a1234 -> 0 * AID_USER_OFFSET + AID_SHARED_GID_START + 1234 (group name only)
// u0_a1234_cache -> 0 * AID_USER_OFFSET + AID_CACHE_GID_START + 1234 (group name only)
// u0_a1234 -> 0 * AID_USER_OFFSET + AID_APP_START + 1234
// u2_i1000 -> 2 * AID_USER_OFFSET + AID_ISOLATED_START + 1000
// u1_system -> 1 * AID_USER_OFFSET + android_ids['system']
// returns 0 and sets errno to ENOENT in case of error.
static id_t app_id_from_name(const char* name, bool is_group) {
char* end;
@ -242,7 +243,13 @@ static id_t app_id_from_name(const char* name, bool is_group) {
}
} else {
// end will point to \0 if the strtoul below succeeds.
appid = strtoul(end+2, &end, 10) + AID_APP;
appid = strtoul(end+2, &end, 10);
if (is_group && !strcmp(end, "_cache")) {
end += 6;
appid += AID_CACHE_GID_START;
} else {
appid += AID_APP_START;
}
}
} else if (end[1] == 'i' && isdigit(end[2])) {
// end will point to \0 if the strtoul below succeeds.
@ -271,20 +278,20 @@ static id_t app_id_from_name(const char* name, bool is_group) {
}
// Check that app id is within range.
if (appid >= AID_USER) {
if (appid >= AID_USER_OFFSET) {
errno = ENOENT;
return 0;
}
return (appid + userid*AID_USER);
return (appid + userid*AID_USER_OFFSET);
}
static void print_app_name_from_uid(const uid_t uid, char* buffer, const int bufferlen) {
const uid_t appid = uid % AID_USER;
const uid_t userid = uid / AID_USER;
const uid_t appid = uid % AID_USER_OFFSET;
const uid_t userid = uid / AID_USER_OFFSET;
if (appid >= AID_ISOLATED_START) {
snprintf(buffer, bufferlen, "u%u_i%u", userid, appid - AID_ISOLATED_START);
} else if (appid < AID_APP) {
} else if (appid < AID_APP_START) {
for (size_t n = 0; n < android_id_count; n++) {
if (android_ids[n].aid == appid) {
snprintf(buffer, bufferlen, "u%u_%s", userid, android_ids[n].name);
@ -292,18 +299,20 @@ static void print_app_name_from_uid(const uid_t uid, char* buffer, const int buf
}
}
} else {
snprintf(buffer, bufferlen, "u%u_a%u", userid, appid - AID_APP);
snprintf(buffer, bufferlen, "u%u_a%u", userid, appid - AID_APP_START);
}
}
static void print_app_name_from_gid(const gid_t gid, char* buffer, const int bufferlen) {
const uid_t appid = gid % AID_USER;
const uid_t userid = gid / AID_USER;
const uid_t appid = gid % AID_USER_OFFSET;
const uid_t userid = gid / AID_USER_OFFSET;
if (appid >= AID_ISOLATED_START) {
snprintf(buffer, bufferlen, "u%u_i%u", userid, appid - AID_ISOLATED_START);
} else if (userid == 0 && appid >= AID_SHARED_GID_START && appid <= AID_SHARED_GID_END) {
snprintf(buffer, bufferlen, "all_a%u", appid - AID_SHARED_GID_START);
} else if (appid < AID_APP) {
} else if (appid >= AID_CACHE_GID_START && appid <= AID_CACHE_GID_END) {
snprintf(buffer, bufferlen, "u%u_a%u_cache", userid, appid - AID_CACHE_GID_START);
} else if (appid < AID_APP_START) {
for (size_t n = 0; n < android_id_count; n++) {
if (android_ids[n].aid == appid) {
snprintf(buffer, bufferlen, "u%u_%s", userid, android_ids[n].name);
@ -311,7 +320,7 @@ static void print_app_name_from_gid(const gid_t gid, char* buffer, const int buf
}
}
} else {
snprintf(buffer, bufferlen, "u%u_a%u", userid, appid - AID_APP);
snprintf(buffer, bufferlen, "u%u_a%u", userid, appid - AID_APP_START);
}
}
@ -371,21 +380,21 @@ static group* oem_id_to_group(gid_t gid, group_state_t* state) {
}
// Translate a uid into the corresponding name.
// 0 to AID_APP-1 -> "system", "radio", etc.
// AID_APP to AID_ISOLATED_START-1 -> u0_a1234
// AID_ISOLATED_START to AID_USER-1 -> u0_i1234
// AID_USER+ -> u1_radio, u1_a1234, u2_i1234, etc.
// 0 to AID_APP_START-1 -> "system", "radio", etc.
// AID_APP_START to AID_ISOLATED_START-1 -> u0_a1234
// AID_ISOLATED_START to AID_USER_OFFSET-1 -> u0_i1234
// AID_USER_OFFSET+ -> u1_radio, u1_a1234, u2_i1234, etc.
// returns a passwd structure (sets errno to ENOENT on failure).
static passwd* app_id_to_passwd(uid_t uid, passwd_state_t* state) {
if (uid < AID_APP) {
if (uid < AID_APP_START) {
errno = ENOENT;
return NULL;
}
print_app_name_from_uid(uid, state->name_buffer_, sizeof(state->name_buffer_));
const uid_t appid = uid % AID_USER;
if (appid < AID_APP) {
const uid_t appid = uid % AID_USER_OFFSET;
if (appid < AID_APP_START) {
snprintf(state->dir_buffer_, sizeof(state->dir_buffer_), "/");
} else {
snprintf(state->dir_buffer_, sizeof(state->dir_buffer_), "/data");
@ -405,7 +414,7 @@ static passwd* app_id_to_passwd(uid_t uid, passwd_state_t* state) {
// Translate a gid into the corresponding app_<gid>
// group structure (sets errno to ENOENT on failure).
static group* app_id_to_group(gid_t gid, group_state_t* state) {
if (gid < AID_APP) {
if (gid < AID_APP_START) {
errno = ENOENT;
return NULL;
}
@ -513,10 +522,10 @@ passwd* getpwent() {
}
start = end;
end += AID_USER - AID_APP; // Do not expose higher users
end += AID_USER_OFFSET - AID_APP_START; // Do not expose higher users
if (state->getpwent_idx < end) {
return app_id_to_passwd(state->getpwent_idx++ - start + AID_APP, state);
return app_id_to_passwd(state->getpwent_idx++ - start + AID_APP_START, state);
}
// We are not reporting u1_a* and higher or we will be here forever
@ -641,11 +650,11 @@ group* getgrent() {
}
start = end;
end += AID_USER - AID_APP; // Do not expose higher groups
end += AID_USER_OFFSET - AID_APP_START; // Do not expose higher groups
if (state->getgrent_idx < end) {
init_group_state(state);
return app_id_to_group(state->getgrent_idx++ - start + AID_APP, state);
return app_id_to_group(state->getgrent_idx++ - start + AID_APP_START, state);
}
// We are not reporting u1_a* and higher or we will be here forever

16
tests/grp_pwd_test.cpp
View file

@ -339,6 +339,22 @@ TEST(getgrnam, app_id_u0_a9999) {
check_get_group("u0_a9999", 19999);
}
TEST(getgrnam, app_id_u0_a0_cache) {
check_get_group("u0_a0_cache", 20000);
}
TEST(getgrnam, app_id_u0_a1234_cache) {
check_get_group("u0_a1234_cache", 21234);
}
TEST(getgrnam, app_id_u0_a9999_cache) {
check_get_group("u0_a9999_cache", 29999);
}
TEST(getgrnam, app_id_u10_a1234_cache) {
check_get_group("u10_a1234_cache", 1021234);
}
// Test the difference between uid and shared gid.
TEST(getgrnam, app_id_all_a9999) {
check_get_group("all_a9999", 59999);