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Deadlock fixes (#1758)
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Hi,

This PR fixes deadlocks that I've noticed within my kernel, with some
minor optimizations around it.

Thanks.

---------

Signed-off-by: Juhyung Park <[email protected]>
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@arter97
arter97 committed May 26, 2024
1 parent 0674841 commit 038dae1
Showing 1 changed file with 104 additions and 44 deletions.
148 changes: 104 additions & 44 deletions kernel/throne_tracker.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@
#include <linux/string.h>
#include <linux/types.h>
#include <linux/version.h>
#include <linux/workqueue.h>

#include "allowlist.h"
#include "klog.h" // IWYU pragma: keep
Expand All @@ -16,8 +15,7 @@

uid_t ksu_manager_uid = KSU_INVALID_UID;

#define SYSTEM_PACKAGES_LIST_PATH "/data/system/packages.list"
static struct work_struct ksu_update_uid_work;
#define SYSTEM_PACKAGES_LIST_PATH "/data/system/packages.list.tmp"

struct uid_data {
struct list_head list;
Expand Down Expand Up @@ -94,8 +92,25 @@ static void crown_manager(const char *apk, struct list_head *uid_data)
}
}

#define DATA_PATH_LEN 384 // 384 is enough for /data/app/<package>/base.apk

struct data_path {
char dirpath[DATA_PATH_LEN];
int depth;
struct list_head list;
};

struct apk_path_hash {
unsigned int hash;
bool exists;
struct list_head list;
};

static struct list_head apk_path_hash_list = LIST_HEAD_INIT(apk_path_hash_list);

struct my_dir_context {
struct dir_context ctx;
struct list_head *data_path_list;
char *parent_dir;
void *private_data;
int depth;
Expand All @@ -119,8 +134,7 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,
{
struct my_dir_context *my_ctx =
container_of(ctx, struct my_dir_context, ctx);
struct file *file;
char dirpath[384]; // 384 is enough for /data/app/<package>/base.apk
char dirpath[DATA_PATH_LEN];

if (!my_ctx) {
pr_err("Invalid context\n");
Expand All @@ -134,38 +148,54 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,
if (!strncmp(name, "..", namelen) || !strncmp(name, ".", namelen))
return FILLDIR_ACTOR_CONTINUE; // Skip "." and ".."

if (snprintf(dirpath, sizeof(dirpath), "%s/%.*s", my_ctx->parent_dir,
namelen, name) >= sizeof(dirpath)) {
if (snprintf(dirpath, DATA_PATH_LEN, "%s/%.*s", my_ctx->parent_dir,
namelen, name) >= DATA_PATH_LEN) {
pr_err("Path too long: %s/%.*s\n", my_ctx->parent_dir, namelen,
name);
return FILLDIR_ACTOR_CONTINUE;
}

if (d_type == DT_DIR && my_ctx->depth > 0 &&
(my_ctx->stop && !*my_ctx->stop)) {
struct my_dir_context sub_ctx = { .ctx.actor = my_actor,
.parent_dir = dirpath,
.private_data =
my_ctx->private_data,
.depth = my_ctx->depth - 1,
.stop = my_ctx->stop };
file = ksu_filp_open_compat(dirpath, O_RDONLY | O_NOFOLLOW, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s, err: %ld\n",
dirpath, PTR_ERR(file));
struct data_path *data = kmalloc(sizeof(struct data_path), GFP_ATOMIC);

if (!data) {
pr_err("Failed to allocate memory for %s\n", dirpath);
return FILLDIR_ACTOR_CONTINUE;
}

iterate_dir(file, &sub_ctx.ctx);
filp_close(file, NULL);
strscpy(data->dirpath, dirpath, DATA_PATH_LEN);
data->depth = my_ctx->depth - 1;
list_add_tail(&data->list, my_ctx->data_path_list);
} else {
if ((namelen == 8) && (strncmp(name, "base.apk", namelen) == 0)) {
struct apk_path_hash *pos, *n;
unsigned int hash = full_name_hash(NULL, dirpath, strlen(dirpath));

list_for_each_entry(pos, &apk_path_hash_list, list) {
if (hash == pos->hash) {
pos->exists = true;
return FILLDIR_ACTOR_CONTINUE;
}
}

bool is_manager = is_manager_apk(dirpath);
pr_info("Found base.apk at path: %s, is_manager: %d\n",
pr_info("Found new base.apk at path: %s, is_manager: %d\n",
dirpath, is_manager);
if (is_manager) {
crown_manager(dirpath, my_ctx->private_data);
*my_ctx->stop = 1;

// Manager found, clear APK cache list
list_for_each_entry_safe(pos, n, &apk_path_hash_list, list) {
list_del(&pos->list);
kfree(pos);
}
} else {
struct apk_path_hash *apk_data = kmalloc(sizeof(struct apk_path_hash), GFP_ATOMIC);
apk_data->hash = hash;
apk_data->exists = true;
list_add_tail(&apk_data->list, &apk_path_hash_list);
}
}
}
Expand All @@ -175,22 +205,58 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,

void search_manager(const char *path, int depth, struct list_head *uid_data)
{
struct file *file;
int stop = 0;
struct my_dir_context ctx = { .ctx.actor = my_actor,
.parent_dir = (char *)path,
.private_data = uid_data,
.depth = depth,
.stop = &stop };

file = ksu_filp_open_compat(path, O_RDONLY | O_NOFOLLOW, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s\n", path);
return;
int i, stop = 0;
struct list_head data_path_list;
INIT_LIST_HEAD(&data_path_list);

// Initialize APK cache list
struct apk_path_hash *pos, *n;
list_for_each_entry(pos, &apk_path_hash_list, list) {
pos->exists = false;
}

iterate_dir(file, &ctx.ctx);
filp_close(file, NULL);
// First depth
struct data_path data;
strscpy(data.dirpath, path, DATA_PATH_LEN);
data.depth = depth;
list_add_tail(&data.list, &data_path_list);

for (i = depth; i > 0; i--) {
struct data_path *pos, *n;

list_for_each_entry_safe(pos, n, &data_path_list, list) {
struct my_dir_context ctx = { .ctx.actor = my_actor,
.data_path_list = &data_path_list,
.parent_dir = pos->dirpath,
.private_data = uid_data,
.depth = pos->depth,
.stop = &stop };
struct file *file;

if (!stop) {
file = ksu_filp_open_compat(pos->dirpath, O_RDONLY | O_NOFOLLOW, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s, err: %ld\n", pos->dirpath, PTR_ERR(file));
return;
}

iterate_dir(file, &ctx.ctx);
filp_close(file, NULL);
}

list_del(&pos->list);
if (pos != &data)
kfree(pos);
}
}

// Remove stale cached APK entries
list_for_each_entry_safe(pos, n, &apk_path_hash_list, list) {
if (!pos->exists) {
list_del(&pos->list);
kfree(pos);
}
}
}

static bool is_uid_exist(uid_t uid, char *package, void *data)
Expand All @@ -209,14 +275,13 @@ static bool is_uid_exist(uid_t uid, char *package, void *data)
return exist;
}

static void do_update_uid(struct work_struct *work)
void track_throne()
{
struct file *fp =
ksu_filp_open_compat(SYSTEM_PACKAGES_LIST_PATH, O_RDONLY, 0);
if (IS_ERR(fp)) {
pr_err("do_update_uid, open " SYSTEM_PACKAGES_LIST_PATH
" failed: %ld\n",
PTR_ERR(fp));
pr_err("%s: open " SYSTEM_PACKAGES_LIST_PATH " failed: %ld\n",
__func__, PTR_ERR(fp));
return;
}

Expand Down Expand Up @@ -303,14 +368,9 @@ static void do_update_uid(struct work_struct *work)
}
}

void track_throne()
{
ksu_queue_work(&ksu_update_uid_work);
}

void ksu_throne_tracker_init()
{
INIT_WORK(&ksu_update_uid_work, do_update_uid);
// nothing to do
}

void ksu_throne_tracker_exit()
Expand Down

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