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Several adjustments

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This commit is contained in:
topjohnwu 2018-06-26 18:45:51 +08:00
parent caa39474cb
commit 2c4001387e
2 changed files with 135 additions and 167 deletions
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37
su.c
View File

@ -22,7 +22,6 @@
#include <libgen.h> #include <libgen.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/auxv.h>
#include <selinux/selinux.h> #include <selinux/selinux.h>
#include "magisk.h" #include "magisk.h"
@ -160,42 +159,6 @@ __attribute__ ((noreturn)) void exit2(int status) {
} }
int su_daemon_main(int argc, char **argv) { int su_daemon_main(int argc, char **argv) {
// Sanitize all secure environment variables (from linker_environ.c in AOSP linker).
/* The same list than GLibc at this point */
static const char* const unsec_vars[] = {
"GCONV_PATH",
"GETCONF_DIR",
"HOSTALIASES",
"LD_AUDIT",
"LD_DEBUG",
"LD_DEBUG_OUTPUT",
"LD_DYNAMIC_WEAK",
"LD_LIBRARY_PATH",
"LD_ORIGIN_PATH",
"LD_PRELOAD",
"LD_PROFILE",
"LD_SHOW_AUXV",
"LD_USE_LOAD_BIAS",
"LOCALDOMAIN",
"LOCPATH",
"MALLOC_TRACE",
"MALLOC_CHECK_",
"NIS_PATH",
"NLSPATH",
"RESOLV_HOST_CONF",
"RES_OPTIONS",
"TMPDIR",
"TZDIR",
"LD_AOUT_LIBRARY_PATH",
"LD_AOUT_PRELOAD",
// not listed in linker, used due to system() call
"IFS",
NULL
};
if (getauxval(AT_SECURE))
for (int i = 0; unsec_vars[i]; ++i)
unsetenv(unsec_vars[i]);
int c, socket_serv_fd, fd; int c, socket_serv_fd, fd;
char result[64]; char result[64];
struct option long_opts[] = { struct option long_opts[] = {

265
su_daemon.c
View File

@ -197,6 +197,106 @@ static struct su_info *get_su_info(unsigned uid) {
return info; return info;
} }
static void su_executor(int client) {
LOGD("su: executor started\n");
// ack
write_int(client, 0);
// Become session leader
xsetsid();
// Migrate environment from client
char path[32], buf[4096];
snprintf(path, sizeof(path), "/proc/%d/cwd", su_ctx->pid);
xreadlink(path, su_ctx->cwd, sizeof(su_ctx->cwd));
snprintf(path, sizeof(path), "/proc/%d/environ", su_ctx->pid);
memset(buf, 0, sizeof(buf));
int fd = open(path, O_RDONLY);
read(fd, buf, sizeof(buf));
clearenv();
for (size_t pos = 0; buf[pos];) {
putenv(buf + pos);
pos += strlen(buf + pos) + 1;
}
// Let's read some info from the socket
int argc = read_int(client);
if (argc < 0 || argc > 512) {
LOGE("unable to allocate args: %d", argc);
exit2(1);
}
LOGD("su: argc=[%d]\n", argc);
char **argv = (char**) xmalloc(sizeof(char*) * (argc + 1));
argv[argc] = NULL;
for (int i = 0; i < argc; i++) {
argv[i] = read_string(client);
LOGD("su: argv[%d]=[%s]\n", i, argv[i]);
// Replace -cn with -z, -mm with -M for supporting getopt_long
if (strcmp(argv[i], "-cn") == 0)
strcpy(argv[i], "-z");
else if (strcmp(argv[i], "-mm") == 0)
strcpy(argv[i], "-M");
}
// Get pts_slave
char *pts_slave = read_string(client);
// The FDs for each of the streams
int infd = recv_fd(client);
int outfd = recv_fd(client);
int errfd = recv_fd(client);
int ptsfd = -1;
// We no longer need the access to socket in the child, close it
close(client);
if (pts_slave[0]) {
LOGD("su: pts_slave=[%s]\n", pts_slave);
// Check pts_slave file is owned by daemon_from_uid
struct stat st;
xstat(pts_slave, &st);
// If caller is not root, ensure the owner of pts_slave is the caller
if(st.st_uid != su_ctx->info->uid && su_ctx->info->uid != 0) {
LOGE("su: Wrong permission of pts_slave");
su_ctx->info->access.policy = DENY;
exit2(1);
}
// Opening the TTY has to occur after the
// fork() and setsid() so that it becomes
// our controlling TTY and not the daemon's
ptsfd = xopen(pts_slave, O_RDWR);
if (infd < 0) {
LOGD("su: stdin using PTY");
infd = ptsfd;
}
if (outfd < 0) {
LOGD("su: stdout using PTY");
outfd = ptsfd;
}
if (errfd < 0) {
LOGD("su: stderr using PTY");
errfd = ptsfd;
}
}
free(pts_slave);
// Swap out stdin, stdout, stderr
xdup2(infd, STDIN_FILENO);
xdup2(outfd, STDOUT_FILENO);
xdup2(errfd, STDERR_FILENO);
close(ptsfd);
// Run the actual main
su_daemon_main(argc, argv);
}
void su_daemon_receiver(int client, struct ucred *credential) { void su_daemon_receiver(int client, struct ucred *credential) {
LOGD("su: request from client: %d\n", client); LOGD("su: request from client: %d\n", client);
@ -231,147 +331,52 @@ void su_daemon_receiver(int client, struct ucred *credential) {
* send the return code back to our client * send the return code back to our client
*/ */
int child = xfork(); int child = xfork();
if (child) { if (child == 0) {
// Wait for results su_ctx = &ctx;
if (ctx.pipefd[0] >= 0) { su_executor(client);
xxread(ctx.pipefd[0], &ctx.info->access.policy, sizeof(policy_t));
close(ctx.pipefd[0]);
close(ctx.pipefd[1]);
}
// The policy is determined, unlock
UNLOCK_UID();
// Info is now useless to us, decrement reference count
--ctx.info->ref;
// Wait result
LOGD("su: waiting child: [%d]\n", child);
int status, code;
if (waitpid(child, &status, 0) > 0)
code = WEXITSTATUS(status);
else
code = -1;
/* Passing the return code back to the client:
* The client might be closed unexpectedly (e.g. swipe a root app out of recents)
* In that case, writing to the client (which doesn't exist) will result in SIGPIPE
* Here we simply just ignore the situation.
*/
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_IGN;
sigaction(SIGPIPE, &act, NULL);
LOGD("su: return code: [%d]\n", code);
write(client, &code, sizeof(code));
close(client);
// Restore default handler for SIGPIPE
act.sa_handler = SIG_DFL;
sigaction(SIGPIPE, &act, NULL);
return;
} }
LOGD("su: child process started\n"); // Wait for results
if (ctx.pipefd[0] >= 0) {
// ack xxread(ctx.pipefd[0], &ctx.info->access.policy, sizeof(policy_t));
write_int(client, 0); close(ctx.pipefd[0]);
close(ctx.pipefd[1]);
// Become session leader
xsetsid();
// Migrate environment from client
char path[32], buf[4096];
snprintf(path, sizeof(path), "/proc/%d/cwd", ctx.pid);
xreadlink(path, ctx.cwd, sizeof(ctx.cwd));
snprintf(path, sizeof(path), "/proc/%d/environ", ctx.pid);
memset(buf, 0, sizeof(buf));
int fd = open(path, O_RDONLY);
read(fd, buf, sizeof(buf));
clearenv();
for (size_t pos = 0; buf[pos];) {
putenv(buf + pos);
pos += strlen(buf + pos) + 1;
} }
// Let's read some info from the socket // The policy is determined, unlock
int argc = read_int(client); UNLOCK_UID();
if (argc < 0 || argc > 512) {
LOGE("unable to allocate args: %d", argc);
exit2(1);
}
LOGD("su: argc=[%d]\n", argc);
char **argv = (char**) xmalloc(sizeof(char*) * (argc + 1)); // Info is now useless to us, decrement reference count
argv[argc] = NULL; --ctx.info->ref;
for (int i = 0; i < argc; i++) {
argv[i] = read_string(client);
LOGD("su: argv[%d]=[%s]\n", i, argv[i]);
// Replace -cn with -z, -mm with -M for supporting getopt_long
if (strcmp(argv[i], "-cn") == 0)
strcpy(argv[i], "-z");
else if (strcmp(argv[i], "-mm") == 0)
strcpy(argv[i], "-M");
}
// Get pts_slave // Wait result
char *pts_slave = read_string(client); LOGD("su: waiting child: [%d]\n", child);
LOGD("su: pts_slave=[%s]\n", pts_slave); int status, code;
// The FDs for each of the streams if (waitpid(child, &status, 0) > 0)
int infd = recv_fd(client); code = WEXITSTATUS(status);
int outfd = recv_fd(client); else
int errfd = recv_fd(client); code = -1;
int ptsfd = -1;
// We no longer need the access to socket in the child, close it /* Passing the return code back to the client:
* The client might be closed unexpectedly (e.g. swipe a root app out of recents)
* In that case, writing to the client (which doesn't exist) will result in SIGPIPE
* Here we simply just ignore the situation.
*/
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_IGN;
sigaction(SIGPIPE, &act, NULL);
LOGD("su: return code: [%d]\n", code);
write(client, &code, sizeof(code));
close(client); close(client);
if (pts_slave[0]) { // Restore default handler for SIGPIPE
// Check pts_slave file is owned by daemon_from_uid act.sa_handler = SIG_DFL;
struct stat st; sigaction(SIGPIPE, &act, NULL);
xstat(pts_slave, &st);
// If caller is not root, ensure the owner of pts_slave is the caller return;
if(st.st_uid != credential->uid && credential->uid != 0) {
LOGE("su: Wrong permission of pts_slave");
exit2(1);
}
// Opening the TTY has to occur after the
// fork() and setsid() so that it becomes
// our controlling TTY and not the daemon's
ptsfd = xopen(pts_slave, O_RDWR);
if (infd < 0) {
LOGD("su: stdin using PTY");
infd = ptsfd;
}
if (outfd < 0) {
LOGD("su: stdout using PTY");
outfd = ptsfd;
}
if (errfd < 0) {
LOGD("su: stderr using PTY");
errfd = ptsfd;
}
}
free(pts_slave);
// Swap out stdin, stdout, stderr
xdup2(infd, STDIN_FILENO);
xdup2(outfd, STDOUT_FILENO);
xdup2(errfd, STDERR_FILENO);
close(ptsfd);
// Give main the reference
su_ctx = &ctx;
su_daemon_main(argc, argv);
} }
/* /*