Qubes/core-agent-linux
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qrexec: add some comments, minor improvement in readability

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This commit is contained in:
Marek Marczykowski-Górecki 2015-11-08 21:59:30 +01:00
parent 1c41ca6284
commit b6d4f5afbf
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GPG Key ID: 063938BA42CFA724
1 changed files with 20 additions and 2 deletions
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22
qrexec/qrexec-agent.c
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@ -65,6 +65,23 @@ void no_colon_in_cmd()
exit(1);
}
/* Start program requested by dom0 in already prepared process
* (stdin/stdout/stderr already set, etc)
* Called in two cases:
* MSG_JUST_EXEC - from qrexec-agent-data.c:handle_new_process_common->handle_just_exec
* MSG_EXEC_CMDLINE - from
* qrexec-agent-data.c:handle_new_process_common->do_fork_exec (callback
* registerd with register_exec_func in init() here)
*
* cmd parameter came from dom0 (MSG_JUST_EXEC or MSG_EXEC_CMDLINE messages), so
* is trusted. Even in VM-VM service request, the command here is controlled by
* dom0 - it will be in form:
* RPC_REQUEST_COMMAND " " service_name " " source_vm_name
* where service_name is already validated against Qrexec RPC policy
*
* If dom0 sends overly long cmd, it will probably crash qrexec-agent (unless
* process can allocate up to 4GB on both stack and heap), sorry.
*/
void do_exec(const char *cmd)
{
char buf[strlen(QUBES_RPC_MULTIPLEXER_PATH) + strlen(cmd) - strlen(RPC_REQUEST_COMMAND) + 1];
@ -75,8 +92,8 @@ void do_exec(const char *cmd)
*realcmd = 0;
realcmd++;
/* ignore "nogui:" prefix in linux agent */
if (strncmp(realcmd, "nogui:", 6) == 0)
realcmd+=6;
if (strncmp(realcmd, "nogui:", strlen("nogui:")) == 0)
realcmd += strlen("nogui:");
/* replace magic RPC cmd with RPC multiplexer path */
if (strncmp(realcmd, RPC_REQUEST_COMMAND " ", strlen(RPC_REQUEST_COMMAND)+1)==0) {
strcpy(buf, QUBES_RPC_MULTIPLEXER_PATH);
@ -221,6 +238,7 @@ void register_vchan_connection(pid_t pid, int fd, int domain, int port)
fprintf(stderr, "No free slot for child %d (connection to %d:%d)\n", pid, domain, port);
}
/* hdr parameter is received from dom0, so it is trusted */
void handle_server_exec_request(struct msg_header *hdr)
{
struct exec_params params;