Linux-Trace-Devel Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH v4] trace-cmd: Add option to execute traced process as given user
@ 2019-07-11 13:03 Tzvetomir Stoyanov (VMware)
  0 siblings, 0 replies; only message in thread
From: Tzvetomir Stoyanov (VMware) @ 2019-07-11 13:03 UTC (permalink / raw)
  To: rostedt; +Cc: linux-trace-devel

A new trace-cmd record option is added: "--user". When it is set with
combination of option -F, the traced process is executed in the context
of the specified user.

Suggested-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
[
   v4 changes:
	- Added check for strdup() failure.
	- Made input user string argument of change_user() and run_cmd()
	 constant.
   v3 changes:
      "--user" does not depend on option -F, it works with any command,
       specified as trace-cmd argument.
   v2 changes:
     - Check for errors in change_user(). If an error occurs while
       changing the user, the message is printed and the traced 
       process is not executed.
]

 Documentation/trace-cmd-record.1.txt |  4 +++
 tracecmd/trace-record.c              | 49 ++++++++++++++++++++++++++--
 tracecmd/trace-usage.c               |  1 +
 3 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/Documentation/trace-cmd-record.1.txt b/Documentation/trace-cmd-record.1.txt
index 4a59de9..6a0f975 100644
--- a/Documentation/trace-cmd-record.1.txt
+++ b/Documentation/trace-cmd-record.1.txt
@@ -122,6 +122,10 @@ OPTIONS
 *--mmap*::
      Used with either *-F* or *-P*, save the traced process memory map into
      the trace.dat file.
+
+*--user*::
+     Execute the specified *command* as given user.
+
 *-C* 'clock'::
      Set the trace clock to "clock".
 
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 48081d4..af52a88 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -33,6 +33,8 @@
 #include <errno.h>
 #include <limits.h>
 #include <libgen.h>
+#include <pwd.h>
+#include <grp.h>
 
 #include "version.h"
 #include "trace-local.h"
@@ -208,6 +210,7 @@ struct common_record_context {
 	struct buffer_instance *instance;
 	const char *output;
 	char *date2ts;
+	char *user;
 	int data_flags;
 
 	int record_all;
@@ -1417,7 +1420,34 @@ static void trace_or_sleep(enum trace_type type)
 		sleep(10);
 }
 
-static void run_cmd(enum trace_type type, int argc, char **argv)
+static int change_user(const char *user)
+{
+	struct passwd *pwd;
+
+	if (!user)
+		return 0;
+
+	pwd = getpwnam(user);
+	if (!pwd)
+		return -1;
+	if (initgroups(user, pwd->pw_gid) < 0)
+		return -1;
+	if (setgid(pwd->pw_gid) < 0)
+		return -1;
+	if (setuid(pwd->pw_uid) < 0)
+		return -1;
+
+	if (setenv("HOME", pwd->pw_dir, 1) < 0)
+		return -1;
+	if (setenv("USER", pwd->pw_name, 1) < 0)
+		return -1;
+	if (setenv("LOGNAME", pwd->pw_name, 1) < 0)
+		return -1;
+
+	return 0;
+}
+
+static void run_cmd(enum trace_type type, const char *user, int argc, char **argv)
 {
 	int status;
 	int pid;
@@ -1438,6 +1468,10 @@ static void run_cmd(enum trace_type type, int argc, char **argv)
 			dup2(save_stdout, 1);
 			close(save_stdout);
 		}
+
+		if (change_user(user) < 0)
+			die("Failed to change user to %s", user);
+
 		if (execvp(argv[0], argv)) {
 			fprintf(stderr, "\n********************\n");
 			fprintf(stderr, " Unable to exec %s\n", argv[0]);
@@ -4548,6 +4582,7 @@ void update_first_instance(struct buffer_instance *instance, int topt)
 }
 
 enum {
+	OPT_user		= 243,
 	OPT_mmap		= 244,
 	OPT_quiet		= 245,
 	OPT_debug		= 246,
@@ -4780,6 +4815,7 @@ static void parse_record_options(int argc,
 			{"quiet", no_argument, NULL, OPT_quiet},
 			{"help", no_argument, NULL, '?'},
 			{"mmap", no_argument, NULL, OPT_mmap},
+			{"user", required_argument, NULL, OPT_user},
 			{"module", required_argument, NULL, OPT_module},
 			{NULL, 0, NULL, 0}
 		};
@@ -5011,6 +5047,11 @@ static void parse_record_options(int argc,
 		case 'i':
 			ignore_event_not_found = 1;
 			break;
+		case OPT_user:
+			ctx->user = strdup(optarg);
+			if (!ctx->user)
+				die("Failed to allocate user name");
+			break;
 		case OPT_mmap:
 			get_mmap = 1;
 			break;
@@ -5079,7 +5120,6 @@ static void parse_record_options(int argc,
 	if (!ctx->filtered && ctx->instance->filter_mod)
 		add_func(&ctx->instance->filter_funcs,
 			 ctx->instance->filter_mod, "*");
-
 	if (filter_task && get_mmap)
 		do_ptrace = 1;
 
@@ -5097,6 +5137,9 @@ static void parse_record_options(int argc,
 			    "Did you mean 'record'?");
 		ctx->run_command = 1;
 	}
+	if (ctx->user && !ctx->run_command)
+		warning("--user %s is ignored, no command is specified",
+			ctx->user);
 }
 
 static enum trace_type get_trace_cmd_type(enum trace_cmd cmd)
@@ -5237,7 +5280,7 @@ static void record_trace(int argc, char **argv,
 	}
 
 	if (ctx->run_command)
-		run_cmd(type, (argc - optind) - 1, &argv[optind + 1]);
+		run_cmd(type, ctx->user, (argc - optind) - 1, &argv[optind + 1]);
 	else {
 		update_task_filter();
 		tracecmd_enable_tracing();
diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
index c658ede..e3e8186 100644
--- a/tracecmd/trace-usage.c
+++ b/tracecmd/trace-usage.c
@@ -58,6 +58,7 @@ static struct usage_help usage_help[] = {
 		"          --max-graph-depth limit function_graph depth\n"
 		"          --no-filter include trace-cmd threads in the trace\n"
 		"          --mmap used with -F or -P, save the traced process memory map into the trace.dat file\n"
+		"          --user execute the specified [command ...] as given user\n"
 	},
 	{
 		"start",
-- 
2.21.0


^ permalink raw reply	[flat|nested] only message in thread

only message in thread, back to index

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-11 13:03 [PATCH v4] trace-cmd: Add option to execute traced process as given user Tzvetomir Stoyanov (VMware)

Linux-Trace-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-trace-devel/0 linux-trace-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-trace-devel linux-trace-devel/ https://lore.kernel.org/linux-trace-devel \
		linux-trace-devel@vger.kernel.org linux-trace-devel@archiver.kernel.org
	public-inbox-index linux-trace-devel


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-trace-devel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox