adds ability to specify user in pyroscope exec

pkg/config/config.go

@@ -87,6 +87,8 @@ type Exec struct {
 	NoLogging              bool          `def:"false" desc:"disables logging from pyroscope"`
 	NoRootDrop             bool          `def:"false" desc:"disables permissions drop when ran under root. use this one if you want to run your command as root"`
 	Pid                    int           `def:"0" desc:"PID of the process you want to profile. Pass -1 to profile the whole system (only supported by ebpfspy)"`
+	UserName               string        `def:"" desc:"starts process under specified user name"`
+	GroupName              string        `def:"" desc:"starts process under specified group name"`
 	PyspyBlocking          bool          `def:"false" desc:"enables blocking mode for pyspy"`
 }
 

pkg/exec/cli.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"os/user"
 	"path"
+	"regexp"
 	"strconv"
 	"strings"
 	"syscall"
@@ -106,6 +107,15 @@ func Cli(cfg *config.Config, args []string) error {
 			}
 		}
 
+		if cfg.Exec.UserName != "" || cfg.Exec.GroupName != "" {
+			creds, err := generateCredentials(cfg.Exec.UserName, cfg.Exec.GroupName)
+			if err != nil {
+				logrus.Errorf("failed to generate credentials: %q", err)
+			} else {
+				cmd.SysProcAttr.Credential = creds
+			}
+		}
+
 		cmd.SysProcAttr.Setpgid = true
 		err := cmd.Start()
 		if err != nil {
@@ -137,9 +147,7 @@ func Cli(cfg *config.Config, args []string) error {
 	sess := agent.NewSession(u, cfg.Exec.ApplicationName, spyName, 100, 10*time.Second, pid, cfg.Exec.DetectSubprocesses)
 
 	sess.Logger = logrus.StandardLogger()
-	logrus.Debug("sess created")
 	err = sess.Start()
-	logrus.Debug("sess started")
 	if err != nil {
 		logrus.Errorf("error when starting session: %q", err)
 	}
@@ -263,3 +271,43 @@ func generateCredentialsDrop() (*syscall.Credential, error) {
 
 	return &syscall.Credential{Uid: uint32(uid), Gid: uint32(gid)}, nil
 }
+
+var digitCheck = regexp.MustCompile(`^[0-9]+$`)
+
+func generateCredentials(userName, groupName string) (*syscall.Credential, error) {
+	c := syscall.Credential{}
+
+	var u *user.User
+	var g *user.Group
+	var err error
+
+	if userName != "" {
+		if digitCheck.MatchString(userName) {
+			u, err = user.LookupId(userName)
+		} else {
+			u, err = user.Lookup(userName)
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		uid, _ := strconv.Atoi(u.Uid)
+		c.Uid = uint32(uid)
+	}
+
+	if groupName != "" {
+		if digitCheck.MatchString(groupName) {
+			g, err = user.LookupGroupId(groupName)
+		} else {
+			g, err = user.LookupGroup(groupName)
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		gid, _ := strconv.Atoi(g.Gid)
+		c.Gid = uint32(gid)
+	}
+
+	return &c, nil
+}