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-rw-r--r--source3/smbd/message.c28
-rw-r--r--source3/smbd/server.c18
-rw-r--r--source3/smbd/uid.c146
3 files changed, 152 insertions, 40 deletions
diff --git a/source3/smbd/message.c b/source3/smbd/message.c
index b26a6605ed..22523aad3b 100644
--- a/source3/smbd/message.c
+++ b/source3/smbd/message.c
@@ -42,8 +42,8 @@ static void msg_deliver(void)
{
pstring s;
fstring name;
- FILE *f;
int i;
+ int fd;
if (! (*lp_msg_command()))
{
@@ -56,21 +56,19 @@ static void msg_deliver(void)
sprintf(s,"/tmp/msg.XXXXXX");
strcpy(name,(char *)mktemp(s));
- f = fopen(name,"w");
- if (!f)
- {
- DEBUG(1,("can't open message file %s\n",name));
- return;
- }
+ fd = open(name,O_WRONLY|O_CREAT|O_TRUNC|O_EXCL,0600);
+ if (fd == -1) {
+ DEBUG(1,("can't open message file %s\n",name));
+ return;
+ }
- for (i=0;i<msgpos;)
- {
- if (msgbuf[i]=='\r' && i<(msgpos-1) && msgbuf[i+1]=='\n')
- i++;
- fputc(msgbuf[i++],f);
+ for (i=0;i<msgpos;) {
+ if (msgbuf[i]=='\r' && i<(msgpos-1) && msgbuf[i+1]=='\n') {
+ i++; continue;
}
-
- fclose(f);
+ write(fd,&msgbuf[i++],1);
+ }
+ close(fd);
/* run the command */
@@ -81,7 +79,7 @@ static void msg_deliver(void)
string_sub(s,"%f",msgfrom);
string_sub(s,"%t",msgto);
standard_sub(-1,s);
- smbrun(s,NULL);
+ smbrun(s,NULL,False);
}
msgpos = 0;
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index 0e0a524f16..a710aef69b 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -567,7 +567,7 @@ int disk_free(char *path,int *bsize,int *dfree,int *dsize)
sprintf(syscmd,"%s %s",df_command,path);
standard_sub_basic(syscmd);
- ret = smbrun(syscmd,outfile);
+ ret = smbrun(syscmd,outfile,False);
DEBUG(3,("Running the command `%s' gave %d\n",syscmd,ret));
{
@@ -923,7 +923,7 @@ static void check_magic(int fnum,int cnum)
sprintf(magic_output,"%s.out",fname);
chmod(fname,0755);
- ret = smbrun(fname,magic_output);
+ ret = smbrun(fname,magic_output,False);
DEBUG(3,("Invoking magic command %s gave %d\n",fname,ret));
unlink(fname);
}
@@ -2096,7 +2096,7 @@ int make_connection(char *service,char *user,char *password, int pwlen, char *de
strcpy(cmd,lp_rootpreexec(SNUM(cnum)));
standard_sub(cnum,cmd);
DEBUG(5,("cmd=%s\n",cmd));
- smbrun(cmd,NULL);
+ smbrun(cmd,NULL,False);
}
if (!become_user(cnum,pcon->uid))
@@ -2149,7 +2149,7 @@ int make_connection(char *service,char *user,char *password, int pwlen, char *de
pstring cmd;
strcpy(cmd,lp_preexec(SNUM(cnum)));
standard_sub(cnum,cmd);
- smbrun(cmd,NULL);
+ smbrun(cmd,NULL,False);
}
/* we've finished with the sensitive stuff */
@@ -2629,7 +2629,7 @@ void close_cnum(int cnum, int uid)
pstring cmd;
strcpy(cmd,lp_postexec(SNUM(cnum)));
standard_sub(cnum,cmd);
- smbrun(cmd,NULL);
+ smbrun(cmd,NULL,False);
unbecome_user();
}
@@ -2640,7 +2640,7 @@ void close_cnum(int cnum, int uid)
pstring cmd;
strcpy(cmd,lp_rootpostexec(SNUM(cnum)));
standard_sub(cnum,cmd);
- smbrun(cmd,NULL);
+ smbrun(cmd,NULL,False);
}
Connections[cnum].open = False;
@@ -2764,8 +2764,10 @@ BOOL claim_connection(int cnum,char *name,int max_connections,BOOL Clear)
if (!file_exist(fname,NULL))
{
+ int oldmask = umask(022);
f = fopen(fname,"w");
if (f) fclose(f);
+ umask(oldmask);
}
total_recs = file_size(fname) / sizeof(crec);
@@ -3617,7 +3619,9 @@ static void usage(char *pname)
fault_setup(exit_server);
- umask(0777 & ~DEF_CREATE_MASK);
+ /* we want total control over the permissions on created files,
+ so set our umask to 0 */
+ umask(0);
init_uid();
diff --git a/source3/smbd/uid.c b/source3/smbd/uid.c
index 555cd457e7..7274c18478 100644
--- a/source3/smbd/uid.c
+++ b/source3/smbd/uid.c
@@ -27,9 +27,6 @@ extern connection_struct Connections[];
static int initial_uid;
static int initial_gid;
-static int old_umask = 022;
-
-static pstring OriginalDir;
/* what user is current? */
struct current_user current_user;
@@ -57,7 +54,7 @@ void init_uid(void)
current_user.cnum = -1;
- GetWd(OriginalDir);
+ ChDir(IDLE_DIR);
}
@@ -69,6 +66,10 @@ static BOOL become_uid(int uid)
if (initial_uid != 0)
return(True);
+ if (uid == -1 || uid == 65535) {
+ DEBUG(1,("WARNING: using uid %d is a security risk\n",uid));
+ }
+
#ifdef AIX
{
/* AIX 3 stuff - inspired by a code fragment in wu-ftpd */
@@ -118,6 +119,10 @@ static BOOL become_gid(int gid)
{
if (initial_uid != 0)
return(True);
+
+ if (gid == -1 || gid == 65535) {
+ DEBUG(1,("WARNING: using gid %d is a security risk\n",gid));
+ }
#ifdef USE_SETRES
if (setresgid(-1,gid,-1) != 0)
@@ -199,7 +204,6 @@ static BOOL check_user_ok(int cnum,user_struct *vuser,int snum)
****************************************************************************/
BOOL become_user(int cnum, int uid)
{
- int new_umask;
user_struct *vuser;
int snum,gid;
int id = uid;
@@ -259,14 +263,11 @@ BOOL become_user(int cnum, int uid)
return(False);
}
- new_umask = 0777 & ~CREATE_MODE(cnum);
- old_umask = umask(new_umask);
-
current_user.cnum = cnum;
current_user.id = id;
- DEBUG(5,("become_user uid=(%d,%d) gid=(%d,%d) new_umask=0%o\n",
- getuid(),geteuid(),getgid(),getegid(),new_umask));
+ DEBUG(5,("become_user uid=(%d,%d) gid=(%d,%d)\n",
+ getuid(),geteuid(),getgid(),getegid()));
return(True);
}
@@ -279,9 +280,7 @@ BOOL unbecome_user(void )
if (current_user.cnum == -1)
return(False);
- ChDir(OriginalDir);
-
- umask(old_umask);
+ ChDir(IDLE_DIR);
if (initial_uid == 0)
{
@@ -318,9 +317,9 @@ BOOL unbecome_user(void )
current_user.uid = initial_uid;
current_user.gid = initial_gid;
- if (ChDir(OriginalDir) != 0)
+ if (ChDir(IDLE_DIR) != 0)
DEBUG(0,("%s chdir(%s) failed in unbecome_user\n",
- timestring(),OriginalDir));
+ timestring(),IDLE_DIR));
DEBUG(5,("unbecome_user now uid=(%d,%d) gid=(%d,%d)\n",
getuid(),geteuid(),getgid(),getegid()));
@@ -332,14 +331,69 @@ BOOL unbecome_user(void )
/****************************************************************************
-run a command via system() using smbrun, being careful about uid/gid handling
+This is a utility function of smbrun(). It must be called only from
+the child as it may leave the caller in a privilaged state.
****************************************************************************/
-int smbrun(char *cmd,char *outfile)
+static BOOL setup_stdout_file(char *outfile,BOOL shared)
+{
+ int fd;
+ mode_t mode = S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH;
+
+ close(1);
+
+ if (shared) {
+ /* become root - unprivilaged users can't delete these files */
+#ifdef USE_SETRES
+ setresgid(0,0,0);
+ setresuid(0,0,0);
+#else
+ setuid(0);
+ seteuid(0);
+#endif
+ }
+
+ /* now create the file with O_EXCL set */
+ unlink(outfile);
+ fd = open(outfile,O_RDWR|O_CREAT|O_TRUNC|O_EXCL,mode);
+
+ if (fd == -1) return False;
+
+ if (fd != 1) {
+ if (dup2(fd,1) != 0) {
+ DEBUG(2,("Failed to create stdout file descriptor\n"));
+ close(fd);
+ return False;
+ }
+ close(fd);
+ }
+ return True;
+}
+
+
+/****************************************************************************
+run a command being careful about uid/gid handling and putting the output in
+outfile (or discard it if outfile is NULL).
+
+if shared is True then ensure the file will be writeable by all users
+but created such that its owned by root. This overcomes a security hole.
+
+if shared is not set then open the file with O_EXCL set
+****************************************************************************/
+int smbrun(char *cmd,char *outfile,BOOL shared)
{
+ int fd,pid;
+ int uid = current_user.uid;
+ int gid = current_user.gid;
+
+#if USE_SYSTEM
int ret;
pstring syscmd;
char *path = lp_smbrun();
+ /* in the old method we use system() to execute smbrun which then
+ executes the command (using system() again!). This involves lots
+ of shell launches and is very slow. It also suffers from a
+ potential security hole */
if (!file_exist(path,NULL))
{
DEBUG(0,("SMBRUN ERROR: Can't find %s. Installation problem?\n",path));
@@ -347,13 +401,69 @@ int smbrun(char *cmd,char *outfile)
}
sprintf(syscmd,"%s %d %d \"(%s 2>&1) > %s\"",
- path,current_user.uid,current_user.gid,cmd,
+ path,uid,gid,cmd,
outfile?outfile:"/dev/null");
DEBUG(5,("smbrun - running %s ",syscmd));
ret = system(syscmd);
DEBUG(5,("gave %d\n",ret));
return(ret);
+#else
+ /* in this newer method we will exec /bin/sh with the correct
+ arguments, after first setting stdout to point at the file */
+
+ if ((pid=fork())) {
+ int status=0;
+ /* the parent just waits for the child to exit */
+ if (waitpid(pid,&status,0) != pid) {
+ DEBUG(2,("waitpid(%d) : %s\n",pid,strerror(errno)));
+ return -1;
+ }
+ return status;
+ }
+
+
+ /* we are in the child. we exec /bin/sh to do the work for us. we
+ don't directly exec the command we want because it may be a
+ pipeline or anything else the config file specifies */
+
+ /* point our stdout at the file we want output to go into */
+ if (outfile && !setup_stdout_file(outfile,shared)) {
+ exit(80);
+ }
+
+ /* now completely lose our privilages. This is a fairly paranoid
+ way of doing it, but it does work on all systems that I know of */
+#ifdef USE_SETRES
+ setresgid(0,0,0);
+ setresuid(0,0,0);
+ setresgid(gid,gid,gid);
+ setresuid(uid,uid,uid);
+#else
+ setuid(0);
+ seteuid(0);
+ setgid(gid);
+ setegid(gid);
+ setuid(uid);
+ seteuid(uid);
+#endif
+
+ if (getuid() != uid || geteuid() != uid ||
+ getgid() != gid || getegid() != gid) {
+ /* we failed to lose our privilages - do not execute the command */
+ exit(81); /* we can't print stuff at this stage, instead use exit codes
+ for debugging */
+ }
+
+ /* close all other file descriptors, leaving only 0, 1 and 2. 0 and
+ 2 point to /dev/null from the startup code */
+ for (fd=3;fd<256;fd++) close(fd);
+
+ execl("/bin/sh","sh","-c",cmd,NULL);
+
+ /* not reached */
+ exit(82);
+#endif
}
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