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o Made children global so check_exec() can lookup a child.

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o Replaced uid in struct childinfo with struct passwd * (for runas)
o new_child() now takes a parent pid so the runas info can be inherited
o Added find_child() to lookup a child by its pid
o update_child() now fills in a struct passwd
o Converted the big if/else mess in set_policy to a switch
o Syscalls that change uid are now "ask" so we get SYSTR_MSG_UGID events
This commit is contained in:
Todd C. Miller
2004-09-25 21:08:48 +00:00
parent ea5307a433
commit e4d64ce1d0
1 changed files with 113 additions and 55 deletions
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168
mon_systrace.c
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@@ -54,7 +54,7 @@ struct listhead {
}; };
struct childinfo { struct childinfo {
pid_t pid; pid_t pid;
uid_t uid; struct passwd *pw;
struct childinfo *next; struct childinfo *next;
}; };
struct syscallhandler { struct syscallhandler {
@@ -73,14 +73,19 @@ int systrace_open __P((void));
int systrace_read __P((int, pid_t, void *, void *, size_t)); int systrace_read __P((int, pid_t, void *, void *, size_t));
int systrace_run __P((char *, char **, int)); int systrace_run __P((char *, char **, int));
ssize_t read_string __P((int, pid_t, void *, char *, size_t)); ssize_t read_string __P((int, pid_t, void *, char *, size_t));
void new_child __P((struct listhead *, pid_t, uid_t)); void new_child __P((pid_t, pid_t));
void new_handler __P((struct listhead *, int, void new_handler __P((struct listhead *, int,
void (*)(int, struct str_msg_ask *, void (*)(int, struct str_msg_ask *,
struct systrace_answer *))); struct systrace_answer *)));
void rm_child __P((struct listhead *, pid_t)); void rm_child __P((pid_t));
void update_child __P((struct listhead *, pid_t, uid_t)); void update_child __P((pid_t, uid_t));
struct childinfo *find_child __P((pid_t));
static int initialized; extern struct passwd *sudo_pwdup __P((const struct passwd *, int));
extern struct passwd *sudo_getpwuid __P((uid_t));
static struct listhead children; /* list of children being traced */
static int initialized; /* set to true when we are inited */
/* /*
* Open the systrace device and return the fd or -1 on failure. * Open the systrace device and return the fd or -1 on failure.
@@ -135,7 +140,7 @@ systrace_attach(pid)
{ {
struct systrace_answer ans; struct systrace_answer ans;
struct str_message msg; struct str_message msg;
struct listhead children, handlers; struct listhead handlers;
sigaction_t sa, osa; sigaction_t sa, osa;
sigset_t set, oset; sigset_t set, oset;
ssize_t nread; ssize_t nread;
@@ -205,8 +210,7 @@ systrace_attach(pid)
if (set_policy(fd, pid, &handlers) != 0) if (set_policy(fd, pid, &handlers) != 0)
goto fail; goto fail;
children.first = NULL; new_child(-1, pid);
new_child(&children, pid, runas_pw->pw_uid);
if (kill(pid, SIGUSR1) != 0) { if (kill(pid, SIGUSR1) != 0) {
warn("unable to wake up sleeping child"); warn("unable to wake up sleeping child");
_exit(1); _exit(1);
@@ -226,11 +230,9 @@ systrace_attach(pid)
case SYSTR_MSG_CHILD: case SYSTR_MSG_CHILD:
/* either a fork or an exit */ /* either a fork or an exit */
if (msg.msg_data.msg_child.new_pid != -1) { if (msg.msg_data.msg_child.new_pid != -1) {
/* XXX - runas_pw->pw_uid may be wrong */ new_child(msg.msg_pid, msg.msg_data.msg_child.new_pid);
new_child(&children, msg.msg_data.msg_child.new_pid,
runas_pw->pw_uid);
} else { } else {
rm_child(&children, msg.msg_pid); rm_child(msg.msg_pid);
if (children.first == NULL) if (children.first == NULL)
_exit(0); _exit(0);
} }
@@ -238,8 +240,10 @@ systrace_attach(pid)
case SYSTR_MSG_UGID: case SYSTR_MSG_UGID:
/* uid/gid change */ /* uid/gid change */
warn("new uid %d", msg.msg_data.msg_ugid.uid); #ifdef DEBUG
update_child(&children, msg.msg_pid, msg.msg_data.msg_ugid.uid); warnx("new uid %d for %d", msg.msg_data.msg_ugid.uid, msg.msg_pid);
#endif
update_child(msg.msg_pid, msg.msg_data.msg_ugid.uid);
memset(&ans, 0, sizeof(ans)); memset(&ans, 0, sizeof(ans));
ans.stra_pid = msg.msg_pid; ans.stra_pid = msg.msg_pid;
ans.stra_seqnr = msg.msg_seqnr; ans.stra_seqnr = msg.msg_seqnr;
@@ -271,7 +275,6 @@ systrace_attach(pid)
if ((ioctl(fd, STRIOCANSWER, &ans)) == -1) if ((ioctl(fd, STRIOCANSWER, &ans)) == -1)
goto fail; goto fail;
break; break;
case SYSTR_MSG_POLICYFREE: case SYSTR_MSG_POLICYFREE:
break; break;
@@ -314,39 +317,44 @@ new_handler(head, num, handler)
} }
/* /*
* Push a new child to the head of the list. * Push a new child to the head of the list, inheriting the struct pw
* of its parent. XXX - do ref counting on pw instead of copying.
*/ */
void void
new_child(head, pid, uid) new_child(ppid, pid)
struct listhead *head; pid_t ppid;
pid_t pid; pid_t pid;
uid_t uid;
{ {
struct childinfo *entry; struct childinfo *entry;
struct passwd *pw;
if (ppid != -1 && (entry = find_child(ppid)) != NULL)
pw = entry->pw;
else
pw = runas_pw;
entry = (struct childinfo *) emalloc(sizeof(*entry)); entry = (struct childinfo *) emalloc(sizeof(*entry));
entry->pid = pid; entry->pid = pid;
entry->uid = uid; entry->pw = sudo_pwdup(pw, 0);
entry->next = head->first; entry->next = children.first;
head->first = entry; children.first = entry;
} }
/* /*
* Remove the named pid from the list. * Remove the named pid from the list.
*/ */
void void
rm_child(head, pid) rm_child(pid)
struct listhead *head;
pid_t pid; pid_t pid;
{ {
struct childinfo *cur, *prev; struct childinfo *cur, *prev;
for (prev = NULL, cur = head->first; cur != NULL; cur = cur->next) { for (prev = NULL, cur = children.first; cur != NULL; cur = cur->next) {
if (cur->pid == pid) { if (cur->pid == pid) {
if (prev != NULL) if (prev != NULL)
prev->next = cur->next; prev->next = cur->next;
else else
head->first = cur->next; children.first = cur->next;
free(cur->pw);
free(cur); free(cur);
break; break;
} }
@@ -355,20 +363,44 @@ rm_child(head, pid)
} }
/* /*
* Update the uid associated with a pid. * Find a child by pid.
*/ */
void struct childinfo *
update_child(head, pid, uid) find_child(pid)
struct listhead *head;
pid_t pid; pid_t pid;
uid_t uid;
{ {
struct childinfo *cur; struct childinfo *cur;
for (cur = head->first; cur != NULL; cur = cur->next) { for (cur = children.first; cur != NULL; cur = cur->next) {
if (cur->pid == pid) { if (cur->pid == pid)
cur->uid = uid; return(cur);
break; }
return(NULL);
}
/*
* Update the uid associated with a pid.
*/
void
update_child(pid, uid)
pid_t pid;
uid_t uid;
{
struct childinfo *child;
if ((child = find_child(pid)) == NULL)
return; /* cannot happen */
if (child->pw->pw_uid != uid) {
free(child->pw);
/* lookup uid in passwd db, using a stub on failure */
if ((child->pw = sudo_getpwuid(uid)) == NULL) {
child->pw = emalloc(sizeof(struct passwd) + MAX_UID_T_LEN + 1);
memset(child->pw, 0, sizeof(struct passwd));
child->pw->pw_uid = uid;
child->pw->pw_name = (char *)child->pw + sizeof(struct passwd);
(void) snprintf(child->pw->pw_name, MAX_UID_T_LEN + 1, "%lu",
(unsigned long) uid);
} }
} }
} }
@@ -391,6 +423,7 @@ set_policy(fd, pid, handlers)
if (ioctl(fd, STRIOCPOLICY, &pol) == -1) if (ioctl(fd, STRIOCPOLICY, &pol) == -1)
return(-1); return(-1);
handlers->first = NULL;
for (i = 0; i < SYS_MAXSYSCALL; i++) { for (i = 0; i < SYS_MAXSYSCALL; i++) {
pol.strp_op = SYSTR_POLICY_ASSIGN; pol.strp_op = SYSTR_POLICY_ASSIGN;
pol.strp_pid = pid; pol.strp_pid = pid;
@@ -398,31 +431,48 @@ set_policy(fd, pid, handlers)
return(-1); return(-1);
pol.strp_op = SYSTR_POLICY_MODIFY; pol.strp_op = SYSTR_POLICY_MODIFY;
pol.strp_code = i; switch (pol.strp_code = i) {
#ifdef SYS_exec #ifdef SYS_exec
if (i == SYS_exec) { case SYS_exec:
pol.strp_policy = SYSTR_POLICY_ASK; pol.strp_policy = SYSTR_POLICY_ASK;
new_handler(handlers, i, check_exec); new_handler(handlers, i, check_exec);
} else break;
#endif #endif
#ifdef SYS_execv #ifdef SYS_execv
if (i == SYS_execv) { case SYS_execv:
pol.strp_policy = SYSTR_POLICY_ASK; pol.strp_policy = SYSTR_POLICY_ASK;
new_handler(handlers, i, check_exec); new_handler(handlers, i, check_exec);
} else break;
#endif #endif
#ifdef SYS_execve #ifdef SYS_execve
if (i == SYS_execve) { case SYS_execve:
pol.strp_policy = SYSTR_POLICY_ASK; pol.strp_policy = SYSTR_POLICY_ASK;
new_handler(handlers, i, check_exec); new_handler(handlers, i, check_exec);
} else break;
#endif #endif
#ifdef SYS_fexecve #ifdef SYS_fexecve
if (i == SYS_fexecve) case SYS_fexecve:
pol.strp_policy = SYSTR_POLICY_NEVER; /* not checkable */ pol.strp_policy = SYSTR_POLICY_NEVER; /* not checkable */
else break;
#endif #endif
pol.strp_policy = SYSTR_POLICY_PERMIT; #ifdef SYS_setuid
case SYS_setuid:
#endif
#ifdef SYS_seteuid
case SYS_seteuid:
#endif
#ifdef SYS_setreuid
case SYS_setreuid:
#endif
#ifdef SYS_setresuid
case SYS_setresuid:
#endif
pol.strp_policy = SYSTR_POLICY_ASK;
break;
default:
pol.strp_policy = SYSTR_POLICY_PERMIT;
break;
}
if (ioctl(fd, STRIOCPOLICY, &pol) == -1) if (ioctl(fd, STRIOCPOLICY, &pol) == -1)
return(-1); return(-1);
} }
@@ -517,7 +567,7 @@ decode_args(fd, pid, askp)
pid_t pid; pid_t pid;
struct str_msg_ask *askp; struct str_msg_ask *askp;
{ {
size_t len; ssize_t len;
char *off, *ap, *cp, *ep; char *off, *ap, *cp, *ep;
static char pbuf[PATH_MAX], abuf[ARG_MAX]; static char pbuf[PATH_MAX], abuf[ARG_MAX];
@@ -570,6 +620,7 @@ check_exec(fd, askp, ansp)
struct systrace_answer *ansp; struct systrace_answer *ansp;
{ {
int validated; int validated;
struct childinfo *info;
/* We're not really initialized until the first exec finishes. */ /* We're not really initialized until the first exec finishes. */
if (initialized == 0) { if (initialized == 0) {
@@ -578,6 +629,13 @@ check_exec(fd, askp, ansp)
return; return;
} }
/* Failure should not be possible. */
if ((info = find_child(ansp->stra_pid)) == NULL) {
ansp->stra_policy = SYSTR_POLICY_NEVER;
ansp->stra_error = ECHILD;
return;
}
/* Fill in user_cmnd, user_base, user_args and user_stat. */ /* Fill in user_cmnd, user_base, user_args and user_stat. */
decode_args(fd, ansp->stra_pid, askp); decode_args(fd, ansp->stra_pid, askp);
if (user_cmnd[0] != '/' || !sudo_goodpath(user_cmnd, user_stat)) { if (user_cmnd[0] != '/' || !sudo_goodpath(user_cmnd, user_stat)) {
@@ -594,11 +652,11 @@ check_exec(fd, askp, ansp)
} else } else
(void) ioctl(fd, STRIOCRESCWD, 0); (void) ioctl(fd, STRIOCRESCWD, 0);
/* XXX - should update user_runas and _runas_pw too! */
/* Check sudoers and log the result. */ /* Check sudoers and log the result. */
init_defaults(); init_defaults();
def_authenticate = FALSE; def_authenticate = FALSE;
runas_pw = info->pw;
user_runas = &info->pw->pw_name;
validated = sudoers_lookup(0); validated = sudoers_lookup(0);
#ifdef DEBUG #ifdef DEBUG
warnx("intercepted: %s %s in %s -> 0x%x", user_cmnd, user_args, user_cwd, validated); warnx("intercepted: %s %s in %s -> 0x%x", user_cmnd, user_args, user_cwd, validated);