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seize: Simplify creds checkers

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Don't do comparisons of creds insize core seizing routine. Instead,
pull the creds on the caller's stack and compare them there if
required.

At the same time more the proc_status_creds_dumpable() to the place
where it's only needed and make it static.

Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
This commit is contained in:
Pavel Emelyanov
2016-09-27 20:45:04 +03:00
parent 6a1c0a071c
commit 5773ad84b3
6 changed files with 88 additions and 91 deletions
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14
criu/cr-exec.c
View File

@@ -119,7 +119,7 @@ int cr_exec(int pid, char **opt)
struct parasite_ctl *ctl;
struct vm_area_list vmas;
int ret, prev_state, exit_code = -1;
struct proc_status_creds *creds = NULL;
struct proc_status_creds creds;
unsigned long p_start;
if (!sys_name) {
@@ -141,19 +141,17 @@ int cr_exec(int pid, char **opt)
if (seize_catch_task(pid))
goto out;
/*
* We don't seize a task's threads here, so there is no reason to
* mess with creds in this use case anyway.
*/
prev_state = ret = seize_wait_task(pid, -1, &creds);
if (ret < 0) {
pr_err("Can't seize task %d\n", pid);
goto out;
}
/*
* We don't seize a task's threads here, and there is no reason to
* compare threads' creds in this use case anyway, so let's just free
* the creds.
*/
free(creds);
ret = collect_mappings(pid, &vmas, NULL);
if (ret) {
pr_err("Can't collect vmas for %d\n", pid);

3
criu/include/proc_parse.h
View File

@@ -94,9 +94,6 @@ struct proc_status_creds {
u32 cap_bnd[PROC_CAP_SIZE];
};
bool proc_status_creds_dumpable(struct proc_status_creds *parent,
struct proc_status_creds *child);
#define INVALID_UID ((uid_t)-1)
extern int parse_pid_stat(pid_t pid, struct proc_pid_stat *s);

2
criu/include/ptrace.h
View File

@@ -76,7 +76,7 @@ struct ptrace_peeksiginfo_args {
extern int processes_to_wait;
extern int seize_catch_task(pid_t pid);
extern int seize_wait_task(pid_t pid, pid_t ppid, struct proc_status_creds **creds);
extern int seize_wait_task(pid_t pid, pid_t ppid, struct proc_status_creds *creds);
extern int suspend_seccomp(pid_t pid);
extern int unseize_task(pid_t pid, int orig_state, int state);
extern int ptrace_peek_area(pid_t pid, void *dst, void *addr, long bytes);

49
criu/proc_parse.c
View File

@@ -2511,55 +2511,6 @@ int aufs_parse(struct mount_info *new)
return ret;
}
bool proc_status_creds_dumpable(struct proc_status_creds *parent,
struct proc_status_creds *child)
{
const size_t size = sizeof(struct proc_status_creds) -
offsetof(struct proc_status_creds, cap_inh);
/*
* The comparison rules are the following
*
* - CAPs can be different
* - seccomp filters should be passed via
* semantic comparison (FIXME) but for
* now we require them to be exactly
* identical
* - the rest of members must match
*/
if (memcmp(parent, child, size)) {
if (!pr_quelled(LOG_DEBUG)) {
pr_debug("Creds undumpable (parent:child)\n"
" uids: %d:%d %d:%d %d:%d %d:%d\n"
" gids: %d:%d %d:%d %d:%d %d:%d\n"
" state: %d:%d"
" ppid: %d:%d\n"
" sigpnd: %llu:%llu\n"
" shdpnd: %llu:%llu\n"
" seccomp_mode: %d:%d\n"
" last_filter: %u:%u\n",
parent->uids[0], child->uids[0],
parent->uids[1], child->uids[1],
parent->uids[2], child->uids[2],
parent->uids[3], child->uids[3],
parent->gids[0], child->gids[0],
parent->gids[1], child->gids[1],
parent->gids[2], child->gids[2],
parent->gids[3], child->gids[3],
parent->state, child->state,
parent->ppid, child->ppid,
parent->sigpnd, child->sigpnd,
parent->shdpnd, child->shdpnd,
parent->seccomp_mode, child->seccomp_mode,
parent->last_filter, child->last_filter);
}
return false;
}
return true;
}
int parse_children(pid_t pid, pid_t **_c, int *_n)
{
pid_t *ch = NULL;

36
criu/ptrace.c
View File

@@ -148,17 +148,11 @@ static int skip_sigstop(int pid, int nr_signals)
* of it so the task would not know if it was saddled
* up with someone else.
*/
int seize_wait_task(pid_t pid, pid_t ppid, struct proc_status_creds **creds)
int seize_wait_task(pid_t pid, pid_t ppid, struct proc_status_creds *creds)
{
siginfo_t si;
int status, nr_sigstop;
int ret = 0, ret2, wait_errno = 0;
struct proc_status_creds cr;
/*
* For the comparison below, let's zero out any padding.
*/
memzero(&cr, sizeof(struct proc_status_creds));
/*
* It's ugly, but the ptrace API doesn't allow to distinguish
@@ -184,26 +178,26 @@ try_again:
wait_errno = errno;
}
ret2 = parse_pid_status(pid, &cr);
ret2 = parse_pid_status(pid, creds);
if (ret2)
goto err;
if (ret < 0 || WIFEXITED(status) || WIFSIGNALED(status)) {
if (cr.state != 'Z') {
if (creds->state != 'Z') {
if (pid == getpid())
pr_err("The criu itself is within dumped tree.\n");
else
pr_err("Unseizable non-zombie %d found, state %c, err %d/%d\n",
pid, cr.state, ret, wait_errno);
pid, creds->state, ret, wait_errno);
return -1;
}
return TASK_DEAD;
}
if ((ppid != -1) && (cr.ppid != ppid)) {
if ((ppid != -1) && (creds->ppid != ppid)) {
pr_err("Task pid reused while suspending (%d: %d -> %d)\n",
pid, ppid, cr.ppid);
pid, ppid, creds->ppid);
goto err;
}
@@ -235,25 +229,13 @@ try_again:
goto try_again;
}
if (*creds == NULL) {
*creds = xzalloc(sizeof(struct proc_status_creds));
if (!*creds)
goto err;
**creds = cr;
} else if (!proc_status_creds_dumpable(*creds, &cr)) {
pr_err("creds don't match %d %d\n", pid, ppid);
goto err;
}
if (cr.seccomp_mode != SECCOMP_MODE_DISABLED && suspend_seccomp(pid) < 0)
if (creds->seccomp_mode != SECCOMP_MODE_DISABLED && suspend_seccomp(pid) < 0)
goto err;
nr_sigstop = 0;
if (cr.sigpnd & (1 << (SIGSTOP - 1)))
if (creds->sigpnd & (1 << (SIGSTOP - 1)))
nr_sigstop++;
if (cr.shdpnd & (1 << (SIGSTOP - 1)))
if (creds->shdpnd & (1 << (SIGSTOP - 1)))
nr_sigstop++;
if (si.si_signo == SIGSTOP)
nr_sigstop++;

75
criu/seize.c
View File

@@ -437,6 +437,7 @@ static int collect_children(struct pstree_item *item)
nr_inprogress = 0;
for (i = 0; i < nr_children; i++) {
struct pstree_item *c;
struct proc_status_creds *creds;
pid_t pid = ch[i];
/* Is it already frozen? */
@@ -462,7 +463,13 @@ static int collect_children(struct pstree_item *item)
/* fails when meets a zombie */
seize_catch_task(pid);
ret = seize_wait_task(pid, item->pid.real, &dmpi(c)->pi_creds);
creds = xzalloc(sizeof(*creds));
if (!creds) {
ret = -1;
goto free;
}
ret = seize_wait_task(pid, item->pid.real, creds);
if (ret < 0) {
/*
* Here is a race window between parse_children() and seize(),
@@ -473,9 +480,11 @@ static int collect_children(struct pstree_item *item)
*/
ret = 0;
xfree(c);
xfree(creds);
continue;
}
dmpi(c)->pi_creds = creds;
c->pid.real = pid;
c->parent = item;
c->pid.state = ret;
@@ -591,6 +600,55 @@ static inline bool thread_collected(struct pstree_item *i, pid_t tid)
return false;
}
static bool creds_dumpable(struct proc_status_creds *parent,
struct proc_status_creds *child)
{
const size_t size = sizeof(struct proc_status_creds) -
offsetof(struct proc_status_creds, cap_inh);
/*
* The comparison rules are the following
*
* - CAPs can be different
* - seccomp filters should be passed via
* semantic comparison (FIXME) but for
* now we require them to be exactly
* identical
* - the rest of members must match
*/
if (memcmp(parent, child, size)) {
if (!pr_quelled(LOG_DEBUG)) {
pr_debug("Creds undumpable (parent:child)\n"
" uids: %d:%d %d:%d %d:%d %d:%d\n"
" gids: %d:%d %d:%d %d:%d %d:%d\n"
" state: %d:%d"
" ppid: %d:%d\n"
" sigpnd: %llu:%llu\n"
" shdpnd: %llu:%llu\n"
" seccomp_mode: %d:%d\n"
" last_filter: %u:%u\n",
parent->uids[0], child->uids[0],
parent->uids[1], child->uids[1],
parent->uids[2], child->uids[2],
parent->uids[3], child->uids[3],
parent->gids[0], child->gids[0],
parent->gids[1], child->gids[1],
parent->gids[2], child->gids[2],
parent->gids[3], child->gids[3],
parent->state, child->state,
parent->ppid, child->ppid,
parent->sigpnd, child->sigpnd,
parent->shdpnd, child->shdpnd,
parent->seccomp_mode, child->seccomp_mode,
parent->last_filter, child->last_filter);
}
return false;
}
return true;
}
static int collect_threads(struct pstree_item *item)
{
struct pid *threads = NULL;
@@ -618,6 +676,7 @@ static int collect_threads(struct pstree_item *item)
nr_inprogress = 0;
for (i = 0; i < nr_threads; i++) {
pid_t pid = threads[i].real;
struct proc_status_creds t_creds = {};
if (thread_collected(item, pid))
continue;
@@ -630,7 +689,7 @@ static int collect_threads(struct pstree_item *item)
if (!opts.freeze_cgroup && seize_catch_task(pid))
continue;
ret = seize_wait_task(pid, item_ppid(item), &dmpi(item)->pi_creds);
ret = seize_wait_task(pid, item_ppid(item), &t_creds);
if (ret < 0) {
/*
* Here is a race window between parse_threads() and seize(),
@@ -651,6 +710,9 @@ static int collect_threads(struct pstree_item *item)
goto err;
}
if (!creds_dumpable(dmpi(item)->pi_creds, &t_creds))
goto err;
if (ret == TASK_STOPPED) {
nr_stopped++;
}
@@ -737,6 +799,7 @@ int collect_pstree(void)
{
pid_t pid = root_item->pid.real;
int ret = -1;
struct proc_status_creds *creds;
timing_start(TIME_FREEZING);
@@ -755,11 +818,17 @@ int collect_pstree(void)
goto err;
}
ret = seize_wait_task(pid, -1, &dmpi(root_item)->pi_creds);
creds = xzalloc(sizeof(*creds));
if (!creds)
goto err;
ret = seize_wait_task(pid, -1, creds);
if (ret < 0)
goto err;
pr_info("Seized task %d, state %d\n", pid, ret);
root_item->pid.state = ret;
dmpi(root_item)->pi_creds = creds;
ret = collect_task(root_item);
if (ret < 0)