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Diffstat (limited to 'fs/pidfs.c')
-rw-r--r--fs/pidfs.c113
1 files changed, 67 insertions, 46 deletions
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 78dee3c201af..dba703d4ce4a 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -39,20 +39,20 @@ void pidfs_get_root(struct path *path)
path_get(path);
}
-/*
- * Stashes information that userspace needs to access even after the
- * process has been reaped.
- */
-struct pidfs_exit_info {
- __u64 cgroupid;
- __s32 exit_code;
- __u32 coredump_mask;
+enum pidfs_attr_mask_bits {
+ PIDFS_ATTR_BIT_EXIT = 0,
+ PIDFS_ATTR_BIT_COREDUMP = 1,
};
struct pidfs_attr {
+ unsigned long attr_mask;
struct simple_xattrs *xattrs;
- struct pidfs_exit_info __pei;
- struct pidfs_exit_info *exit_info;
+ struct /* exit info */ {
+ __u64 cgroupid;
+ __s32 exit_code;
+ };
+ __u32 coredump_mask;
+ __u32 coredump_signal;
};
static struct rb_root pidfs_ino_tree = RB_ROOT;
@@ -293,6 +293,15 @@ static __u32 pidfs_coredump_mask(unsigned long mm_flags)
return 0;
}
+/* This must be updated whenever a new flag is added */
+#define PIDFD_INFO_SUPPORTED (PIDFD_INFO_PID | \
+ PIDFD_INFO_CREDS | \
+ PIDFD_INFO_CGROUPID | \
+ PIDFD_INFO_EXIT | \
+ PIDFD_INFO_COREDUMP | \
+ PIDFD_INFO_SUPPORTED_MASK | \
+ PIDFD_INFO_COREDUMP_SIGNAL)
+
static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
{
struct pidfd_info __user *uinfo = (struct pidfd_info __user *)arg;
@@ -300,12 +309,13 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
struct pid *pid = pidfd_pid(file);
size_t usize = _IOC_SIZE(cmd);
struct pidfd_info kinfo = {};
- struct pidfs_exit_info *exit_info;
struct user_namespace *user_ns;
struct pidfs_attr *attr;
const struct cred *c;
__u64 mask;
+ BUILD_BUG_ON(sizeof(struct pidfd_info) != PIDFD_INFO_SIZE_VER2);
+
if (!uinfo)
return -EINVAL;
if (usize < PIDFD_INFO_SIZE_VER0)
@@ -323,20 +333,24 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
attr = READ_ONCE(pid->attr);
if (mask & PIDFD_INFO_EXIT) {
- exit_info = READ_ONCE(attr->exit_info);
- if (exit_info) {
+ if (test_bit(PIDFS_ATTR_BIT_EXIT, &attr->attr_mask)) {
+ smp_rmb();
kinfo.mask |= PIDFD_INFO_EXIT;
#ifdef CONFIG_CGROUPS
- kinfo.cgroupid = exit_info->cgroupid;
+ kinfo.cgroupid = attr->cgroupid;
kinfo.mask |= PIDFD_INFO_CGROUPID;
#endif
- kinfo.exit_code = exit_info->exit_code;
+ kinfo.exit_code = attr->exit_code;
}
}
if (mask & PIDFD_INFO_COREDUMP) {
- kinfo.mask |= PIDFD_INFO_COREDUMP;
- kinfo.coredump_mask = READ_ONCE(attr->__pei.coredump_mask);
+ if (test_bit(PIDFS_ATTR_BIT_COREDUMP, &attr->attr_mask)) {
+ smp_rmb();
+ kinfo.mask |= PIDFD_INFO_COREDUMP | PIDFD_INFO_COREDUMP_SIGNAL;
+ kinfo.coredump_mask = attr->coredump_mask;
+ kinfo.coredump_signal = attr->coredump_signal;
+ }
}
task = get_pid_task(pid, PIDTYPE_PID);
@@ -355,14 +369,15 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
if (!c)
return -ESRCH;
- if ((kinfo.mask & PIDFD_INFO_COREDUMP) && !(kinfo.coredump_mask)) {
- task_lock(task);
+ if ((mask & PIDFD_INFO_COREDUMP) && !kinfo.coredump_mask) {
+ guard(task_lock)(task);
if (task->mm) {
unsigned long flags = __mm_flags_get_dumpable(task->mm);
kinfo.coredump_mask = pidfs_coredump_mask(flags);
+ kinfo.mask |= PIDFD_INFO_COREDUMP;
+ /* No coredump actually took place, so no coredump signal. */
}
- task_unlock(task);
}
/* Unconditionally return identifiers and credentials, the rest only on request */
@@ -409,6 +424,13 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg)
return -ESRCH;
copy_out:
+ if (mask & PIDFD_INFO_SUPPORTED_MASK) {
+ kinfo.mask |= PIDFD_INFO_SUPPORTED_MASK;
+ kinfo.supported_mask = PIDFD_INFO_SUPPORTED;
+ }
+
+ /* Are there bits in the return mask not present in PIDFD_INFO_SUPPORTED? */
+ WARN_ON_ONCE(~PIDFD_INFO_SUPPORTED & kinfo.mask);
/*
* If userspace and the kernel have the same struct size it can just
* be copied. If userspace provides an older struct, only the bits that
@@ -603,24 +625,25 @@ void pidfs_exit(struct task_struct *tsk)
{
struct pid *pid = task_pid(tsk);
struct pidfs_attr *attr;
- struct pidfs_exit_info *exit_info;
#ifdef CONFIG_CGROUPS
struct cgroup *cgrp;
#endif
might_sleep();
- guard(spinlock_irq)(&pid->wait_pidfd.lock);
- attr = pid->attr;
- if (!attr) {
- /*
- * No one ever held a pidfd for this struct pid.
- * Mark it as dead so no one can add a pidfs
- * entry anymore. We're about to be reaped and
- * so no exit information would be available.
- */
- pid->attr = PIDFS_PID_DEAD;
- return;
+ /* Synchronize with pidfs_register_pid(). */
+ scoped_guard(spinlock_irq, &pid->wait_pidfd.lock) {
+ attr = pid->attr;
+ if (!attr) {
+ /*
+ * No one ever held a pidfd for this struct pid.
+ * Mark it as dead so no one can add a pidfs
+ * entry anymore. We're about to be reaped and
+ * so no exit information would be available.
+ */
+ pid->attr = PIDFS_PID_DEAD;
+ return;
+ }
}
/*
@@ -631,41 +654,39 @@ void pidfs_exit(struct task_struct *tsk)
* is put
*/
- exit_info = &attr->__pei;
-
#ifdef CONFIG_CGROUPS
rcu_read_lock();
cgrp = task_dfl_cgroup(tsk);
- exit_info->cgroupid = cgroup_id(cgrp);
+ attr->cgroupid = cgroup_id(cgrp);
rcu_read_unlock();
#endif
- exit_info->exit_code = tsk->exit_code;
+ attr->exit_code = tsk->exit_code;
/* Ensure that PIDFD_GET_INFO sees either all or nothing. */
- smp_store_release(&attr->exit_info, &attr->__pei);
+ smp_wmb();
+ set_bit(PIDFS_ATTR_BIT_EXIT, &attr->attr_mask);
}
#ifdef CONFIG_COREDUMP
void pidfs_coredump(const struct coredump_params *cprm)
{
struct pid *pid = cprm->pid;
- struct pidfs_exit_info *exit_info;
struct pidfs_attr *attr;
- __u32 coredump_mask = 0;
attr = READ_ONCE(pid->attr);
VFS_WARN_ON_ONCE(!attr);
VFS_WARN_ON_ONCE(attr == PIDFS_PID_DEAD);
- exit_info = &attr->__pei;
- /* Note how we were coredumped. */
- coredump_mask = pidfs_coredump_mask(cprm->mm_flags);
- /* Note that we actually did coredump. */
- coredump_mask |= PIDFD_COREDUMPED;
+ /* Note how we were coredumped and that we coredumped. */
+ attr->coredump_mask = pidfs_coredump_mask(cprm->mm_flags) |
+ PIDFD_COREDUMPED;
/* If coredumping is set to skip we should never end up here. */
- VFS_WARN_ON_ONCE(coredump_mask & PIDFD_COREDUMP_SKIP);
- smp_store_release(&exit_info->coredump_mask, coredump_mask);
+ VFS_WARN_ON_ONCE(attr->coredump_mask & PIDFD_COREDUMP_SKIP);
+ /* Expose the signal number that caused the coredump. */
+ attr->coredump_signal = cprm->siginfo->si_signo;
+ smp_wmb();
+ set_bit(PIDFS_ATTR_BIT_COREDUMP, &attr->attr_mask);
}
#endif
generated by cgit v1.2.3 (git 2.46.0) at 2025-12-09 15:04:46 +0000