summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorChristian Brauner <christian.brauner@ubuntu.com>2020-06-08 17:28:50 +0200
committerChristian Brauner <christian.brauner@ubuntu.com>2020-06-22 14:38:38 +0200
commit3af8588c77186bf08e55e7281da83d88373481d7 (patch)
tree8bd71c87da9028b5d81320e7896f667469e6ae1b
parent48778464bb7d346b47157d21ffde2af6b2d39110 (diff)
downloadlinux-3af8588c77186bf08e55e7281da83d88373481d7.tar.bz2
fork: fold legacy_clone_args_valid() into _do_fork()
This separate helper only existed to guarantee the mutual exclusivity of CLONE_PIDFD and CLONE_PARENT_SETTID for legacy clone since CLONE_PIDFD abuses the parent_tid field to return the pidfd. But we can actually handle this uniformely thus removing the helper. For legacy clone we can detect that CLONE_PIDFD is specified in conjunction with CLONE_PARENT_SETTID because they will share the same memory which is invalid and for clone3() setting the separate pidfd and parent_tid fields to the same memory is bogus as well. So fold that helper directly into _do_fork() by detecting this case. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: linux-m68k@lists.linux-m68k.org Cc: x86@kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
-rw-r--r--arch/m68k/kernel/process.c3
-rw-r--r--arch/x86/kernel/sys_ia32.c3
-rw-r--r--include/linux/sched/task.h1
-rw-r--r--kernel/fork.c30
4 files changed, 14 insertions, 23 deletions
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 90ae376b7ab1..0608439ba452 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -125,9 +125,6 @@ asmlinkage int m68k_clone(struct pt_regs *regs)
.tls = regs->d5,
};
- if (!legacy_clone_args_valid(&args))
- return -EINVAL;
-
return _do_fork(&args);
}
diff --git a/arch/x86/kernel/sys_ia32.c b/arch/x86/kernel/sys_ia32.c
index f8d65c99feb8..720cde885042 100644
--- a/arch/x86/kernel/sys_ia32.c
+++ b/arch/x86/kernel/sys_ia32.c
@@ -251,9 +251,6 @@ COMPAT_SYSCALL_DEFINE5(ia32_clone, unsigned long, clone_flags,
.tls = tls_val,
};
- if (!legacy_clone_args_valid(&args))
- return -EINVAL;
-
return _do_fork(&args);
}
#endif /* CONFIG_IA32_EMULATION */
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 38359071236a..ddce0ea515d1 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -96,7 +96,6 @@ extern void exit_files(struct task_struct *);
extern void exit_itimers(struct signal_struct *);
extern long _do_fork(struct kernel_clone_args *kargs);
-extern bool legacy_clone_args_valid(const struct kernel_clone_args *kargs);
extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
struct task_struct *fork_idle(int);
struct mm_struct *copy_init_mm(void);
diff --git a/kernel/fork.c b/kernel/fork.c
index 142b23645d82..9875aeb2ba41 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2423,6 +2423,20 @@ long _do_fork(struct kernel_clone_args *args)
long nr;
/*
+ * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
+ * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
+ * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
+ * field in struct clone_args and it still doesn't make sense to have
+ * them both point at the same memory location. Performing this check
+ * here has the advantage that we don't need to have a separate helper
+ * to check for legacy clone().
+ */
+ if ((args->flags & CLONE_PIDFD) &&
+ (args->flags & CLONE_PARENT_SETTID) &&
+ (args->pidfd == args->parent_tid))
+ return -EINVAL;
+
+ /*
* Determine whether and which event to report to ptracer. When
* called from kernel_thread or CLONE_UNTRACED is explicitly
* requested, no event is reported; otherwise, report if the event
@@ -2479,16 +2493,6 @@ long _do_fork(struct kernel_clone_args *args)
return nr;
}
-bool legacy_clone_args_valid(const struct kernel_clone_args *kargs)
-{
- /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
- if ((kargs->flags & CLONE_PIDFD) &&
- (kargs->flags & CLONE_PARENT_SETTID))
- return false;
-
- return true;
-}
-
#ifndef CONFIG_HAVE_COPY_THREAD_TLS
/* For compatibility with architectures that call do_fork directly rather than
* using the syscall entry points below. */
@@ -2508,9 +2512,6 @@ long do_fork(unsigned long clone_flags,
.stack_size = stack_size,
};
- if (!legacy_clone_args_valid(&args))
- return -EINVAL;
-
return _do_fork(&args);
}
#endif
@@ -2593,9 +2594,6 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
.tls = tls,
};
- if (!legacy_clone_args_valid(&args))
- return -EINVAL;
-
return _do_fork(&args);
}
#endif