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coredump: kill MMF_DUMPABLE and MMF_DUMP_SECURELY 

Nobody actually needs MMF_DUMPABLE/MMF_DUMP_SECURELY, they are only used
to enforce the encoding of SUID_DUMP_* enum in mm->flags &
MMF_DUMPABLE_MASK.

Now that set_dumpable() updates both bits atomically we can kill them and
simply store the value "as is" in 2 lower bits.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Alex Kelly <alex.page.kelly@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-01-23 15:55:32 -08:00 committed by Linus Torvalds
parent abacd2fe3c
commit 7288e1187b
2 changed files with 7 additions and 18 deletions
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21
fs/exec.c
View File

@ -1613,33 +1613,24 @@ void set_binfmt(struct linux_binfmt *new)
EXPORT_SYMBOL(set_binfmt);
/*
* set_dumpable converts traditional three-value dumpable to two flags and
* stores them into mm->flags.
* set_dumpable stores three-value SUID_DUMP_* into mm->flags.
*/
void set_dumpable(struct mm_struct *mm, int value)
{
unsigned long old, new;
if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
return;
do {
old = ACCESS_ONCE(mm->flags);
new = old & ~MMF_DUMPABLE_MASK;
switch (value) {
case SUID_DUMP_ROOT:
new |= (1 << MMF_DUMP_SECURELY);
case SUID_DUMP_USER:
new |= (1<< MMF_DUMPABLE);
}
new = (old & ~MMF_DUMPABLE_MASK) | value;
} while (cmpxchg(&mm->flags, old, new) != old);
}
int __get_dumpable(unsigned long mm_flags)
{
int ret;
ret = mm_flags & MMF_DUMPABLE_MASK;
return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
return mm_flags & MMF_DUMPABLE_MASK;
}
/*

4
include/linux/sched.h
View File

@ -400,10 +400,8 @@ extern int get_dumpable(struct mm_struct *mm);
#define SUID_DUMP_ROOT 2 /* Dump as root */
/* mm flags */
/* dumpable bits */
#define MMF_DUMPABLE 0 /* core dump is permitted */
#define MMF_DUMP_SECURELY 1 /* core file is readable only by root */
/* for SUID_DUMP_* above */
#define MMF_DUMPABLE_BITS 2
#define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)