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>
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2 changed files with 7 additions and 18 deletions
21
fs/exec.c
21
fs/exec.c
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@ -1613,33 +1613,24 @@ void set_binfmt(struct linux_binfmt *new)
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EXPORT_SYMBOL(set_binfmt);
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/*
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* set_dumpable converts traditional three-value dumpable to two flags and
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* stores them into mm->flags.
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* set_dumpable stores three-value SUID_DUMP_* into mm->flags.
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*/
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void set_dumpable(struct mm_struct *mm, int value)
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{
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unsigned long old, new;
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if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
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return;
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do {
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old = ACCESS_ONCE(mm->flags);
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new = old & ~MMF_DUMPABLE_MASK;
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switch (value) {
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case SUID_DUMP_ROOT:
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new |= (1 << MMF_DUMP_SECURELY);
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case SUID_DUMP_USER:
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new |= (1<< MMF_DUMPABLE);
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}
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new = (old & ~MMF_DUMPABLE_MASK) | value;
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} while (cmpxchg(&mm->flags, old, new) != old);
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}
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int __get_dumpable(unsigned long mm_flags)
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{
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int ret;
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ret = mm_flags & MMF_DUMPABLE_MASK;
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return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
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return mm_flags & MMF_DUMPABLE_MASK;
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}
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/*
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@ -400,10 +400,8 @@ extern int get_dumpable(struct mm_struct *mm);
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#define SUID_DUMP_ROOT 2 /* Dump as root */
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/* mm flags */
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/* dumpable bits */
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#define MMF_DUMPABLE 0 /* core dump is permitted */
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#define MMF_DUMP_SECURELY 1 /* core file is readable only by root */
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/* for SUID_DUMP_* above */
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#define MMF_DUMPABLE_BITS 2
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#define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)
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