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05 April 2024, 19:05:47 UTC
Revision 22f6b4d34fcf039c63a94e7670e0da24f8575a5a authored by Jann Horn on 15 September 2016, 22:31:22 UTC, committed by Linus Torvalds on 15 September 2016, 22:49:28 UTC 
aio: mark AIO pseudo-fs noexec
 
This ensures that do_mmap() won't implicitly make AIO memory mappings
executable if the READ_IMPLIES_EXEC personality flag is set.  Such
behavior is problematic because the security_mmap_file LSM hook doesn't
catch this case, potentially permitting an attacker to bypass a W^X
policy enforced by SELinux.

I have tested the patch on my machine.

To test the behavior, compile and run this:

    #define _GNU_SOURCE
    #include <unistd.h>
    #include <sys/personality.h>
    #include <linux/aio_abi.h>
    #include <err.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <sys/syscall.h>

    int main(void) {
        personality(READ_IMPLIES_EXEC);
        aio_context_t ctx = 0;
        if (syscall(__NR_io_setup, 1, &ctx))
            err(1, "io_setup");

        char cmd[1000];
        sprintf(cmd, "cat /proc/%d/maps | grep -F '/[aio]'",
            (int)getpid());
        system(cmd);
        return 0;
    }

In the output, "rw-s" is good, "rwxs" is bad.

Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 024c7e3
History
Tip revision: 22f6b4d34fcf039c63a94e7670e0da24f8575a5a authored by Jann Horn on 15 September 2016, 22:31:22 UTC
aio: mark AIO pseudo-fs noexec
Tip revision: 22f6b4d
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arch
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certs
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drivers
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include
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kernel
lib
mm
net
samples
scripts
security
sound
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usr
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.cocciconfig -rw-r--r-- 59 bytes
.get_maintainer.ignore -rw-r--r-- 31 bytes
.gitignore -rw-r--r-- 1.3 KB
.mailmap -rw-r--r-- 7.3 KB
COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 95.5 KB
Kbuild -rw-r--r-- 2.8 KB
Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 363.6 KB
Makefile -rw-r--r-- 56.8 KB
README -rw-r--r-- 18.1 KB
REPORTING-BUGS -rw-r--r-- 7.3 KB

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