Messages in this thread Patch in this message | | | From | Adrian Reber <> | Subject | [PATCH v5 5/6] prctl: Allow checkpoint/restore capable processes to change exe link | Date | Wed, 15 Jul 2020 16:49:53 +0200 |
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From: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Allow CAP_CHECKPOINT_RESTORE capable users to change /proc/self/exe.
This commit also changes the permission error code from -EINVAL to -EPERM for consistency with the rest of the prctl() syscall when checking capabilities.
Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com> Signed-off-by: Adrian Reber <areber@redhat.com> --- kernel/sys.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/sys.c b/kernel/sys.c index 00a96746e28a..dd59b9142b1d 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2007,12 +2007,14 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data if (prctl_map.exe_fd != (u32)-1) { /* - * Make sure the caller has the rights to - * change /proc/pid/exe link: only local sys admin should - * be allowed to. + * Check if the current user is checkpoint/restore capable. + * At the time of this writing, it checks for CAP_SYS_ADMIN + * or CAP_CHECKPOINT_RESTORE. + * Note that a user with access to ptrace can masquerade an + * arbitrary program as any executable, even setuid ones. */ - if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN)) - return -EINVAL; + if (!checkpoint_restore_ns_capable(current_user_ns())) + return -EPERM; error = prctl_set_mm_exe_file(mm, prctl_map.exe_fd); if (error) -- 2.26.2
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