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https://github.com/torvalds/linux
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aedb60a67c
The original justification for cap_task_kill() was as follows: check_kill_permission() does appropriate uid equivalence checks. However with file capabilities it becomes possible for an unprivileged user to execute a file with file capabilities resulting in a more privileged task with the same uid. However now that cap_task_kill() always returns 0 (permission granted) when p->uid==current->uid, the whole hook is worthless, and only likely to create more subtle problems in the corner cases where it might still be called but return -EPERM. Those cases are basically when uids are different but euid/suid is equivalent as per the check in check_kill_permission(). One example of a still-broken application is 'at' for non-root users. This patch removes cap_task_kill(). Signed-off-by: Serge Hallyn <serge@hallyn.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Earlier-version-tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
82 lines
2.3 KiB
C
82 lines
2.3 KiB
C
/*
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* Capabilities Linux Security Module
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/security.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/skbuff.h>
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#include <linux/netlink.h>
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#include <linux/ptrace.h>
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#include <linux/moduleparam.h>
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static struct security_operations capability_ops = {
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.ptrace = cap_ptrace,
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.capget = cap_capget,
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.capset_check = cap_capset_check,
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.capset_set = cap_capset_set,
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.capable = cap_capable,
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.settime = cap_settime,
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.netlink_send = cap_netlink_send,
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.netlink_recv = cap_netlink_recv,
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.bprm_apply_creds = cap_bprm_apply_creds,
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.bprm_set_security = cap_bprm_set_security,
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.bprm_secureexec = cap_bprm_secureexec,
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.inode_setxattr = cap_inode_setxattr,
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.inode_removexattr = cap_inode_removexattr,
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.inode_need_killpriv = cap_inode_need_killpriv,
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.inode_killpriv = cap_inode_killpriv,
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.task_setscheduler = cap_task_setscheduler,
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.task_setioprio = cap_task_setioprio,
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.task_setnice = cap_task_setnice,
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.task_post_setuid = cap_task_post_setuid,
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.task_reparent_to_init = cap_task_reparent_to_init,
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.syslog = cap_syslog,
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.vm_enough_memory = cap_vm_enough_memory,
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};
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/* flag to keep track of how we were registered */
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static int secondary;
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static int capability_disable;
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module_param_named(disable, capability_disable, int, 0);
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static int __init capability_init (void)
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{
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if (capability_disable) {
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printk(KERN_INFO "Capabilities disabled at initialization\n");
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return 0;
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}
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/* register ourselves with the security framework */
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if (register_security (&capability_ops)) {
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/* try registering with primary module */
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if (mod_reg_security (KBUILD_MODNAME, &capability_ops)) {
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printk (KERN_INFO "Failure registering capabilities "
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"with primary security module.\n");
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return -EINVAL;
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}
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secondary = 1;
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}
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printk (KERN_INFO "Capability LSM initialized%s\n",
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secondary ? " as secondary" : "");
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return 0;
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}
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security_initcall (capability_init);
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