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Add mpo_vnode_check_setmode MAC method to MAC/veriexec.

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In the method, disallow changing SUID/SGID on verified files.

Obtained from:	Juniper Networks, Inc.
This commit is contained in:
Stephen J. Kiernan 2018-07-14 17:21:16 +00:00
parent 8c0873714c
commit ade9788665
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=336289
1 changed files with 33 additions and 0 deletions
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33
sys/security/mac_veriexec/mac_veriexec.c
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@ -549,6 +549,38 @@ mac_veriexec_vnode_check_open(struct ucred *cred, struct vnode *vp,
return (error);
}
/**
* @brief Check mode changes on file to ensure they should be allowed.
*
* We cannot allow chmod of SUID or SGID on verified files.
*
* @param cred credentials to use
* @param vp vnode of the file to open
* @param label vnode label assigned to the vnode
* @param mode mode flags to set
*
* @return 0 if the mode change should be allowed, EAUTH otherwise.
*/
static int
mac_veriexec_vnode_check_setmode(struct ucred *cred, struct vnode *vp,
struct label *label __unused, mode_t mode)
{
int error;
if ((mac_veriexec_state & VERIEXEC_STATE_ENFORCE) == 0)
return (0);
/*
* Do not allow chmod (set-[gu]id) of verified file
*/
error = mac_veriexec_check_vp(cred, vp, VVERIFY);
if (error == EAUTH) /* it isn't verified */
return (0);
if (error == 0 && (mode & (S_ISUID|S_ISGID)) != 0)
return (EAUTH);
return (0);
}
/**
* @internal
* @brief Initialize the mac_veriexec MAC policy
@ -673,6 +705,7 @@ static struct mac_policy_ops mac_veriexec_ops =
.mpo_proc_check_debug = mac_veriexec_proc_check_debug,
.mpo_vnode_check_exec = mac_veriexec_vnode_check_exec,
.mpo_vnode_check_open = mac_veriexec_vnode_check_open,
.mpo_vnode_check_setmode = mac_veriexec_vnode_check_setmode,
.mpo_vnode_copy_label = mac_veriexec_copy_label,
.mpo_vnode_destroy_label = mac_veriexec_vnode_destroy_label,
.mpo_vnode_init_label = mac_veriexec_vnode_init_label,