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Subject[PATCH] Smack: Use secureexec with SMACK64EXEC
Date
SMACK64EXEC extended attribute allows switching to
another security context when executing a file.

This patch enables secureexec bit in ELF auxiliary
vector so that code cannot be injected from executers
security context.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
---
security/smack/smack.h | 5 +++++
security/smack/smack_lsm.c | 15 ++++++++++++++-
2 files changed, 19 insertions(+), 1 deletions(-)

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 2b6c6a5..e41fb07 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -181,6 +181,11 @@ struct smack_known {
#define SMK_NUM_ACCESS_TYPE 4

/*
+ * Passed in the bprm->unsafe field
+ */
+#define SMK_SECUREEXEC_NEEDED 0x8000
+
+/*
* Smack audit data; is empty if CONFIG_AUDIT not set
* to save some stack
*/
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index b9c5e14..3ea018d 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -465,12 +465,24 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)

isp = dp->d_inode->i_security;

- if (isp->smk_task != NULL)
+ if (isp->smk_task != NULL) {
tsp->smk_task = isp->smk_task;
+ bprm->unsafe = SMK_SECUREEXEC_NEEDED;
+ }

return 0;
}

+int smack_bprm_secureexec(struct linux_binprm *bprm)
+{
+ int ret = cap_bprm_secureexec(bprm);
+
+ if (!ret && (bprm->unsafe & SMK_SECUREEXEC_NEEDED))
+ ret = 1;
+
+ return ret;
+}
+
/*
* Inode hooks
*/
@@ -3409,6 +3421,7 @@ struct security_operations smack_ops = {
.sb_umount = smack_sb_umount,

.bprm_set_creds = smack_bprm_set_creds,
+ .bprm_secureexec = smack_bprm_secureexec,

.inode_alloc_security = smack_inode_alloc_security,
.inode_free_security = smack_inode_free_security,
--
1.7.4.1


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