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    Subject[RFC][PATCH -v2] Smack: Integrate with Audit
    From
    Hi!,

    Setup the new Audit hooks for Smack. The AUDIT_SUBJ_USER and
    AUDIT_OBJ_USER SELinux flags are recycled to avoid `auditd'
    userspace modifications. Smack only needs auditing on
    a subject/object bases, so those flags were enough.

    Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
    ---

    smack_lsm.c | 153 ++++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 153 insertions(+)

    diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
    index afa7967..d471839 100644
    --- a/security/smack/smack_lsm.c
    +++ b/security/smack/smack_lsm.c
    @@ -26,6 +26,7 @@
    #include <linux/pipe_fs_i.h>
    #include <net/netlabel.h>
    #include <net/cipso_ipv4.h>
    +#include <linux/audit.h>

    #include "smack.h"

    @@ -759,6 +760,17 @@ static int smack_inode_listsecurity(struct inode *inode, char *buffer,
    return -EINVAL;
    }

    +/**
    + * smack_inode_getsecid - Extract inode's security id
    + * @inode: inode to extract the info from
    + * @secid: where result will be saved
    + */
    +static void smack_inode_getsecid(const struct inode *inode, u32 *secid)
    +{
    + struct inode_smack *isp = inode->i_security;
    + *secid = smack_to_secid(isp->smk_inode);
    +}
    +
    /*
    * File Hooks
    */
    @@ -1814,6 +1826,17 @@ static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
    return smk_curacc(isp, may);
    }

    +/**
    + * smack_ipc_getsecid - Extract ipc object security id
    + * @ipp: the object permissions
    + * @secid: where result will be saved
    + */
    +static void smack_ipc_getsecid(struct kern_ipc_perm *ipp, u32 *secid)
    +{
    + char *smack = ipp->security;
    + *secid = smack_to_secid(smack);
    +}
    +
    /* module stacking operations */

    /**
    @@ -2391,6 +2414,124 @@ static int smack_key_permission(key_ref_t key_ref,
    #endif /* CONFIG_KEYS */

    /*
    + * Smack Audit hooks
    + *
    + * Audit requires a unique representation of each Smack specific
    + * rule. This unique representation is used to distinguish the
    + * object to be audited from remaining kernel objects and also
    + * works as a glue between the audit hooks.
    + *
    + * Since repository entries are added but never deleted, we'll use
    + * the smack_known label address related to the given audit rule as
    + * the needed unique representation. This also better fits the smack
    + * model where nearly everything is a label.
    + */
    +#ifdef CONFIG_AUDIT
    +
    +/**
    + * smack_audit_rule_init - Initialize a smack audit rule
    + * @field: audit rule fields given from user-space (audit.h)
    + * @op: required testing operator (=, !=, >, <, ...)
    + * @rulestr: smack label to be audited
    + * @vrule: pointer to save our own audit rule representation
    + *
    + * Prepare to audit cases where (@field @op @rulestr) is true.
    + * The label to be audited is created if necessay.
    + */
    +static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
    +{
    + char **rule = (char **)vrule;
    + *rule = NULL;
    +
    + if (field != AUDIT_SUBJ_USER && field != AUDIT_OBJ_USER)
    + return -EINVAL;
    +
    + if (op != AUDIT_EQUAL && op != AUDIT_NOT_EQUAL)
    + return -EINVAL;
    +
    + *rule = smk_import(rulestr, 0);
    +
    + return 0;
    +}
    +
    +/**
    + * smack_audit_rule_known - Distinguish Smack audit rules
    + * @krule: rule of interest, in Audit kernel representation format
    + *
    + * This is used to filter Smack rules from remaining Audit ones.
    + * If it's proved that this rule belongs to us, the
    + * audit_rule_match hook will be called to do the final judgement.
    + */
    +static int smack_audit_rule_known(struct audit_krule *krule)
    +{
    + struct audit_field *f;
    + int i;
    +
    + for (i = 0; i < krule->field_count; i++) {
    + f = &krule->fields[i];
    +
    + if (f->type == AUDIT_SUBJ_USER || f->type == AUDIT_OBJ_USER)
    + return 1;
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * smack_audit_rule_match - Audit given object ?
    + * @secid: security id for identifying the object to test
    + * @field: audit rule flags given from user-space
    + * @op: required testing operator
    + * @vrule: smack internal rule presentation
    + * @actx: audit context associated with the check
    + *
    + * The core Audit hook. It's used to take the decision of
    + * whether to audit or not to audit a given object.
    + */
    +static int smack_audit_rule_match(u32 secid, u32 field, u32 op, void *vrule,
    + struct audit_context *actx)
    +{
    + char *smack;
    + char *rule = vrule;
    +
    + if (!rule) {
    + audit_log(actx, GFP_KERNEL, AUDIT_SELINUX_ERR,
    + "Smack: missing rule\n");
    + return -ENOENT;
    + }
    +
    + if (field != AUDIT_SUBJ_USER && field != AUDIT_OBJ_USER)
    + return 0;
    +
    + smack = smack_from_secid(secid);
    +
    + /*
    + * No need to do string comparisons since we're sure
    + * that if a match occurs, both pointers will point
    + * to the same smack_konwn label.
    + */
    + if (op == AUDIT_EQUAL)
    + return (rule == smack);
    + if (op == AUDIT_NOT_EQUAL)
    + return (rule != smack);
    +
    + return 0;
    +}
    +
    +/**
    + * smack_audit_rule_free - free smack rule representation
    + * @vrule: rule to be freed.
    + *
    + * No memory was allocated.
    + */
    +static void smack_audit_rule_free(void *vrule)
    +{
    + /* No-op */
    +}
    +
    +#endif /* CONFIG_AUDIT */
    +
    +/*
    * smack_secid_to_secctx - return the smack label for a secid
    * @secid: incoming integer
    * @secdata: destination
    @@ -2476,6 +2617,7 @@ struct security_operations smack_ops = {
    .inode_getsecurity = smack_inode_getsecurity,
    .inode_setsecurity = smack_inode_setsecurity,
    .inode_listsecurity = smack_inode_listsecurity,
    + .inode_getsecid = smack_inode_getsecid,

    .file_permission = smack_file_permission,
    .file_alloc_security = smack_file_alloc_security,
    @@ -2506,6 +2648,7 @@ struct security_operations smack_ops = {
    .task_to_inode = smack_task_to_inode,

    .ipc_permission = smack_ipc_permission,
    + .ipc_getsecid = smack_ipc_getsecid,

    .msg_msg_alloc_security = smack_msg_msg_alloc_security,
    .msg_msg_free_security = smack_msg_msg_free_security,
    @@ -2550,12 +2693,22 @@ struct security_operations smack_ops = {
    .sk_free_security = smack_sk_free_security,
    .sock_graft = smack_sock_graft,
    .inet_conn_request = smack_inet_conn_request,
    +
    /* key management security hooks */
    #ifdef CONFIG_KEYS
    .key_alloc = smack_key_alloc,
    .key_free = smack_key_free,
    .key_permission = smack_key_permission,
    #endif /* CONFIG_KEYS */
    +
    + /* Audit hooks */
    +#ifdef CONFIG_AUDIT
    + .audit_rule_init = smack_audit_rule_init,
    + .audit_rule_known = smack_audit_rule_known,
    + .audit_rule_match = smack_audit_rule_match,
    + .audit_rule_free = smack_audit_rule_free,
    +#endif /* CONFIG_AUDIT */
    +
    .secid_to_secctx = smack_secid_to_secctx,
    .secctx_to_secid = smack_secctx_to_secid,
    .release_secctx = smack_release_secctx,
    --

    "Better to light a candle, than curse the darkness"

    Ahmed S. Darwish
    Homepage: http://darwish.07.googlepages.com
    Blog: http://darwish-07.blogspot.com



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