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smack: differentiate between subjective and objective task credentials
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With the split of the security_task_getsecid() into subjective and
objective variants it's time to update Smack to ensure it is using
the correct task creds.

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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@pcmoore
pcmoore committed Mar 22, 2021
1 parent eb1231f commit 1fb057d
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Showing 2 changed files with 44 additions and 14 deletions.
18 changes: 17 additions & 1 deletion security/smack/smack.h
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Original file line number Diff line number Diff line change
Expand Up @@ -383,7 +383,23 @@ static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
return tsp->smk_task;
}

static inline struct smack_known *smk_of_task_struct(
static inline struct smack_known *smk_of_task_struct_subj(
const struct task_struct *t)
{
struct smack_known *skp;
const struct cred *cred;

rcu_read_lock();

cred = rcu_dereference(t->cred);
skp = smk_of_task(smack_cred(cred));

rcu_read_unlock();

return skp;
}

static inline struct smack_known *smk_of_task_struct_obj(
const struct task_struct *t)
{
struct smack_known *skp;
Expand Down
40 changes: 27 additions & 13 deletions security/smack/smack_lsm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -159,7 +159,7 @@ static int smk_bu_current(char *note, struct smack_known *oskp,
static int smk_bu_task(struct task_struct *otp, int mode, int rc)
{
struct task_smack *tsp = smack_cred(current_cred());
struct smack_known *smk_task = smk_of_task_struct(otp);
struct smack_known *smk_task = smk_of_task_struct_obj(otp);
char acc[SMK_NUM_ACCESS_TYPE + 1];

if (rc <= 0)
Expand Down Expand Up @@ -479,7 +479,7 @@ static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
{
struct smack_known *skp;

skp = smk_of_task_struct(ctp);
skp = smk_of_task_struct_obj(ctp);

return smk_ptrace_rule_check(current, skp, mode, __func__);
}
Expand Down Expand Up @@ -2033,7 +2033,7 @@ static int smk_curacc_on_task(struct task_struct *p, int access,
const char *caller)
{
struct smk_audit_info ad;
struct smack_known *skp = smk_of_task_struct(p);
struct smack_known *skp = smk_of_task_struct_subj(p);
int rc;

smk_ad_init(&ad, caller, LSM_AUDIT_DATA_TASK);
Expand Down Expand Up @@ -2078,15 +2078,29 @@ static int smack_task_getsid(struct task_struct *p)
}

/**
* smack_task_getsecid - get the secid of the task
* @p: the object task
* smack_task_getsecid_subj - get the subjective secid of the task
* @p: the task
* @secid: where to put the result
*
* Sets the secid to contain a u32 version of the smack label.
* Sets the secid to contain a u32 version of the task's subjective smack label.
*/
static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
{
struct smack_known *skp = smk_of_task_struct_subj(p);

*secid = skp->smk_secid;
}

/**
* smack_task_getsecid_obj - get the objective secid of the task
* @p: the task
* @secid: where to put the result
*
* Sets the secid to contain a u32 version of the task's objective smack label.
*/
static void smack_task_getsecid(struct task_struct *p, u32 *secid)
static void smack_task_getsecid_obj(struct task_struct *p, u32 *secid)
{
struct smack_known *skp = smk_of_task_struct(p);
struct smack_known *skp = smk_of_task_struct_obj(p);

*secid = skp->smk_secid;
}
Expand Down Expand Up @@ -2174,7 +2188,7 @@ static int smack_task_kill(struct task_struct *p, struct kernel_siginfo *info,
{
struct smk_audit_info ad;
struct smack_known *skp;
struct smack_known *tkp = smk_of_task_struct(p);
struct smack_known *tkp = smk_of_task_struct_obj(p);
int rc;

if (!sig)
Expand Down Expand Up @@ -2212,7 +2226,7 @@ static int smack_task_kill(struct task_struct *p, struct kernel_siginfo *info,
static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
{
struct inode_smack *isp = smack_inode(inode);
struct smack_known *skp = smk_of_task_struct(p);
struct smack_known *skp = smk_of_task_struct_obj(p);

isp->smk_inode = skp;
isp->smk_flags |= SMK_INODE_INSTANT;
Expand Down Expand Up @@ -3483,7 +3497,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
*/
static int smack_getprocattr(struct task_struct *p, char *name, char **value)
{
struct smack_known *skp = smk_of_task_struct(p);
struct smack_known *skp = smk_of_task_struct_subj(p);
char *cp;
int slen;

Expand Down Expand Up @@ -4759,8 +4773,8 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
LSM_HOOK_INIT(task_getsid, smack_task_getsid),
LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid),
LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid),
LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
LSM_HOOK_INIT(task_setnice, smack_task_setnice),
LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
LSM_HOOK_INIT(task_getioprio, smack_task_getioprio),
Expand Down

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