[PATCH bpf-next v4 06/20] lsm: Refactor return value of LSM hook getselfattr

Xu Kuohai
2024-07-11T11:14:06Z

From: Xu Kuohai <xukuohai@huawei.com>

To be consistent with most LSM hooks, convert the return value of
hook getselfattr to 0 or a negative error code.

Before:
- Hook getselfattr returns number of attributes found on success
or a negative error code on failure.

After:
- Hook getselfattr returns 0 on success or a negative error code
on failure. An output parameter @nattr is introduced to hold
the number of attributes found on success.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
---
include/linux/lsm_hook_defs.h | 2 +-
include/linux/security.h | 5 +++--
security/apparmor/lsm.c | 5 +++--
security/lsm_syscalls.c | 6 +++++-
security/security.c | 18 +++++++++++-------
security/selinux/hooks.c | 13 +++++++++----
security/smack/smack_lsm.c | 13 +++++++++----
7 files changed, 41 insertions(+), 21 deletions(-)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 1b7761ae2777..dbc16f14f42f 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -282,7 +282,7 @@ LSM_HOOK(int, 0, netlink_send, struct sock *sk, struct sk_buff *skb)
LSM_HOOK(void, LSM_RET_VOID, d_instantiate, struct dentry *dentry,
struct inode *inode)
LSM_HOOK(int, -EOPNOTSUPP, getselfattr, unsigned int attr,
- struct lsm_ctx __user *ctx, u32 *size, u32 flags)
+ struct lsm_ctx __user *ctx, u32 *size, u32 flags, u32 *nattr)
LSM_HOOK(int, -EOPNOTSUPP, setselfattr, unsigned int attr,
struct lsm_ctx *ctx, u32 size, u32 flags)
LSM_HOOK(int, -EINVAL, getprocattr, struct task_struct *p, const char *name,
diff --git a/include/linux/security.h b/include/linux/security.h
index 0ed53e232c4d..96a63e132abf 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -491,7 +491,7 @@ int security_sem_semop(struct kern_ipc_perm *sma, struct sembuf *sops,
unsigned nsops, int alter);
void security_d_instantiate(struct dentry *dentry, struct inode *inode);
int security_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
- u32 __user *size, u32 flags);
+ u32 __user *size, u32 flags, u32 *nattr);
int security_setselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
u32 size, u32 flags);
int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
@@ -1420,7 +1420,8 @@ static inline void security_d_instantiate(struct dentry *dentry,

static inline int security_getselfattr(unsigned int attr,
struct lsm_ctx __user *ctx,
- size_t __user *size, u32 flags)
+ size_t __user *size, u32 flags,
+ u32 *nattr)
{
return -EOPNOTSUPP;
}
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 6239777090c4..72dd09993f28 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -779,7 +779,7 @@ static int apparmor_sb_pivotroot(const struct path *old_path,
}

static int apparmor_getselfattr(unsigned int attr, struct lsm_ctx __user *lx,
- u32 *size, u32 flags)
+ u32 *size, u32 flags, u32 *nattr)
{
int error = -ENOENT;
struct aa_task_ctx *ctx = task_ctx(current);
@@ -815,7 +815,8 @@ static int apparmor_getselfattr(unsigned int attr, struct lsm_ctx __user *lx,

if (error < 0)
return error;
- return 1;
+ *nattr = 1;
+ return 0;
}

static int apparmor_getprocattr(struct task_struct *task, const char *name,
diff --git a/security/lsm_syscalls.c b/security/lsm_syscalls.c
index 8440948a690c..845866f94b03 100644
--- a/security/lsm_syscalls.c
+++ b/security/lsm_syscalls.c
@@ -77,7 +77,11 @@ SYSCALL_DEFINE4(lsm_set_self_attr, unsigned int, attr, struct lsm_ctx __user *,
SYSCALL_DEFINE4(lsm_get_self_attr, unsigned int, attr, struct lsm_ctx __user *,
ctx, u32 __user *, size, u32, flags)
{
- return security_getselfattr(attr, ctx, size, flags);
+ int rc;
+ u32 nattr;
+
+ rc = security_getselfattr(attr, ctx, size, flags, &nattr);
+ return rc < 0 ? rc : nattr;
}

/**
diff --git a/security/security.c b/security/security.c
index 12215ca286af..095e78efcb32 100644
--- a/security/security.c
+++ b/security/security.c
@@ -3969,21 +3969,23 @@ EXPORT_SYMBOL(security_d_instantiate);
* @flags: special handling options. LSM_FLAG_SINGLE indicates that only
* attributes associated with the LSM identified in the passed @ctx be
* reported.
+ * @nattr: number of attributes found on success
*
* A NULL value for @uctx can be used to get both the number of attributes
* and the size of the data.
*
- * Returns the number of attributes found on success, negative value
- * on error. @size is reset to the total size of the data.
- * If @size is insufficient to contain the data -E2BIG is returned.
+ * Returns 0 on success, a negative error code on failure. @size is reset
+ * to the total size of the data. If @size is insufficient to contain the
+ * data -E2BIG is returned.
*/
int security_getselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
- u32 __user *size, u32 flags)
+ u32 __user *size, u32 flags, u32 *nattr)
{
struct security_hook_list *hp;
struct lsm_ctx lctx = { .id = LSM_ID_UNDEF, };
u8 __user *base = (u8 __user *)uctx;
u32 entrysize;
+ u32 entrycount;
u32 total = 0;
u32 left;
bool toobig = false;
@@ -4024,7 +4026,8 @@ int security_getselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
entrysize = left;
if (base)
uctx = (struct lsm_ctx __user *)(base + total);
- rc = hp->hook.getselfattr(attr, uctx, &entrysize, flags);
+ rc = hp->hook.getselfattr(attr, uctx, &entrysize, flags,
+ &entrycount);
if (rc == -EOPNOTSUPP) {
rc = 0;
continue;
@@ -4039,7 +4042,7 @@ int security_getselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
left -= entrysize;

total += entrysize;
- count += rc;
+ count += entrycount;
if (single)
break;
}
@@ -4047,9 +4050,10 @@ int security_getselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
return -EFAULT;
if (toobig)
return -E2BIG;
+ *nattr = count;
if (count == 0)
return LSM_RET_DEFAULT(getselfattr);
- return count;
+ return 0;
}

/*
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f9a6637dfd78..0d35bb93baca 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6536,15 +6536,17 @@ static int selinux_lsm_setattr(u64 attr, void *value, size_t size)
* @ctx: buffer to receive the result
* @size: buffer size (input), buffer size used (output)
* @flags: unused
+ * @nattr: number of attributes found on success.
*
* Fill the passed user space @ctx with the details of the requested
* attribute.
*
- * Returns the number of attributes on success, an error code otherwise.
- * There will only ever be one attribute.
+ * Returns 0 on success or a negative error code on failure.
+ * There will only ever be one attribute, so @nattr is set to
+ * 1 on success.
*/
static int selinux_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
- u32 *size, u32 flags)
+ u32 *size, u32 flags, u32 *nattr)
{
int rc;
char *val = NULL;
@@ -6555,7 +6557,10 @@ static int selinux_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
return val_len;
rc = lsm_fill_user_ctx(ctx, size, val, val_len, LSM_ID_SELINUX, 0);
kfree(val);
- return (!rc ? 1 : rc);
+ if (rc < 0)
+ return rc;
+ *nattr = 1;
+ return 0;
}

static int selinux_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index ae8f1c2d0ca6..63d9c5f456c1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3648,15 +3648,17 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
* @ctx: buffer to receive the result
* @size: available size in, actual size out
* @flags: unused
+ * @nattr: number of attributes found on success
*
* Fill the passed user space @ctx with the details of the requested
* attribute.
*
- * Returns the number of attributes on success, an error code otherwise.
- * There will only ever be one attribute.
+ * Returns 0 on success or a ngetaive error code on failure.
+ * There will only ever be one attribute, so @nattr is set to
+ * 1 on success.
*/
static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
- u32 *size, u32 flags)
+ u32 *size, u32 flags, u32 *nattr)
{
int rc;
struct smack_known *skp;
@@ -3668,7 +3670,10 @@ static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
rc = lsm_fill_user_ctx(ctx, size,
skp->smk_known, strlen(skp->smk_known) + 1,
LSM_ID_SMACK, 0);
- return (!rc ? 1 : rc);
+ if (rc < 0)
+ return rc;
+ *nattr = 1;
+ return 0;
}

/**
--
2.30.2