Re: [PATCH v12 03/11] proc: Use lsmids instead of lsm names for attrs

Mickaël Salaün <mic@xxxxxxxxxxx> · Tue, 11 Jul 2023 17:36:01 +0200

On 29/06/2023 21:55, Casey Schaufler wrote:
Use the LSM ID number instead of the LSM name to identify which
security module's attibute data should be shown in /proc/self/attr.
The security_[gs]etprocattr() functions have been changed to expect
the LSM ID. The change from a string comparison to an integer comparison
in these functions will provide a minor performance improvement.

Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Serge Hallyn <serge@xxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx

Reviewed-by: Mickaël Salaün <mic@xxxxxxxxxxx>

---
  fs/proc/base.c           | 29 +++++++++++++++--------------
  fs/proc/internal.h       |  2 +-
  include/linux/security.h | 11 +++++------
  security/security.c      | 15 +++++++--------
  4 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 05452c3b9872..f999bb5c497b 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -97,6 +97,7 @@
  #include <linux/resctrl.h>
  #include <linux/cn_proc.h>
  #include <linux/ksm.h>
+#include <uapi/linux/lsm.h>
  #include <trace/events/oom.h>
  #include "internal.h"
  #include "fd.h"
@@ -146,10 +147,10 @@ struct pid_entry {
  	NOD(NAME, (S_IFREG|(MODE)),			\
  		NULL, &proc_single_file_operations,	\
  		{ .proc_show = show } )
-#define ATTR(LSM, NAME, MODE)				\
+#define ATTR(LSMID, NAME, MODE)				\
  	NOD(NAME, (S_IFREG|(MODE)),			\
  		NULL, &proc_pid_attr_operations,	\
-		{ .lsm = LSM })
+		{ .lsmid = LSMID })
  
  /*
   * Count the number of hardlinks for the pid_entry table, excluding the .
@@ -2730,7 +2731,7 @@ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
  	if (!task)
  		return -ESRCH;
  
-	length = security_getprocattr(task, PROC_I(inode)->op.lsm,
+	length = security_getprocattr(task, PROC_I(inode)->op.lsmid,
  				      file->f_path.dentry->d_name.name,
  				      &p);
  	put_task_struct(task);
@@ -2788,7 +2789,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
  	if (rv < 0)
  		goto out_free;
  
-	rv = security_setprocattr(PROC_I(inode)->op.lsm,
+	rv = security_setprocattr(PROC_I(inode)->op.lsmid,
  				  file->f_path.dentry->d_name.name, page,
  				  count);
  	mutex_unlock(&current->signal->cred_guard_mutex);
@@ -2837,27 +2838,27 @@ static const struct inode_operations proc_##LSM##_attr_dir_inode_ops = { \
  
  #ifdef CONFIG_SECURITY_SMACK
  static const struct pid_entry smack_attr_dir_stuff[] = {
-	ATTR("smack", "current",	0666),
+	ATTR(LSM_ID_SMACK, "current",	0666),
  };
  LSM_DIR_OPS(smack);
  #endif
  
  #ifdef CONFIG_SECURITY_APPARMOR
  static const struct pid_entry apparmor_attr_dir_stuff[] = {
-	ATTR("apparmor", "current",	0666),
-	ATTR("apparmor", "prev",	0444),
-	ATTR("apparmor", "exec",	0666),
+	ATTR(LSM_ID_APPARMOR, "current",	0666),
+	ATTR(LSM_ID_APPARMOR, "prev",		0444),
+	ATTR(LSM_ID_APPARMOR, "exec",		0666),
  };
  LSM_DIR_OPS(apparmor);
  #endif
  
  static const struct pid_entry attr_dir_stuff[] = {
-	ATTR(NULL, "current",		0666),
-	ATTR(NULL, "prev",		0444),
-	ATTR(NULL, "exec",		0666),
-	ATTR(NULL, "fscreate",		0666),
-	ATTR(NULL, "keycreate",		0666),
-	ATTR(NULL, "sockcreate",	0666),
+	ATTR(LSM_ID_UNDEF, "current",	0666),
+	ATTR(LSM_ID_UNDEF, "prev",		0444),
+	ATTR(LSM_ID_UNDEF, "exec",		0666),
+	ATTR(LSM_ID_UNDEF, "fscreate",	0666),
+	ATTR(LSM_ID_UNDEF, "keycreate",	0666),
+	ATTR(LSM_ID_UNDEF, "sockcreate",	0666),
  #ifdef CONFIG_SECURITY_SMACK
  	DIR("smack",			0555,
  	    proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 9dda7e54b2d0..a889d9ef9584 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -92,7 +92,7 @@ union proc_op {
  	int (*proc_show)(struct seq_file *m,
  		struct pid_namespace *ns, struct pid *pid,
  		struct task_struct *task);
-	const char *lsm;
+	int lsmid;
  };
  
  struct proc_inode {
diff --git a/include/linux/security.h b/include/linux/security.h
index 569b1d8ab002..945101b0d404 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -470,10 +470,9 @@ int security_sem_semctl(struct kern_ipc_perm *sma, int cmd);
  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_getprocattr(struct task_struct *p, const char *lsm, const char *name,
+int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
  			 char **value);
-int security_setprocattr(const char *lsm, const char *name, void *value,
-			 size_t size);
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size);
  int security_netlink_send(struct sock *sk, struct sk_buff *skb);
  int security_ismaclabel(const char *name);
  int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
@@ -1332,14 +1331,14 @@ static inline void security_d_instantiate(struct dentry *dentry,
  					  struct inode *inode)
  { }
  
-static inline int security_getprocattr(struct task_struct *p, const char *lsm,
+static inline int security_getprocattr(struct task_struct *p, int lsmid,
  				       const char *name, char **value)
  {
  	return -EINVAL;
  }
  
-static inline int security_setprocattr(const char *lsm, char *name,
-				       void *value, size_t size)
+static inline int security_setprocattr(int lsmid, char *name, void *value,
+				       size_t size)
  {
  	return -EINVAL;
  }
diff --git a/security/security.c b/security/security.c
index 5a699e47478b..d942b0c8e32f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -3801,7 +3801,7 @@ EXPORT_SYMBOL(security_d_instantiate);
  /**
   * security_getprocattr() - Read an attribute for a task
   * @p: the task
- * @lsm: LSM name
+ * @lsmid: LSM identification
   * @name: attribute name
   * @value: attribute value
   *
@@ -3809,13 +3809,13 @@ EXPORT_SYMBOL(security_d_instantiate);
   *
   * Return: Returns the length of @value on success, a negative value otherwise.
   */
-int security_getprocattr(struct task_struct *p, const char *lsm,
-			 const char *name, char **value)
+int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
+			 char **value)
  {
  	struct security_hook_list *hp;
  
  	hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
-		if (lsm != NULL && strcmp(lsm, hp->lsmid->name))
+		if (lsmid != 0 && lsmid != hp->lsmid->id)
  			continue;
  		return hp->hook.getprocattr(p, name, value);
  	}
@@ -3824,7 +3824,7 @@ int security_getprocattr(struct task_struct *p, const char *lsm,
  
  /**
   * security_setprocattr() - Set an attribute for a task
- * @lsm: LSM name
+ * @lsmid: LSM identification
   * @name: attribute name
   * @value: attribute value
   * @size: attribute value size
@@ -3834,13 +3834,12 @@ int security_getprocattr(struct task_struct *p, const char *lsm,
   *
   * Return: Returns bytes written on success, a negative value otherwise.
   */
-int security_setprocattr(const char *lsm, const char *name, void *value,
-			 size_t size)
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size)
  {
  	struct security_hook_list *hp;
  
  	hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
-		if (lsm != NULL && strcmp(lsm, hp->lsmid->name))
+		if (lsmid != 0 && lsmid != hp->lsmid->id)
  			continue;
  		return hp->hook.setprocattr(name, value, size);
  	}






