[PATCH 1/5] selinux: introduce security_context_str_to_sid

Rasmus Villemoes
2015-09-25T22:34:49Z

There seems to be a little confusion as to whether the scontext_len
parameter of security_context_to_sid() includes the nul-byte or
not. Reading security_context_to_sid_core(), it seems that the
expectation is that it does not (both the string copying and the test
for scontext_len being zero hint at that).

Introduce the helper security_context_str_to_sid() to do the strlen()
call and fix all callers.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
security/selinux/hooks.c | 12 ++++--------
security/selinux/include/security.h | 2 ++
security/selinux/selinuxfs.c | 26 +++++++++-----------------
security/selinux/ss/services.c | 5 +++++
4 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e4369d86e588..fd50cd5ac2ec 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -674,10 +674,9 @@ static int selinux_set_mnt_opts(struct super_block *sb,

if (flags[i] == SBLABEL_MNT)
continue;
- rc = security_context_to_sid(mount_options[i],
- strlen(mount_options[i]), &sid, GFP_KERNEL);
+ rc = security_context_str_to_sid(mount_options[i], &sid, GFP_KERNEL);
if (rc) {
- printk(KERN_WARNING "SELinux: security_context_to_sid"
+ printk(KERN_WARNING "SELinux: security_context_str_to_sid"
"(%s) failed for (dev %s, type %s) errno=%d\n",
mount_options[i], sb->s_id, name, rc);
goto out;
@@ -2617,15 +2616,12 @@ static int selinux_sb_remount(struct super_block *sb, void *data)

for (i = 0; i < opts.num_mnt_opts; i++) {
u32 sid;
- size_t len;

if (flags[i] == SBLABEL_MNT)
continue;
- len = strlen(mount_options[i]);
- rc = security_context_to_sid(mount_options[i], len, &sid,
- GFP_KERNEL);
+ rc = security_context_str_to_sid(mount_options[i], &sid, GFP_KERNEL);
if (rc) {
- printk(KERN_WARNING "SELinux: security_context_to_sid"
+ printk(KERN_WARNING "SELinux: security_context_str_to_sid"
"(%s) failed for (dev %s, type %s) errno=%d\n",
mount_options[i], sb->s_id, sb->s_type->name, rc);
goto out_free_opts;
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index 6a681d26bf20..223e9fd15d66 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -166,6 +166,8 @@ int security_sid_to_context_force(u32 sid, char **scontext, u32 *scontext_len);
int security_context_to_sid(const char *scontext, u32 scontext_len,
u32 *out_sid, gfp_t gfp);

+int security_context_str_to_sid(const char *scontext, u32 *out_sid, gfp_t gfp);
+
int security_context_to_sid_default(const char *scontext, u32 scontext_len,
u32 *out_sid, u32 def_sid, gfp_t gfp_flags);

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 5bed7716f8ab..c02da25d7b63 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -731,13 +731,11 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
goto out;

- length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;

- length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;

@@ -819,13 +817,11 @@ static ssize_t sel_write_create(struct file *file, char *buf, size_t size)
objname = namebuf;
}

- length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;

- length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;

@@ -882,13 +878,11 @@ static ssize_t sel_write_relabel(struct file *file, char *buf, size_t size)
if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
goto out;

- length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;

- length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;

@@ -940,7 +934,7 @@ static ssize_t sel_write_user(struct file *file, char *buf, size_t size)
if (sscanf(buf, "%s %s", con, user) != 2)
goto out;

- length = security_context_to_sid(con, strlen(con) + 1, &sid, GFP_KERNEL);
+ length = security_context_str_to_sid(con, &sid, GFP_KERNEL);
if (length)
goto out;

@@ -1000,13 +994,11 @@ static ssize_t sel_write_member(struct file *file, char *buf, size_t size)
if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
goto out;

- length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
if (length)
goto out;

- length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
- GFP_KERNEL);
+ length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
if (length)
goto out;

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index b7df12ba61d8..c550df0e0ff1 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -1476,6 +1476,11 @@ int security_context_to_sid(const char *scontext, u32 scontext_len, u32 *sid,
sid, SECSID_NULL, gfp, 0);
}

+int security_context_str_to_sid(const char *scontext, u32 *sid, gfp_t gfp)
+{
+ return security_context_to_sid(scontext, strlen(scontext), sid, gfp);
+}
+
/**
* security_context_to_sid_default - Obtain a SID for a given security context,
* falling back to specified default if needed.
--
2.1.3