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Message-ID: <20250520120000.25501-40-stephen.smalley.work@gmail.com>
Date: Tue, 20 May 2025 07:59:36 -0400
From: Stephen Smalley <stephen.smalley.work@...il.com>
To: selinux@...r.kernel.org
Cc: paul@...l-moore.com,
omosnace@...hat.com,
netdev@...r.kernel.org,
Stephen Smalley <stephen.smalley.work@...il.com>
Subject: [PATCH v3 38/42] selinux: make open_perms namespace-aware
Adjust the handling of the open_perms policy capability to
be namespace-aware. This ensures that file open permission
is checked against each namespace in accordance with the
namespace policy. Otherwise, a child SELinux namespace
could escape checking of file open permission in the
parent namespace by disabling it in its own policy.
Signed-off-by: Stephen Smalley <stephen.smalley.work@...il.com>
---
security/selinux/hooks.c | 111 +++++++++++++++++++++-------
security/selinux/include/security.h | 5 +-
2 files changed, 85 insertions(+), 31 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 9bcd84ea7c95..850533412896 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2022,22 +2022,6 @@ static inline u32 file_to_av(const struct file *file)
return av;
}
-/*
- * Convert a file to an access vector and include the correct
- * open permission.
- */
-static inline u32 open_file_to_av(struct file *file)
-{
- u32 av = file_to_av(file);
- struct inode *inode = file_inode(file);
-
- if (selinux_policycap_openperm() &&
- inode->i_sb->s_magic != SOCKFS_MAGIC)
- av |= FILE__OPEN;
-
- return av;
-}
-
/* Hook functions begin here. */
static int selinux_binder_set_context_mgr(const struct cred *mgr)
@@ -3321,7 +3305,13 @@ static int selinux_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
const struct cred *cred = current_cred();
struct inode *inode = d_backing_inode(dentry);
unsigned int ia_valid = iattr->ia_valid;
- u32 av = FILE__WRITE;
+ struct inode_security_struct *isec;
+ struct task_security_struct *tsec;
+ struct selinux_state *state;
+ struct common_audit_data ad;
+ u32 ssid, tsid, av, requested;
+ u16 sclass;
+ int rc;
/* ATTR_FORCE is just used for ATTR_KILL_S[UG]ID. */
if (ia_valid & ATTR_FORCE) {
@@ -3335,13 +3325,41 @@ static int selinux_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_TIMES_SET))
return dentry_has_perm(cred, dentry, FILE__SETATTR);
- if (selinux_policycap_openperm() &&
- inode->i_sb->s_magic != SOCKFS_MAGIC &&
- (ia_valid & ATTR_SIZE) &&
- !(ia_valid & ATTR_FILE))
- av |= FILE__OPEN;
+ /*
+ * The following is an inlined version of dentry_has_perm()->
+ * inode_has_perm()->cred_tsid_has_perm() in order to specialize
+ * the requested permissions based on the open_perms policycap
+ * value in each namespace.
+ */
+ ad.type = LSM_AUDIT_DATA_DENTRY;
+ ad.u.dentry = dentry;
+ __inode_security_revalidate(inode, dentry, true);
+ if (unlikely(IS_PRIVATE(inode)))
+ return 0;
+ isec = selinux_inode(inode);
+ tsid = isec->sid;
+ sclass = isec->sclass;
+ av = FILE__WRITE;
+
+ do {
+ tsec = selinux_cred(cred);
+ ssid = tsec->sid;
+ state = tsec->state;
+ requested = av;
+
+ if (selinux_policycap_openperm(state) &&
+ inode->i_sb->s_magic != SOCKFS_MAGIC &&
+ (ia_valid & ATTR_SIZE) &&
+ !(ia_valid & ATTR_FILE))
+ requested |= FILE__OPEN;
+
+ rc = avc_has_perm(state, ssid, tsid, sclass, requested, &ad);
+ if (rc)
+ return rc;
+ cred = tsec->parent_cred;
+ } while (cred);
- return dentry_has_perm(cred, dentry, av);
+ return 0;
}
static int selinux_inode_getattr(const struct path *path)
@@ -4169,11 +4187,17 @@ static int selinux_file_receive(struct file *file)
static int selinux_file_open(struct file *file)
{
- struct file_security_struct *fsec;
- struct inode_security_struct *isec;
+ struct file_security_struct *fsec = selinux_file(file);
+ struct inode *inode = file_inode(file);
+ struct inode_security_struct *isec = inode_security(inode);
+ const struct cred *cred = file->f_cred;
+ struct task_security_struct *tsec;
+ struct selinux_state *state;
+ struct common_audit_data ad;
+ u32 ssid, tsid, av, requested;
+ u16 sclass;
+ int rc;
- fsec = selinux_file(file);
- isec = inode_security(file_inode(file));
/*
* Save inode label and policy sequence number
* at open-time so that selinux_file_permission
@@ -4191,7 +4215,38 @@ static int selinux_file_open(struct file *file)
* new inode label or new policy.
* This check is not redundant - do not remove.
*/
- return file_path_has_perm(file->f_cred, file, open_file_to_av(file));
+ /*
+ * The following is an inlined version of file_path_has_perm()->
+ * inode_has_perm()->cred_tsid_has_perm() in order to specialize
+ * the requested permissions based on the open_perms policycap
+ * value in each namespace.
+ */
+ ad.type = LSM_AUDIT_DATA_FILE;
+ ad.u.file = file;
+ cred = file->f_cred;
+ if (unlikely(IS_PRIVATE(inode)))
+ return 0;
+ tsid = isec->sid;
+ sclass = isec->sclass;
+ av = file_to_av(file);
+
+ do {
+ tsec = selinux_cred(cred);
+ ssid = tsec->sid;
+ state = tsec->state;
+ requested = av;
+
+ if (selinux_policycap_openperm(state) &&
+ inode->i_sb->s_magic != SOCKFS_MAGIC)
+ requested |= FILE__OPEN;
+
+ rc = avc_has_perm(state, ssid, tsid, sclass, requested, &ad);
+ if (rc)
+ return rc;
+ cred = tsec->parent_cred;
+ } while (cred);
+
+ return 0;
}
/* task security operations */
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index e1c1b2da9256..a9ef6d97b88d 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -229,10 +229,9 @@ static inline bool selinux_policycap_netpeer(void)
current_selinux_state->policycap[POLICYDB_CAP_NETPEER]);
}
-static inline bool selinux_policycap_openperm(void)
+static inline bool selinux_policycap_openperm(struct selinux_state *state)
{
- return READ_ONCE(
- current_selinux_state->policycap[POLICYDB_CAP_OPENPERM]);
+ return READ_ONCE(state->policycap[POLICYDB_CAP_OPENPERM]);
}
static inline bool selinux_policycap_extsockclass(void)
--
2.49.0
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