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Subject[PATCH] Remove use of mnt_ns->root and fix a couple of bugs in d_namespace_path
Date
Remove the unnecassary use of mnt_ns->root from path lookups, and replace
it with passing stuct path { NULL, NULL } to __d_path. As part of this
remove the disconnect case CHROOT_NSCONNECT which is ununsed.
Fix the sysctl check to use path.dentry, instead of the unsafe tmp.dentry

Adjust the return code for disconnected from -ESTALE to -EACCES as AppArmor
is denying access.

Signed-off-by: John Johansen <john.johansen@canonical.com>
---
security/apparmor/file.c | 2 +-
security/apparmor/path.c | 57 +++++++++++++++++++--------------------------
2 files changed, 25 insertions(+), 34 deletions(-)
diff --git a/security/apparmor/file.c b/security/apparmor/file.c
index 7312db7..8d7806e 100644
--- a/security/apparmor/file.c
+++ b/security/apparmor/file.c
@@ -289,7 +289,7 @@ int aa_path_perm(int op, struct aa_profile *profile, struct path *path,
perms.allow = request;
} else if (error == -ENOENT)
info = "Failed name lookup - deleted entry";
- else if (error == -ESTALE)
+ else if (error == -EACCES)
info = "Failed name lookup - disconnected path";
else if (error == -ENAMETOOLONG)
info = "Failed name lookup - name too long";
diff --git a/security/apparmor/path.c b/security/apparmor/path.c
index 36cc0cc..670d40d 100644
--- a/security/apparmor/path.c
+++ b/security/apparmor/path.c
@@ -57,22 +57,17 @@ static int prepend(char **buffer, int buflen, const char *str, int namelen)
static int d_namespace_path(struct path *path, char *buf, int buflen,
char **name, int flags)
{
- struct path root, tmp;
+ struct path root, tmp = { };
char *res;
- int connected, error = 0;
+ int error = 0;
+
+ get_fs_root(current->fs, &root);

/* Get the root we want to resolve too, released below */
- if (flags & PATH_CHROOT_REL) {
+ if (flags & PATH_CHROOT_REL)
/* resolve paths relative to chroot */
- get_fs_root(current->fs, &root);
- } else {
- /* resolve paths relative to namespace */
- root.mnt = current->nsproxy->mnt_ns->root;
- root.dentry = root.mnt->mnt_root;
- path_get(&root);
- }
+ tmp = root;

- tmp = root;
res = __d_path(path, &tmp, buf, buflen);

*name = res;
@@ -97,10 +92,17 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
goto out;
}

- /* Determine if the path is connected to the expected root */
- connected = tmp.dentry == root.dentry && tmp.mnt == root.mnt;
+ /* is the path a sysctl? */
+ if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
+ strncmp(*name, "/sys/", 5) == 0) {
+ /* TODO: convert over to using a per namespace
+ * control instead of hard coded /proc
+ */
+ error = prepend(name, *name - buf, "/proc", 5);
+ }

- /* If the path is not connected,
+ /* Determine if the path is connected to the expected root
+ * If the path is not connected,
* check if it is a sysctl and handle specially else remove any
* leading / that __d_path may have returned.
* Unless
@@ -111,25 +113,14 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
* of chroot) and specifically directed to connect paths to
* namespace root.
*/
- if (!connected) {
- /* is the disconnect path a sysctl? */
- if (tmp.dentry->d_sb->s_magic == PROC_SUPER_MAGIC &&
- strncmp(*name, "/sys/", 5) == 0) {
- /* TODO: convert over to using a per namespace
- * control instead of hard coded /proc
- */
- error = prepend(name, *name - buf, "/proc", 5);
- } else if (!(flags & PATH_CONNECT_PATH) &&
- !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) &&
- (tmp.mnt == current->nsproxy->mnt_ns->root &&
- tmp.dentry == tmp.mnt->mnt_root))) {
- /* disconnected path, don't return pathname starting
- * with '/'
- */
- error = -ESTALE;
- if (*res == '/')
- *name = res + 1;
- }
+ if ((tmp.dentry == root.dentry && tmp.mnt == root.mnt) &&
+ !(flags & PATH_CONNECT_PATH)) {
+ /* disconnected path, don't return pathname starting
+ * with '/'
+ */
+ error = -EACCES;
+ if (*res == '/')
+ *name = res + 1;
}

out:
--
1.7.5.4


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