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authorJohn Johansen <john.johansen@canonical.com>2018-03-15 22:31:38 -0700
committerJohn Johansen <john.johansen@canonical.com>2018-03-23 17:33:52 -0700
commit1180b4c757aab5506f1be367000364dd5cf5cd02 (patch)
treeeb142855036307a48aef79de645a0169d408f836 /security
parentd53c9f4d212c25b09670a71e2a993071d1e637a2 (diff)
downloadlinux-stericsson-1180b4c757aab5506f1be367000364dd5cf5cd02.tar.gz
apparmor: fix dangling symlinks to policy rawdata after replacement
When policy replacement occurs the symlinks in the profile directory need to be updated to point to the new rawdata, otherwise once the old rawdata is removed the symlink becomes broken. Fix this by dynamically generating the symlink everytime it is read. These links are used enough that their value needs to be cached and this way we can avoid needing locking to read and update the link value. Fixes: a481f4d917835 ("apparmor: add custom apparmorfs that will be used by policy namespace files") BugLink: http://bugs.launchpad.net/bugs/1755563 Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security')
-rw-r--r--security/apparmor/apparmorfs.c126
1 files changed, 95 insertions, 31 deletions
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 701cb3e5ec3b..62301ddbbe5e 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -310,6 +310,7 @@ static struct dentry *aafs_create_dir(const char *name, struct dentry *parent)
* @name: name of dentry to create
* @parent: parent directory for this dentry
* @target: if symlink, symlink target string
+ * @private: private data
* @iops: struct of inode_operations that should be used
*
* If @target parameter is %NULL, then the @iops parameter needs to be
@@ -318,17 +319,17 @@ static struct dentry *aafs_create_dir(const char *name, struct dentry *parent)
static struct dentry *aafs_create_symlink(const char *name,
struct dentry *parent,
const char *target,
+ void *private,
const struct inode_operations *iops)
{
struct dentry *dent;
char *link = NULL;
if (target) {
- link = kstrdup(target, GFP_KERNEL);
if (!link)
return ERR_PTR(-ENOMEM);
}
- dent = aafs_create(name, S_IFLNK | 0444, parent, NULL, link, NULL,
+ dent = aafs_create(name, S_IFLNK | 0444, parent, private, link, NULL,
iops);
if (IS_ERR(dent))
kfree(link);
@@ -1479,26 +1480,95 @@ static int profile_depth(struct aa_profile *profile)
return depth;
}
-static int gen_symlink_name(char *buffer, size_t bsize, int depth,
- const char *dirname, const char *fname)
+static char *gen_symlink_name(int depth, const char *dirname, const char *fname)
{
+ char *buffer, *s;
int error;
+ int size = depth * 6 + strlen(dirname) + strlen(fname) + 11;
+
+ s = buffer = kmalloc(size, GFP_KERNEL);
+ if (!buffer)
+ return ERR_PTR(-ENOMEM);
for (; depth > 0; depth--) {
- if (bsize < 7)
- return -ENAMETOOLONG;
- strcpy(buffer, "../../");
- buffer += 6;
- bsize -= 6;
+ strcpy(s, "../../");
+ s += 6;
+ size -= 6;
}
- error = snprintf(buffer, bsize, "raw_data/%s/%s", dirname, fname);
- if (error >= bsize || error < 0)
- return -ENAMETOOLONG;
+ error = snprintf(s, size, "raw_data/%s/%s", dirname, fname);
+ if (error >= size || error < 0)
+ return ERR_PTR(-ENAMETOOLONG);
- return 0;
+ return buffer;
+}
+
+static void rawdata_link_cb(void *arg)
+{
+ kfree(arg);
+}
+
+static const char *rawdata_get_link_base(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done,
+ const char *name)
+{
+ struct aa_proxy *proxy = inode->i_private;
+ struct aa_label *label;
+ struct aa_profile *profile;
+ char *target;
+ int depth;
+
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
+ label = aa_get_label_rcu(&proxy->label);
+ profile = labels_profile(label);
+ depth = profile_depth(profile);
+ target = gen_symlink_name(depth, profile->rawdata->name, name);
+ aa_put_label(label);
+
+ if (IS_ERR(target))
+ return target;
+
+ set_delayed_call(done, rawdata_link_cb, target);
+
+ return target;
}
+static const char *rawdata_get_link_sha1(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ return rawdata_get_link_base(dentry, inode, done, "sha1");
+}
+
+static const char *rawdata_get_link_abi(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ return rawdata_get_link_base(dentry, inode, done, "abi");
+}
+
+static const char *rawdata_get_link_data(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ return rawdata_get_link_base(dentry, inode, done, "raw_data");
+}
+
+static const struct inode_operations rawdata_link_sha1_iops = {
+ .get_link = rawdata_get_link_sha1,
+};
+
+static const struct inode_operations rawdata_link_abi_iops = {
+ .get_link = rawdata_get_link_abi,
+};
+static const struct inode_operations rawdata_link_data_iops = {
+ .get_link = rawdata_get_link_data,
+};
+
+
/*
* Requires: @profile->ns->lock held
*/
@@ -1569,34 +1639,28 @@ int __aafs_profile_mkdir(struct aa_profile *profile, struct dentry *parent)
}
if (profile->rawdata) {
- char target[64];
- int depth = profile_depth(profile);
-
- error = gen_symlink_name(target, sizeof(target), depth,
- profile->rawdata->name, "sha1");
- if (error < 0)
- goto fail2;
- dent = aafs_create_symlink("raw_sha1", dir, target, NULL);
+ dent = aafs_create_symlink("raw_sha1", dir, NULL,
+ profile->label.proxy,
+ &rawdata_link_sha1_iops);
if (IS_ERR(dent))
goto fail;
+ aa_get_proxy(profile->label.proxy);
profile->dents[AAFS_PROF_RAW_HASH] = dent;
- error = gen_symlink_name(target, sizeof(target), depth,
- profile->rawdata->name, "abi");
- if (error < 0)
- goto fail2;
- dent = aafs_create_symlink("raw_abi", dir, target, NULL);
+ dent = aafs_create_symlink("raw_abi", dir, NULL,
+ profile->label.proxy,
+ &rawdata_link_abi_iops);
if (IS_ERR(dent))
goto fail;
+ aa_get_proxy(profile->label.proxy);
profile->dents[AAFS_PROF_RAW_ABI] = dent;
- error = gen_symlink_name(target, sizeof(target), depth,
- profile->rawdata->name, "raw_data");
- if (error < 0)
- goto fail2;
- dent = aafs_create_symlink("raw_data", dir, target, NULL);
+ dent = aafs_create_symlink("raw_data", dir, NULL,
+ profile->label.proxy,
+ &rawdata_link_data_iops);
if (IS_ERR(dent))
goto fail;
+ aa_get_proxy(profile->label.proxy);
profile->dents[AAFS_PROF_RAW_DATA] = dent;
}