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-rw-r--r--fs/overlayfs/file.c4
-rw-r--r--fs/overlayfs/namei.c98
-rw-r--r--fs/overlayfs/ovl_entry.h2
-rw-r--r--fs/overlayfs/params.c40
-rw-r--r--fs/overlayfs/readdir.c4
-rw-r--r--fs/overlayfs/util.c9
6 files changed, 77 insertions, 80 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 969b458100fe..dfea7bd800cb 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -48,8 +48,8 @@ static struct file *ovl_open_realfile(const struct file *file,
if (!inode_owner_or_capable(real_idmap, realinode))
flags &= ~O_NOATIME;
- realfile = backing_file_open(&file->f_path, flags, realpath,
- current_cred());
+ realfile = backing_file_open(file_user_path((struct file *) file),
+ flags, realpath, current_cred());
}
ovl_revert_creds(old_cred);
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index bf722daf19a9..0b8b28392eb7 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -16,6 +16,7 @@
struct ovl_lookup_data {
struct super_block *sb;
+ struct dentry *dentry;
const struct ovl_layer *layer;
struct qstr name;
bool is_dir;
@@ -24,6 +25,7 @@ struct ovl_lookup_data {
bool stop;
bool last;
char *redirect;
+ char *upperredirect;
int metacopy;
/* Referring to last redirect xattr */
bool absolute_redirect;
@@ -1024,6 +1026,31 @@ int ovl_verify_lowerdata(struct dentry *dentry)
return ovl_maybe_validate_verity(dentry);
}
+/*
+ * Following redirects/metacopy can have security consequences: it's like a
+ * symlink into the lower layer without the permission checks.
+ *
+ * This is only a problem if the upper layer is untrusted (e.g comes from an USB
+ * drive). This can allow a non-readable file or directory to become readable.
+ *
+ * Only following redirects when redirects are enabled disables this attack
+ * vector when not necessary.
+ */
+static bool ovl_check_follow_redirect(struct ovl_lookup_data *d)
+{
+ struct ovl_fs *ofs = OVL_FS(d->sb);
+
+ if (d->metacopy && !ofs->config.metacopy) {
+ pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", d->dentry);
+ return false;
+ }
+ if ((d->redirect || d->upperredirect) && !ovl_redirect_follow(ofs)) {
+ pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n", d->dentry);
+ return false;
+ }
+ return true;
+}
+
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
@@ -1039,7 +1066,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int ctr = 0;
struct inode *inode = NULL;
bool upperopaque = false;
- char *upperredirect = NULL;
+ bool check_redirect = (ovl_redirect_follow(ofs) || ofs->numdatalayer);
struct dentry *this;
unsigned int i;
int err;
@@ -1047,12 +1074,14 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
int metacopy_size = 0;
struct ovl_lookup_data d = {
.sb = dentry->d_sb,
+ .dentry = dentry,
.name = dentry->d_name,
.is_dir = false,
.opaque = false,
.stop = false,
- .last = ovl_redirect_follow(ofs) ? false : !ovl_numlower(poe),
+ .last = check_redirect ? false : !ovl_numlower(poe),
.redirect = NULL,
+ .upperredirect = NULL,
.metacopy = 0,
};
@@ -1094,8 +1123,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (d.redirect) {
err = -ENOMEM;
- upperredirect = kstrdup(d.redirect, GFP_KERNEL);
- if (!upperredirect)
+ d.upperredirect = kstrdup(d.redirect, GFP_KERNEL);
+ if (!d.upperredirect)
goto out_put_upper;
if (d.redirect[0] == '/')
poe = roe;
@@ -1113,7 +1142,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
for (i = 0; !d.stop && i < ovl_numlower(poe); i++) {
struct ovl_path lower = ovl_lowerstack(poe)[i];
- if (!ovl_redirect_follow(ofs))
+ if (!ovl_check_follow_redirect(&d)) {
+ err = -EPERM;
+ goto out_put;
+ }
+
+ if (!check_redirect)
d.last = i == ovl_numlower(poe) - 1;
else if (d.is_dir || !ofs->numdatalayer)
d.last = lower.layer->idx == ovl_numlower(roe);
@@ -1126,13 +1160,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (!this)
continue;
- if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {
- dput(this);
- err = -EPERM;
- pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);
- goto out_put;
- }
-
/*
* If no origin fh is stored in upper of a merge dir, store fh
* of lower dir and set upper parent "impure".
@@ -1185,23 +1212,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
ctr++;
}
- /*
- * Following redirects can have security consequences: it's like
- * a symlink into the lower layer without the permission checks.
- * This is only a problem if the upper layer is untrusted (e.g
- * comes from an USB drive). This can allow a non-readable file
- * or directory to become readable.
- *
- * Only following redirects when redirects are enabled disables
- * this attack vector when not necessary.
- */
- err = -EPERM;
- if (d.redirect && !ovl_redirect_follow(ofs)) {
- pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n",
- dentry);
- goto out_put;
- }
-
if (d.stop)
break;
@@ -1212,10 +1222,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}
}
- /* Defer lookup of lowerdata in data-only layers to first access */
+ /*
+ * Defer lookup of lowerdata in data-only layers to first access.
+ * Don't require redirect=follow and metacopy=on in this case.
+ */
if (d.metacopy && ctr && ofs->numdatalayer && d.absolute_redirect) {
d.metacopy = 0;
ctr++;
+ } else if (!ovl_check_follow_redirect(&d)) {
+ err = -EPERM;
+ goto out_put;
}
/*
@@ -1298,20 +1314,26 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
/*
* It's safe to assign upperredirect here: the previous
- * assignment of happens only if upperdentry is non-NULL, and
+ * assignment happens only if upperdentry is non-NULL, and
* this one only if upperdentry is NULL.
*/
- upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0);
- if (IS_ERR(upperredirect)) {
- err = PTR_ERR(upperredirect);
- upperredirect = NULL;
+ d.upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0);
+ if (IS_ERR(d.upperredirect)) {
+ err = PTR_ERR(d.upperredirect);
+ d.upperredirect = NULL;
goto out_free_oe;
}
+
err = ovl_check_metacopy_xattr(ofs, &upperpath, NULL);
if (err < 0)
goto out_free_oe;
- uppermetacopy = err;
+ d.metacopy = uppermetacopy = err;
metacopy_size = err;
+
+ if (!ovl_check_follow_redirect(&d)) {
+ err = -EPERM;
+ goto out_free_oe;
+ }
}
if (upperdentry || ctr) {
@@ -1319,7 +1341,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
.upperdentry = upperdentry,
.oe = oe,
.index = index,
- .redirect = upperredirect,
+ .redirect = d.upperredirect,
};
/* Store lowerdata redirect for lazy lookup */
@@ -1361,7 +1383,7 @@ out_put_upper:
kfree(origin_path);
}
dput(upperdentry);
- kfree(upperredirect);
+ kfree(d.upperredirect);
out:
kfree(d.redirect);
ovl_revert_creds(old_cred);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index cb449ab310a7..afb7762f873f 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -51,7 +51,7 @@ struct ovl_path {
struct ovl_entry {
unsigned int __numlower;
- struct ovl_path __lowerstack[];
+ struct ovl_path __lowerstack[] __counted_by(__numlower);
};
/* private information held for overlayfs's superblock */
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 6759f7d040c8..f42488c01957 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -871,18 +871,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
config->uuid = OVL_UUID_NULL;
}
- /* Resolve verity -> metacopy dependency */
- if (config->verity_mode && !config->metacopy) {
- /* Don't allow explicit specified conflicting combinations */
- if (set.metacopy) {
- pr_err("conflicting options: metacopy=off,verity=%s\n",
- ovl_verity_mode(config));
- return -EINVAL;
- }
- /* Otherwise automatically enable metacopy. */
- config->metacopy = true;
- }
-
/*
* This is to make the logic below simpler. It doesn't make any other
* difference, since redirect_dir=on is only used for upper.
@@ -890,18 +878,13 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW)
config->redirect_mode = OVL_REDIRECT_ON;
- /* Resolve verity -> metacopy -> redirect_dir dependency */
+ /* metacopy -> redirect_dir dependency */
if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) {
if (set.metacopy && set.redirect) {
pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
ovl_redirect_mode(config));
return -EINVAL;
}
- if (config->verity_mode && set.redirect) {
- pr_err("conflicting options: verity=%s,redirect_dir=%s\n",
- ovl_verity_mode(config), ovl_redirect_mode(config));
- return -EINVAL;
- }
if (set.redirect) {
/*
* There was an explicit redirect_dir=... that resulted
@@ -970,7 +953,7 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
}
- /* Resolve userxattr -> !redirect && !metacopy && !verity dependency */
+ /* Resolve userxattr -> !redirect && !metacopy dependency */
if (config->userxattr) {
if (set.redirect &&
config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
@@ -982,11 +965,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
pr_err("conflicting options: userxattr,metacopy=on\n");
return -EINVAL;
}
- if (config->verity_mode) {
- pr_err("conflicting options: userxattr,verity=%s\n",
- ovl_verity_mode(config));
- return -EINVAL;
- }
/*
* Silently disable default setting of redirect and metacopy.
* This shall be the default in the future as well: these
@@ -1025,11 +1003,6 @@ int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
*/
}
- if (ctx->nr_data > 0 && !config->metacopy) {
- pr_err("lower data-only dirs require metacopy support.\n");
- return -EINVAL;
- }
-
return 0;
}
@@ -1078,17 +1051,16 @@ int ovl_show_options(struct seq_file *m, struct dentry *dentry)
seq_printf(m, ",redirect_dir=%s",
ovl_redirect_mode(&ofs->config));
if (ofs->config.index != ovl_index_def)
- seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
+ seq_printf(m, ",index=%s", str_on_off(ofs->config.index));
if (ofs->config.uuid != ovl_uuid_def())
seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config));
if (ofs->config.nfs_export != ovl_nfs_export_def)
- seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
- "on" : "off");
+ seq_printf(m, ",nfs_export=%s",
+ str_on_off(ofs->config.nfs_export));
if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs))
seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config));
if (ofs->config.metacopy != ovl_metacopy_def)
- seq_printf(m, ",metacopy=%s",
- ofs->config.metacopy ? "on" : "off");
+ seq_printf(m, ",metacopy=%s", str_on_off(ofs->config.metacopy));
if (ofs->config.ovl_volatile)
seq_puts(m, ",volatile");
if (ofs->config.userxattr)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 44e208da417c..474c80d210d1 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -13,6 +13,7 @@
#include <linux/security.h>
#include <linux/cred.h>
#include <linux/ratelimit.h>
+#include <linux/overflow.h>
#include "overlayfs.h"
struct ovl_cache_entry {
@@ -147,9 +148,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
u64 ino, unsigned int d_type)
{
struct ovl_cache_entry *p;
- size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
- p = kmalloc(size, GFP_KERNEL);
+ p = kmalloc(struct_size(p, name, len + 1), GFP_KERNEL);
if (!p)
return NULL;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 0819c739cc2f..dcccb4b4a66c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -15,6 +15,7 @@
#include <linux/uuid.h>
#include <linux/namei.h>
#include <linux/ratelimit.h>
+#include <linux/overflow.h>
#include "overlayfs.h"
/* Get write access to upper mnt - may fail if upper sb was remounted ro */
@@ -145,9 +146,9 @@ void ovl_stack_free(struct ovl_path *stack, unsigned int n)
struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
{
- size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]);
- struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+ struct ovl_entry *oe;
+ oe = kzalloc(struct_size(oe, __lowerstack, numlower), GFP_KERNEL);
if (oe)
oe->__numlower = numlower;
@@ -305,7 +306,9 @@ enum ovl_path_type ovl_path_realdata(struct dentry *dentry, struct path *path)
struct dentry *ovl_dentry_upper(struct dentry *dentry)
{
- return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
+ struct inode *inode = d_inode(dentry);
+
+ return inode ? ovl_upperdentry_dereference(OVL_I(inode)) : NULL;
}
struct dentry *ovl_dentry_lower(struct dentry *dentry)
generated by cgit (git 2.34.1) at 2025-06-08 05:09:31 +0000