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ovl: filter trusted xattr for non-admin

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Filesystems filter out extended attributes in the "trusted." domain for
unprivlieged callers.

Overlay calls underlying filesystem's method with elevated privs, so need
to do the filtering in overlayfs too.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2017-05-29 15:15:27 +02:00
parent f3a1568582
commit a082c6f680
1 changed files with 11 additions and 1 deletions
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12
fs/overlayfs/inode.c
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@ -240,6 +240,16 @@ int ovl_xattr_get(struct dentry *dentry, const char *name,
return res; return res;
} }
static bool ovl_can_list(const char *s)
{
/* List all non-trusted xatts */
if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
return true;
/* Never list trusted.overlay, list other trusted for superuser only */
return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
}
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{ {
struct dentry *realdentry = ovl_dentry_real(dentry); struct dentry *realdentry = ovl_dentry_real(dentry);
@ -263,7 +273,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
return -EIO; return -EIO;
len -= slen; len -= slen;
if (ovl_is_private_xattr(s)) { if (!ovl_can_list(s)) {
res -= slen; res -= slen;
memmove(s, s + slen, len); memmove(s, s + slen, len);
} else { } else {