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e3fea3f70f
OK, what we have so far is e.g. setxattr(path, name, whatever, 0, XATTR_REPLACE) with name being good enough to get through xattr_permission(). Then we reach security_inode_setxattr() with the desired value and size. Aha. name should begin with "security.selinux", or we won't get that far in selinux_inode_setxattr(). Suppose we got there and have enough permissions to relabel that sucker. We call security_context_to_sid() with value == NULL, size == 0. OK, we want ss_initialized to be non-zero. I.e. after everything had been set up and running. No problem... We do 1-byte kmalloc(), zero-length memcpy() (which doesn't oops, even thought the source is NULL) and put a NUL there. I.e. form an empty string. string_to_context_struct() is called and looks for the first ':' in there. Not found, -EINVAL we get. OK, security_context_to_sid_core() has rc == -EINVAL, force == 0, so it silently returns -EINVAL. All it takes now is not having CAP_MAC_ADMIN and we are fucked. All right, it might be a different bug (modulo strange code quoted in the report), but it's real. Easily fixed, AFAICS: Deal with size == 0, value == NULL case in selinux_inode_setxattr() Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Dave Jones <davej@redhat.com> Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: James Morris <james.l.morris@oracle.com> |
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include | ||
ss | ||
.gitignore | ||
avc.c | ||
exports.c | ||
hooks.c | ||
Kconfig | ||
Makefile | ||
netif.c | ||
netlabel.c | ||
netlink.c | ||
netnode.c | ||
netport.c | ||
nlmsgtab.c | ||
selinuxfs.c | ||
xfrm.c |