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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Miklos Szeredi <mszeredi@redhat.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 07/50] cap: fix conversions on getxattr
Date: Mon, 22 Feb 2021 13:12:58 +0100
Message-ID: <20210222121021.690228921@linuxfoundation.org> (raw)
In-Reply-To: <20210222121019.925481519@linuxfoundation.org>

From: Miklos Szeredi <mszeredi@redhat.com>

[ Upstream commit f2b00be488730522d0fb7a8a5de663febdcefe0a ]

If a capability is stored on disk in v2 format cap_inode_getsecurity() will
currently return in v2 format unconditionally.

This is wrong: v2 cap should be equivalent to a v3 cap with zero rootid,
and so the same conversions performed on it.

If the rootid cannot be mapped, v3 is returned unconverted.  Fix this so
that both v2 and v3 return -EOVERFLOW if the rootid (or the owner of the fs
user namespace in case of v2) cannot be mapped into the current user
namespace.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/commoncap.c | 67 ++++++++++++++++++++++++++++----------------
 1 file changed, 43 insertions(+), 24 deletions(-)

diff --git a/security/commoncap.c b/security/commoncap.c
index f86557a8e43f6..a1dee0ab345a2 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -377,10 +377,11 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
 {
 	int size, ret;
 	kuid_t kroot;
+	u32 nsmagic, magic;
 	uid_t root, mappedroot;
 	char *tmpbuf = NULL;
 	struct vfs_cap_data *cap;
-	struct vfs_ns_cap_data *nscap;
+	struct vfs_ns_cap_data *nscap = NULL;
 	struct dentry *dentry;
 	struct user_namespace *fs_ns;
 
@@ -402,46 +403,61 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
 	fs_ns = inode->i_sb->s_user_ns;
 	cap = (struct vfs_cap_data *) tmpbuf;
 	if (is_v2header((size_t) ret, cap)) {
-		/* If this is sizeof(vfs_cap_data) then we're ok with the
-		 * on-disk value, so return that.  */
-		if (alloc)
-			*buffer = tmpbuf;
-		else
-			kfree(tmpbuf);
-		return ret;
-	} else if (!is_v3header((size_t) ret, cap)) {
-		kfree(tmpbuf);
-		return -EINVAL;
+		root = 0;
+	} else if (is_v3header((size_t) ret, cap)) {
+		nscap = (struct vfs_ns_cap_data *) tmpbuf;
+		root = le32_to_cpu(nscap->rootid);
+	} else {
+		size = -EINVAL;
+		goto out_free;
 	}
 
-	nscap = (struct vfs_ns_cap_data *) tmpbuf;
-	root = le32_to_cpu(nscap->rootid);
 	kroot = make_kuid(fs_ns, root);
 
 	/* If the root kuid maps to a valid uid in current ns, then return
 	 * this as a nscap. */
 	mappedroot = from_kuid(current_user_ns(), kroot);
 	if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
+		size = sizeof(struct vfs_ns_cap_data);
 		if (alloc) {
-			*buffer = tmpbuf;
+			if (!nscap) {
+				/* v2 -> v3 conversion */
+				nscap = kzalloc(size, GFP_ATOMIC);
+				if (!nscap) {
+					size = -ENOMEM;
+					goto out_free;
+				}
+				nsmagic = VFS_CAP_REVISION_3;
+				magic = le32_to_cpu(cap->magic_etc);
+				if (magic & VFS_CAP_FLAGS_EFFECTIVE)
+					nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
+				memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
+				nscap->magic_etc = cpu_to_le32(nsmagic);
+			} else {
+				/* use allocated v3 buffer */
+				tmpbuf = NULL;
+			}
 			nscap->rootid = cpu_to_le32(mappedroot);
-		} else
-			kfree(tmpbuf);
-		return size;
+			*buffer = nscap;
+		}
+		goto out_free;
 	}
 
 	if (!rootid_owns_currentns(kroot)) {
-		kfree(tmpbuf);
-		return -EOPNOTSUPP;
+		size = -EOVERFLOW;
+		goto out_free;
 	}
 
 	/* This comes from a parent namespace.  Return as a v2 capability */
 	size = sizeof(struct vfs_cap_data);
 	if (alloc) {
-		*buffer = kmalloc(size, GFP_ATOMIC);
-		if (*buffer) {
-			struct vfs_cap_data *cap = *buffer;
-			__le32 nsmagic, magic;
+		if (nscap) {
+			/* v3 -> v2 conversion */
+			cap = kzalloc(size, GFP_ATOMIC);
+			if (!cap) {
+				size = -ENOMEM;
+				goto out_free;
+			}
 			magic = VFS_CAP_REVISION_2;
 			nsmagic = le32_to_cpu(nscap->magic_etc);
 			if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
@@ -449,9 +465,12 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
 			memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
 			cap->magic_etc = cpu_to_le32(magic);
 		} else {
-			size = -ENOMEM;
+			/* use unconverted v2 */
+			tmpbuf = NULL;
 		}
+		*buffer = cap;
 	}
+out_free:
 	kfree(tmpbuf);
 	return size;
 }
-- 
2.27.0




  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 12:12 [PATCH 4.19 00/50] 4.19.177-rc1 review Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 01/50] tracing: Do not count ftrace events in top level enable output Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 02/50] tracing: Check length before giving out the filter buffer Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 03/50] arm/xen: Dont probe xenbus as part of an early initcall Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 04/50] arm64: dts: rockchip: Fix PCIe DT properties on rk3399 Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 05/50] platform/x86: hp-wmi: Disable tablet-mode reporting by default Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 06/50] ovl: perform vfs_getxattr() with mounter creds Greg Kroah-Hartman
2021-02-22 12:12 ` Greg Kroah-Hartman [this message]
2021-02-22 12:12 ` [PATCH 4.19 08/50] ovl: skip getxattr of security labels Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 09/50] drm/amd/display: Fix dc_sink kref count in emulated_link_detect Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 10/50] drm/amd/display: Free atomic state after drm_atomic_commit Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 11/50] riscv: virt_addr_valid must check the address belongs to linear mapping Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 12/50] bfq-iosched: Revert "bfq: Fix computation of shallow depth" Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 13/50] ARM: dts: lpc32xx: Revert set default clock rate of HCLK PLL Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 14/50] ARM: ensure the signal page contains defined contents Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 15/50] ARM: kexec: fix oops after TLB are invalidated Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 16/50] mt76: dma: fix a possible memory leak in mt76_add_fragment() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 17/50] bpf: Check for integer overflow when using roundup_pow_of_two() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 18/50] netfilter: xt_recent: Fix attempt to update deleted entry Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 19/50] netfilter: flowtable: fix tcp and udp header checksum update Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 20/50] xen/netback: avoid race in xenvif_rx_ring_slots_available() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 21/50] net: stmmac: set TxQ mode back to DCB after disabling CBS Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 22/50] netfilter: conntrack: skip identical origin tuple in same zone only Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 23/50] net: hns3: add a check for queue_id in hclge_reset_vf_queue() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 24/50] firmware_loader: align .builtin_fw to 8 Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 25/50] i2c: stm32f7: fix configuration of the digital filter Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 26/50] h8300: fix PREEMPTION build, TI_PRE_COUNT undefined Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 27/50] usb: dwc3: ulpi: fix checkpatch warning Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 28/50] usb: dwc3: ulpi: Replace CPU-based busyloop with Protocol-based one Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 29/50] net: fix iteration for sctp transport seq_files Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 30/50] net/vmw_vsock: improve locking in vsock_connect_timeout() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 31/50] net: watchdog: hold device global xmit lock during tx disable Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 32/50] vsock/virtio: update credit only if socket is not closed Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 33/50] vsock: fix locking in vsock_shutdown() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 34/50] net/rds: restrict iovecs length for RDS_CMSG_RDMA_ARGS Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 35/50] net/qrtr: restrict user-controlled length in qrtr_tun_write_iter() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 36/50] ovl: expand warning in ovl_d_real() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 37/50] x86/build: Disable CET instrumentation in the kernel for 32-bit too Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 38/50] KVM: SEV: fix double locking due to incorrect backport Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 39/50] net: qrtr: Fix port ID for control messages Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 40/50] Xen/x86: dont bail early from clear_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 41/50] Xen/x86: also check kernel mapping in set_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 42/50] Xen/gntdev: correct dev_bus_addr handling in gntdev_map_grant_pages() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 43/50] Xen/gntdev: correct error checking " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 44/50] xen/arm: dont ignore return errors from set_phys_to_machine Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 45/50] xen-blkback: dont "handle" error by BUG() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 46/50] xen-netback: " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 47/50] xen-scsiback: " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 48/50] xen-blkback: fix error handling in xen_blkbk_map() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 49/50] scsi: qla2xxx: Fix crash during driver load on big endian machines Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 50/50] kvm: check tlbs_dirty directly Greg Kroah-Hartman
2021-02-22 18:40 ` [PATCH 4.19 00/50] 4.19.177-rc1 review Pavel Machek
2021-02-22 21:28 ` Guenter Roeck
2021-02-22 21:49 ` Igor
2021-02-23 10:10 ` Naresh Kamboju
2021-02-23 21:17 ` Shuah Khan

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