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authorDmitry Kasatkin <d.kasatkin@samsung.com>2014-10-28 14:28:49 +0200
committerMimi Zohar <zohar@linux.vnet.ibm.com>2014-10-28 10:06:31 -0400
commit3b1deef6b1289a99505858a3b212c5b50adf0c2f (patch)
tree11e5e61319b3d2c45c718b044425fc35719de3a1 /security/integrity
parentima: check xattr value length and type in the ima_inode_setxattr() (diff)
downloadlinux-dev-3b1deef6b1289a99505858a3b212c5b50adf0c2f.tar.xz
linux-dev-3b1deef6b1289a99505858a3b212c5b50adf0c2f.zip
evm: check xattr value length and type in evm_inode_setxattr()
evm_inode_setxattr() can be called with no value. The function does not check the length so that following command can be used to produce the kernel oops: setfattr -n security.evm FOO. This patch fixes it. Changes in v3: * there is no reason to return different error codes for EVM_XATTR_HMAC and non EVM_XATTR_HMAC. Remove unnecessary test then. Changes in v2: * testing for validity of xattr type [ 1106.396921] BUG: unable to handle kernel NULL pointer dereference at (null) [ 1106.398192] IP: [<ffffffff812af7b8>] evm_inode_setxattr+0x2a/0x48 [ 1106.399244] PGD 29048067 PUD 290d7067 PMD 0 [ 1106.399953] Oops: 0000 [#1] SMP [ 1106.400020] Modules linked in: bridge stp llc evdev serio_raw i2c_piix4 button fuse [ 1106.400020] CPU: 0 PID: 3635 Comm: setxattr Not tainted 3.16.0-kds+ #2936 [ 1106.400020] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 1106.400020] task: ffff8800291a0000 ti: ffff88002917c000 task.ti: ffff88002917c000 [ 1106.400020] RIP: 0010:[<ffffffff812af7b8>] [<ffffffff812af7b8>] evm_inode_setxattr+0x2a/0x48 [ 1106.400020] RSP: 0018:ffff88002917fd50 EFLAGS: 00010246 [ 1106.400020] RAX: 0000000000000000 RBX: ffff88002917fdf8 RCX: 0000000000000000 [ 1106.400020] RDX: 0000000000000000 RSI: ffffffff818136d3 RDI: ffff88002917fdf8 [ 1106.400020] RBP: ffff88002917fd68 R08: 0000000000000000 R09: 00000000003ec1df [ 1106.400020] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800438a0a00 [ 1106.400020] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 1106.400020] FS: 00007f7dfa7d7740(0000) GS:ffff88005da00000(0000) knlGS:0000000000000000 [ 1106.400020] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1106.400020] CR2: 0000000000000000 CR3: 000000003763e000 CR4: 00000000000006f0 [ 1106.400020] Stack: [ 1106.400020] ffff8800438a0a00 ffff88002917fdf8 0000000000000000 ffff88002917fd98 [ 1106.400020] ffffffff812a1030 ffff8800438a0a00 ffff88002917fdf8 0000000000000000 [ 1106.400020] 0000000000000000 ffff88002917fde0 ffffffff8116d08a ffff88002917fdc8 [ 1106.400020] Call Trace: [ 1106.400020] [<ffffffff812a1030>] security_inode_setxattr+0x5d/0x6a [ 1106.400020] [<ffffffff8116d08a>] vfs_setxattr+0x6b/0x9f [ 1106.400020] [<ffffffff8116d1e0>] setxattr+0x122/0x16c [ 1106.400020] [<ffffffff811687e8>] ? mnt_want_write+0x21/0x45 [ 1106.400020] [<ffffffff8114d011>] ? __sb_start_write+0x10f/0x143 [ 1106.400020] [<ffffffff811687e8>] ? mnt_want_write+0x21/0x45 [ 1106.400020] [<ffffffff811687c0>] ? __mnt_want_write+0x48/0x4f [ 1106.400020] [<ffffffff8116d3e6>] SyS_setxattr+0x6e/0xb0 [ 1106.400020] [<ffffffff81529da9>] system_call_fastpath+0x16/0x1b [ 1106.400020] Code: c3 0f 1f 44 00 00 55 48 89 e5 41 55 49 89 d5 41 54 49 89 fc 53 48 89 f3 48 c7 c6 d3 36 81 81 48 89 df e8 18 22 04 00 85 c0 75 07 <41> 80 7d 00 02 74 0d 48 89 de 4c 89 e7 e8 5a fe ff ff eb 03 83 [ 1106.400020] RIP [<ffffffff812af7b8>] evm_inode_setxattr+0x2a/0x48 [ 1106.400020] RSP <ffff88002917fd50> [ 1106.400020] CR2: 0000000000000000 [ 1106.428061] ---[ end trace ae08331628ba3050 ]--- Reported-by: Jan Kara <jack@suse.cz> Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com> Cc: stable@vger.kernel.org Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Diffstat (limited to 'security/integrity')
-rw-r--r--security/integrity/evm/evm_main.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 9685af330de5..c5ee1a7c5e8a 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -319,9 +319,12 @@ int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
{
const struct evm_ima_xattr_data *xattr_data = xattr_value;
- if ((strcmp(xattr_name, XATTR_NAME_EVM) == 0)
- && (xattr_data->type == EVM_XATTR_HMAC))
- return -EPERM;
+ if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
+ if (!xattr_value_len)
+ return -EINVAL;
+ if (xattr_data->type != EVM_IMA_XATTR_DIGSIG)
+ return -EPERM;
+ }
return evm_protect_xattr(dentry, xattr_name, xattr_value,
xattr_value_len);
}