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    Subject[PATCH 3.17 239/319] ima: check xattr value length and type in the ima_inode_setxattr()
    Date
    3.17-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dmitry Kasatkin <d.kasatkin@samsung.com>

    commit a48fda9de94500a3152a56b723d0a64ae236547c upstream.

    ima_inode_setxattr() can be called with no value. Function does not
    check the length so that following command can be used to produce
    kernel oops: setfattr -n security.ima FOO. This patch fixes it.

    Changes in v3:
    * for stable reverted "allow setting hash only in fix or log mode"
    It will be a separate patch.

    Changes in v2:
    * testing validity of xattr type
    * allow setting hash only in fix or log mode (Mimi)

    [ 261.562522] BUG: unable to handle kernel NULL pointer dereference at (null)
    [ 261.564109] IP: [<ffffffff812af272>] ima_inode_setxattr+0x3e/0x5a
    [ 261.564109] PGD 3112f067 PUD 42965067 PMD 0
    [ 261.564109] Oops: 0000 [#1] SMP
    [ 261.564109] Modules linked in: bridge stp llc evdev serio_raw i2c_piix4 button fuse
    [ 261.564109] CPU: 0 PID: 3299 Comm: setxattr Not tainted 3.16.0-kds+ #2924
    [ 261.564109] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
    [ 261.564109] task: ffff8800428c2430 ti: ffff880042be0000 task.ti: ffff880042be0000
    [ 261.564109] RIP: 0010:[<ffffffff812af272>] [<ffffffff812af272>] ima_inode_setxattr+0x3e/0x5a
    [ 261.564109] RSP: 0018:ffff880042be3d50 EFLAGS: 00010246
    [ 261.564109] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000015
    [ 261.564109] RDX: 0000001500000000 RSI: 0000000000000000 RDI: ffff8800375cc600
    [ 261.564109] RBP: ffff880042be3d68 R08: 0000000000000000 R09: 00000000004d6256
    [ 261.564109] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88002149ba00
    [ 261.564109] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
    [ 261.564109] FS: 00007f6c1e219740(0000) GS:ffff88005da00000(0000) knlGS:0000000000000000
    [ 261.564109] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [ 261.564109] CR2: 0000000000000000 CR3: 000000003b35a000 CR4: 00000000000006f0
    [ 261.564109] Stack:
    [ 261.564109] ffff88002149ba00 ffff880042be3df8 0000000000000000 ffff880042be3d98
    [ 261.564109] ffffffff812a101b ffff88002149ba00 ffff880042be3df8 0000000000000000
    [ 261.564109] 0000000000000000 ffff880042be3de0 ffffffff8116d08a ffff880042be3dc8
    [ 261.564109] Call Trace:
    [ 261.564109] [<ffffffff812a101b>] security_inode_setxattr+0x48/0x6a
    [ 261.564109] [<ffffffff8116d08a>] vfs_setxattr+0x6b/0x9f
    [ 261.564109] [<ffffffff8116d1e0>] setxattr+0x122/0x16c
    [ 261.564109] [<ffffffff811687e8>] ? mnt_want_write+0x21/0x45
    [ 261.564109] [<ffffffff8114d011>] ? __sb_start_write+0x10f/0x143
    [ 261.564109] [<ffffffff811687e8>] ? mnt_want_write+0x21/0x45
    [ 261.564109] [<ffffffff811687c0>] ? __mnt_want_write+0x48/0x4f
    [ 261.564109] [<ffffffff8116d3e6>] SyS_setxattr+0x6e/0xb0
    [ 261.564109] [<ffffffff81529da9>] system_call_fastpath+0x16/0x1b
    [ 261.564109] Code: 48 89 f7 48 c7 c6 58 36 81 81 53 31 db e8 73 27 04 00 85 c0 75 28 bf 15 00 00 00 e8 8a a5 d9 ff 84 c0 75 05 83 cb ff eb 15 31 f6 <41> 80 7d 00 03 49 8b 7c 24 68 40 0f 94 c6 e8 e1 f9 ff ff 89 d8
    [ 261.564109] RIP [<ffffffff812af272>] ima_inode_setxattr+0x3e/0x5a
    [ 261.564109] RSP <ffff880042be3d50>
    [ 261.564109] CR2: 0000000000000000
    [ 261.599998] ---[ end trace 39a89a3fc267e652 ]---

    Reported-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
    Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    security/integrity/ima/ima_appraise.c | 2 ++
    security/integrity/integrity.h | 1 +
    2 files changed, 3 insertions(+)

    --- a/security/integrity/ima/ima_appraise.c
    +++ b/security/integrity/ima/ima_appraise.c
    @@ -378,6 +378,8 @@ int ima_inode_setxattr(struct dentry *de
    result = ima_protect_xattr(dentry, xattr_name, xattr_value,
    xattr_value_len);
    if (result == 1) {
    + if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
    + return -EINVAL;
    ima_reset_appraise_flags(dentry->d_inode,
    (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
    result = 0;
    --- a/security/integrity/integrity.h
    +++ b/security/integrity/integrity.h
    @@ -61,6 +61,7 @@ enum evm_ima_xattr_type {
    EVM_XATTR_HMAC,
    EVM_IMA_XATTR_DIGSIG,
    IMA_XATTR_DIGEST_NG,
    + IMA_XATTR_LAST
    };

    struct evm_ima_xattr_data {



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