[PATCH 5.15 131/177] selinux: fix sleeping function called from invalid context

Greg Kroah-Hartman
2021-12-20T15:15:54Z

From: Scott Mayhew <smayhew@redhat.com>

commit cc274ae7763d9700a56659f3228641d7069e7a3f upstream.

selinux_sb_mnt_opts_compat() is called via sget_fc() under the sb_lock
spinlock, so it can't use GFP_KERNEL allocations:

[ 868.565200] BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:230
[ 868.568246] in_atomic(): 1, irqs_disabled(): 0,
non_block: 0, pid: 4914, name: mount.nfs
[ 868.569626] preempt_count: 1, expected: 0
[ 868.570215] RCU nest depth: 0, expected: 0
[ 868.570809] Preemption disabled at:
[ 868.570810] [<0000000000000000>] 0x0
[ 868.571848] CPU: 1 PID: 4914 Comm: mount.nfs Kdump: loaded
Tainted: G W 5.16.0-rc5.2585cf9dfa #1
[ 868.573273] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS 1.14.0-4.fc34 04/01/2014
[ 868.574478] Call Trace:
[ 868.574844] <TASK>
[ 868.575156] dump_stack_lvl+0x34/0x44
[ 868.575692] __might_resched.cold+0xd6/0x10f
[ 868.576308] slab_pre_alloc_hook.constprop.0+0x89/0xf0
[ 868.577046] __kmalloc_track_caller+0x72/0x420
[ 868.577684] ? security_context_to_sid_core+0x48/0x2b0
[ 868.578569] kmemdup_nul+0x22/0x50
[ 868.579108] security_context_to_sid_core+0x48/0x2b0
[ 868.579854] ? _nfs4_proc_pathconf+0xff/0x110 [nfsv4]
[ 868.580742] ? nfs_reconfigure+0x80/0x80 [nfs]
[ 868.581355] security_context_str_to_sid+0x36/0x40
[ 868.581960] selinux_sb_mnt_opts_compat+0xb5/0x1e0
[ 868.582550] ? nfs_reconfigure+0x80/0x80 [nfs]
[ 868.583098] security_sb_mnt_opts_compat+0x2a/0x40
[ 868.583676] nfs_compare_super+0x113/0x220 [nfs]
[ 868.584249] ? nfs_try_mount_request+0x210/0x210 [nfs]
[ 868.584879] sget_fc+0xb5/0x2f0
[ 868.585267] nfs_get_tree_common+0x91/0x4a0 [nfs]
[ 868.585834] vfs_get_tree+0x25/0xb0
[ 868.586241] fc_mount+0xe/0x30
[ 868.586605] do_nfs4_mount+0x130/0x380 [nfsv4]
[ 868.587160] nfs4_try_get_tree+0x47/0xb0 [nfsv4]
[ 868.587724] vfs_get_tree+0x25/0xb0
[ 868.588193] do_new_mount+0x176/0x310
[ 868.588782] __x64_sys_mount+0x103/0x140
[ 868.589388] do_syscall_64+0x3b/0x90
[ 868.589935] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 868.590699] RIP: 0033:0x7f2b371c6c4e
[ 868.591239] Code: 48 8b 0d dd 71 0e 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00
00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d aa 71
0e 00 f7 d8 64 89 01 48
[ 868.593810] RSP: 002b:00007ffc83775d88 EFLAGS: 00000246
ORIG_RAX: 00000000000000a5
[ 868.594691] RAX: ffffffffffffffda RBX: 00007ffc83775f10 RCX: 00007f2b371c6c4e
[ 868.595504] RDX: 0000555d517247a0 RSI: 0000555d51724700 RDI: 0000555d51724540
[ 868.596317] RBP: 00007ffc83775f10 R08: 0000555d51726890 R09: 0000555d51726890
[ 868.597162] R10: 0000000000000000 R11: 0000000000000246 R12: 0000555d51726890
[ 868.598005] R13: 0000000000000003 R14: 0000555d517246e0 R15: 0000555d511ac925
[ 868.598826] </TASK>

Cc: stable@vger.kernel.org
Fixes: 69c4a42d72eb ("lsm,selinux: add new hook to compare new mount to an existing mount")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
[PM: cleanup/line-wrap the backtrace]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/selinux/hooks.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)

--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -611,10 +611,11 @@ static int bad_option(struct superblock_
return 0;
}

-static int parse_sid(struct super_block *sb, const char *s, u32 *sid)
+static int parse_sid(struct super_block *sb, const char *s, u32 *sid,
+ gfp_t gfp)
{
int rc = security_context_str_to_sid(&selinux_state, s,
- sid, GFP_KERNEL);
+ sid, gfp);
if (rc)
pr_warn("SELinux: security_context_str_to_sid"
"(%s) failed for (dev %s, type %s) errno=%d\n",
@@ -685,7 +686,8 @@ static int selinux_set_mnt_opts(struct s
*/
if (opts) {
if (opts->fscontext) {
- rc = parse_sid(sb, opts->fscontext, &fscontext_sid);
+ rc = parse_sid(sb, opts->fscontext, &fscontext_sid,
+ GFP_KERNEL);
if (rc)
goto out;
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid,
@@ -694,7 +696,8 @@ static int selinux_set_mnt_opts(struct s
sbsec->flags |= FSCONTEXT_MNT;
}
if (opts->context) {
- rc = parse_sid(sb, opts->context, &context_sid);
+ rc = parse_sid(sb, opts->context, &context_sid,
+ GFP_KERNEL);
if (rc)
goto out;
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid,
@@ -703,7 +706,8 @@ static int selinux_set_mnt_opts(struct s
sbsec->flags |= CONTEXT_MNT;
}
if (opts->rootcontext) {
- rc = parse_sid(sb, opts->rootcontext, &rootcontext_sid);
+ rc = parse_sid(sb, opts->rootcontext, &rootcontext_sid,
+ GFP_KERNEL);
if (rc)
goto out;
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid,
@@ -712,7 +716,8 @@ static int selinux_set_mnt_opts(struct s
sbsec->flags |= ROOTCONTEXT_MNT;
}
if (opts->defcontext) {
- rc = parse_sid(sb, opts->defcontext, &defcontext_sid);
+ rc = parse_sid(sb, opts->defcontext, &defcontext_sid,
+ GFP_KERNEL);
if (rc)
goto out;
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid,
@@ -2701,14 +2706,14 @@ static int selinux_sb_mnt_opts_compat(st
return (sbsec->flags & SE_MNTMASK) ? 1 : 0;

if (opts->fscontext) {
- rc = parse_sid(sb, opts->fscontext, &sid);
+ rc = parse_sid(sb, opts->fscontext, &sid, GFP_NOWAIT);
if (rc)
return 1;
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
return 1;
}
if (opts->context) {
- rc = parse_sid(sb, opts->context, &sid);
+ rc = parse_sid(sb, opts->context, &sid, GFP_NOWAIT);
if (rc)
return 1;
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
@@ -2718,14 +2723,14 @@ static int selinux_sb_mnt_opts_compat(st
struct inode_security_struct *root_isec;

root_isec = backing_inode_security(sb->s_root);
- rc = parse_sid(sb, opts->rootcontext, &sid);
+ rc = parse_sid(sb, opts->rootcontext, &sid, GFP_NOWAIT);
if (rc)
return 1;
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
return 1;
}
if (opts->defcontext) {
- rc = parse_sid(sb, opts->defcontext, &sid);
+ rc = parse_sid(sb, opts->defcontext, &sid, GFP_NOWAIT);
if (rc)
return 1;
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
@@ -2748,14 +2753,14 @@ static int selinux_sb_remount(struct sup
return 0;

if (opts->fscontext) {
- rc = parse_sid(sb, opts->fscontext, &sid);
+ rc = parse_sid(sb, opts->fscontext, &sid, GFP_KERNEL);
if (rc)
return rc;
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
goto out_bad_option;
}
if (opts->context) {
- rc = parse_sid(sb, opts->context, &sid);
+ rc = parse_sid(sb, opts->context, &sid, GFP_KERNEL);
if (rc)
return rc;
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
@@ -2764,14 +2769,14 @@ static int selinux_sb_remount(struct sup
if (opts->rootcontext) {
struct inode_security_struct *root_isec;
root_isec = backing_inode_security(sb->s_root);
- rc = parse_sid(sb, opts->rootcontext, &sid);
+ rc = parse_sid(sb, opts->rootcontext, &sid, GFP_KERNEL);
if (rc)
return rc;
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
goto out_bad_option;
}
if (opts->defcontext) {
- rc = parse_sid(sb, opts->defcontext, &sid);
+ rc = parse_sid(sb, opts->defcontext, &sid, GFP_KERNEL);
if (rc)
return rc;
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))