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scottmayhewpcmoore
scottmayhew
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pcmoore
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selinux: fix sleeping function called from invalid context
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: [email protected] Fixes: 69c4a42 ("lsm,selinux: add new hook to compare new mount to an existing mount") Signed-off-by: Scott Mayhew <[email protected]> [PM: cleanup/line-wrap the backtrace] Signed-off-by: Paul Moore <[email protected]>
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‎security/selinux/hooks.c‎

Lines changed: 19 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -611,10 +611,11 @@ static int bad_option(struct superblock_security_struct *sbsec, char flag,
611611
return 0;
612612
}
613613

614-
static int parse_sid(struct super_block *sb, const char *s, u32 *sid)
614+
static int parse_sid(struct super_block *sb, const char *s, u32 *sid,
615+
gfp_t gfp)
615616
{
616617
int rc = security_context_str_to_sid(&selinux_state, s,
617-
sid, GFP_KERNEL);
618+
sid, gfp);
618619
if (rc)
619620
pr_warn("SELinux: security_context_str_to_sid"
620621
"(%s) failed for (dev %s, type %s) errno=%d\n",
@@ -685,7 +686,8 @@ static int selinux_set_mnt_opts(struct super_block *sb,
685686
*/
686687
if (opts) {
687688
if (opts->fscontext) {
688-
rc = parse_sid(sb, opts->fscontext, &fscontext_sid);
689+
rc = parse_sid(sb, opts->fscontext, &fscontext_sid,
690+
GFP_KERNEL);
689691
if (rc)
690692
goto out;
691693
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid,
@@ -694,7 +696,8 @@ static int selinux_set_mnt_opts(struct super_block *sb,
694696
sbsec->flags |= FSCONTEXT_MNT;
695697
}
696698
if (opts->context) {
697-
rc = parse_sid(sb, opts->context, &context_sid);
699+
rc = parse_sid(sb, opts->context, &context_sid,
700+
GFP_KERNEL);
698701
if (rc)
699702
goto out;
700703
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid,
@@ -703,7 +706,8 @@ static int selinux_set_mnt_opts(struct super_block *sb,
703706
sbsec->flags |= CONTEXT_MNT;
704707
}
705708
if (opts->rootcontext) {
706-
rc = parse_sid(sb, opts->rootcontext, &rootcontext_sid);
709+
rc = parse_sid(sb, opts->rootcontext, &rootcontext_sid,
710+
GFP_KERNEL);
707711
if (rc)
708712
goto out;
709713
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid,
@@ -712,7 +716,8 @@ static int selinux_set_mnt_opts(struct super_block *sb,
712716
sbsec->flags |= ROOTCONTEXT_MNT;
713717
}
714718
if (opts->defcontext) {
715-
rc = parse_sid(sb, opts->defcontext, &defcontext_sid);
719+
rc = parse_sid(sb, opts->defcontext, &defcontext_sid,
720+
GFP_KERNEL);
716721
if (rc)
717722
goto out;
718723
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid,
@@ -2702,14 +2707,14 @@ static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
27022707
return (sbsec->flags & SE_MNTMASK) ? 1 : 0;
27032708

27042709
if (opts->fscontext) {
2705-
rc = parse_sid(sb, opts->fscontext, &sid);
2710+
rc = parse_sid(sb, opts->fscontext, &sid, GFP_NOWAIT);
27062711
if (rc)
27072712
return 1;
27082713
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
27092714
return 1;
27102715
}
27112716
if (opts->context) {
2712-
rc = parse_sid(sb, opts->context, &sid);
2717+
rc = parse_sid(sb, opts->context, &sid, GFP_NOWAIT);
27132718
if (rc)
27142719
return 1;
27152720
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
@@ -2719,14 +2724,14 @@ static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
27192724
struct inode_security_struct *root_isec;
27202725

27212726
root_isec = backing_inode_security(sb->s_root);
2722-
rc = parse_sid(sb, opts->rootcontext, &sid);
2727+
rc = parse_sid(sb, opts->rootcontext, &sid, GFP_NOWAIT);
27232728
if (rc)
27242729
return 1;
27252730
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
27262731
return 1;
27272732
}
27282733
if (opts->defcontext) {
2729-
rc = parse_sid(sb, opts->defcontext, &sid);
2734+
rc = parse_sid(sb, opts->defcontext, &sid, GFP_NOWAIT);
27302735
if (rc)
27312736
return 1;
27322737
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
@@ -2749,14 +2754,14 @@ static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
27492754
return 0;
27502755

27512756
if (opts->fscontext) {
2752-
rc = parse_sid(sb, opts->fscontext, &sid);
2757+
rc = parse_sid(sb, opts->fscontext, &sid, GFP_KERNEL);
27532758
if (rc)
27542759
return rc;
27552760
if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
27562761
goto out_bad_option;
27572762
}
27582763
if (opts->context) {
2759-
rc = parse_sid(sb, opts->context, &sid);
2764+
rc = parse_sid(sb, opts->context, &sid, GFP_KERNEL);
27602765
if (rc)
27612766
return rc;
27622767
if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
@@ -2765,14 +2770,14 @@ static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
27652770
if (opts->rootcontext) {
27662771
struct inode_security_struct *root_isec;
27672772
root_isec = backing_inode_security(sb->s_root);
2768-
rc = parse_sid(sb, opts->rootcontext, &sid);
2773+
rc = parse_sid(sb, opts->rootcontext, &sid, GFP_KERNEL);
27692774
if (rc)
27702775
return rc;
27712776
if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
27722777
goto out_bad_option;
27732778
}
27742779
if (opts->defcontext) {
2775-
rc = parse_sid(sb, opts->defcontext, &sid);
2780+
rc = parse_sid(sb, opts->defcontext, &sid, GFP_KERNEL);
27762781
if (rc)
27772782
return rc;
27782783
if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))

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