diff options
| author | Benjamin Berg <benjamin@sipsolutions.net> | 2025-06-02 16:00:49 +0300 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2025-06-02 16:17:19 +0300 |
| commit | 8420e08fe3a594b6ffa07705ac270faa2ed452c5 (patch) | |
| tree | 22b578adabd9ef875fdaf560bd8d6a37eb8309b6 /arch/um/include/asm | |
| parent | b1e1bd2e69430445021394536740352be1b41cd0 (diff) | |
| download | linux-8420e08fe3a594b6ffa07705ac270faa2ed452c5.tar.xz | |
um: Track userspace children dying in SECCOMP mode
When in seccomp mode, we would hang forever on the futex if a child has
died unexpectedly. In contrast, ptrace mode will notice it and kill the
corresponding thread when it fails to run it.
Fix this issue using a new IRQ that is fired after a SIGCHLD and keeping
an (internal) list of all MMs. In the IRQ handler, find the affected MM
and set its PID to -1 as well as the futex variable to FUTEX_IN_KERN.
This, together with futex returning -EINTR after the signal is
sufficient to implement a race-free detection of a child dying.
Note that this also enables IRQ handling while starting a userspace
process. This should be safe and SECCOMP requires the IRQ in case the
process does not come up properly.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20250602130052.545733-5-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'arch/um/include/asm')
| -rw-r--r-- | arch/um/include/asm/irq.h | 5 | ||||
| -rw-r--r-- | arch/um/include/asm/mmu.h | 3 |
2 files changed, 6 insertions, 2 deletions
diff --git a/arch/um/include/asm/irq.h b/arch/um/include/asm/irq.h index 749dfe8512e8..36dbedd1af48 100644 --- a/arch/um/include/asm/irq.h +++ b/arch/um/include/asm/irq.h @@ -13,17 +13,18 @@ #define TELNETD_IRQ 8 #define XTERM_IRQ 9 #define RANDOM_IRQ 10 +#define SIGCHLD_IRQ 11 #ifdef CONFIG_UML_NET_VECTOR -#define VECTOR_BASE_IRQ (RANDOM_IRQ + 1) +#define VECTOR_BASE_IRQ (SIGCHLD_IRQ + 1) #define VECTOR_IRQ_SPACE 8 #define UM_FIRST_DYN_IRQ (VECTOR_IRQ_SPACE + VECTOR_BASE_IRQ) #else -#define UM_FIRST_DYN_IRQ (RANDOM_IRQ + 1) +#define UM_FIRST_DYN_IRQ (SIGCHLD_IRQ + 1) #endif diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h index a3eaca41ff61..4d0e4239f3cc 100644 --- a/arch/um/include/asm/mmu.h +++ b/arch/um/include/asm/mmu.h @@ -6,11 +6,14 @@ #ifndef __ARCH_UM_MMU_H #define __ARCH_UM_MMU_H +#include "linux/types.h" #include <mm_id.h> typedef struct mm_context { struct mm_id id; + struct list_head list; + /* Address range in need of a TLB sync */ unsigned long sync_tlb_range_from; unsigned long sync_tlb_range_to; |