From 12df58ad294253ac1d8df0c9bb9cf726397a671d Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 31 Jul 2025 01:47:30 +0200 Subject: bpf: Add cookie object to bpf maps Add a cookie to BPF maps to uniquely identify BPF maps for the timespan when the node is up. This is different to comparing a pointer or BPF map id which could get rolled over and reused. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f9cd2164ed23..308530c8326b 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -310,6 +310,7 @@ struct bpf_map { bool free_after_rcu_gp; atomic64_t sleepable_refcnt; s64 __percpu *elem_count; + u64 cookie; /* write-once */ }; static inline const char *btf_field_type_name(enum btf_field_type type) -- cgit v1.2.3 From fd1c98f0ef5cbcec842209776505d9e70d8fcd53 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 31 Jul 2025 01:47:31 +0200 Subject: bpf: Move bpf map owner out of common struct Given this is only relevant for BPF tail call maps, it is adding up space and penalizing other map types. We also need to extend this with further objects to track / compare to. Therefore, lets move this out into a separate structure and dynamically allocate it only for BPF tail call maps. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-2-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 308530c8326b..a87646cc5398 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -260,6 +260,18 @@ struct bpf_list_node_kern { void *owner; } __attribute__((aligned(8))); +/* 'Ownership' of program-containing map is claimed by the first program + * that is going to use this map or by the first program which FD is + * stored in the map to make sure that all callers and callees have the + * same prog type, JITed flag and xdp_has_frags flag. + */ +struct bpf_map_owner { + enum bpf_prog_type type; + bool jited; + bool xdp_has_frags; + const struct btf_type *attach_func_proto; +}; + struct bpf_map { const struct bpf_map_ops *ops; struct bpf_map *inner_map_meta; @@ -292,18 +304,8 @@ struct bpf_map { struct rcu_head rcu; }; atomic64_t writecnt; - /* 'Ownership' of program-containing map is claimed by the first program - * that is going to use this map or by the first program which FD is - * stored in the map to make sure that all callers and callees have the - * same prog type, JITed flag and xdp_has_frags flag. - */ - struct { - const struct btf_type *attach_func_proto; - spinlock_t lock; - enum bpf_prog_type type; - bool jited; - bool xdp_has_frags; - } owner; + spinlock_t owner_lock; + struct bpf_map_owner *owner; bool bypass_spec_v1; bool frozen; /* write-once; write-protected by freeze_mutex */ bool free_after_mult_rcu_gp; @@ -2109,6 +2111,16 @@ static inline bool bpf_map_flags_access_ok(u32 access_flags) (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG); } +static inline struct bpf_map_owner *bpf_map_owner_alloc(struct bpf_map *map) +{ + return kzalloc(sizeof(*map->owner), GFP_ATOMIC); +} + +static inline void bpf_map_owner_free(struct bpf_map *map) +{ + kfree(map->owner); +} + struct bpf_event_entry { struct perf_event *event; struct file *perf_file; -- cgit v1.2.3 From 9621e60f59eae87eb9ffe88d90f24f391a1ef0f0 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 31 Jul 2025 01:47:32 +0200 Subject: bpf: Move cgroup iterator helpers to bpf.h Move them into bpf.h given we also need them in core code. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- include/linux/bpf-cgroup.h | 5 ----- include/linux/bpf.h | 22 ++++++++++++++-------- 2 files changed, 14 insertions(+), 13 deletions(-) (limited to 'include/linux') diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h index 082ccd8ad96b..aedf573bdb42 100644 --- a/include/linux/bpf-cgroup.h +++ b/include/linux/bpf-cgroup.h @@ -77,9 +77,6 @@ to_cgroup_bpf_attach_type(enum bpf_attach_type attach_type) extern struct static_key_false cgroup_bpf_enabled_key[MAX_CGROUP_BPF_ATTACH_TYPE]; #define cgroup_bpf_enabled(atype) static_branch_unlikely(&cgroup_bpf_enabled_key[atype]) -#define for_each_cgroup_storage_type(stype) \ - for (stype = 0; stype < MAX_BPF_CGROUP_STORAGE_TYPE; stype++) - struct bpf_cgroup_storage_map; struct bpf_storage_buffer { @@ -510,8 +507,6 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map, #define BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock, level, optname, optval, optlen, \ kernel_optval) ({ 0; }) -#define for_each_cgroup_storage_type(stype) for (; false; ) - #endif /* CONFIG_CGROUP_BPF */ #endif /* _BPF_CGROUP_H */ diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a87646cc5398..02aa41e301a5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -208,6 +208,20 @@ enum btf_field_type { BPF_RES_SPIN_LOCK = (1 << 12), }; +enum bpf_cgroup_storage_type { + BPF_CGROUP_STORAGE_SHARED, + BPF_CGROUP_STORAGE_PERCPU, + __BPF_CGROUP_STORAGE_MAX +#define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX +}; + +#ifdef CONFIG_CGROUP_BPF +# define for_each_cgroup_storage_type(stype) \ + for (stype = 0; stype < MAX_BPF_CGROUP_STORAGE_TYPE; stype++) +#else +# define for_each_cgroup_storage_type(stype) for (; false; ) +#endif /* CONFIG_CGROUP_BPF */ + typedef void (*btf_dtor_kfunc_t)(void *); struct btf_field_kptr { @@ -1085,14 +1099,6 @@ struct bpf_prog_offload { u32 jited_len; }; -enum bpf_cgroup_storage_type { - BPF_CGROUP_STORAGE_SHARED, - BPF_CGROUP_STORAGE_PERCPU, - __BPF_CGROUP_STORAGE_MAX -}; - -#define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX - /* The longest tracepoint has 12 args. * See include/trace/bpf_probe.h */ -- cgit v1.2.3 From abad3d0bad72a52137e0c350c59542d75ae4f513 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 31 Jul 2025 01:47:33 +0200 Subject: bpf: Fix oob access in cgroup local storage Lonial reported that an out-of-bounds access in cgroup local storage can be crafted via tail calls. Given two programs each utilizing a cgroup local storage with a different value size, and one program doing a tail call into the other. The verifier will validate each of the indivial programs just fine. However, in the runtime context the bpf_cg_run_ctx holds an bpf_prog_array_item which contains the BPF program as well as any cgroup local storage flavor the program uses. Helpers such as bpf_get_local_storage() pick this up from the runtime context: ctx = container_of(current->bpf_ctx, struct bpf_cg_run_ctx, run_ctx); storage = ctx->prog_item->cgroup_storage[stype]; if (stype == BPF_CGROUP_STORAGE_SHARED) ptr = &READ_ONCE(storage->buf)->data[0]; else ptr = this_cpu_ptr(storage->percpu_buf); For the second program which was called from the originally attached one, this means bpf_get_local_storage() will pick up the former program's map, not its own. With mismatching sizes, this can result in an unintended out-of-bounds access. To fix this issue, we need to extend bpf_map_owner with an array of storage_cookie[] to match on i) the exact maps from the original program if the second program was using bpf_get_local_storage(), or ii) allow the tail call combination if the second program was not using any of the cgroup local storage maps. Fixes: 7d9c3427894f ("bpf: Make cgroup storages shared between programs on the same cgroup") Reported-by: Lonial Con Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20250730234733.530041-4-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 02aa41e301a5..cc700925b802 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -283,6 +283,7 @@ struct bpf_map_owner { enum bpf_prog_type type; bool jited; bool xdp_has_frags; + u64 storage_cookie[MAX_BPF_CGROUP_STORAGE_TYPE]; const struct btf_type *attach_func_proto; }; -- cgit v1.2.3 From 5ccaeedb489b41ce6cb857d0de488992746be282 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 1 Aug 2025 00:10:06 +0000 Subject: cfi: add C CFI type macro Currently x86 and riscv open-code 4 instances of the same logic to define a u32 variable with the KCFI typeid of a given function. Replace the duplicate logic with a common macro. Signed-off-by: Mark Rutland Co-developed-by: Maxwell Bland Signed-off-by: Maxwell Bland Co-developed-by: Sami Tolvanen Signed-off-by: Sami Tolvanen Tested-by: Dao Huang Acked-by: Will Deacon Link: https://lore.kernel.org/r/20250801001004.1859976-6-samitolvanen@google.com Signed-off-by: Alexei Starovoitov --- include/linux/cfi_types.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'include/linux') diff --git a/include/linux/cfi_types.h b/include/linux/cfi_types.h index 6b8713675765..685f7181780f 100644 --- a/include/linux/cfi_types.h +++ b/include/linux/cfi_types.h @@ -41,5 +41,28 @@ SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) #endif +#else /* __ASSEMBLY__ */ + +#ifdef CONFIG_CFI_CLANG +#define DEFINE_CFI_TYPE(name, func) \ + /* \ + * Force a reference to the function so the compiler generates \ + * __kcfi_typeid_. \ + */ \ + __ADDRESSABLE(func); \ + /* u32 name __ro_after_init = __kcfi_typeid_ */ \ + extern u32 name; \ + asm ( \ + " .pushsection .data..ro_after_init,\"aw\",\%progbits \n" \ + " .type " #name ",\%object \n" \ + " .globl " #name " \n" \ + " .p2align 2, 0x0 \n" \ + #name ": \n" \ + " .4byte __kcfi_typeid_" #func " \n" \ + " .size " #name ", 4 \n" \ + " .popsection \n" \ + ); +#endif + #endif /* __ASSEMBLY__ */ #endif /* _LINUX_CFI_TYPES_H */ -- cgit v1.2.3 From f1befc82addda926c8301436123d041bf3249505 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Fri, 1 Aug 2025 00:10:07 +0000 Subject: cfi: Move BPF CFI types and helpers to generic code Instead of duplicating the same code for each architecture, move the CFI type hash variables for BPF function types and related helper functions to generic CFI code, and allow architectures to override the function definitions if needed. Signed-off-by: Sami Tolvanen Link: https://lore.kernel.org/r/20250801001004.1859976-7-samitolvanen@google.com Signed-off-by: Alexei Starovoitov --- include/linux/cfi.h | 47 +++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 39 insertions(+), 8 deletions(-) (limited to 'include/linux') diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 1db17ecbb86c..52a98886a455 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -11,16 +11,9 @@ #include #include +#ifdef CONFIG_CFI_CLANG extern bool cfi_warn; -#ifndef cfi_get_offset -static inline int cfi_get_offset(void) -{ - return 0; -} -#endif - -#ifdef CONFIG_CFI_CLANG enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr, unsigned long *target, u32 type); @@ -29,6 +22,44 @@ static inline enum bug_trap_type report_cfi_failure_noaddr(struct pt_regs *regs, { return report_cfi_failure(regs, addr, NULL, 0); } + +#ifndef cfi_get_offset +/* + * Returns the CFI prefix offset. By default, the compiler emits only + * a 4-byte CFI type hash before the function. If an architecture + * uses -fpatchable-function-entry=N,M where M>0 to change the prefix + * offset, they must override this function. + */ +static inline int cfi_get_offset(void) +{ + return 4; +} +#endif + +#ifndef cfi_get_func_hash +static inline u32 cfi_get_func_hash(void *func) +{ + u32 hash; + + if (get_kernel_nofault(hash, func - cfi_get_offset())) + return 0; + + return hash; +} +#endif + +/* CFI type hashes for BPF function types */ +extern u32 cfi_bpf_hash; +extern u32 cfi_bpf_subprog_hash; + +#else /* CONFIG_CFI_CLANG */ + +static inline int cfi_get_offset(void) { return 0; } +static inline u32 cfi_get_func_hash(void *func) { return 0; } + +#define cfi_bpf_hash 0U +#define cfi_bpf_subprog_hash 0U + #endif /* CONFIG_CFI_CLANG */ #ifdef CONFIG_ARCH_USES_CFI_TRAPS -- cgit v1.2.3