From bd7525dacd7e204f8cae061941fb9001c89d6988 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 14 Jan 2021 14:40:42 +0100 Subject: bpf: Move stack_map_get_build_id into lib Moving stack_map_get_build_id into lib with declaration in linux/buildid.h header: int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id); This function returns build id for given struct vm_area_struct. There is no functional change to stack_map_get_build_id function. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20210114134044.1418404-2-jolsa@kernel.org --- kernel/bpf/stackmap.c | 143 ++------------------------------------------------ 1 file changed, 4 insertions(+), 139 deletions(-) (limited to 'kernel/bpf/stackmap.c') diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index aea96b6384734..55d254a59f073 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -7,10 +7,9 @@ #include #include #include -#include -#include #include #include +#include #include "percpu_freelist.h" #define STACK_CREATE_FLAG_MASK \ @@ -143,140 +142,6 @@ free_smap: return ERR_PTR(err); } -#define BPF_BUILD_ID 3 -/* - * Parse build id from the note segment. This logic can be shared between - * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are - * identical. - */ -static inline int stack_map_parse_build_id(void *page_addr, - unsigned char *build_id, - void *note_start, - Elf32_Word note_size) -{ - Elf32_Word note_offs = 0, new_offs; - - /* check for overflow */ - if (note_start < page_addr || note_start + note_size < note_start) - return -EINVAL; - - /* only supports note that fits in the first page */ - if (note_start + note_size > page_addr + PAGE_SIZE) - return -EINVAL; - - while (note_offs + sizeof(Elf32_Nhdr) < note_size) { - Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); - - if (nhdr->n_type == BPF_BUILD_ID && - nhdr->n_namesz == sizeof("GNU") && - nhdr->n_descsz > 0 && - nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { - memcpy(build_id, - note_start + note_offs + - ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), - nhdr->n_descsz); - memset(build_id + nhdr->n_descsz, 0, - BPF_BUILD_ID_SIZE - nhdr->n_descsz); - return 0; - } - new_offs = note_offs + sizeof(Elf32_Nhdr) + - ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); - if (new_offs <= note_offs) /* overflow */ - break; - note_offs = new_offs; - } - return -EINVAL; -} - -/* Parse build ID from 32-bit ELF */ -static int stack_map_get_build_id_32(void *page_addr, - unsigned char *build_id) -{ - Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; - Elf32_Phdr *phdr; - int i; - - /* only supports phdr that fits in one page */ - if (ehdr->e_phnum > - (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) - return -EINVAL; - - phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); - - for (i = 0; i < ehdr->e_phnum; ++i) { - if (phdr[i].p_type == PT_NOTE && - !stack_map_parse_build_id(page_addr, build_id, - page_addr + phdr[i].p_offset, - phdr[i].p_filesz)) - return 0; - } - return -EINVAL; -} - -/* Parse build ID from 64-bit ELF */ -static int stack_map_get_build_id_64(void *page_addr, - unsigned char *build_id) -{ - Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; - Elf64_Phdr *phdr; - int i; - - /* only supports phdr that fits in one page */ - if (ehdr->e_phnum > - (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) - return -EINVAL; - - phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); - - for (i = 0; i < ehdr->e_phnum; ++i) { - if (phdr[i].p_type == PT_NOTE && - !stack_map_parse_build_id(page_addr, build_id, - page_addr + phdr[i].p_offset, - phdr[i].p_filesz)) - return 0; - } - return -EINVAL; -} - -/* Parse build ID of ELF file mapped to vma */ -static int stack_map_get_build_id(struct vm_area_struct *vma, - unsigned char *build_id) -{ - Elf32_Ehdr *ehdr; - struct page *page; - void *page_addr; - int ret; - - /* only works for page backed storage */ - if (!vma->vm_file) - return -EINVAL; - - page = find_get_page(vma->vm_file->f_mapping, 0); - if (!page) - return -EFAULT; /* page not mapped */ - - ret = -EINVAL; - page_addr = kmap_atomic(page); - ehdr = (Elf32_Ehdr *)page_addr; - - /* compare magic x7f "ELF" */ - if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) - goto out; - - /* only support executable file and shared object file */ - if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) - goto out; - - if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) - ret = stack_map_get_build_id_32(page_addr, build_id); - else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) - ret = stack_map_get_build_id_64(page_addr, build_id); -out: - kunmap_atomic(page_addr); - put_page(page); - return ret; -} - static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u64 *ips, u32 trace_nr, bool user) { @@ -317,18 +182,18 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, for (i = 0; i < trace_nr; i++) { id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; - memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE); + memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); } return; } for (i = 0; i < trace_nr; i++) { vma = find_vma(current->mm, ips[i]); - if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) { + if (!vma || build_id_parse(vma, id_offs[i].build_id)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; - memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE); + memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); continue; } id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] -- cgit v1.2.3 From 921f88fc891922b325b3668cd026a386571ed602 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 14 Jan 2021 14:40:43 +0100 Subject: bpf: Add size arg to build_id_parse function It's possible to have other build id types (other than default SHA1). Currently there's also ld support for MD5 build id. Adding size argument to build_id_parse function, that returns (if defined) size of the parsed build id, so we can recognize the build id type. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210114134044.1418404-3-jolsa@kernel.org --- include/linux/buildid.h | 3 ++- kernel/bpf/stackmap.c | 2 +- lib/buildid.c | 29 +++++++++++++++++++++-------- 3 files changed, 24 insertions(+), 10 deletions(-) (limited to 'kernel/bpf/stackmap.c') diff --git a/include/linux/buildid.h b/include/linux/buildid.h index 08028a212589f..40232f90db6e5 100644 --- a/include/linux/buildid.h +++ b/include/linux/buildid.h @@ -6,6 +6,7 @@ #define BUILD_ID_SIZE_MAX 20 -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id); +int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, + __u32 *size); #endif diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 55d254a59f073..cabaf7db8efc0 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -189,7 +189,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, for (i = 0; i < trace_nr; i++) { vma = find_vma(current->mm, ips[i]); - if (!vma || build_id_parse(vma, id_offs[i].build_id)) { + if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; id_offs[i].ip = ips[i]; diff --git a/lib/buildid.c b/lib/buildid.c index 4a4f520c0e293..6156997c3895e 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -12,6 +12,7 @@ */ static inline int parse_build_id(void *page_addr, unsigned char *build_id, + __u32 *size, void *note_start, Elf32_Word note_size) { @@ -38,6 +39,8 @@ static inline int parse_build_id(void *page_addr, nhdr->n_descsz); memset(build_id + nhdr->n_descsz, 0, BUILD_ID_SIZE_MAX - nhdr->n_descsz); + if (size) + *size = nhdr->n_descsz; return 0; } new_offs = note_offs + sizeof(Elf32_Nhdr) + @@ -50,7 +53,8 @@ static inline int parse_build_id(void *page_addr, } /* Parse build ID from 32-bit ELF */ -static int get_build_id_32(void *page_addr, unsigned char *build_id) +static int get_build_id_32(void *page_addr, unsigned char *build_id, + __u32 *size) { Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; Elf32_Phdr *phdr; @@ -65,7 +69,7 @@ static int get_build_id_32(void *page_addr, unsigned char *build_id) for (i = 0; i < ehdr->e_phnum; ++i) { if (phdr[i].p_type == PT_NOTE && - !parse_build_id(page_addr, build_id, + !parse_build_id(page_addr, build_id, size, page_addr + phdr[i].p_offset, phdr[i].p_filesz)) return 0; @@ -74,7 +78,8 @@ static int get_build_id_32(void *page_addr, unsigned char *build_id) } /* Parse build ID from 64-bit ELF */ -static int get_build_id_64(void *page_addr, unsigned char *build_id) +static int get_build_id_64(void *page_addr, unsigned char *build_id, + __u32 *size) { Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; Elf64_Phdr *phdr; @@ -89,7 +94,7 @@ static int get_build_id_64(void *page_addr, unsigned char *build_id) for (i = 0; i < ehdr->e_phnum; ++i) { if (phdr[i].p_type == PT_NOTE && - !parse_build_id(page_addr, build_id, + !parse_build_id(page_addr, build_id, size, page_addr + phdr[i].p_offset, phdr[i].p_filesz)) return 0; @@ -97,8 +102,16 @@ static int get_build_id_64(void *page_addr, unsigned char *build_id) return -EINVAL; } -/* Parse build ID of ELF file mapped to vma */ -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id) +/* + * Parse build ID of ELF file mapped to vma + * @vma: vma object + * @build_id: buffer to store build id, at least BUILD_ID_SIZE long + * @size: returns actual build id size in case of success + * + * Returns 0 on success, otherwise error (< 0). + */ +int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, + __u32 *size) { Elf32_Ehdr *ehdr; struct page *page; @@ -126,9 +139,9 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id) goto out; if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) - ret = get_build_id_32(page_addr, build_id); + ret = get_build_id_32(page_addr, build_id, size); else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) - ret = get_build_id_64(page_addr, build_id); + ret = get_build_id_64(page_addr, build_id, size); out: kunmap_atomic(page_addr); put_page(page); -- cgit v1.2.3