coredump: add a new elf note with siginfo of the signal

Existing PRSTATUS note contains only si_signo, si_code, si_errno fields
from the siginfo of the signal which caused core to be dumped.

There are tools which try to analyze crashes for possible security
implications, and they want to use, among other data, si_addr field from
the SIGSEGV.

This patch adds a new elf note, NT_SIGINFO, which contains the complete
siginfo_t of the signal which killed the process.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Amerigo Wang <amwang@redhat.com>
Cc: "Jonathan M. Foote" <jmfoote@cert.org>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a1a9613a3210f0f6b55af9330ccb6a89eec23918..8c8ee40171d133b2ef42deb547263dd820861527 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -36,6 +36,10 @@
 #include <asm/param.h>
 #include <asm/page.h>
 
+#ifndef user_siginfo_t
+#define user_siginfo_t siginfo_t
+#endif
+
 static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs);
 static int load_elf_library(struct file *);
 static unsigned long elf_map(struct file *, unsigned long, struct elf_phdr *,
@@ -1371,6 +1375,16 @@ static void fill_auxv_note(struct memelfnote *note, struct mm_struct *mm)
        fill_note(note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
 }
 
+static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
+               siginfo_t *siginfo)
+{
+       mm_segment_t old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       copy_siginfo_to_user((user_siginfo_t __user *) csigdata, siginfo);
+       set_fs(old_fs);
+       fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
+}
+
 #ifdef CORE_DUMP_USE_REGSET
 #include <linux/regset.h>
 
@@ -1384,7 +1398,9 @@ struct elf_thread_core_info {
 struct elf_note_info {
        struct elf_thread_core_info *thread;
        struct memelfnote psinfo;
+       struct memelfnote signote;
        struct memelfnote auxv;
+       user_siginfo_t csigdata;
        size_t size;
        int thread_notes;
 };
@@ -1558,6 +1574,9 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
        fill_psinfo(psinfo, dump_task->group_leader, dump_task->mm);
        info->size += notesize(&info->psinfo);
 
+       fill_siginfo_note(&info->signote, &info->csigdata, siginfo);
+       info->size += notesize(&info->signote);
+
        fill_auxv_note(&info->auxv, current->mm);
        info->size += notesize(&info->auxv);
 
@@ -1587,6 +1606,8 @@ static int write_note_info(struct elf_note_info *info,
 
                if (first && !writenote(&info->psinfo, file, foffset))
                        return 0;
+               if (first && !writenote(&info->signote, file, foffset))
+                       return 0;
                if (first && !writenote(&info->auxv, file, foffset))
                        return 0;
 
@@ -1680,6 +1701,7 @@ struct elf_note_info {
 #ifdef ELF_CORE_COPY_XFPREGS
        elf_fpxregset_t *xfpu;
 #endif
+       user_siginfo_t csigdata;
        int thread_status_size;
        int numnote;
 };
@@ -1689,8 +1711,8 @@ static int elf_note_info_init(struct elf_note_info *info)
        memset(info, 0, sizeof(*info));
        INIT_LIST_HEAD(&info->thread_list);
 
-       /* Allocate space for six ELF notes */
-       info->notes = kmalloc(6 * sizeof(struct memelfnote), GFP_KERNEL);
+       /* Allocate space for ELF notes */
+       info->notes = kmalloc(7 * sizeof(struct memelfnote), GFP_KERNEL);
        if (!info->notes)
                return 0;
        info->psinfo = kmalloc(sizeof(*info->psinfo), GFP_KERNEL);
@@ -1762,6 +1784,7 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 
        info->numnote = 2;
 
+       fill_siginfo_note(&info->notes[info->numnote++], &info->csigdata, siginfo);
        fill_auxv_note(&info->notes[info->numnote++], current->mm);
 
        /* Try to dump the FPU. */

diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index 112e45a17e99717e1226f3b229c5ffe73c8193f3..0fbcf634743743d6217885a2913758d9246ff115 100644 (file)
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c
@@ -37,6 +37,12 @@
 #define elf_note       elf32_note
 #define elf_addr_t     Elf32_Addr
 
+/*
+ * Some data types as stored in coredump.
+ */
+#define user_siginfo_t         compat_siginfo_t
+#define copy_siginfo_to_user   copy_siginfo_to_user32
+
 /*
  * The machine-dependent core note format types are defined in elfcore-compat.h,
  * which requires asm/elf.h to define compat_elf_gregset_t et al.

diff --git a/include/linux/elf.h b/include/linux/elf.h
index 0a05051a8924df5e2d1e55562c1d66698702a7db..dc62da7447ca1e3390737ec45aee3248e4a7afb5 100644 (file)
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -372,6 +372,11 @@ typedef struct elf64_shdr {
 #define NT_PRPSINFO    3
 #define NT_TASKSTRUCT  4
 #define NT_AUXV                6
+/*
+ * Note to userspace developers: size of NT_SIGINFO note may increase
+ * in the future to accomodate more fields, don't assume it is fixed!
+ */
+#define NT_SIGINFO      0x53494749
 #define NT_PRXFPREG     0x46e62b7f      /* copied from gdb5.1/include/elf/common.h */
 #define NT_PPC_VMX     0x100           /* PowerPC Altivec/VMX registers */
 #define NT_PPC_SPE     0x101           /* PowerPC SPE/EVR registers */