core_pattern: ignore RLIMIT_CORE if core_pattern is a pipe

For some time /proc/sys/kernel/core_pattern has been able to set its output
destination as a pipe, allowing a user space helper to receive and
intellegently process a core.  This infrastructure however has some
shortcommings which can be enhanced.  Specifically:

1) The coredump code in the kernel should ignore RLIMIT_CORE limitation
   when core_pattern is a pipe, since file system resources are not being
   consumed in this case, unless the user application wishes to save the core,
   at which point the app is restricted by usual file system limits and
   restrictions.

2) The core_pattern code should be able to parse and pass options to the
   user space helper as an argv array.  The real core limit of the uid of the
   crashing proces should also be passable to the user space helper (since it
   is overridden to zero when called).

3) Some miscellaneous bugs need to be cleaned up (specifically the
   recognition of a recursive core dump, should the user mode helper itself
   crash.  Also, the core dump code in the kernel should not wait for the user
   mode helper to exit, since the same context is responsible for writing to
   the pipe, and a read of the pipe by the user mode helper will result in a
   deadlock.

This patch:

Remove the check of RLIMIT_CORE if core_pattern is a pipe.  In the event that
core_pattern is a pipe, the entire core will be fed to the user mode helper.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Cc: <martin.pitt@ubuntu.com>
Cc: <wwoods@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/mips/kernel/irixelf.c b/arch/mips/kernel/irixelf.c
index 5a3fe43e3019cb56c3e722af0ce3622d1cb90150..b997af713eb393aa6d4322d8f1d3d326e5dd57e9 100644 (file)
--- a/arch/mips/kernel/irixelf.c
+++ b/arch/mips/kernel/irixelf.c
@@ -44,7 +44,7 @@
 static int load_irix_binary(struct linux_binprm * bprm, struct pt_regs * regs);
 static int load_irix_library(struct file *);
 static int irix_core_dump(long signr, struct pt_regs * regs,
-                          struct file *file);
+                          struct file *file, unsigned long limit);
 
 static struct linux_binfmt irix_format = {
        .module         = THIS_MODULE,
@@ -1091,7 +1091,7 @@ end_coredump:
  * and then they are actually written out.  If we run out of core limit
  * we just truncate.
  */
-static int irix_core_dump(long signr, struct pt_regs * regs, struct file *file)
+static int irix_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
        int has_dumped = 0;
        mm_segment_t fs;
@@ -1101,7 +1101,6 @@ static int irix_core_dump(long signr, struct pt_regs * regs, struct file *file)
        struct vm_area_struct *vma;
        struct elfhdr elf;
        off_t offset = 0, dataoff;
-       int limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
        int numnote = 3;
        struct memelfnote notes[3];
        struct elf_prstatus prstatus;   /* NT_PRSTATUS */

diff --git a/arch/sparc64/kernel/binfmt_aout32.c b/arch/sparc64/kernel/binfmt_aout32.c
index c8acbeab49b482c0bd96d554edd12aad769214d6..92c1b36a2e16bee668aa11fd414243d8ad0028f2 100644 (file)
--- a/arch/sparc64/kernel/binfmt_aout32.c
+++ b/arch/sparc64/kernel/binfmt_aout32.c
@@ -35,7 +35,7 @@
 
 static int load_aout32_binary(struct linux_binprm *, struct pt_regs * regs);
 static int load_aout32_library(struct file*);
-static int aout32_core_dump(long signr, struct pt_regs * regs, struct file *file);
+static int aout32_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 
 static struct linux_binfmt aout32_format = {
        .module         = THIS_MODULE,
@@ -86,7 +86,7 @@ if (file->f_op->llseek) { \
  * dumping of the process results in another error..
  */
 
-static int aout32_core_dump(long signr, struct pt_regs *regs, struct file *file)
+static int aout32_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
        mm_segment_t fs;
        int has_dumped = 0;
@@ -105,13 +105,11 @@ static int aout32_core_dump(long signr, struct pt_regs *regs, struct file *file)
 
 /* If the size of the dump file exceeds the rlimit, then see what would happen
    if we wrote the stack, but not the data area.  */
-       if ((dump.u_dsize+dump.u_ssize) >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if (dump.u_dsize + dump.u_ssize > limit)
                dump.u_dsize = 0;
 
 /* Make sure we have enough room to write the stack and data areas. */
-       if ((dump.u_ssize) >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if (dump.u_ssize > limit)
                dump.u_ssize = 0;
 
 /* make sure we actually have a data and stack area to dump */

diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index 08781370256da313e8b3b7f401b41a1bc10b7373..7cf1c29bf90e36fc91df048e2bf18b3989e89bff 100644 (file)
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -40,7 +40,7 @@ static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
 static int load_aout_library(struct file*);
 
 #ifdef CORE_DUMP
-static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file);
+static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 
 /*
  * fill in the user structure for a core dump..
@@ -148,7 +148,7 @@ if (file->f_op->llseek) { \
  * dumping of the process results in another error..
  */
 
-static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
+static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
        mm_segment_t fs;
        int has_dumped = 0;
@@ -168,13 +168,11 @@ static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
 
 /* If the size of the dump file exceeds the rlimit, then see what would happen
    if we wrote the stack, but not the data area.  */
-       if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if ((dump.u_dsize + dump.u_ssize + 1) * PAGE_SIZE > limit)
                dump.u_dsize = 0;
 
 /* Make sure we have enough room to write the stack and data areas. */
-       if ((dump.u_ssize+1) * PAGE_SIZE >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
                dump.u_ssize = 0;
 
 /* make sure we actually have a data and stack area to dump */

diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 813a887cd2b3257d4b4b039091d0194c3a232721..e176d195e7e53982659388b970d60270f9bb695b 100644 (file)
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -31,7 +31,7 @@
 
 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
 static int load_aout_library(struct file*);
-static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file);
+static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 
 static struct linux_binfmt aout_format = {
        .module         = THIS_MODULE,
@@ -88,7 +88,7 @@ if (file->f_op->llseek) { \
  * dumping of the process results in another error..
  */
 
-static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
+static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
        mm_segment_t fs;
        int has_dumped = 0;
@@ -123,23 +123,19 @@ static int aout_core_dump(long signr, struct pt_regs * regs, struct file *file)
 /* If the size of the dump file exceeds the rlimit, then see what would happen
    if we wrote the stack, but not the data area.  */
 #ifdef __sparc__
-       if ((dump.u_dsize+dump.u_ssize) >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if ((dump.u_dsize + dump.u_ssize) > limit)
                dump.u_dsize = 0;
 #else
-       if ((dump.u_dsize+dump.u_ssize+1) * PAGE_SIZE >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
                dump.u_dsize = 0;
 #endif
 
 /* Make sure we have enough room to write the stack and data areas. */
 #ifdef __sparc__
-       if ((dump.u_ssize) >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if (dump.u_ssize > limit)
                dump.u_ssize = 0;
 #else
-       if ((dump.u_ssize+1) * PAGE_SIZE >
-           current->signal->rlim[RLIMIT_CORE].rlim_cur)
+       if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
                dump.u_ssize = 0;
 #endif
 

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 2f31c4c3fd48500fc236564e787bb47d2c093289..3dc6a123fa10d148ad110afc03032400a50cab52 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -52,7 +52,7 @@ static unsigned long elf_map (struct file *, unsigned long, struct elf_phdr *, i
  * don't even try.
  */
 #if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
-static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file);
+static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 #else
 #define elf_core_dump  NULL
 #endif
@@ -1488,7 +1488,7 @@ static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
  * and then they are actually written out.  If we run out of core limit
  * we just truncate.
  */
-static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file)
+static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
 #define        NUM_NOTES       6
        int has_dumped = 0;
@@ -1499,7 +1499,6 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file)
        struct vm_area_struct *vma, *gate_vma;
        struct elfhdr *elf = NULL;
        loff_t offset = 0, dataoff, foffset;
-       unsigned long limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
        int numnote;
        struct memelfnote *notes = NULL;
        struct elf_prstatus *prstatus = NULL;   /* NT_PRSTATUS */

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index faae021895985a591461ba98f3c6459ebdf915d6..033861c6b8f13028905826bcd6424bd3121f8eb2 100644 (file)
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -75,7 +75,7 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *,
                                             struct file *, struct mm_struct *);
 
 #if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
-static int elf_fdpic_core_dump(long, struct pt_regs *, struct file *);
+static int elf_fdpic_core_dump(long, struct pt_regs *, struct file *, unsigned long limit);
 #endif
 
 static struct linux_binfmt elf_fdpic_format = {
@@ -1552,7 +1552,7 @@ static int elf_fdpic_dump_segments(struct file *file, size_t *size,
  * we just truncate.
  */
 static int elf_fdpic_core_dump(long signr, struct pt_regs *regs,
-                              struct file *file)
+                              struct file *file, unsigned long limit)
 {
 #define        NUM_NOTES       6
        int has_dumped = 0;
@@ -1563,7 +1563,6 @@ static int elf_fdpic_core_dump(long signr, struct pt_regs *regs,
        struct vm_area_struct *vma;
        struct elfhdr *elf = NULL;
        loff_t offset = 0, dataoff;
-       unsigned long limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
        int numnote;
        struct memelfnote *notes = NULL;
        struct elf_prstatus *prstatus = NULL;   /* NT_PRSTATUS */

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index fcb3405bb14e99b64aa322f7e3856ee3fa2ddbb1..265fac86806709a9392c1c721213464252a13b0a 100644 (file)
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -75,7 +75,7 @@ static int load_flat_shared_library(int id, struct lib_info *p);
 #endif
 
 static int load_flat_binary(struct linux_binprm *, struct pt_regs * regs);
-static int flat_core_dump(long signr, struct pt_regs * regs, struct file *file);
+static int flat_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 
 static struct linux_binfmt flat_format = {
        .module         = THIS_MODULE,
@@ -90,7 +90,7 @@ static struct linux_binfmt flat_format = {
  * Currently only a stub-function.
  */
 
-static int flat_core_dump(long signr, struct pt_regs * regs, struct file *file)
+static int flat_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 {
        printk("Process %s:%d received signr %d and should have core dumped\n",
                        current->comm, current->pid, (int) signr);

diff --git a/fs/binfmt_som.c b/fs/binfmt_som.c
index 5bcdaaf4eae082f26adb82f0d2fe843dd4fc6ad1..9208c41209f9a1b21c93ee74f7981346740fa844 100644 (file)
--- a/fs/binfmt_som.c
+++ b/fs/binfmt_som.c
@@ -44,7 +44,7 @@ static int load_som_library(struct file *);
  * don't even try.
  */
 #if 0
-static int som_core_dump(long signr, struct pt_regs * regs);
+static int som_core_dump(long signr, struct pt_regs *regs, unsigned long limit);
 #else
 #define som_core_dump  NULL
 #endif

diff --git a/fs/exec.c b/fs/exec.c
index 550ae9b22f8d048ee80d96a1e8f827fbdfe82282..86c455447bc885909ac89ad5b56ef926c3ce21bd 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1697,6 +1697,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
        int fsuid = current->fsuid;
        int flag = 0;
        int ispipe = 0;
+       unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
 
        audit_core_dumps(signr);
 
@@ -1730,9 +1731,6 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
         */
        clear_thread_flag(TIF_SIGPENDING);
 
-       if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
-               goto fail_unlock;
-
        /*
         * lock_kernel() because format_corename() is controlled by sysctl, which
         * uses lock_kernel()
@@ -1740,7 +1738,20 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
        lock_kernel();
        ispipe = format_corename(corename, core_pattern, signr);
        unlock_kernel();
+       /*
+        * Don't bother to check the RLIMIT_CORE value if core_pattern points
+        * to a pipe.  Since we're not writing directly to the filesystem
+        * RLIMIT_CORE doesn't really apply, as no actual core file will be
+        * created unless the pipe reader choses to write out the core file
+        * at which point file size limits and permissions will be imposed
+        * as it does with any other process
+        */
+       if ((!ispipe) &&
+          (core_limit < binfmt->min_coredump))
+               goto fail_unlock;
+
        if (ispipe) {
+               core_limit = RLIM_INFINITY;
                /* SIGPIPE can happen, but it's just never processed */
                if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
                        printk(KERN_INFO "Core dump to %s pipe failed\n",
@@ -1770,7 +1781,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
        if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
                goto close_fail;
 
-       retval = binfmt->core_dump(signr, regs, file);
+       retval = binfmt->core_dump(signr, regs, file, core_limit);
 
        if (retval)
                current->signal->group_exit_code |= 0x80;

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 63d54366e0e570884544a9259a113b8833a21516..3a6512f8ec94023e3fc41dd0e2b050c7944271e1 100644 (file)
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -67,7 +67,7 @@ struct linux_binfmt {
        struct module *module;
        int (*load_binary)(struct linux_binprm *, struct  pt_regs * regs);
        int (*load_shlib)(struct file *);
-       int (*core_dump)(long signr, struct pt_regs * regs, struct file * file);
+       int (*core_dump)(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
        unsigned long min_coredump;     /* minimal dump size */
        int hasvdso;
 };